Gen Bio II BIO102

1. Chapter 40:
Basic Principles of Animal
Form & Function
Rob Swatski
Associate Professor of Biology
HACC – York Campus
1

2. Exchange with the Environment
• An animal’s size & shape
directly affect how it
exchanges energy & materials
with its environment
• Exchange occurs as dissolved
substances diffuse & are
transported across the cells’
plasma membranes
• A unicellular protist living in
water has enough surface area
of plasma membrane to
service its entire volume of
cytoplasm
2

3. Multicellular
organisms with a
sac body plan have
body walls that are
only 2 cells thick,
which facilitates
diffusion
3

4. More complex organisms have highly folded internal
surfaces for exchanging materials
0.5 cm
Nutrients
Digestive
system
Lining of small intestine
Mouth
Food
External environment
Animal
body
CO2 O2
Circulatory
system
Heart
Respiratory
system
Cells
Interstitial
fluid
Excretory
system
Anus
Unabsorbed
matter (feces)
Metabolic waste products
(nitrogenous waste)
Kidney tubules
10 µm
50µm
Lung tissue
4

5. Epithelial Tissue
Cuboidal
epithelium
Simple
columnar
epithelium
Pseudostratified
ciliated
columnar
epithelium
Stratified
squamous
epithelium
Simple
squamous
epithelium
5

6. Connective Tissue
Collagenous fiber
Loose
connective
tissue
Elastic fiber
120µm
Cartilage
Chondrocytes
100µm
Chondroitin
sulfate
Adipose
tissue
Fat droplets
150µm
White blood cells
55µm
Plasma Red blood
cells
Blood
Nuclei
Fibrous
connective
tissue
30µm
Osteon
Bone
Central canal
700µm
6

7. Muscle Tissue
50 µm
Skeletal
muscle
Multiple
nuclei
Muscle fiber
Sarcomere
100 µm
Smooth
muscle
Cardiac muscle
Nucleus
Muscle
fibers
25 µm
Nucleus Intercalated
disk
7

8. Glial cells
Nervous Tissue
15 µm
Dendrites
Cell body
Axon
Neuron
Axons
Blood vessel
40 µm
8

9. Coordination and Control
• Depends on both the endocrine & nervous systems
• The endocrine system: transmits chemical signals
(hormones) to receptive cells throughout the body via
blood
- a hormone may affect 1 or more regions throughout
the body
• Hormones are relatively slow acting, but can have
long-lasting effects
9

10. Stimulus
Endocrine
cell
Hormone
Signal travels
everywhere
via the
bloodstream.
Blood
vessel
Response
(a) Signaling by hormones 10

11. • The nervous system: transmits information
between specific locations
• The information conveyed depends on a nerve
signal’s (impulse) pathway, not the type of signal
- impulse transmission is very fast
- impulses can be received by neurons, muscle cells,
& endocrine cells
11

12. Stimulus
Neuron
Axon
Signal
Signal travels
along axon to
a specific
location.
Signal
Axons
Response
(b) Signaling by neurons 12

13. Feedback Control Loops
• Animals manage their internal environment by
regulating or conforming to the external
environment
• Regulators: use internal control mechanisms to
moderate internal change in the face of external,
environmental fluctuation
• Conformers: allow internal conditions to vary with
certain external changes
13

14. River otter (temperature regulator)
Largemouth bass
(temperature conformer)
Bodytemperature(°C)
0 10
10
20
20
30
30
40
40
Ambient (environmental) temperature (ºC) 14

15. Homeostasis
• Organisms use homeostasis to maintain a “steady
state” (internal balance) regardless of external
environment
• In humans, body temperature, blood pH, & glucose
concentration are each maintained at a constant
level
15

16. Mechanisms of Homeostasis
• Moderate changes in the internal environment
• For a given variable, fluctuations above or below a set
point act as a stimulus
- stimuli are detected by a sensor & trigger a response
- the response returns the variable back to the set
point
16

17. Response:
Heater
turned
off
Stimulus:
Control center
(thermostat)
reads too hot
Room
temperature
decreases
Set
point:
20ºC
Room
temperature
increases
Stimulus:
Control center
(thermostat)
reads too cold
Response:
Heater
turned
on 17

18. Homeostasis
Stimulus:
Perturbation/stress
Response/effector
Control center
Sensor/receptor
18

19. Feedback Loops in Homeostasis
• The dynamic equilibrium of most homeostasis is
maintained by negative feedback loops
- helps to return a variable to either a normal range or
a set point
- buildup of the end product shuts the system off
• Positive feedback loops: do not usually contribute
much to homeostasis
19

