Ecosystem Energy Flow

ECOSYSTEMS AND ENERGY FLOW - Moore 1
LIVING WITH THE EARTH
Objectives for this Chapter
• A student reading this chapter will be able to:
– 1. Discuss and define the concepts of biosphere and
climate.
– 2. List and explain the factors influencing climate.
– 3. Define the term biome. List the major global
biomes and discuss their primary features.
– 4. Describe the flow of energy through ecosystems.
Describe and explain the various trophic levels.
– 5. List and explain the various nutrient cycles
including the carbon, nitrogen, and phosphorous
cycles.

– 6. Define the term succession, explain the mechanisms
of succession, and discuss the types of human
intervention that interfere with succession.
ECOSYSTEMS AND ENERGY FLOW
• INTRODUCTION
– We are immersed in life.
– Conditions for most life are found in a layer about the
globe that extends from approximately 5 miles in the
atmosphere (where some microbial spores and insects
may be found) to 5 miles below the ocean surface.
BIOSPHERE
– This theoretical “layer of life”, is called a biosphere
because life is thought not to exist outside this area.
– Most life occurs in a narrow layer extending from
about a 600 foot depth in the ocean where sunlight is
able to penetrate, to the summer snow line of high
mountain peaks where a thin layer of soil supports
plant life such as lichens and mosses.

BIOMES
– Biomes are based on the dominant types of vegetation
which are strongly correlated with regional climate
patterns.
CLIMATE - What is it?
– Climate can be viewed as average weather within a
geographical area viewed over years, or even
centuries.
– Climate, like weather, includes temperature,
precipitation, humidity, wind velocity and direction,
cloud cover, and associated solar radiation.
What Causes Climate?
– (1) changes in ocean temperatures;
– (2) changes in the earth’s orbital geometry;
– (3) volcanic activity with increased atmospheric dust
and reduced sunlight penetration;
– (4) variations in solar radiation; or
– (5) increases in atmospheric gases that absorb heat

energy.
How is Climate Affected?
– Climate is most affected by temperature
– The amount of sunlight striking the earth varies by
region and time.
– The seasons are caused by the tilt of the earth on its
axis as it revolves around the sun. (Figure 1-1).
Fig. 1-1
– The sun impacts the earth in bands of decreasing
energy extending north and south from the equator
(Fig. 1-2).
Fig. 1-2

Presenter
Presentation Notes
Arctic- Mostly subzero weather, very little precipitation.
Tundra- 6-10 months winter, mean temperature <0 degrees
Celsius, <5 inches/year precipitation
Taiga- Subpolar, severe winters up to 6 months long.
Temperatures below freezing to 32.5 degrees Celsius. 15-20
inches/year of precipitation, winter drought.
Temperate- Warmer continental and humid subtropical climates,
20-60 inches a year of precipitation
Tropical- Mean monthly temp >17.8 degrees Celsius, >100
inches a year of precipitation
– More recent models show that there are multiple
Hadley cells known as the three-zone model (Fig. 1-3a
and Fig. 1-3a).
Fig. 1-3A, 1-3B
Presenter
Presentation Notes
Hadley model on the left contrasted with the Three-Zone Model

on the right. Three-Zone model has multiple smaller versions of
Hadley cells along with various winds: the polar easterlies,
westerlies, Northeast tradewinds, equatorial doldrums, and
southeast tradewinds.
– The deflection of air masses to the east or west is a
result of the earth’s rotation, causing the deflection of
air from its northerly or southerly path and this is
known as the Coriolis effect (Fig. 1-4).
Fig. 1-4
Adapted from Godish, 1
Presenter
Presentation Notes
Air is deflected from its direct southerly direction to the
southwest in the northern subtropical Hadley cell. This
deflection is caused by the Earth’s rotation along with friction.
Image shows rotation of earth and wind’s changing path.
ECOSYSTEMS AND BIOMES

• Ecosystems
– Ecosystems are often a component of a biome. The
relationship of biosphere, biomes, ecosystems and
populations is shown in Figure 1-5.
– Ecosystems refers to identifiable areas within nature
where the organisms interact among themselves and
their physical environment and exchange nutrient.
Fig. 1-5
Ecosystems
– The biotic components include living organisms and
the products of these organisms
– The abiotic components of the ecosystem include
such things as water, air, sunlight, minerals, and their
interaction.
Biomes
– Biomes may be seen as groupings of plants and

animals on a regional scale whose distribution patterns
depend heavily on patterns of climate.
– The biome is identified by the climax vegetation or
community.
– A climax community forms in an undisturbed
environment and continues to grow and perpetuate
itself in the absence of further disturbance.
Biomes
• Tundra (Fig. 1-6)
– Limited to the upper latitudes of the northern
hemispheres and forms a belt around the arctic ocean.
– Barren, treeless, low-lying shrubs, mosses and lichens.
– Long winters, short growing season, little
precipitation.
– Little soil under permafrost.
Tundra (Fig. 1-6)
Photo purchased from Photodisc,
Inc. Seattle, WA 08124

Biomes
• Taiga (Fig. 1-7)
– Coniferous (cone-bearing) trees extending in a
giant arc from Alaska, North America and
Canada, through Europe and Siberia.
– Rainfall 15-20 inches annually, long severe
winters.
– Conical, needleleaf trees adapted to harsh
winter.
– Moose, elk, deer, snowshoe hare: Predators
whose coats become white in winter.
Taiga (Fig. 1-7)
Biomes
• Temperate Broadleaf Deciduous Forest (Fig. 1-8)
– Broadleaf deciduous forests are located in western and

central Europe, eastern Asia and eastern North America.
– Receive 20 to 60 inches of precipitation distributed
evenly throughout the year.
– Carnivores have been mostly eliminated by habitat
destruction and hunting.
– Nut-eaters such as squirrels and chipmunks; omnivores
such as raccoons, skunks, black bear and opossum.
Temperate Broadleaf
Deciduous Forest (Fig. 1-8)
Biomes
• Temperate Evergreen Forest
– Where soil is poor and droughts and fires are frequent,
the predominant species tend to be evergreens.
– Cool coastal climates where there is considerable
rainfall or frequent heavy fogs may produce temperate
rainforests (redwoods).

Biomes
• Chaparrals
– Moderately dry climate characterized by small (3-15
foot) shrubs with leathery leaves that contain aromatic
and flammable substances.
Biomes
• Temperate Grasslands (Fig. 1-9)
– Includes prairies, steppes, veldt, pampas.
– 10 to 20 inches of precipitation a year, much of which
falls as snow.
– Predominant plant forms are perennial grasses, forbs,
and members of the sunflower and pea families.
– Ground squirrels, prairie dogs, and pocket gophers.
Temperate Grasslands
(Fig. 1-9)

Biomes
• The Tropical Rainforest (Fig. 1-10)
– Constant warmth, with average monthly temperatures
above 17.8ºC.There are no seasons in the rainforest.
– Precipitation greater than 100 inches per year.
– More than 40 percent of world’s plant and animals
grow in the tropical rainforest.
– The life of the forest occurs in the canopy.
The Tropical Rainforest (Fig. 1-10)
Canopy
Emergent trees
Understory

Biomes
• Deserts (Fig. 1-11).
– Defined by arid climates averaging less than 10
inches of precipitation a year and where evaporation
exceeds this precipitation.
– Can reach temperatures higher than 37.8°C (100°C)
on summer days while some plummet to -6.7°C (20°F)
at night.
Deserts (Fig. 1-11)
Biomes
• Conditions Creating Deserts
– Easterly winds keep moist air rising off the
oceans from reaching the coast.
– Near the 30° latitude, subtropical air descends
in association with the Hadley cell, then
compresses causing the formation of heat and
dry, warm air.

– Temperate deserts are generally located in areas
known as rain shadows (Fig. 1-12).
– Located in the interiors of continents.
Rain Shadows (Fig. 1-12)
Adapted from Turk & Turk. 3
Presenter
Presentation Notes
Air flow from ocean toward shore. Moisture from the ocean
cools and condenses to form rain on the windward side of the
mountains. Dry air falls on the leeward side. The air compresses
as it falls, and so it warms and then absorbs moisture.
ENERGY FLOW
• Energy Source
– The energy comes from the sun.
– 99.9 % of the sun’s energy reaching the earth is
reflected into space, absorbed as heat, or evaporates
water (Fig 1-13).
– 0.1 % of sun’s energy used by plants for
photosynthesis to create simple sugars from carbon

dioxide and water with the release of oxygen.
Energy Flow (Fig 1-13)
Presenter
Presentation Notes
Figure 1.13- 99.9% of sun’s energy striking the earth is
reflected to space, absorbed, or used to evaporate water, 0.1%
of sun’s energy is absorbed by plants. Most is in the visible
blue and red spectrum.
At 180,000 miles a second, the sun’s rays take less than 10
minutes to reach the earth.
Sunlight: 6CO2+ 6H20---C6H12O6 + 6O2
The energy is used to create high energy sugars in a process
called photosynthesis
ENERGY FLOW
• Energy Source
– Heterotrophs convert about 10 % of the consumed
Kcalories into flesh or organic matter (Fig. 1-14).
– 90 % of consumed energy used in respiration
necessary for the energy of motion.
– As energy is transferred through the food chain, about
90 percent of that available energy is lost with each

transfer.
Energy
Flow
and
Hetero-
trophs
(Fig. 1-14)
Presenter
Presentation Notes
99.9% of the sun’s energy reaching the earth is reflected to
space, or absorbed, or evaporates waters. .1% of this energy is
used by plants. About 20% of this used in plant respiration, 50-
80% used for plant growth. Plants are autotrophs and are first
trophic level producers.
About 10% of available energy in plants is used by herbivores.
A small amount is used for growth, most is used for respiration.
Herbivores are in the second trophic level, are primary
consumers, and are heterotrophs/
About 10% of available energy in herbivores is used by flesh-
eating animals (carnivores). A small amount is used for growth,
most used for respiration. Carnivores are in the third trophic
level, are secondary consumers or higher, and are heterotrophs.
ENERGY FLOW

