Nervous System Nervous System

      The nervous system is our processing system which keeps us in contact with the outer world. Or,The nervous system is the part of human body that coordinates the voluntary action to transmit signals between the different parts of bodyOur Nervous system is made up of different nerve cells. The number of these nerve cell in a human nervous system has been estimated at 100 to 200 billion. They are basically alike in structure but appear in different lengths, sizes and shapes designed for specialized functions.

The Nervous System is divided into 2 parts-
1.The Central Nervous System (CNS)2.Peripheral Nervous System (PNS).1.The Central Nervous System (CNS)-

The CNS is a central part of Nervous system, which consists Brain and Spinal cord. Lies in well protected in bony case of Skull and spine,CNS comprises 2% of body weight (3–4 pounds).Receives 15% of blood supply

Human Brain is the Master Tissue of the Body. It is located within the skull. Brain is the largest and important aspects  and center of  Nervous system.

Human Brain weights almost 3 pounds(1.36 Kg) ,which is quite big and weighty compared to other animals except Elephant and Whale.

•Brain uses 20% of oxygen consumed by body at res

•Brain uses 50% of glucose consumed by body at rest

Or, we can call Brain as the  control room of the huge complicated telephone system of the body .It is composed of three main divisions:

                 1.The forebrain2.Mid Brain and
Hind Brain

1.The Forebrain – It is at the Very top of the Brain. Its important structures are :

vThe Thalamus

vHypothalamus

vThe Cerebrum 

a.The Thalamus- It consists two egg shape structures situated in central core of fore brain just over the brainstem. Little role in reflex action.

ØAll Sensory impulses except Smell pass through it to the higher centers. Therefore it is known as relay station. (It receives input from all incoming fibers as seeing,hearing,pressure,pain,temperature,body position, and test ,except Olfaction(Smell)

ØIt is also known as sensory switch Board because it transforms and modify the inputs before sending to other parts.

ØPlays role in Alertness and reaction. 

The Hind Brain is situated behind and under the fore brain. It connects the upper part of spinal cord with the lowest part of the brain.

It is composed of three structures.

ØMedulla

ØPons

ØCerebellum 

1.Medulla –Medulla is the bulb like structure of hind brain which is near spinal cord. It controls many important Reflex and complex process like:

Respiration, Digestion and Circulation which are necessary for the preservation of life.

Ø It controls blood pressure, heart rate, digestion, vomiting & Breathing

ØIt relays incoming information to other brain centers and outgoing message to spinal cord.

.The Pons – It connects the cerebellum at the top of the brain.

It assists the breathing, transmitting impulses from the cerebellum to the higher brain regions and coordinatinating the activities of both sides of the brain.

ØIt plays important role in arousal and sleep.

ØIt consists of respiratory centers that play role in regulating respiration .

ØIt controls salivation. 

3.The cerebellum – It is composed of two circular hemispheres . It helps in performing many bodily functions.

It is responsible for body balance and the coordination of body movements.

ØIt is responsible for body movements.

Øit co-ordinates muscles so that movement is smooth.

ØIt plays vital role in normal speech.

ØIt plays important role in learning motor skills.

ØMovements in playing basketball, football, dancing, typing and playing the piano etc are controlled by cerebellum. 

Glands

Glands- A Gland is a group of cell in organism’s body that produces chemicals.

The substances produced by glands may be Hormones or breast Milk.

Glands can be divided into two types:

1.Exocrine Glands: Exocrine glands are the type of glands which do not pour their secretion in blood. They have their ducts to pour their secretion to Target organs.

Eg- Tear Glands, Sweat Glands, Salivary Glands.

2.Endocrine Glands:

Endocrine System and its function

These glands are also known as ductless glands.

These glands secrete the chemical substances called hormones and directly pour hormones into blood or lymph system.

There are number of endocrine Glands secreting different hormones.

Such glands are responsible for controlling human behaviours.

Six different Endocrine Glands are described below:

1) Pituitary Gland: Pituitary gland is oval shaped structure lying at the base of the brain. The pituitary gland is often referred as the master gland for the hormones it produces control other endocrine secretions.

 It has two lobes called Anterior and Posterior pituitary.

a. Anterior pituitary secrets various hormones including growth hormone.

b.Posterior pituitary

Functions:

vPosterior pituitary releases hormones that regulate the absorption of  water by kidney.

vIn female the production of pituitary gland (Prolactin) plays role in production and release of milk.

2.Adrenal Gland: There are two adrenal glands located at the tip of the kidneys.

 Each adrenal gland has two parts:

A. An inner layer called Adrenal Medulla

B. Outer layer called Adrenal Cortex

Functions:

vThe secretion of Adrenal Cortex controls the body minerals and increases carbohydrate metabolism.

vSecretion of Adrenal Medulla helps to increase the sympathetic activity during emergency and prepares individual to deal with stress.

vThe adrenal cortex also makes sex hormones.

vAdrenal gland also plays role in controlling heart rate and blood pressure.

3.Thyroid gland: The thyroid gland is a brownish-red structure lying on the sides of the throat.

The secretion of thyroid gland called thyroxin is an important regulator of metabolic rate.

Functions:

vThe steady secretion of thyroxin provides for the minimum rate at which body cells take in sources of energy, consume oxygen and eliminate wastes.

vThe secretion of thyroid gland plays vital role in regulating body temperature

vThe hormone is very important for normal growth and development especially in Central nervous system.

vThyroxin also assists other organs in body in their function.

vLow level of thyroxin leads to mental retardation)

v

while high level of it produces  may lead to (over excitability, and  reduced capacity to focus upon a particular task).

