1. Human population
Population can be defined as the total number of individuals
occupying at a particular area at a particular time. The
organisms are capable of interbreeding among themselves.
The size and the density of a population depends on different
factors;
1.Birth or Natality rate
2.Mortality or death rate
3.Immigration
4.Population growth
2. . Human population growth
History of human being is only about 50,000 years old. But
there are no records available about the human population
since that period. Global human population growth amounts to
around 75 million annually, or 1.1% per year. The global
population has grown from 1 billion in 1800 to 7 billion in
2012. It is expected to keep growing, where estimates have put
the total population at 8.4 billion by mid-2030, and 9.6 billion
by mid-2050. The population growth rate is the rate at which
the number of individuals in a population increases in a given
time period as a fraction of the initial population. Specifically,
population growth rate refers to the change in population over
a unit time period, often expressed as a percentage of the
number of individuals in the population at the beginning of
that period.
3. Population in Nepal:
Like other countries, the population of Nepal is also increasing day by
day.
The population of Nepal is estimated to be 30,494,504 people based on
the 2014 census, with a population growth rate of 1.596% and a median
age of 21.6 years. Female median age is estimated to be 22.5 years, and
male median age to be 20.7 years. Only 4.4% of the population is
estimated to be more than 65 years old, comprising 681,252 females and
597,628 males. Sixty one per cent of the population is between 15 and 64
years old, and 34.6% is younger than 14 years. Birth rate is estimated to
be 22.17 births/1,000 populations with an infant mortality rate of 44.54
deaths per 1,000 live births. Life expectancy at birth is estimated to be
67.44 years for females and 64.94 years for males. Death rate is
estimated to be 681 deaths per 100,000 people. Net migration rate is
estimated to be 61 migrants per 100,000 people. According to the 2001
census, only 48.6% of the total population is literate of which 62.7% are
male and 34.9% are female. According to doubling time rate of
population, the population of Nepal double within 33 years.
4. Patterns of population growth (growth curves):
The pattern of increase of population is expressed in the form of curve
is called growth curve. The mathematical model of population growth
curve are basically two types;
1. J-shaped curve:
The J-shaped growth pattern of population is shown in the given figure.
This type of population growth is seen in algae, some insects, annual
plants and lemmings of tundra. At the beginning, growth is slow. When
the population adapts in the nature, the population increases rapidly in
geometric ratio. Finally, this growth curve shows rapid increase in
mortality rate & growth stops & curve appears J shaped.. It consists of
two phases namely lag phase and exponential phase
5. 2. S-shaped curve (Sigmoid curve):
This type of growth is observed in yeast cell and most of the
organisms including human beings. Finally, this growth curve
shows zero growth rate as birth rate equals to death rate. It
consists of three phases namely lag phase(little growth or no
growth), exponential phase(growth rate very high) and
stationary phase(growth constant or no growth).
6. Difference between J-shaped curve and S-shaped curve
J-Shaped curve S-shaped curve
1.Finally, this growth curve
shows rapid increase in
mortality rate.
1.Finally, this growth curve
shows zero growth rate as birth
rate equals to death rate.
2.examples- Bacteria, some
insects, lemming of tundra.
2.examples- yeast cells, most of
the organisms including human.
3.It consists of two phases
namely lag phase and
exponential phase.
3.It consists of three phases
namely lag phase, exponential
phase and stationary phase.
7. Reasons or causes of Increase in Human population
1.Advancement in agricultural technology: due to Advancement of
science and technology production of food has been enhanced.
2.Better public health: Due to better health care and greater medical
attention, life expectancy of people is increasing.
3.Control of various epidemic diseases.
4.Lack of education because the ratio of increase is more in rural area.
5.Misbelieves like in male dominant society, people prefer to have more
sons than daughter.
6.In some region, polygamy is very common.
7.Early the marriage, sooner the child.