– A wolf which consumes deer or rabbits that eat grass
would be a secondary consumer and would receive
(1/10 x 1/10 = 1/100) of the available energy in the
plant.
– 3,000 lbs. of corn would feed one steer which would
feed one person, while the grain would feed 20 people.
(Fig. 1-15).
Efficiency of Primary Consumers (Fig. 1-15)
Presenter
Presentation Notes
3,000 pounds of corn and grain may be used to feed one cow.
The meat from one cow may feed one person over the same time
period.
3,000 pounds of corn and grain may be used to feed about 20
people over the same time period.
Consumption Types
– Animals that eat only plants are herbivores.
– Animals that eat primarily animal flesh are called
carnivores.
– Animals that eat plants and animals are termed

omnivores and include rats, bears, humans, hogs, and
foxes.
Trophic Levels
– Plants are producers and belong to the first trophic
level.
– Primary consumers or herbivores belong to the second
trophic level.
– Secondary consumers (carnivores) belong to the third
trophic level (or higher).
Trophic Levels
– Patterns of consumption tend to be complicated and
the term food web has been used to refer to these
complex patterns (Fig 1-16).
Food Web (Fig 1-16)

Presenter
Presentation Notes
Food web with plants, iherbivores, omnivores, and carnivores.
Plant producer has arrows to all omnivores and herbivores,
herbivores have arrows to carnivores.
Nutrients
• Recycling
– Nutrients are recycled in a process called
biogeochemical cycling.
– Scavengers prefer to feed upon the dead
remains of animals.
– Decomposers are insects, bacteria, fungi, and
protozoans that SEQUENTIALLY break down
complex organic materials into low energy
mineral nutrients that once again may be
reabsorbed and used by plants.
Recycling
– Sulfur, phosphorous, carbon, oxygen, hydrogen, and
nitrogen are known as macronutrients.
– Elements required in tiny amounts such as zinc,
manganese, chlorine, iron, and copper that are termed

trace elements.
Nutrient Cycles
• Carbon Cycle
– Includes physical states of gas, liquid, or solid, and
chemical forms include organic and inorganic (Fig 1-
17).
– CO2 comes from respiration, combustion of fossil
fuels, and decomposition of organic matter.
Carbon Cycle (Fig 1-17)
Presenter
Presentation Notes
Carbon Cycle. (1.5% in land organisms). CO2 is released from
human and animal respiration and decomposition of dead
animals and animal waste. CO2 gasses dissolve in atmosphere.
CO2 is used by plants in photosynthesis. O2 is released by
healthy plants, CO2 is released by cutting and burning forests.
CO2 is 2.5 % decayed material and 21% in fossil fuels- coal
and oil. CO2 is released by combusted fossil fuels, Ca2+ is
dissolved and released from rocks by acidity in rain. Rain made
slightly acidic by CO2 dissolved in clouds. CO32- + Ca2+
Makes CaCO3.

There is 71% carbon in oceans, 3 % in organic matter at bottom
of oceans. CO2 in oceanse is source of CO 32-. When dissolved
CO2 evaporates, cycle perpetuates with acid rain falling once
mpre/
Nutrient Cycles
• Carbon Cycle
– Highest levels of carbon are found in oceans.
– Plants convert inorganic carbon to carbohydrates by
photosynthesis. The plants may be consumed,
decompose, or eventually converted to fossil fuels.
Nutrient Cycles
• Nitrogen Cycle (Fig. 1-18)
– Atmospheric nitrogen must be converted to nitrates,
nitrites, or ammonia before used by plants or animals.
– Conversion to these forms is natural or synthetic.
Nitrogen Cycle (Fig. 1-18)

Presenter
Presentation Notes
Atmospheric Nitrogen is converted in multiple ways. Lightning
combines nitrogen with oxygen to form nitrates after a series of
steps. The rain produced contains nitrates (Nox). Fixed nitrogen
is used by plants to synthesize amino acids which are consumed
by animals, who produce urea which goes through microbial
decomposition, producing amino acids and then ammonia. The
runoff from urea and amino acids leads to denitrifying bacteria
under anaerobic conditions in sediment and mud, which
combines with lightning to repeat the cycle. It also gets
absorbed by roots and soil.
Additionally, Nox produced by combustion process in factories,
vehicles. Factories produce nitrogen fertilizers adding NO2 and
NH4+ to soil, water. This is absorbed by soil and roots as well.
Atmospheric nitrogen also goes into soil and roots where it is
met with nitrogen-fixing bacteria.
Nutrient Cycles
• Natural Nitrogen Conversion
– By nitrogen-fixing bacteria (Rhizobium spp.) or some
species of organobacteria.
– By lightning.
– Released from erosion of nitrate-rich rocks

Nutrient Cycles
• Man-made Nitrogen Conversion
– Manufacture of fertilizers
– NOx created in boilers and internal combustion
engines , then converted to nitrates and nitrites in the
atmosphere.
Nutrient Cycles
• Recycled
– Converted from complex organics back into to
atmospheric nitrogen by denitrifying bacteria.
– The bacteria are anaerobic and live in mud and
sediment of lakes, streams, and ponds.
Nutrient Cycles
• Phosphorous
– Gradually leached from sedimentary rock by the
actions of rain or erosion, in a process referred to as
the sedimentary cycle.
– Phosphorous is the main element in compounds such

as adenosine triphosphate (ATP).
– Animal wastes and decomposing animals release
phosphorous back to the soil for reuse by plants .
Nutrient Cycles
• Phosphorous
– Mining and agriculture can erode soil and carry
phosphorous into streams, etc.
– Phosphate rocks are a non-renewable resource that
were created millions of years ago.
– Phosphate being rapidly depleted.
– Infertile soils likely to develop.
SUCCESSION
– Succession refers to the predictable and gradual
progressive changes of biotic communities toward the
establishment of a climax community.
– A climax community is one which perpetuates itself
with no further succession within an undisturbed
ecosystem.

SUCCESSION
– Primary succession must take place by first creating
soil on the barren lava or exposed rock surfaces.
– Dust is captured in cracks and crevices along with
microscopic organisms and seeds carried by the wind
or deposited by small animals and birds. Mixtures of
fungi and algae grow together and are known as
lichens.
SUCCESSION
– When soil conditions are disrupted but there remains
topsoil and some limited vegetation, succession can
take place much more quickly. This process has been
termed secondary succession.
– Early plants are also known as pioneer plants, and may
include wildflowers, followed by tall grasses and
compact woody bushes.
SUCCESSION
– Stable ecosystems are ones in which materials are

constantly recycled within the system through growth,
consumption and decomposition.
– These processes tend to balance each other so that
there is little net loss over long periods of time in a
process called dynamic equilibrium.
SUCCESSION
– Poor land management techniques may result in fewer
overall species in a process called retrogression.
– The species remaining may be less desirable from a
human point of view.
THE CONCLUSION
– The human population is exerting enormous pressure
upon ecosystems throughout the world as it continues
to multiply in logarithmic proportions and develop
energy intensive technologies resulting in the
discharge of dramatic levels of toxic substance into the
air, water, and land.

THE CONCLUSION
– Most biotic communities are proving unable to
respond to the unrelenting pressures of disruption
causing major losses in species, soil degradation,
desertification, contaminated water, possible climate
changes, and other changes in global ecosystems that
are not in the best interests for human survival or
quality of life.
LIVING WITH THE EARTHObjectives for this
ChapterObjectives for this ChapterLIVING WITH THE EARTH
ECOSYSTEMS AND ENERGY FLOW
�BIOSPHEREBIOMESCLIMATE - What is it? What Causes
Climate?How is Climate Affected?Fig. 1-1How is Climate
Affected?Fig. 1-2 How is Climate Affected?Fig. 1-3A, 1-3B
How is Climate Affected?Fig. 1-4ECOSYSTEMS AND
BIOMESFig. 1-5EcosystemsBiomesBiomesTundra (Fig. 1-
6)BiomesTaiga (Fig. 1-7)BiomesTemperate Broadleaf
�Deciduous Forest (Fig. 1-8)BiomesBiomesBiomesTemperate
Grasslands �(Fig. 1-9)BiomesThe Tropical Rainforest (Fig. 1-
10)BiomesDeserts (Fig. 1-11)BiomesRain Shadows (Fig. 1-
12)ENERGY FLOWEnergy Flow (Fig 1-13)ENERGY
FLOWEnergy Flow and Hetero-trophs (Fig. 1-14)ENERGY
FLOWEfficiency of Primary Consumers (Fig. 1-
15)Consumption TypesTrophic LevelsTrophic LevelsFood Web
(Fig 1-16)NutrientsRecyclingNutrient CyclesCarbon Cycle (Fig
1-17)Nutrient CyclesNutrient CyclesNitrogen Cycle (Fig. 1-
18)Nutrient CyclesNutrient CyclesNutrient CyclesNutrient
CyclesNutrient
CyclesSUCCESSIONSUCCESSIONSUCCESSIONSUCCESSIO
NSUCCESSIONTHE CONCLUSIONTHE CONCLUSION
Running head: COURSE EVALUATION