4. Parathyroid gland: Parathyroid gland is a set of four small organs lying behind the thyroid gland in neck.

The parathyroid gland secretes a hormone called parathyrin that is responsible to produce calcium and phosphorus metabolism.

Function:

vparathyrin contributes for the maintaining the optimum level of calcium in body.

vDeficiency of too low level of calcium in body produces hyper excitability (may lead to seizures attacks) while too high level of calcium produces low excitability)

vThe calcium is ultimately responsible for the development of bone..

5. Gonads: The gonads is also known as sex glands, are different in men and women.

The gonad in male is called Testes and in female called Ovaries.

These glands are primarily responsible for producing sex hormones that contribute for primary and secondary sexual characteristics in men and women.

 The hormone produced by testes is called Testosterone and that produced by ovary in women are called Estrogen.

6.Pineal Gland: Pineal gland is small endocrine gland that lies within the brain between two cerebral hemispheres.

 It secrets the hormone called Melatonin.

Functions:

vIt regulates sleeping cycle.

vIt acts to keep child’s body from undergoing sexual meturation.This is supported by the fact that children with tumors of the pinal glaneal gland often reach sexual maturity unusually early in life.presumbaly because the pineal’s production of melatonin has been hampered.

Methods of sociology (Scientific methods and limitations, sociology as a science)

Sociology has been trying  to develop its own method of study. Some key methods of  sociology  are listed below

1.The comparative method

2.The historical method

3.The statistical method

4.The case study method

5.The functional method (Functionalism)

6.  The scientific method

7.  Limitation of scientific method in sociology

8.  The scientific view point

9.  Sociology is a science

10.  The sociology point of view

 The Scientific Method

•Any kind of science has its own method of study. So, being a  social science sociology has also specific scientific  methods for study

•The scientific methods consists of certain steps which are described below

1.Formulation of the problem

•A problem is the gap of knowledge, something not understood.

•Problem may be simple or complex

•Problem should define properly

•The causal  observation and  an idea regarding the  existing amount of knowledge  on the particular issue may help to define  the problem properly.

• 2.Formulation of Hypothesis

•Primary idea which guide us  in our study is the hypothesis

•It is the tentative explanation of phenomenon

•It is provisional ( temporary) supposition (belief)  which is not at proved  but is anticipated  to be correct.

•Example : There will be significant differences across gender, ethnicity and year of

experiences  of leaders and their leadership in society.

• 3. Observation and collection of data

•The formulated hypothesis will have to be tested.

•For this it is necessary to  collect facts

•In social investigation  data will be collected by  interview schedule, questionnaire, field observation etc.

4.Analysis and synthesis

• After collecting the data they must be  processed and analyzed in order to  draw proper  inferences (conclusion )

•In this step we should conduct classification of data i.e arranging the data in different groups as per their nature.

5.Generalization

• After  the data have been collected, processed and analyzed we have to draw board inferences or conclusions or generalizations.

6.Formulation of theory and law

•When a scientist successes  in describing and explaining the relation between various facts he/she has formulated a theory.

•When those facts have been tested  and accepted   by the scientist as a true mater then the theory may be properly regarded  as a law.

6. Problem of objectivity

•There is the subjective nature of social phenomenon. The social researcher  or observer is also

a component of the society. so,  in the study there is the possibility of biasness .

In conclusion

•  There is limitation of the scientific method of study of sociology. In addition to scientific

method sociology should adopt other method like comparative, statistically, social survey etc.

Sociology as a science

According to W.F.Ogburn an American, sociologist sociology is a science, according to him

science  is to be judged  by three criteria

1.The reliability of  its body of knowledge

2.The organization of knowledge  and,

3.its method

•In order to judge  whether sociology is science or not, it is necessary to examine using above

three criteria

  Methods

•Scientific methods start with problem identification and  formulating hypothesis. We

adopt this method in sociology as well though experimentation of laboratory situation is dificult

in sociology.

In conclusion

• Science is the method for discovering the truth. There are many methods and techniques in

sociology. If these are properly applied , sociology acts as a genuine science.

   Methods of Sociology

Comparative Method

•In this method, different institutions are studied in various societies in the various points of

time.

• After the study, analysis and comparison is drawn to discover new facts or relations.

•Thus it is a method of comparing various societies or groups within the same society to show

why they are similar or different in certain respects.

Historical Method

•Historical method is that approach of study that draws our attention towards details of the past.

• The classical sociologists did not have modern transport and communication system to visit

various places and naturally they had to rely more on written records than our actual

observation of the social phenomena.

•Darwin’s theory of evolution and Karl Marx’s law of economic determinism are examples of

this method.

Statistical Method

•Statistical method refers to the method that is used to measure social phenomena

mathematically.

•Statistics include collection of numerical facts relating to any field of inquiry in a systematic

matter and their analysis and interpretation.

Case Study Method

•The case study is a form of qualitative analysis. It involves very careful and complete

observation of a person, situation or institution.

•The idea behind this method is that any case being studied is representative of many similar

cases and thus it makes generalization possible.

Functional Method

•Functional method is based on an assumption that the total social system of the society is made

up of parts, which are interrelated and interdependent.•It is believed that each part has the

specialized function and any one part of the social system can be understood only in its 

relationships with other parts as well as with the whole system.