20. Alterations in Homeostasis
• Set points & normal ranges can change with age or
show cyclic variation
• Homeostasis can adjust to changes in external
environment, a process called acclimatization
20

21. Thermoregulation: process where animals maintain an
internal temperature within a tolerable range
• Ectothermic animals: gain heat from external sources
- include most invertebrates, fishes, amphibians, &
reptiles
• Endothermic animals: generate heat by metabolism
- birds & mammals
21

22. • Ectotherms generally tolerate more internal
temperature variations
• Endotherms are active at a greater range of
external temperatures
- more energetically expensive than ectothermy
22

23. Variation in Body Temperature
• Poikilotherm: body temperature varies with its
environment
• Homeotherm: body temperature is relatively
constant
23

24. Balancing Heat Loss and Gain
Organisms exchange heat by 4 physical
processes:
Conduction
Convection
Radiation
Evaporation
24

25. Radiation Evaporation
Convection Conduction 25

26. Heat regulation in mammals often involves the integumentary
system: skin, hair, & nails
Epidermis
Dermis
Hypodermis
Adipose tissue
Blood vessels
Hair
Sweat
pore
Muscle
Nerve
Sweat
gland
Oil gland
Hair follicle 26

27. 5 general adaptations help animals
thermoregulate:
– Insulation
– Circulatory adaptations
– Cooling by evaporative heat loss
– Behavioral responses
– Adjusting metabolic heat production
27

28. Insulation
Major thermoregulatory adaptation in mammals & birds
Skin, feathers, fur, & blubber reduce heat flow between
an animal & its environment
28

29. Circulatory Adaptations
• Regulation of blood flow near the body surface
significantly affects thermoregulation
• Many endotherms (& some ectotherms) can alter the
amount of blood flowing between the body core &
the skin
- Vasodilation: blood flow in the skin increases,
facilitating heat loss
- Vasoconstriction: blood flow in the skin decreases,
reducing heat loss
29

30. • The arrangement of blood vessels in many marine
mammals & birds allows for countercurrent exchange
- transfer heat between fluids flowing in opposite
directions
- important mechanism for minimizing heat loss
30

31. Canada goose Bottlenose
dolphin
Artery
Artery
Vein Vein
Blood flow
33º35ºC
27º30º
18º20º
10º 9º
31

32. Some bony fishes & sharks also use countercurrent heat
exchange
Many endothermic insects also use this to help maintain
a high temperature in the thorax
32

33. Cooling by Evaporative Heat Loss
• Many types of animals lose heat through evaporation
of water in sweat
• Panting increases the cooling effect in birds & many
mammals
• Sweating or bathing moistens the skin, helping to cool
an animal down
33

34. Behavioral Responses
• Both endotherms & ectotherms use behavioral
responses to control body temperature
- some terrestrial invertebrates have postures that
minimize or maximize absorption of solar heat
34

35. Adjusting Metabolic Heat Production
• Some animals can regulate body temperature by
adjusting their rate of metabolic heat production
• Heat production is increased by muscle activity
(moving or shivering)
35

36. RESULTS
Contractions per minute
O2consumption(mLO2/hr)perkg
0
0
20
2015105 25 30 35
40
60
80
100
120
36

37. PREFLIGHT PREFLIGHT
WARM-UP
FLIGHT
Thorax
Abdomen
Time from onset of warm-up (min)
Temperature(ºC)
0 2 4
25
30
35
40
37

38. Acclimatization in Thermoregulation
• Birds & mammals can vary their insulation to
acclimatize to seasonal temperature changes
• When temperatures are subzero, some
ectotherms produce “antifreeze” compounds to
prevent ice formation in their cells
- “plugs” gaps in existing crystals
38

39. 39

40. Physiological Thermostats and Fever
• Thermoregulation is controlled by a region of the brain
called the hypothalamus
- triggers heat loss or heat-generating mechanisms
• Fever is the result of a change to the set point for a
biological thermostat
40

41. Sweat glands secrete sweat,
which evaporates, cooling the
body.
Thermostat in hypothalamus
activates cooling mechanisms.
Blood vessels in
skin dilate:
capillaries fill;
heat radiates from
skin.
Increased body
temperature
Decreased body
temperature
Thermostat in
hypothalamus
activates warming
mechanisms.
Blood vessels in skin
constrict, reducing heat
loss.
Skeletal muscles contract;
shivering generates heat.
Body temperature
increases; thermostat
shuts off warming
mechanisms.
Homeostasis:
Internal temperature of
36–38°C
Body temperature
decreases;
thermostat
shuts off cooling
mechanisms.
41