1
COURSE EVALUATION
6
Course Evaluation
Course Evaluation Template
September 10, 2019
Course Evaluation
Need a form created and placed in here and need corrections
based on feedback file for the executive summary
Executive Summary
The rationale for the assessment and evaluation of assignment is
informed by the student’s capacity to attain the learning
objectives. The project had specific expected outcomes. In
particular, a student ought to identify a clear understanding of
palliative care in the pediatric intensive care unit. The
information gathered from different course work materials
should have been helpful to a student. The total grade and
scores in different categories of the assignment play a crucial in
the assessment by a tutor. Course evaluation should align with
the learning objectives. Therefore, tutors provide valuable
materials and inferences to study to improve their exposure to
the wealth of information. The assessment in making
recommendations in future assignments and course work.
The criteria for evaluation look into several important issues in
academic writing and assignments. The structure of the
assignment should adhere to the rules of academic assignments
(Pereira, Flores & Niklasson, 2016). It should be clear to
improve readability and attainment of higher marks. The

information in the assignment should be relevant with
appropriate evidence. The components required by the tutor
should be captured appropriately. The information ranging from
findings, conclusions, and personal thoughts should relevant
and high to earn higher points. The learning objectives and
expected outcomes form an important component in the
completion of an assignment. The demands for high-quality and
relevant papers play a role in the attainment of higher marks.
The method and points for each criterion are informed by the
need to award marks through close examination of all important
scenarios. In most class assignments, a tutor is not interested in
the correct information; rather, he or she looks at other
important elements in academic writing. Therefore, the
requirements are provided to the students to make them of the
expectations (González-Gómez, Jeong, & Rodríguez, 2016). It
is not enough to have the right structure and formatting; rather,
it is equally important to observe the correct mechanics
throughout the paper.
The grading for each criterion will depend on the length and
expected outcomes. The tutor will have the specific maximum
points for each component. The approach is helpful in ensuring
that students get points based on the quality and relevance of
the paper assignment. The evaluation method will also greatly
consider adherence to professional writing guidelines. The
school has already provided enough resources on professional
writing to enable students to get relevant and valuable
information in the course of class assignments (Rowan et al.,
2017). A student’s paper must show consistency in citations,
formatting, in-text citations, headings, and references, among
other important components.
Information arising from empirical studies reveals the
significance of creating awareness on the guidelines to promote
safety culture. Regular audit on the level of compliance in
hospitals is necessary to reduce infections (Pereira, Flores &

Niklasson, 2016). Some of the key elements that can improve
compliance include clinical preferences and convenience. Such
contextual factors are mostly linked to in-service education.
Since nurses are aware of the importance of observing hand
hygiene, they need to be at the forefront of creating awareness
in communities (Wittenberg et al., 2016). In addition, health
literacy among people is crucial to help in understanding the
significance of observing hand hygiene. A student ought to
capture the information to get higher points.
Quality papers by a student on the particular topic on palliative
care in the intensive paediatric unit should show quality and
relevance. High marks are attainable by a student who remains
consistent in information, research, evidence, reflection, and
professional writing guidelines (Alcarria, Bordel & de AndrÃ,
2018). In addition, quality and relevant papers should reflect
graduate-level vocabulary and voice. By the same token, a
student should at presenting a paper devoid of grammatical
errors and other mechanical mistakes. The content of the paper
should be similar to the course and learning objectives.
The evaluation rationale identifies the most critical element for
use in awarding points to students after completion of the
assignment. The assignment on palliative care in the pediatric
care unit reveals important findings and information for
prospective nurses and other professionals in the area (Alcarria,
Bordel & de AndrÃ, 2018). It has been identified that the
formulation of appropriate measures to promote safety culture
in health facilities requires collaboration between the nursing
professionals, patients, and the community. The interventions
should aim at interventions that ensure that hospitals have
resources that enhance hand hygiene. Knowledge acquired
through nursing should promote the welfare of the entire
population. Hand hygiene may appear as a less important issue,
but data and findings from various studies reveal the importance
of complying with the recommended guidelines (Pereira, Flores
& Niklasson, 2016). Nosocomial infections can thus be reduced

if the nursing professionals create awareness on observing hand
hygiene. The information will improve professional growth in
the field besides opening areas of future research studies. The
ultimate goal in the nursing practice is to reduce the challenges
affecting the people. A healthy population plays a critical role
in ensuring the wellbeing of future generations.
References
Alcarria, R., Bordel, B., & de AndrÃ, D. M. (2018). Enhanced
peer assessment in MOOC evaluation through assignment and
review analysis. International Journal of Emerging
Technologies in Learning (iJET), 13(1), 206-219.
González-Gómez, D., Jeong, J. S., & Rodríguez, D. A. (2016).
Performance and perception in the flipped learning model: an
initial approach to evaluate the effectiveness of a new teaching
methodology in a general science classroom. Journal of Science
Education and Technology, 25(3), 450-459.
Pereira, D., Flores, M. A., & Niklasson, L. (2016). Assessment
revisited: a review of research in Assessment and Evaluation in
Higher Education. Assessment & Evaluation in Higher
Education, 41(7), 1008-1032.
Rowan, S., Newness, E. J., Tetradis, S., Prasad, J. L., Ko, C. C.,
& Sanchez, A. (2017). Should student evaluation of teaching
play a significant role in the formal assessment of dental
faculty? Two viewpoints: Viewpoint 1: Formal faculty
assessment should include student evaluation of teaching and
viewpoint 2: Student evaluation of teaching should not be part
of formal faculty assessment. Journal of dental education,
81(11), 1362-1372.
Wittenberg, E., Ferrell, B., Goldsmith, J., Ragan, S. L., &
Paice, J. (2016). Assessment of a statewide palliative care team
training course: COMFORT Communication for Palliative Care
Teams. Journal of palliative medicine, 19(7), 746-752.

HUMAN POPULATION - Moore 1
• A student reading this chapter will be able
to:
– 1. Define the attributes of populations including
birth and death rates, growth rate, density, and
mobility (immigration and emigration).
– 2. Calculate rate of natural increase from birth
and death rates, and mathematically
demonstrate the effects of age-sex composition
on a population.
– 3. Define biotic potential and maximum growth
rate, and list the various limits to growth
– 4. Identify, list, and explain the population
growth forms.
– 5. Recognize and explain the concept of

population explosion with respect to complete
and incomplete demographic transition. Define
population implosion and discuss the conditions
that lead to this phenomena.
– 6. Explain the role of urbanization in
influencing sustainability of populations.
– 7. Explain global population projections and
differentiate between developed and lesser
developed countries with respect to those
projections.
– 8. List and discuss the various options for
fertility control methods, while contrasting the
effectiveness, risks, and benefits of each type.
HUMAN POPULATION
INTRODUCTION
– Understanding the dynamics of human
populations is a first order of business in
beginning the study of environmental health.

– There is growing realization that surging
populations, environmental degradation, and
ethnic conflict are strongly intertwined.
LESSER DEVELOPED
COUNTRIES
– Overpopulation, infectious disease, unprovoked
crime, few resources, and the influx of more
refugees, increases the erosion of nation-states
leading to the empowerment of private armies,
security firms and international drug cartels.
LESSER DEVELOPED
COUNTRIES
– This is a vision of the early 21st century in
many parts of the lesser developed countries
(LDCs), and threatens to expand along with the
growth of human populations.
THE CHARACTERISTICS OF
POPULATIONS

• Species
– A species is normally considered to be a group
of organisms that can breed together with the
production of a viable and fertile offspring.
– Different species not only have differing
physical attributes, but they also differ in the
population characteristics.
Population
– A population is considered to be the breeding
group for an organism.
– Each population has characteristics that help to
identify it.
– Some of these characteristics are birth rate,
death rate, rate of natural increase, age
distribution, and sex ratio.
Birth Rate
– Birth rate refers to the number of individuals
added to a population through reproduction
(live births) and is normally expressed as the
number of live births per 1,000 population

(counting the population at the midpoint of the
year)(Fig. 2-1).
Death Rate
– Death rate is also similarly calculated using
total deaths divided by the mid-year total
population (Fig. 2-1).
Rate of Natural Increase
– The rate of natural increase is determined by
subtracting the death rate from the birth rate
(Fig. 2-1).
– The rate of natural increase reflects the growth
rate in which migration is not considered.
– The growth of a population in the absence of
migration must depend on the birth rate being
higher than the death rate.
Fig. 2-1

Presenter
Presentation Notes
Birth rate equals the number of live children born in a year per
1 000 total population
Birth rate in year Y = Number of live children born in year Y
over the midyear population in year Y
Birth rate in year 1998= 4,345,600 (children born in 1998) over
271,600,000 (population in mid-1998)= 16/1000
Death rate in year y= 2,172,800 (deaths in 1998) over
271,600,000 (population in mid-1998) = 8/1000
Rate of natural increase in year 1998 = (Birth rate - Death rate)
= 811000 or 0.8 percent*
*These are approximate numbers for the United States used only
for example.
Age Distribution
– The age-sex composition of the population has
a profound effect on the birth and death rates of
a country because the probability of dying or
giving birth within any given year depends
upon the age and sex of the population
members Fig. 2-2.
Age Distribution (Fig. 2-2)
Presenter

Presentation Notes
Graph showing the age distribution in different regions. The
reproductive ages are noted as 15-50, which has the most people
in stable and declining populations. Expanding populations have
more children under 14 than any other ages
Expanding populations: Mexico, Asia, and Africa have a bell
curve distribution between relationship of percentage of
population and age, with 7% of the population being under the
age of 14 and 2-3% over the age of 55.
The United States is a stable population with a much steeper,
more jagged bell curve with people over 55 making up 3% of
the population and children making about 3.5% of the
population
Western Europe and Japan are declining populations with an
even steeper curve, with only 3% children and 1-2% adults over
55
POPULATIONS
• Total Fertility Rates
– Total fertility rates(TFR) represent the number
of children a woman in a given population is
likely to bear during her reproductive lifetime
providing that birth rates remain constant for at
least a generation.

POPULATIONS
• Immigration
– In nature, when the density of organisms
becomes too great, the intense competition for
food, water, and other resources damages the
entire population. Some species have the ability
to disperse or migrate out of the area and in
doing so, temporarily relieve the overcrowding.
– This process is called emigration.
Immigration
– When species emigrate from an area, they must
immigrate or enter into another area.
– Driven by natural disasters, war, disease, and
disappearing resources, the numbers of
refugees worldwide may exceed 15 million,
with about 880,000 to 1.4 million immigrants
entering the United States each year, including
more than 200,000 who enter illegally.
POPULATIONS DYNAMICS

– There are periodic upsurges in many
populations that lead to overwhelming
numbers.
– Whether these population explosions occur in
rabbits, lemmings, soldier ants, or locusts, there
is always some natural pressures that bring the
population back into balance with their natural
surroundings.
• Biotic Potential
– The unrestricted growth of populations
resulting in the maximum growth rate for a
particular population is called its biotic
potential.
– The biotic potential of species differs markedly
and is influenced by: (1) the frequency of
reproduction; (2) the total number of times the
organism reproduces; (3) the number of
offspring from each reproductive cycle; and (4)
the age at which reproduction starts.