8. Problems or Consequences of over population:
1.Socio-economic problems
a.Space: New towns and cities are coming up to accommodate the growing
population. This put a great strain on agricultural lands and forest areas.
b.Food supply: It will lead to the food crisis resulting in famines, hunger etc.
c.Unemployment: Rise in population has resulted in large scale unemployment.
d.Education: Higher population decreases the quality of education.
e.Poverty: Birth of every child adds the poverty.
f. increases in social crimes.
2.Shortages of natural resources:
a.Energy crisis: Increases in the population has created greater demand for energy.
b.Shortage of drinking water: Drinking water is the major problem in over populated
areas.
3.Eco- degradation
a.Pollution: Rise in the population causes environmental pollutions.
b.Sanitation and epidemic diseases: Poor sanitation caused by overpopulation leads to
the development of various epidemic diseases.
c.Deforestation: Forest trees are cut and forest areas are encroached.
9. Control of over population
The people are suggested following ways of controlling over population;
1.Education about population must be focused in the curriculum of all
grades.
2.Late marriage can help in reducing population growth.
3.Abortion is usually applied to the deliberate destruction of a foetus by
drug, which help to control over population.
4. Family planning is also main way to control population.1) natural(
coitus inter ruptus, rhythm or calendar method & 2) artificial. It is 2
types:- i) temporary ( use of condoms by male or females, use of
diaphragm-cervical caps, copper T, foam tablets, oral pills, depo-provera
or Sangini by females) ii) permanent ( tubectomy in females &
vasectomy in males).
10. Health Disorders
1) Cardiovascular disorders include following disorders of heart &
blood vessels-
a) Coronary artery disease: Coronary artery disease, also known
as coronary heart disease, is the most common type of heart disease.
It develops when the arteries that supply blood to the heart become
clogged with plaque. This causes them to harden and narrow. Plaque
contains cholesterol and other substances.
As a result, the blood supply reduces and the heart receives less oxygen
and fewer nutrients. In this time, the heart muscle weakens and there is
a risk of heart failure and arrhythmias.
When plaque builds up in the arteries, it is called atherosclerosis. Plaque
in the arteries can rupture from blockages and cause blood flow to stop,
which can lead to a heart attack.
11. b) Heart failure
When a person has heart failure, their heart is still working but not as
well as it should be. Congestive heart failure is a type of heart failure
that can occur from problems with the pumping or relaxing function.
Heart failure can result from untreated coronary artery disease, high
blood pressure, arrhythmias, and other conditions. These conditions can
affect the heart’s ability to pump or relax properly.
Heart failure can be life threatening, but seeking early treatment for
heart-related conditions can help to prevent complications.
c) Arrhythmia
Arrhythmia refers to an irregular heart beat. It occurs when the
electrical impulses that coordinate the heart beat do not work correctly.
As a result, the heart may beat too quickly, too slowly, or erratically.
There are various types of arrhythmias, including:
Tachycardia: This refers to a rapid heart beat. Bradycardia: This refers to
a slow heartbeat. Premature contractions: This refers to an early
heartbeat.Atrial fibrillation: This is a type of irregular heartbeat.
In some cases, arrhythmias can be life threatening .
12. d) Heart valve problems: It occurs when one of the four valves in
the heart doesn’t work properly. The blood can leak through the valve in
wrong direction is called regurgitation or may block the blood flow is
called stenosis or unusual heart beat is called heart murmur.
e) Stroke: It is due to lack of blood in the brain when blood clots
travelling in the blood vessels of brain or bleeding in the brain.
f) Congenital heart defects:
A congenital heart defect is also known as CHDs or defect in the
structure of heart or blood vessels . There are many types of congenital
heart defects-
Atypical heart valves: Valves may not open properly, or they may leak
blood.
Septal defects: There is a hole in the wall between either the lower
chambers or the upper chambers of the heart.
Atresia: One of the heart valves is missing.
Many congenital heart defects do not cause any noticeable symptoms
and only become apparent during a routine medical check.