42. Energy requirements are related to animal
size, activity, and environment
• Bioenergetics: the overall flow & transformation of
energy in an animal
• It determines how much food an animal needs &
relates to an animal’s size, activity, & environment
42

43. Energy Allocation and Use
• Animals harvest chemical energy from food
• Energy-containing molecules from food are usually
used to make ATP, which powers cellular work
• After the needs of staying alive are met, remaining
food molecules can be used in biosynthesis
• Biosynthesis includes body growth & repair,
synthesis of storage material (fat), & production of
gametes
43

44. Organic molecules
in foodExternal
environment
Animal
body Digestion and
absorption
Nutrient molecules
in body cells
Carbon
skeletons
Cellular
respiration
ATP
Heat
Energy lost
in feces
Energy lost in
nitrogenous
waste
Heat
Biosynthesis
Heat
Heat
Cellular
work
44

45. Quantifying Energy Use
• Metabolic rate: the amount of energy an animal uses in a
unit of time
• Measured by determining the amount of O2 consumed or
CO2 produced
45

46. Minimum Metabolic Rate and
Thermoregulation
• Basal metabolic rate (BMR): the metabolic rate of an
endotherm at rest at a “comfortable” temperature
• Standard metabolic rate (SMR): the metabolic rate of an
ectotherm at rest at a specific temperature
• Both rates assume a nongrowing, fasting, & nonstressed
animal
• Ectotherms have much lower metabolic rates than
endotherms of a comparable size
46

47. Shrew
Harvest mouse
Mouse
Ground squirrel
Rat
Cat Dog
Sheep
Human
Horse
Elephant
Body mass (kg) (log scale)
BMR(LO2/hr)(logscale)
(a) Relationship of BMR to body size
10–3 10–2
10–2
10–1
10–1
1
1
10 102
103
10
102
103
47

48. Size and Metabolic Rate
• Metabolic rate per gram is inversely related to
body size among similar animals
- 1 g of mouse body mass requires 20-times more
calories than 1 g of elephant body mass!
• Smaller animals have a higher metabolic rate per
gram
- leads to a higher O2 delivery rate, breathing rate,
heart rate, & greater (relative) blood volume,
compared with a larger animal
- must also eat much more food per unit of body
mass
48

49. 103
10210110–110–210–3
0
1
2
3
4
5
6
7
8
Body mass (kg) (log scale)
(b) Relationship of BMR per kilogram of body mass to body size
BMR(LO2/hr)(perkg)
Shrew
Harvest mouse
Mouse
Rat
Ground squirrel
Cat
Sheep
Dog
Human
Horse
Elephant
49

50. Activity and Metabolic Rate
• Activity greatly affects metabolic rate for
endotherms & ectotherms
• In general, the maximum metabolic rate an
animal can sustain is inversely related to the
duration of the activity
50

51. Energy Budgets
• Different species use energy & materials in food in
different ways, depending on their environment
• Use of energy is partitioned to BMR (or SMR), activity,
thermoregulation, growth, & reproduction
51

52. Annualenergyexpenditure(kcal/hr)
60-kg female human
from temperate climate
800,000
Basal
(standard)
metabolism
Reproduction
Thermoregulation
Growth
Activity
340,000
4-kg male Adélie penguin
from Antarctica (brooding)
4,000
0.025-kg female deer mouse
from temperate
North America
8,000
4-kg female eastern
indigo snake
Endotherms Ectotherm
52

53. Torpor and Energy Conservation
• Torpor: physiological state in which activity is low &
metabolism decreases
- enables animals to save energy while avoiding
difficult & dangerous conditions
• Hibernation: long-term torpor that is an adaptation
to winter cold & food scarcity
53

54. Additional metabolism that would be
necessary to stay active in winterActual
metabolism
Arousals
Body
temperature
Outside
temperature
Burrow
temperature
Metabolicrate
(kcalperday)Temperature(°C)
June August October December February April
–15
–10
–5
0
5
15
10
25
20
35
30
0
100
200
54

55. Estivation (summer torpor):
enables animals to
survive long periods of
high temperatures and
scarce water supplies
Daily torpor: exhibited by
many small birds &
mammals
- adapted to feeding
patterns
55