• Environmental Resistance
– Environmental resistance refers to those
pressures that limit population and may include
such factors as disease, wars, predatory
behavior, toxic waste accumulation, or species
competition (Fig. 2-3).
Fig 2-3
Presenter
Presentation Notes
Biotic potential – environmental resistance = actual rate of
resistance.
Graph with population on y axis and time on x axis
Environmental resistance is food, light, or space shortage,
climate changes, disease, predatory behavior, toxic wastes,
competition

– By plating bacteria as outlined in figure 2-4,
one can examine and then plot a bacterial
growth curve (Fig. 2-5).
• Lag Phase
– The initial part of the curve in which the
organisms show no increase in growth rate, but
are preparing for the exponential growth phase
which follows.
Fig. 2-4
Presenter
Presentation Notes
Original inoculum is diverted into various test tubes, one to
another, so it loses potency.
The first tube creates too many confluent colonies to count on a
nutrient agar plate, the next creates less, the third less than that,
and the final creates 2x10 to the sixth power colonies/ml
Calculation: Number of colonies on plate x reciprocal of
dilution of sample= bacteria/ml. In this example, there are 20
colonies on the plate of 1:100,000 dilution = 2 million
bacteria/ml. A growth curve can be constructed if the original
inoculum is counted by this process hourly for 24 to 48 hours.
Fig. 2-5

Presenter
Presentation Notes
Graph with time up to 24 hours on the x axis and log of numbers
of bacteria on the y axis. An S curve shoes the lag phase for the
first 6 hours, the log or exponential growth phase for the next
six hours, the stationary phase for six hours after that and the
death or logarithmic decline phase for the remaining 12 hours
Fig. 2-6
– If an organism grows too
rapidly and the population
escalates beyond the carrying
capacity of the environment
in which it is located, a “J”
type growth curve may
develop (Fig. 2-6).
Presenter
Presentation Notes
X axis is time and y axis is log of numbers of organisms. A
short lag phase is followed by a steep log or exponential growth
phase which exceeds carrying capacity
– This behavior sometimes oscillates every few

years as in the case of lemmings that inhabit the
arctic tundra north of the Canadian forest.
– Every 3 to 4 years the population explodes,
then crashes the following year, followed by a 2
year cycle of slow recovery (Fig 2-7).
– Figure 2.8 shows the effects of predators on
populations.
Fig. 2-7
Presenter
Presentation Notes
Graphic depiction of lemming population cycles. Every 3 to 4
years the population explodes, then crashes the following year,
followed by a 2 year cycle of slow recovery.
Fig. 2-8
Presenter
Presentation Notes
Population size cycles but is relatively constant. This can be
effected by the presence of predators. Graphic shows a squiggly
but relatively constant rate of population for animals’
population size, then the same population over time in the

presence of a predator, with a pronounced decline.
• k-Strategy (type I”)
– When large organisms with relatively long life
spans have only a few offspring, but devote
their energies to protecting and nurturing the
offspring to enhance their individual survival
until they can reproduce (Fig.2-9).
– Density dependent factors include such items as
food supply, which becomes more limiting as
the size of the population grows.
• r-Strategy
– r-strategy populations are typically small, short-lived
organisms, which produce large numbers of
offspring and receive little or no parental care (Fig.
2-9).
– These organisms are limited by density-independent
factors such as a drought that dries up a pond, or
sudden climactic changes such as El nino which
alters the temperature of the water making it
uninhabitable for certain species.

Fig. 2-9Adapted from Turk & Turk. 7
Presenter
Presentation Notes
Graph of r-strategy, Type II and k strategy/type I populations
with number of survivors on the y axis and age on the x axis.
R-strategy populations are Type III: insects, fungi, fish,
mollusks, plants. They produce large numbers of offspring and
receive little or no parental care. They don’t live long. K-
strategy organisms with relatively long life spans have only a
few offspring, but devote their energies to protecting and
nurturing the offspring to enhance their individual survival until
they can reproduce. Type II populations are some birds, and
humans experiencing malnutrition and disease.
POPULATION TRENDS IN THE
WORLD
– Demographers use the information on
population size, fertility rates, migration, birth
and death rates, growth rates, infant mortality,
density, age-sex composition and other factors
to statistically characterize human populations.
– Their purpose is to predict what will happen to

that population over time.
POPULATION TRENDS IN THE
WORLD
• Historical Trends
– After earth’s temperature stabilized about
10,000 years ago, humans began to domesticate
animals and cultivate crops, this allowed the
human population to increase (Fig. 2-10).
– Since then, the world growth rate has increased
dramatically, although we are currently
experiencing a downward trend (Fig 2.11).
Fig. 2-10Adapted from Turk & Turk.
7
Presenter
Presentation Notes
Graph with population in billions on the y axis ranging from 0
to 6 and year on the x axis. Ranging from 2 million BC to 1998.
2 million BC to 0 BC is considered to be before the Christian
era. Once the Christian era began, population began to steadily
increase and spiked in 1998, when it reached 6 billion.

Fig. 2-11
Presenter
Presentation Notes
Graph showing thesteady increase in the annual rate on natural
population increase in the world from 1700 to modern times.
There was a spike in population in 1970, with a 2.06%
increase and slow decline to a 1.4% increase in 1997.
Historical Trends
• Growth Rate
– The rate of births is the ratio of births to the
population, and death rates represent the ratio of deaths
to the population.
– Growth rate is then determined by the birth rate minus
the death rate.
– The population has grown so much, that even the
smaller growth rates lead to additions of larger numbers
of people to the global population (Fig 2-12).
Fig. 2-12

Presenter
Presentation Notes
Graph of population growth from 1960-2000. Year is depicted
on the x axis. Annual increase in world population from 0-90
million on the y axis. Even smaller growth rates lead to
additions of larger numbers of people to the global population,
growing 1.7% in 1960 lead to 51 million more people and a
total population of 3 billion, whereas growing 1.4% between
1998-2000 lead to 85 million more people and a total population
of 6 billion.
Historical Trends
• Doubling Time
– Another useful way to demonstrate growth rate
is to present it as doubling time (Fig. 2-13), or
the number of years for a human population to
double its size. The doubling time can be
calculated according to the following
relationship:
doubling time = 0.70 / growth rate
Fig. 2-13

Presenter
Presentation Notes
Doubling time in years from 0 to 700 on the y axis, countries
and regions on the x axis. Northern Europe has taken 700 years
to double at 0.1 %- the rate of natural increase. Southern Europe
has taken 350 years to increase .2%, Western Europe has taken
233 to increase .3%, U.S, 87.5 to grow .8%, Oceania 53.8 to
grow 1.3%, Asia 50 to grow 1.4%, South America 46.6 to grow
1.5%, and Africa 26.9 years to grow 2.6%
Historical Trends
• Demographic Transition
– Developed countries have exhibited slowly declining
birth and death rates over the last century.
– This has resulted in a diminishing difference between
birth rates and death rates and a very low rate of
natural increase resulting in a stable population with
very long doubling times (Fig. 2-14).
Fig. 2-14
Adapted from United nations Population Fund. 3
Presenter
Presentation Notes
DeBirth rate vs. death rate in more developed countries between

1750-2000. Slowly declining birth and death rates have resulted
in a low rate of natural increase. Birth rate = 11/1000
Death rate = 10/1000. 11-10=0.1 rate of natural increase and a
doubling time of 700 years
Historical Trends
• Incomplete Demographic Transition
– LDCs do not have the resources to institute
social security, and have unstable policies that
fail to capture the trust of its citizens.
– The populations had remained stable with high
birth rates and high death rates.
– Developed countries introduced better
sanitation and nutrition to LDCs, resulting in a
decrease of the death rate (Fig. 2-15).
Fig. 2-15Adapted from United nations Population Fund. 3
Presenter
Presentation Notes
Less developed countries have high birth rates and newly lower
death rates, with a high rate of natural increase. Birth rate =
31/1000. Death rate = 10/1000. 31 – 10= 2.1 rate of natural
increase. Doubling time = 33 years.

Current Population Trends
– The world’s population is growing at a rate of
1.4 percent annually and is expected to reach
six billion people by the middle of 1999
– Almost 98 percent of the annual increase in the
world’s population is occurring in the LDCs.
Population Decreases in the
Developed Countries
• Declines in Fertility
– In 1970 there were 19 countries reporting
declining fertility rates while in 1997 over 57
countries have reported below-replacement
fertility rates.
– By the year 2060, Europe will have lost almost
25 percent of its population.

Developed Countries
• Concerns About Decline
– There is a concern throughout Europe and
Japan that the declining population will result
in decreasing house and land prices as the
demand declines along with the population.
– In the southern island of Kyushu, Japan,
officials are offering a gift of $5,000 to parents
who have a fourth or subsequent child.
Developed Countries
• Concerns About Decline
– Higher education for women with new
aspirations and higher incomes, is considered to
be a factor for declining fertility rates in many
countries.
– In fact, as illiteracy among women decreases in
a country, the average number of children born
to those women declines (Fig. 2-16).

Fig. 2-16
Presenter
Presentation Notes
The greater the level of illiteracy among women, the more
children they are likely to have. The more money a woman
earns in the home, the fewer children she is likely to have.
Developed Countries
• Fertility Rates in the United States
– The replacement TFR level for most countries
is accepted as being 2.1.
– Subtle changes in social attitude appeared to
produce rather significant changes in fertility
rates (Fig. 2-17).
Fig. 2-17Source: U.S. Bureau of the Census
Presenter
Presentation Notes
Total fertility rate on y axis between 0 and 4.0. X axis has the
years between 1920-1997. The replacement TFR is 2.1. The US
has spent more than 20 years at below replacement level.

