Population growth

                                    Human population growths and problems

-         History of man is only 50,000 yrs old.

-         Uses of tools, improvement in hunting and food gathering was the first revolution occurred about 20,000 yrs ago.

-         Farming and social life was second revolution occurred about 6000 yrs ago

-         Food production, industry medicine was third revolution brought about 3000 yrs ago.

-         Population is defined as total number of a species in a particular area at particular time. Population density(D) is define as D=n\at  where D is a density

                      n is number of people

                        t   is time taken present

-         Population of world is 7 billions. Study of human population is called demography. A demographer studies   birth rate death rate migration age ratio and family size etc of population.

Every nation has to pass through five stage of demographic cycle.

First stage – Both birth rate and death rate are high. B=D

Second stage- Death rate tend to fall but birth rate is same so population is extremely high at the stage .B>D

Third stage- Date rate and birth are falling.

Fourth stage- Both death rate and birth rate are law.

Fifth stage- Birth rate becomes lower than death rate. B

                        Important demographic terms

1. Birth rate (Natality)               7. Migration

2. Death rate (Mortality)                       8. Immigration

3. Sex ratio                                           9. Biotic-potential

4. Age ratio                                          10.Environment resistance

5. Zero growth rate                               11. Carrying capacity

6. Population explosion

            Population growth curves are population increases patterns. There are two types of growth curve.

A. J-shaped curved

Number of organism but growth of population stops due to different environmental resistance( frost excessive rain, change of climate etc).

In this pattern population density reaches the upper limit, remains constant at a point for a time then suddenly declines.

Examples- Growth of algae, some insects, bacteria etc.

B. S-shaped curve (sigmoid curve)

            It has three phases

i.   log phase- Little or no growth due to new habitat or environment

ii. Exponential growth phases- Growth rate is very high due to adjustment with environment.

iii. Stationary phases- growth remains constant or no growth remains mortality and natality.It is also                                 

           called zero growth.

            Example. - Growth of yeast cell and most of developed organisms including tall man

Q. Write differences between J-shaped curve and s-shaped curve

 

 Q. Mention the population 11^th census and annual growth rate in Nepal.

ð     factors of population growth are

I.                    Natality

II.                 Mortality

III.               Age distribution

IV.              Population dispersion or distribution.

V.                 Population growth or growth form.

Causes of increase in human population

1. Scientific agriculture technology- Production of food has been increased. Animal husbandry become

      Success so that people become healthy.

2.  Better public health- Be ware of health against diseases, availability of medicine increase life expectancy.

3.  Control of various epidemic diseases- malaria cholera like diseases are under control in many places.

4.  Education- Due to lack of education population is more common in rural area.

Problems of over population.

1.  Food crisis result malnutrition, poor manpower.

2.  Shortage of clothing and shelter.

3.  Shortage of drinking water.

4.  Air water and land pollution

5.  Unemployment

6.  Destruction of natural recourses.

Control of population

1.  Natural method

     i. coitus interrupts

            Insemination outside the vagina before ejaculation.

    ii. Rhythm methods

Avoid sex from 9^th to 21^st day of menstrual cycle (or one week before and one week after of menstrual cycle partner do sex)

2. Hormonal methods

            Various contraceptive have been developed by combinations of oestrogen and progesterone hormones. These are sunaulo  Gualf, Nilocan white, Kanchan Depo-Provera. These chemicals inhabit ovulation. These cause too much side effects.

3. Mechanical methods- These are cheap, safe and less side effect.

            a. Intra-uterine contraceptic devices (IUCD)

Commonly used in Nepal is copper-T. It is inserted and fitted inside the uterus. It avoids implantation of zygote on wall of endometrial.

                                                                                               b. use of condoms

.

These are special plastic rubber sheaths used by men. These are cheap, effective and no side effect. These are fitted on penis just before sexual intercourse. It also prevents the spread of STDs.

4. Chemical methods

Kamal chaki, foaming tablets etc made up of citric acid, lactic acid, potassium permanganate, zinc sulphate etc.The chemicals are introduced in vagina before sexual intercourse.

5. Surgical methods

            a.  Tubectomy or laparoscopy in female.

Both fallopian tubes are cut and ligated (tied) by simple surgical.

b. vasectomy in males

Vasa differentia are cut and ligated by simple surgery.

6. Mass communication

Messages of birth control and family planning are speeded through radio, television, newspapers, magazines hoarding board and posters. People are educated about disadvantages of over population through curriculum of school and campus levels.