13. 2. Respiratory disorders
Diseases that affect the lungs & other parts of respiratory system are
called respiratory disorders. Such diseases are caused by bacteria,
viruses & air pollutants.
a) Asthma: It is a long-term disease of the lungs. It causes airways to
get inflamed and narrow and it makes it hard to breathe.
Severe asthma can cause trouble talking or being active. Some people
refer to asthma as "bronchial asthma."
Asthma sufferers wheeze, cough, have difficulty in breathing ,
inflammation & irritation of bronchi and tighten of bronchial wall
(bronchoconstriction). Asthma is a serious disease that affects about
334 million people and 14% of children every year globally as common
chronic respiratory disease.
14. b) Chronic obstructive pulmonary disease (COPD) :
Chronic obstructive pulmonary disease (COPD) is a progressive lung
disease that is caused by the long-term exposure to the substances that
irritate & damage lungs. These substances include cigarette smoke &
other inhaled pollutants. Two main COPD are chronic bronchitis &
emphysema. About 65 million people suffer from COPD & 3 million
people die every year.
c) Chronic bronchitis: It is a long-term inflammation of bronchi &
common among smokers which ultimately get lung infections more
easily.
d) Emphysema: It is a respiratory disease in which walls of lung
alveoli are destroyed & thus exchange of gases are reduced showing of
symptoms like shortness of breath ,coughing & wheezing.
15. e) Lung cancer: It is also known as lung carcinomas or malignant lung
tumor in which uncontrolled growth of lung tissue occurs. The growth of
tissues may be beyond the lungs in other parts of the body called
metastasis. The common symptoms – coughing up blood, shortness of
breath, chest pain, weight loss etc. It can cause about 1.6 million people
every year.
f) Cystic fibrosis/ Bronchiectasis: It is a chronic abnormal lung
condition in which abnormal widening & scarring of bronchial tubes
occur. It makes the tubes hard & difficulty in moving in & out air of the
lungs. It causes persistent cough, excess sputum & recurrent pulmonary
infections.
g) Pneumonia: It is an infection of lungs in which inflammation of
lung alveoli takes place by filling with fluid or pus. Its symptoms are
cough with pus, fever ,chills & difficulty in breathing. The causative
agents of Pneumonia are bacteria & viruses. This disease can kills
millions of people annually & can cause the death among children under
the age of 5 years.
16. 3. Renal disorders
a) Chronic kidney disease :
Chronic kidney disease includes conditions that damage our kidneys and
decrease their ability to keep us healthy by filtering wastes from the
blood. If kidney become worse, wastes can build to high levels in our
blood and make us feel sick. We may develop complications like:
•high blood pressure , diabetes or high blood sugar level
•anemia (low blood count)
•weak bones
•poor nutritional health
•nerve damage
Kidney disease also increases risk of having heart and blood vessel
disease. These problems may happen slowly over a long time. Early
detection and treatment can often keep chronic kidney disease from
getting worse. When kidney disease progresses, it may eventually lead
to kidney failure or end stage of kidney disease, which requires dialysis
or a kidney transplant to maintain life.
17. b) Kidney stones:
Kidney stones (also called renal calculi, nephrolithiasis or urolithiasis)
are hard deposits made of minerals and salts that form inside our
kidneys. Kidney stones usually come out of the body during urination.
Diet, excess body weight, some medical conditions and certain
supplements and medications are the primary causes of kidney stones.
c) Polycystic kidney disease:
Polycystic kidney disease (PKD) is an inherited disorder in which
clusters of cysts develop primarily within our kidneys, causing kidneys
to enlarge and lose function over time. Cysts are non-cancerous round
sacs containing fluid. The cysts vary in size and they can grow very large.
It is caused by the abnormal genes .
d) Urinary tract infection: A urinary tract infection (UTI) is an
bacterial infection in any part of urinary system, kidneys, ureters,
bladder and urethra. Most infections are in the lower urinary tract i.e,
bladder and urethra. Women are at greater risk of developing UTI than
men. Infection to bladder can be painful and annoying. If left untreated,
infections can spread to the kidneys & thus cause kidney failure.