Developed Countries
• Immigration and the Changing Racial Landscape
in the United States
– Although the TFR has remained below replacement
levels, immigration adds at least another 850,000 to
1.2 million people to the United States each year.
– The expanding population of elderly white will be
expecting support from a working population of
tremendous diversity and proportionally fewer
workers per retiree (Fig. 2-18).
Fig. 2-18
Presenter
Presentation Notes
In 1950 there were 16.5 workers per retiree. In 1997 there were
3.3 workers per retiree/ By 2025 there will only be 2.2 workers
per retiree.
Current Population Trends in the

Less Developed Countries
– More than 80 percent of the world lives in the
LDCs.
– In the next 20 years 1.76 billion children will
be born in the LDCs (Fig. 2-19).
Fig. 2-19Adapted from Population reference Bureau 2and the
United Nations Population Fund.3
Presenter
Presentation Notes
Population in a bar graph showing contrast between developed
and lesser developed countries from 1750 to 2100. Developed
countries have a significantly slower population growth. By
2100, 2 billion people will live in developed countries and 12
billion in lesser developed countries.
Predicted Future Trends in
Populations
– The median or best estimate by the United
Nations is that the world population will
stabilize at 11.5 billion people around the year
2150 if the world fertility rate drops to 2.06 and
life expectancy is 85 years (Fig.2-20).

Fig. 2-20Adapted from Doyle18 and Motavallui.19
Presenter
Presentation Notes
Projections of population growth. With a TFR of 2.5 there will
be 28 billion people in 2150. With a TFR of 2.06 there will be
11.5 billion. With a TFR of 1.7 there will be 4 billion in 2150.
Urbanization - What is it?
– The mass migration of people to the cities.
• Megacities
– Defined as having a population of more than 10
million, will be commonplace by the year 2015,
with 9 of the 10 largest cities being in the the
developing countries. (Figs.2-21, 22).
Fig. 2-21Adapted from the Environment.17
Presenter
Presentation Notes
Bar graph of urbanization across the globe, will Tokyo being

the only city in a developed country that houses much of the
population at about 30 million, Bombay India has roughly the
same amount. Lagos Nigeria and Shanghai China have about 22
million. Jakarta Indonesia has just over 20 million, Sao Paulo
Brazil and Karachi Pakistan have about 20 million Beijing
China, Dhaka Bangladesh, and Mexico City Mexico have about
18-19 million.
Fig. 2-22. Borders of W. Africa
merged by megacities
Urbanization
• Facilitates the spread of disease.
• Potential increase in violence
• Environmental degradation
THE CONTROL OF
POPULATION
• Empowerment or Force
– Countries attempting to bring population
growth under control without first empowering
women and providing effective birth control

have often resorted to oppressive population
control policies.
Population Policies in Some
Countries
• India
– India was the first country to introduce family
planning in 1951, with the rhythm method.
• China
– China continues to enforce a one-child policy in
the nation’s largest cities such as Beijing and
Shanghai.
Family Planning Versus
Population Control
• Population Control
– Government directed programs that set a policy
for establishing an optimum population size.

Family Planning Versus
Population Control
• Family planning
– Population control is in contrast to family
planning programs that are directed at assisting
couples in having the number of children they
desire regardless of how many.
METHODS OF FERTILITY
CONTROL
• Introduction
– Methods that prevent fertilization of the egg are
called contraception.
– Methods vary in their risks to health, their
efficacy in preventing pregnancies, ease of use,
acceptance, and costs.
Contraceptive Methods that are
Reversible
• Natural Birth Control and Family Planning
• Hormonal

– Oral Contraceptives (Fig. 2-23)
– Depo-Provera
– Norplant (Fig. 2-24)
Fig. 2-23
Fig 2-24
Reversible
• Spermicides (Fig. 2-25)
• Barrier Methods
– Male Condom (Fig.2-26)
– Female Condom (Fig. 2-27), Diaphragms, and
Cervical Caps (Fig. 2-28)
• Intrauterine Devices (IUD’s) (Fig. 2-29)

Fig. 2-25
Fig. 2-26
Fig. 2-27
Fig. 2-28
Fig. 2-29
Permanent
– Sterilization has become one of the most
popular methods for contraception in the
United States among married couples who have

achieved their desired level of parenthood
Permanent
• Vasectomy
– Male sterilization by making an incision on
either side of the scrotum and snipping out a
piece of the vas deferens.
• Tubal Ligation
– Blocks the entry of eggs into uterus, eggs
released from the ovaries dissolve and are
reabsorbed into the body.
Permanent
• Abortion
– The medical means of terminating a pregnancy.
– Nearly 60 million abortions occur annually on a
worldwide basis.
– Abortion can also be safely induced within the
first 9 weeks of pregnancy by administering the

drug RU-486.
LIVING WITH THE EARTHObjectives for this Chapter
Objectives for this ChapterObjectives for this
ChapterLIVING WITH THE EARTHLESSER DEVELOPED
COUNTRIESLESSER DEVELOPED COUNTRIESTHE
CHARACTERISTICS OF POPULATIONSPopulationBirth
RateDeath RateRate of Natural IncreaseFig. 2-1Age
DistributionAge Distribution (Fig. 2-2)THE
CHARACTERISTICS OF POPULATIONSTHE
CHARACTERISTICS OF
POPULATIONSImmigrationPOPULATIONS
DYNAMICSPOPULATIONS DYNAMICS POPULATIONS
DYNAMICSPOPULATIONS DYNAMICS Fig 2-
3POPULATIONS DYNAMICSFig. 2-4Fig. 2-5Fig. 2-
6POPULATIONS DYNAMICSFig. 2-7Fig. 2-8POPULATIONS
DYNAMICSPOPULATIONS DYNAMICSFig. 2-
9POPULATION TRENDS IN THE WORLDPOPULATION
TRENDS IN THE WORLDFig. 2-10Fig. 2-11Historical
TrendsFig. 2-12Historical Trends Fig. 2-13Historical TrendsFig.
2-14Historical TrendsFig. 2-15Current Population
TrendsPopulation Decreases in the Developed Countries
Population Decreases in the Developed Countries Population
Decreases in the Developed CountriesFig. 2-16Population
Decreases in the Developed CountriesFig. 2-17Population
Decreases in the Developed CountriesFig. 2-18Current
Population Trends in the Less Developed CountriesFig. 2-
19Predicted Future Trends in PopulationsFig. 2-20Urbanization
- What is it?Fig. 2-21Fig. 2-22. Borders of W. Africa merged by
megacitiesUrbanizationTHE CONTROL OF
POPULATIONPopulation Policies in Some CountriesFamily
Planning Versus Population ControlFamily Planning Versus
Population ControlMETHODS OF FERTILITY
CONTROLContraceptive Methods that are ReversibleFig. 2-
23Fig 2-24Contraceptive Methods that are ReversibleFig. 2-
25Fig. 2-26Fig. 2-27Fig. 2-28Fig. 2-29Contraceptive Methods
that are PermanentContraceptive Methods that are

PermanentContraceptive Methods that are Permanent
ENVIRONMENTAL DEGRADATION AND FOOD SECURITY
- Moore 1
Cooking
a meal in
Africa
- Moore 2
• A student reading this chapter will be able
to:
– 1. Discuss the impact of population on
resources and ecosystems.
– 2. Define the following terms and explain their
response to population growth: retrogression,
soil erosion, desertification, deforestation,
wetlands destruction, and wildlife destruction
- Moore 3

– 3. Define the term food security and discuss the
reasons leading to food insecurity among many
nations worldwide.
– 4. List the suggested steps that might be taken
to minimize global food insecurity.
- Moore 4
– 5. Explain the most likely reasons for a growing
food insecurity in the United States.
– 6. List and discuss the demographics of the
populations in the United States at risk to food
insecurity.
- Moore 5
ENVIRONMENTAL DEGRADATION AND
FOOD SECURITY
INTRODUCTION: THE DEBATE
– The ability of our planet to sustain and feed the

dramatic increases in human population growth
has been an on-going debate stretching back
over 200 years.
- Moore 6
The Viewpoint of Malthus and
Followers
• Neo-Malthusians (Malthus, 1789)
– Human growth is logarithmic and plants grow
arithmetically. Growth will eventually surpass
the ability of the land to feed the expanding
population.
- Moore 7
Technology and Policy Will Save
the Day
• Cornucopians
– The real threat to global stability is the failure
of nations to pursue economic trade and
research policies that increase food production,
more evenly distribute food and resources, and
limit environmental pollution.

- Moore 8
Technology and Policy Will Save
the Day
• The Green Revolution
– Strains of plants are being developed that resist
diseases, pests, drought and flooding.
– So striking has been the increased production,
that the incorporation of these new variety of
seeds and processes became known as the
“Green Revolution.”
- Moore 9
The Green Revolution
– The world markets and the “Green Revolution”
may promote monocultural technology that
could prove to be ecologically unstable (Fig. 3-
1).
- Moore 10
Fig. 3-1

- Moore 11
• Cross-breeding (Fig. 3-2)
• Induced Mutation (Fig. 3-2)
• Gene Transfer (Fig. 3-3)
• Precision Farming (Fig. 3-4)
- Moore 12
Fig. 3-2. Cross-breeding and
Mutation
Presenter
Presentation Notes
Hybridization- pollination or cross breeding. Corn with thin
stalk and multiple ears + corn with thick stalk and few ears—
select corn with thick stalk and multiple ears
Induced mutation- Seeds are grown to produce second
generation. Gamma or ultraviolet irradiation of seeds– select
corn with thick stalk and multiple ears
- Moore 13
Fig. 3-3. Gene TransferAdapted from Budiansky.6

Presenter
Presentation Notes
“Gene gun”- recently developed “gene guns” propel gold
particles coated with DNA by bursts of helium. .22 caliber
blank cartridge is used to propel plastic bullet containing
desirable genes. The plastic bullet impacts against stopping
plate and explosively releases genes. Genes strike and pierce
plant cells at more than 1400 feet a second. Leaf cells with new
DNA are placed in agar dishes with growth hormones. New
shoots develop with many having the desired characteristics.
- Moore 14
Fig. 3-4 Precision Farming
Presenter
Presentation Notes
Global positioning satellite (GPS) sends specific signals on
location and local soil condition to receiving systems on
tractors. Computers onboard tractor receive signal from GPS
satellite and determine field coordinates, then adjust fertilizer
dispersion.
- Moore 15
– These advances in agricultural technologies
have contributed significantly to reducing

hunger in millions of people.
– However, the growth of the human population
in many of the lesser developed countries has
exceeded the capacity of even these
technological wonders in agricultural
production.
- Moore 16
Energy
– Wood is being used at such a rapid pace in
some LDCs that forested regions have been
decimated, and the collection of wood for fuel
may require several hours each day or as much
as 25 percent of average income.
- Moore 17
Energy
– On the other hand, the history of fuel use in the
developed nations moved from wood to more
efficient fuels.
- Moore 18