                        Drugs and Diseases (Definition, types, effects, control, treatment)

Drugs are the chemical substance that modifies one or more functions of living organism.

Drug abuse

Misuse of drug is called drug abuse.

The disease that brings abnormal changes or mental illness due to smoking, drug, alcohol etc known as mental diseases. One percent of world population suffers from mental illness and ten percentages from mild mental disorders. A condition of habit or feeling compelled to take certain drugs is called drug addiction.

Drugs are either depressants or stimulants.

Depressants slow down the activity of brain. Stimulants excite the activity of brain.

Type’s and effects

i) Tranquilizers and depressants-

These lower the activities of CNS. These do not affect the working efficiency. Examples are- Equanil,                                Valium (diazepam) calm pose etc. Their excessive use causes addiction.

ii) Narcotics-These are used to free from anxiety (nervous and worried).These produce sleep and relieve

      pain. Examples are Opium, Morphine, caffeine and Heroin.                                                                                                   

iii) Psychedelic or vision producing drugs-

These effect on sense organ and cerebrum strongly. Individual may see strange colour and sound for                 nothing. Examples are LSD (Lysergic Acid diethylamide) Marijuana and Hashish.

Effects on health

1. Depressant and hypnotic:

Depressed brain and deep sleep.

2. Stimulants: Restless, and BP, heart beat appetite are affected.
3. Narcotics: Reduce respiratory and cardio-vascular activities, Cause nausea and vomiting. Supress brain activity, anxiety and fever.
4. Psychedelics hallucinogens: Damage CNS leading to suicide.

Reasons of drug addiction

1. curiosity-
2. Family history-
3. Peer pressure ( pressure of friend)-
4. Relief from pain-
5. To do more work-
6. Frustration-

Control measures

1. Hospitalization of sick or addict
2. Counseling
3. Banning of smuggling of drugs
4. Strictly implementation of law
5. Education

Alcohol addiction (Alcoholism)

Alcohol is obtained through the fermentation (decaying) of different food ( rice, millets, potati, molasses and fruits) by yeast or fungi.

Two kinds of alcohols

1. Less concentration- beer, wine etc. these are not distilled.
2. More concentrated- whiskey, brandy rum gin, vodka, etc. Distilled well

The prolonged use ( long time ) of alcohol causes dependence of body called alcohol addiction or alcoholic. Alcohol is a depressant drug.

Effects of alcoholism (symptoms)

1. CNS- loss of sensation, emotional control, visual problems, neuritis ( any projection from cell body) Amnesis (loss of memory)
2. Gastrilitis
3. Liver is highly affected
4. Increase blood pressure and mal-function of heart
5. On kidney- hyper-osmotic ( less concentration) urine
6. Lower the blood sugar level.
7. Affect on ovulation and unborn baby in women.
8. Cause family and social problems.
9. Crimes( rape, kill)

Reasons of alcohol addiction

1. feeling of independence
2. Frustrations
3. To increases confidence
4. Social pressure
5. curiosity

Controls

a. Treatment and hospitalization

b. Rehabilitation

c. psychological treatment

d. strict on laws

e. Education

Smoking

Regular consumption of tobacco in different forms (cigarette, chewing) is called smoking.

It is made from leaves of tobacco plant ( Nicotiana tobaccum and N. ristica)  

Tobacco smoking contains 4000 different chemicals. Major are nicotine cyanide, formaldehyde, tar, co etc.

Effect off nicotine

1. If nicotine is injected intravenously can kill a human.

2. stimulates the conduction of nerve impulse, secrete adrenaline.

3. BP and heart beat increase

4. Decrease the breathing capacity

Hemp Plant ( cannabis indica c. sativa)

(Ganja ko buta)

1.   Charas- resinc of c. indica

2.   Bhang- Leaf and seed of  c.indica

3.   Marijuana (hashish) - leaves and flowers tops of c. sativa

Effects (short term)

1. Senseless, confusion and fears.

2. Intense in color and sound.

3. BP and heart beat increase.

4. Red eye and dry mouth.

Long term effects

1. cancer- tobacco is carcinogenic c to form cancerous cell). It cause oral cancer and lung cancer

2. Bronchitis- Reduce lung is gaseous exchange capacity.

3. Emphysema- breakdown of wall of alveolar wall during coughing so reduce the gaseous exchange.

4. Heart diseases- Nicotine constrict blood vessel result increase of heart beats.

5. Birth defects- In a pregnant woman it causes low birth weight, metal disability and damage of internal organ.

6. Duodenal ulcers, tuberculosis and lack of o₂ in blood.

Controls

 Same like alcoholism.