Energy
– The impact of human activity on environments
can be summarized by the following
relationship:
I=P*A*T
Paul Errlich, Stanford
- Moore 19
Energy
I=P*A*T
–Where:
• I: the impact of human energy-related
activity on the globe
• P: is the population size
• A: is the affluence in terms of per capita
consumption
• T: is the technologies to supply each unit
of consumption
- Moore 20

Attitude and Behavior
– Will we progress in a smooth transition to a
world of global stability and health, or will
national and personal interests prevail at the
expense of the larger global community?
- Moore 21
What are the attitudes and behaviors that may
have an impact on this outcome?
• Tragedy of the Commons
– Many members of any society will likely pass
on the consequences of their destructive actions
if they will benefit in the short term and receive
little or no negative consequences from that
action. Garrett Harden
- Moore 22
• The Pioneer
– The consequences of laying waste to a land in
the past were minimized by the ability of the

population to emigrate.
– The pioneer mentality cannot be continued
indefinitely in the presence of massive
population increases.
– We must seek a sustainable development.
- Moore 23
• Declining Investment in Technologies
– Government funding for organizations which
are largely responsible for the Green
Revolution has been falling.
– The major gains in food crops experienced as
part of the Green Revolution are unlikely to
continue in the absence of investment in
research and development.
- Moore 24
• Family Planning Cuts
– The United States reduced overall foreign

assistance in 1996 with a 25 percent decrease in
USAIDs funds and a 35 percent cut in the
family planning/population assistance budget.
- Moore 25
These cuts could result in:
• 220 million unintended pregnancies;
• 117,000 additional maternal deaths and 1.5
million women who experience permanent
impairment;
• 9.3 million additional deaths of infants and
young children.
- Moore 26
IMPACTS ON THE
ENVIRONMENT
• As the population increases the need for
food increases.
• As the need for food increases, land is
cleared, soil is degraded, and desertification
occurs.

- Moore 27
Deforestation
– Biomes include tropical rainforests, temperate
forests, prairies, deserts, and arctic tundra.
– The majority of tropical forest biomes occur in
areas of the world at risk from overpopulation
and many are being threatened with slash and
burn techniques to make room for croplands.
- Moore 28
Deforestation
– Defined as the permanent decline in crown
cover of trees to a level that is less than 10
percent of the original cover.
- Moore 29
Deforestation
• The Benefits of Rainforests are:
– a major producer of oxygen for the global
atmosphere;

– the major carbon dioxide sink;
– a potential source of new pharmaceuticals
useful in the treatment of human disease;
– and an important source of species diversity.
- Moore 30
Deforestation
• Rainforests (Fig. 3-5, 3-6)
– In spite of the numerous benefits from
rainforests, they are disappearing at an alarming
rate.
– By 1987, tropical rainforests were disappearing
at the rate of 42 million acres each year,
representing a loss of 115,000 acres each day.
- Moore 31
Fig. 3-5Source from NASA..24
- Moore 32
Fig. 3-6Adapted from NASA.24

Presenter
Presentation Notes
Map that highlights the locations of some of the world’s major
rainforests, including Mexico, Belize, Honduras, Guatemala, El
Salvador, Nicaragua, Costa Rica, Columbia, Ecuador,
Venezuela, Brazil, Cote d Ivoire, Nigeria, Central African
Republic, Congo, Malaysia, Indonesia, Philippines and Papua
New Guinea
- Moore 33
Soil Degradation
• What is soil?
– Soil consists of small particles of rock and
minerals mixed with a major proportion of
plant and animal matter in various stages of
decay.
- Moore 34
Soil Degradation
– Plants are called autotrophic because they
synthesize their own food from inorganic
substances.
– Plants also derive nutrients from soil

• Micronutrients
• Macronutrients
- Moore 35
Soil Degradation
• Loam
– Soils best suited for agriculture consist of sand,
silt, and some clay in a homogeneous mixture
referred to as loam.
• Humus
– Complex organic matter that has been
biologically broken down so that original plant
and animal matter is unrecognizable.
- Moore 36
Soil Degradation
• Humus serves to:
– retain moisture much as a sponge;
– serve as an insulator to heat and cold;
– and to bind and release nutrients to plants in
useable forms.

- Moore 37
Fig. 3-7 Major Soil Biomes
Presenter
Presentation Notes
Map of major soil biomes. Tundra are in the top half of the
globe. Taiga is in the upper third of the globe under Tundra.
Temperate forest, grassland and woodland are below Taiga.
Deserts are below Temperate forest and below tropical
rainforests, which are sandwiched between the two prominent
desert regions.
- Moore 38
Soil Degradation
• Soil Erosion
– As woods are cut and fields are plowed to plant
crops, soils are lost to the effects of wind and
runoff water (Fig. 3-8).
- Moore 39
Fig. 3-8Adapted from Turk and Turk.7

Presenter
Presentation Notes
Pie Chart of soil erosion. Woods have 0.4% moisture loss and 0
tons of topsoil loss. Grass cover has 1.9% moisture loss, 0 tons
of topsoil loss. Grain crops have 26% moisture loss, 86 tons of
topsoil loss. Freshly tilled soil has 50.4% moisture loss, 161
tons of topsoil loss. About ¼ of the chart is labeled as “other”
- Moore 40
Soil Degradation
• Farming techniques practiced to reduce soil
erosion are:
– Rotation
– Fallowing
– Terracing
- Moore 41
Soil Erosion
– Globally, soil erosion claims over a billion
acres every year, and 1.2 billion acres of global
cropland is losing topsoil so rapidly that these
acres are expected to become unproductive in
the next few decades.

- Moore 42
The Process of Desertification
• What is desertification?
– Land degradation in arid, semi-arid and dry
sub-humid areas resulting from various factors,
including climactic variations and human
activities.
- Moore 43
Desertification
– About 15 billion acres or one third of the earth
is dry land, and 2.5 billion (or 16 percent of the
earth’s surface) of these dryland acres are
hyperarid deserts where there is little or no
growth.
- Moore 44
– Poverty and the need for food is an enormous
pressure that defies a flexible land use response
and leads to desertification (Fig. 3-9).

- Moore 45
Fig. 3-9
Once forested land in Africa
- Moore 46
• The Costs of Desertification
– Economic losses from desertification are
calculated to be $40 billion while the cost of
recovering these lands worldwide is estimated
at $10 billion annually.
- Moore 47
Wetlands – What are they?
– Wetlands are those areas of land where water
saturation is the major factor influencing the
nature of soil development and the communities
of plants and animals that live in the soil and on
the surface.

- Moore 48
Wetlands
• Types of wetlands (Fig.3-10):
– Swamps
– Bogs
– Prairie potholes
– Bottomland Hardwood Forests
– Estuaries
- Moore 49
Fig. 3.10Source> USEPA, Office of Wetlands, Oceans, and
Watershed. 40
- Moore 50
Freshwater Marshes & Swamps
Source> USEPA, Office of Wetlands, Oceans, and Watershed.
40
- Moore 51

BogsSource> USEPA, Office of Wetlands, Oceans, and
Watershed. 40
- Moore 52
Prairie potholesSource> USEPA, Office of Wetlands, Oceans,
and Watershed. 40
- Moore 53
Bottomland Hardwood Forests
40
- Moore 54
Coastal Marshes and Estuaries
40
- Moore 55
Benefits of Wetlands

– Wetlands purify and replenish water supplies.
– Wetlands are extremely rich in biomass (the
amount of plant and animal life).
– Wetlands are an important source of food.
- Moore 56
Benefits of Wetlands
– Wetlands absorb large amounts of carbon
dioxide from the air.
– Wetlands control flooding in low-lying areas as
they work like sponges
– Wetlands protect coastal areas from storms.
– Wetlands provide recreation and beauty.
- Moore 57
Wetland Losses
– An estimated 300,000 acres (120,000 hectares)
of wetlands are drained or filled every year in
the U.S.
– Wetlands were considered a nuisance to farmers
and settlers and these areas were filled in.

- Moore 58
The Loss of Biodiversity and
Extinction of Species
– Biodiversity refers to the range of animal and
plant species and the genetic variability among
those species.
– Why is biodiversity important?
• The greater the range of genetic variation, the more
likely there will be a survivor species in the event of
major catastrophies.
- Moore 59
• Background
– 99% of all species that ever existed are thought
to be extinct.
– The Permian extinction caused 90 percent of all
species in the oceans to disappear, two thirds of
reptiles and amphibian families perished, and
up to 30 percent of insect orders were lost.

- Moore 60
• Background
– Records of fossils show that entire groups of
organisms including fish, reptiles, birds and
mammals have replaced one another over long
periods of time (Fig. 3-11).
- Moore 61
Fig. 3-11
Presenter
Presentation Notes
Graph of relative number of species in correlation with millions
of years ago from 330-recent. The majority of species have been
reptiles, with birds and mammals arriving in the last 80 million
years.
- Moore 62

• Background
– It appears that the planet is now losing more
species than are being created, and that the
activities of humans are the reason for a rapidly
growing species extinction and loss in
biodiversity.
- Moore 63
Loss in Biodiversity
– Of the 4,327 known mammal species, 1,096 are
at risk, and 169 are in extremely high risk of
extinction in the wild in the immediate future
(Fig. 3-12)
- Moore 64
Fig. 3-12Adpated from Doyle. 51
Presenter
Presentation Notes
Map showing areas of the world where more than 15% of
mammal species are threatened in gray, and countries with the
most threatened mammal species and including 43% of the
world’s population in blue. The countries are China and India
with 75 species apiece, and Indonesia with 128 species.

- Moore 65
Threats to Biodiversity
• Loss of Habitat
– Most significant threat to biodivesity today is
elimination of habitat for agriculture and
housing. Half of 300 mussel species lost in US
to pollution of rivers and creation of dams.
• Over-harvesting
– Cod in the North Sea off New England are
heavily exploited with as much 60 percent of
the fishable stock being removed annually.
- Moore 66
Threats to Biodiversity
• Non-native Species
– Rainbow trout never encountered “whirling
disease” before the parasite was unknowingly
transplanted here from Europe.
• Pollution
– The acidification of lakes and streams has led to
juvenile recruitment failure among fish

resulting in the disappearance of many species
in a number of industrialized countries.
- Moore 67
Protecting Endangered and
Threatened species
– Legislation first aimed at protecting wildlife in
the United States was introduced as a bill in
1926.
– In 1973, the Endangered Species Act (ESA)
was promulgated in the United States (Fig. 3-
13). The Act currently protects 1,135 speciesof
plants and animals.
- Moore 68
Fig. 3-13
Species being restored
Source> US Fish & Wildlife Service: Whooping Crane-Steve
Hillebrand; Grizzly bear – Don Redfern; Bald eagle – Robert
Fields; Gray wolf - USFWS

- Moore 69
Protecting Endangered and
Threatened species
– Many environmentalists praise the ESA for
reducing the extinction rate of some animal
species in the United States, and even
increasing numbers in as many as 65 species.
– Others have attacked the Act as interfering with
livelihood and taking away personal property
rights.
- Moore 70
Babbitt tells Nation: Species
protection Works
– May 7, 1998, Secretary of the Interior Bruce
Babbitt announced 29 different animals, plants
and birds have recovered sufficiently to take off
the ESA list.
– Paul Nickerson, head of the Endangered
Species Div of the Fish and Wildlife ‘s
Northeast Regional Office, Hadley sees
continued protection of species under State law.
- Moore 71

FOOD SECURITY
– One of the biggest debates for the 21st century
concerns whether or not the world can produce
enough food to feed another few billion people.
- Moore 72
FOOD SECURITY
– Food security is said to occur when all people
have physical and economic access to the basic
food they need to work and function normally.
- Moore 73
Food Production
– For nearly 40 years, the world production of
grain has risen by more than 2 percent a year,
but declined to scarcely 1 percent a year in the
1990s.
- Moore 74
Food Production

– Countries with critical or low food security are
shown in figure 3-14.
- Moore 75
Fig. 3-14Adapted from Brown and Kane. 69
Presenter
Presentation Notes
Countries facing critical or low food security include Peru,
Bolivia, Mali, Niger, Sudan, Chad, Somalia, Central African
Republic, Kenya, Tanzania, Mozambique, Zimbabwe, Zambia,
Angola, Cameroon, Nigeria, Benin, Togo, Ghana, Liberia,
Sierra Leone, Burkina, Mali, and Afghanistan
- Moore 76
Reasons for Regional Food
Shortages
– Food production fell behind population growth
in 64 of 105 developing countries between
1985 to 1995.
– The main reasons for food shortages in eastern
Africa derive mainly from recent droughts
followed by floods.

- Moore 77
Shortages
– If countries are to feed the 9 billion expected by
the year 2050, Africa would have to increase
production by 300 percent, Latin America by
80 percent, Asia by 70 percent, and North
America by 30 percent (Fig. 3-15).
- Moore 78
Fig.3-15
Adapted from FAO. 10
Presenter
Presentation Notes
Bar graphs for the world, Asia, Africa, Russia, and Latin
America showing the percent change from 1961 where per
capita food production equals 100 and the years between 1961-
1994.
Russia has had the greatest decrease, Asia has had the greatest
increase, and the others have maintained relatively stable over
time.
- Moore 79

Shortages
– Growth rates in cereal production have been
declining from 2.8 percent in the 1960s, to
nearly 2.1 percent in 1992 (Fig. 3-16).
- Moore 80
Fig. 3-16
Adapted from FAO. 10
Presenter
Presentation Notes
3 graphs. The first shows world growth rate in cereal
production. From 1961-1969 it grew 4%, from 1970-1979 it
grew 3%, from 1980-1988 it grew 1.25% , and from 1990-1996
it grew 1 %.
The second graph shows world growth rate in agricultural
production. From 1961-1969, it grew 3.25%, from 1970-1979 it
grew 2.5%, from 1980-1988 it grew 2.5% , and from 1990-1996
it grew 2.25 %.
The third graph shows growth rates in yields of all cereals in 93
developing countries. From 1961-1969 it grew 3%, from 1970-
1979 it grew 2.75%, from 1980-1988 it grew 2.5% , and from
1990-1996 it grew 1 %.
- Moore 81
Sources – Where will the Food

Come From?
• Increases in food supply must come from
one or more of the following sources (Fig.
3-17):
– increases in yield (tons per acre);
– increases in arable land placed under
cultivation;
– and cropping intensity (fewer fallow periods or
more than one crop per year or field).
- Moore 82
Fig. 3-17Adapted from FAO. 10
Presenter
Presentation Notes
Increases in food supply pie chart. 66% comes from increased
yields (tons of crops harvested per acre), 21% from arable land
expansion, and 13% from increasing cropping intensity (fewer
fallow periods or more than one crop per year or field)
- Moore 83
Sources
– There are scientists who believe that the ability
to expand cropland is limited, and that it is

disappearing in many areas of the world.
- Moore 84
Sources
• The potential for increasing agricultural
land is limited by:
– the significant costs of developing an
infrastructure in remote areas;
– the lesser productivity of these alternative
areas;
– and the trade-offs in environmental destruction
of sensitive ecosystems.
- Moore 85
Sources
– Alternative strategies are being evaluated and
promoted that are more friendly to the
environment.
- Moore 86

Sources
• These strategies are:
– improved irrigation systems;
– structured water pricing to reduce overuse;
– alternative rotation of crops;
– selective pesticide use;
- Moore 87
Sources
• These strategies are:
– use of pest-resistant varieties;
– improved soil testing and fertilizer application;
– regional crop breeding programs;
– and more education to farmers.
- Moore 88
Food Security
• Worldwide
– Chronic undernutrition is a difficult and
pervasive problem resulting in a food security
crisis in many LDCs.
– Net imports to LDCs are expected to increase

from 90 to 160 million tons in the years from
1990 to 2010.
- Moore 89
Hunger in America
– More than 25 million Americans, almost 50
percent of them under 17, resort to using food
distribution programs such as soup kitchens and
food pantries (Fig. 3-18).
– Nearly 35 million Americans live in hungry or
food-insecure households.
- Moore 90
Fig. 3-18Adapted from Roberts and Roberts. 80
Presenter
Presentation Notes
4 pie charts describing the makeup of Americans using food
distribution programs. The sex distribution is 62.4% female,
37.6% male. The age distribution is 46% are between 16-64,
38% are less than 15 and 16% are more than 65. The race
distribution is 47.7% White, 2.1 % black, 14.6% Hispanic, 2.5%
Native American, 2.5% other, and 0.7% Asian.LIVING WITH
THE EARTHObjectives for this ChapterObjectives for this
ChapterObjectives for this ChapterLIVING WITH THE

EARTHThe Viewpoint of Malthus and FollowersTechnology
and Policy Will Save the DayTechnology and Policy Will Save
the DayThe Green RevolutionFig. 3-1The Green RevolutionFig.
3-2. Cross-breeding and MutationFig. 3-3. Gene TransferFig. 3-
4 Precision FarmingThe Green
RevolutionEnergyEnergyEnergyEnergyAttitude and
BehaviorAttitude and BehaviorAttitude and BehaviorAttitude
and Behavior Attitude and BehaviorThese cuts could result
in:IMPACTS ON THE
ENVIRONMENTDeforestationDeforestationDeforestationDefor
estation Fig. 3-5Fig. 3-6Soil DegradationSoil DegradationSoil
DegradationSoil Degradation Fig. 3-7 Major Soil BiomesSoil
DegradationFig. 3-8Soil DegradationSoil ErosionThe Process of
DesertificationDesertificationThe Process of DesertificationFig.
3-9 The Process of DesertificationWetlands – What are
they?WetlandsFig. 3.10Freshwater Marshes &
SwampsBogsPrairie potholesBottomland Hardwood
ForestsCoastal Marshes and EstuariesBenefits of
WetlandsBenefits of WetlandsWetland LossesThe Loss of
Biodiversity and Extinction of SpeciesThe Loss of Biodiversity
and Extinction of SpeciesThe Loss of Biodiversity and
Extinction of SpeciesFig. 3-11The Loss of Biodiversity and
Extinction of SpeciesLoss in BiodiversityFig. 3-12Threats to
BiodiversityThreats to BiodiversityProtecting Endangered and
Threatened species Fig. 3-13 Protecting Endangered and
Threatened species Babbitt tells Nation: Species protection
WorksFOOD SECURITYFOOD SECURITYFood
ProductionFood ProductionFig. 3-14Reasons for Regional Food
ShortagesReasons for Regional Food ShortagesFig.3-15Reasons
for Regional Food ShortagesFig. 3-16Sources – Where will the
Food Come From?Fig. 3-
17SourcesSourcesSourcesSourcesSourcesFood SecurityHunger
in AmericaFig. 3-18

TOXICITY AND TOXINS -Moore
ObjectivesA student reading this chapter will be able to:1.
Discuss and define the concepts of toxic triangle, poison,
hazardous material, and hazardous waste. 2. List and explain the
various methods of absorption including diffusion, facilitated
diffusion, active transport, and special processes.
Objectives3. Explain the processes of endocytosis including
phagocytosis, pinocytosis, and receptor-mediated endocytosis.
4. Describe and discuss the major mechanisms by which toxic
materials produce their adverse effects including: (1)
inactivation of enzymes, (2) direct effect on cells and tissues,
and (3) production of intermediate compounds or secondary
action.
Objectives5.Describe and provide an overview of the immune
system, the cellular and humoral immune system, and allergic
mechanisms.6. Discuss and describe the adverse health. effects
associated with endocrine disruptors, PCBs, dioxin, lead,
mercury, asbestos, and organic solvents.

TOXICITY AND TOXINS
IntroductionIn the United States, there are currently more than
70,000 synthetic chemicals currently in commercial use, and for
most of them, their toxicity is not widely known or understood.
TOXICITY AND TOXINS
IntroductionSince 1,000 - 2,000 new chemicals are introduced
each year into our society, there is significant opportunity for
untested materials to enter our environment and expose humans,
wildlife, and plants to toxic effects.
TOXICITY AND TOXINS
IntroductionA potentially toxic substance produces its adverse
effect by interacting with humans (or organisms) and the
environment in a relationship referred to as the toxic triangle
(Fig. 5-1).
Fig. 5-1
TOXICITY AND TOXINS
IntroductionA poison or toxic substance does not constitute a
hazard unless contact is made with the organism in a form and

quantity that can cause harm.
Hazardous SubstanceA hazardous substance is defined in the
Comprehensive Environmental Response Compensation and
Liability Act (CERCLA) as any chemical regulated under the
the following Acts:Clean Air Act (CAA)Toxic Substances
Control Act (TSCA)Clean Water Act (CWA)
Toxic SubstanceToxic substances are those that:(1) can produce
reversible or irreversible bodily injury; (2) have the capacity to
cause tumors, neoplastic effects, or cancer; (3) can cause
reproductive errors including mutations and teratogenic effects;
Toxic SubstanceToxic substances are those that:(4) produce
irritation or sensitization of mucous membranes; (5) cause a
reduction in motivation, mental alertness, or capability; (6) alter
behavior; or cause death of the organism.
EXPOSURE AND ENTRY ROUTESExposureIn order for a
toxic substance to produce its harmful effects on the human
body, a person must first be exposed to the chemical.

ExposureAbsorptionThe passage of substances across the
membranes through some body surfaces into body fluids and
tissues by any of a variety of processes that may include
diffusion, facilitated diffusion, active transport, or special
processes.
ExposureDiffusionA passive process that occurs when
molecules move from areas of high concentration to one of low
concentration.
ExposureFacilitated DiffusionSome molecules such as amino
acids and sugars require specialized carrier proteins to be
transported across a membranes.No high energy phosphate
bonds such as ATP are required in this process.
ExposureActive TransportIn this process, ATP is required in
conjunction with special carrier proteins to move molecules
through a membrane against a concentration gradient (i.e., low
concentration to high).
ExposureEndocytosisParticles and large molecules that might
otherwise be restricted from crossing a plasma membrane can be
brought in or removed by this process.

Three Major Types of
EndocytosisPhagocytosisPinocytosisReceptor-mediated
endocytosisLigands
Routes of EntryThere are several ways in which toxic
substances can enter the the body:lungs by inhalation,through
the skin, mucous membranes or eyes by absorption,
orgastrointestinal tract by ingestion.
The Respiratory SystemThe respiratory system is composed of
the nose, pharynx, larynx, trachea, bronchi, and lungs (Fig 5-2).
Fig. 5-2
The Respiratory SystemExternal RespirationThe act of
breathing or ventilation brings air into and out of the
lungs.Internal RespirationThe exchange of gases between blood
and individual cells.

The Respiratory SystemBronchoconstriction narrows the lumen
and restricts the flow of air, other gases, and particles from
reaching more delicate tissues deeper in the lung (Fig. 5-3).
Fig. 5-3
The SkinThe skin is the body’s largest organs consisting of
many interconnected tissues covering an area of nearly 3,000
in.2 in the average adult.
The SkinThe skin helps to:(1) regulate body temperature
through sweat glands; (2) provide a physical barrier to
dehydration, microbial invasion, and some chemical insults;
The SkinThe skin helps to:(3) excrete salts, water, and organic
compounds; (4) serve as a sensory organ for touch, temperature,
pressure, and pain; and (5) provide some important components
of immunity.

The SkinThe skin has two layers (Fig. 5-4):Epidermis Dermis
Fig. 5-4
The SkinMaterials may pass through the skin by:Absorption
through hair follicles or sweat glandsBreaks in the
skinInjectionsInsect bitesHigh pressure steam or liquid
The Gastrointestinal TractThe gastrointestinal tract is a major
route of absorption for many toxic agents including mercury,
lead, and cadmium which appear in food and water.
The Gastrointestinal TractThe components of the GI tract
include the:MouthPharynxEsophagusStomachSmall and large
intestineAnus (Fig. 5-5)
Fig. 5-5

The Gastrointestinal TractNutrients as well as toxic agents can
penetrate through the epithelial cells of the villus, enter the
blood and lymph vessels, and be carried to various parts of the
body (Fig. 5-6).
Fig. 5-6
Mechanisms of ActionThe harmful effects of environmental
toxins are dominated by three principal mechanisms which
include: (1) the toxins influence on enzymes; (2) direct
chemical combination of the toxin with a cell constituent and;
(3) secondary action as a result of the toxins presence in the
system.
Effects of Toxic Agents on
EnzymesHoloenzymeApoenzymeCofactor
Effects of Toxic Agents on EnzymesEnzymes act on substrates
to add or remove molecules of water, oxygen or hydrogen, or

amino- or other functional groups. Enzymes may also rearrange
atoms within a molecule, or join molecules (Fig. 5-7).
Fig. 5-7
Effects of Toxic Agents on EnzymesMany toxic substances have
the ability to: (1) interfere with or block the active sites of the
enzyme; (2) inactivate or remove the co-factor;
Effects of Toxic Agents on EnzymesMany toxic substances have
the ability to: (3) compete with the co-factor for a site on the
enzyme; or (4) altering enzyme structure directly thereby
changing the specific three-dimensional nature of the active site
(Fig. 5-8).
Fig. 5-8
The Direct Action of Pollutants on Cell ComponentsStrong
acids, bases, and phenols can directly etch tissueNitrous and

sulfuric acids, and ozone can oxidize cellular materialCarbon
monoxide can react directly with hemoglobin and prevent the
attachment of oxygen
Pollutants that Cause
Secondary ActionsOtherwise harmless substances may cause the
formation of chemicals in the body that are harmful or
potentially lethal.Fluoroacetate (rodenticide 1080) may be
converted in the body to fluorocitric acid which is often lethal
in small quantities.Allergens may produce discomforting or
even fatal reactions by causing the immune system to release
intermediary products such as histamines.
Immunity and AllergiesImmunity is based on the premise that
certain immune cells in the body can recognize microbes,
tissues and other substances that are “non-self” or foreign, and
so destroy, encapsulate, or remove them.
Immunity and AllergiesTwo separate but cooperating
components of the immune system are known as:Humoral
(antibody-mediated) immunity Cellular (cell-mediated)
immunity.The responses of cellular and humoral immunity are
quite different (Fig. 5-9).

Fig. 5-9
Immunity and AllergyEach component of the immune system is
formed in the embryonic stages from lymphocytic stem cells
that appear in bone marrow (Fig. 5-10).
Fig. 5-10
Immunity and AllergyThe Initial Immune ResponseThe immune
system responds to agents, cells, or substances that are foreign
or non-self, are collectively called antigens.
The Initial Immune ResponseHaptenMacrophageHuman
Leukocyte Associated antigens (HLA)
Cellular ImmunityT cells respond to a particular antigen then
enlarge, divide, and give rise to clones of several
subpopulations of T cells (Fig. 5-11a,b).

Fig. 5-11a
Adapted from Tortora and Anagnostakos11 and Tortora.12
Fig. 5-11b
Humoral ImmunityB CellsProduce liquid proteins (humoral)
known as antibodies and secrete them into the blood stream
where they can travel to the affected site and carry out their
destructive action (Fig. 5-12).
Fig. 5-12a
Fig. 5-12b

The Antibody MoleculeAntibodies (also called
immunoglobulins) are proteins (Fig. 5-13).
Fig. 5-13
The Antibody MoleculeThe five major classes of antibodies
known as:ImmunoglobulinsIgGIgA IgMIgD IgE.
The Antibody MoleculeThe variable regions of the antibody are
created in a specific three-dimensional form that is pre-
configured in the B cell clone to only one antigenic group (Fig.
5-14).
Fig. 5-14

Antibody ActivitiesThe binding of an antibody with its specific
antigen can activate the complement system. The complement
system enhances phagocytosis, inflammation, and cell lysis
(Fig. 5-15).
Fig. 5-15
HypersensitivityAn exaggerated immune response to the
presence of an antigen is termed hypersensitivity or allergy.
HypersensitivityThere are four major types of hypersensitivity
reactions:Cytotoxic, Cell-mediated,Immune complex
Anaphylactic (Fig. 5-16)
Fig. 5-16
Factors Governing ToxicityThe outcome of exposure to a toxin
depends on a number of factors that may include: The Properties

of the ChemicalConcentrationEffective
DoseBioaccumulationBiotransformation
Factors Governing ToxicityThe outcome of exposure to a toxin
depends on a number of factors that may include:
InteractionsSynergisticAntagonisticAgeExercise and Physical
StressHealth Status
SOME SPECIFIC EXAMPLES OF TOXIC AGENTSEndocrine
Disrupters and Reproductive HealthHormone FunctionHormones
are critical in the regulation of many life processes, including
sexual development, metabolic functions, development of the
brain, human growth, and stress response.
Hormone FunctionAndrogensRegulate the development and
maintenance of male sexual characteristicsEstrogens Stimulate
the development of female sexual characteristics
Adverse Effects of Endocrine Disruption(1) reduced sperm
counts; (2) precocious puberty; (3) increase in non-Hodgkin
lymphoma; (4) marked increase in males having undescended
testicles, and(5) testicular cancer.

What are Endocrine Disruptors?Examples of Endocrine
DisruptorsPesticides such as DDTPlasticizers such as phthalates
and alkylphenolsPCBs, DioxinA variety of naturally occurring
plant compounds or phytoestrogens
Endocrine Disruptors-How Do They Work?There are at least
four different mechanisms by which endocrine disruptors can
exert their adverse effects (Fig. 5-17).
Fig.
5-17a
Fig.
5-17b
Reducing ExposureEndocrine Disruptors find their way into the
food supply through:(1) ingestion of contaminated grains and
grasses by livestock which then store the lipophilic chemicals in

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