Tips and Tricks

Nervous system:It is a system of internal communication made up of nervous tissue.
The nervous system of man consists of three components:

Follow up:

1.  Central Nervous System (C.N.S)        2.  Peripheral Nervous System (P.N.S)
3.  Autonomic Nervous System (A.N.S)

CENTRAL NERVOUS SYSTEM:

It consists of Brain and Spinal cord. 

PERIPHERAL NERVOUS SYSTEM:

The nerves that come from brain and spinal cord which controls the voluntary organs are together called P.N.S.  It is also called Somatic Nervous System.

AUTONOMIC NERVOUS SYSTEM:

• The nerves that come from brain and spinal cord that controls involuntary organs are together called autonomic nervous system.

• There are 2 parts in A.N.S.

(i)  Sympathetic Nervous System        (ii) Para Sympathetic Nervous System

STRUCTURE OF HUMAN BRAIN:

• The brain is a complex mass of nervous tissue present in cranium. It weighs about 1300 gms
  

• It is covered by connective tissue membranes called meninges.  There are 3 meanings.

a)  DURAMETER – Outer membrane                  b) ARACHNOID – Middle membrane 
c)  PIAMETER – Inner vascular membrane

• The space present between arachnoid and piameter is called subarachnoid space.  The space present between Durameter and arachnoid is called sub dural space.

• The extra cellular fluid present in C.N.S is called cerebro spinal fluid (C.S.F).  It is produced by a group of  capillaries called CHOROID PLEXUS present in piameter.

• The CSF is an alkaline fluid acts as shock absorber, protects the brain from friction and act as intermediate      medium between the blood vessels and nervous tissue (CNS).

• The CSF is present in subarachnoid space, the central canal of spinal cord and four cavities present in the  brain. These cavities are called VENTRICLES

• First and second ventricles present in two cerebral hemispheres. These are called PARACOEL.

• Third ventricle present in diencephalons. It is called DIOCOEL.

• Fourth ventricle present in medulla oblongata. It is called METACOEL.

• The opening present between paracoel and diocoel is called FORAMEN OF MANRO. Diocoel opens into fourth ventricle through a passage called FORAMEN OF ITER.

• The brain consists of 4 regions.

a)  Cerebrum        b) Cerebellum        c) Medulla oblongata             and           d)  Pons varolli

CEREBRUM:

• It is the largest part of the brain.  It is incompletely divided into 2 lobes called cerebral hemispheres.

• The two cerebral hemispheres are joined by fibrous nervous tissue called CORPOUS CALLOSUM.

• The groove present between the two cerebral hemispheres is called LONGITUDINAL GROOVE.

• The cerebrum shows two regions.  
  

(1)  Grey matter        (2) White matter

• The grey matter is present towards the periphery and the white matter is present towards the centre.

• The cerebral cortex contains foldings called CONVOLUTIONS.  The elevated part of each convolution is called  Gyri.  The space present between two gyri is called Sulci.

• Each cerebral hemisphere contains 4 lobes.

a)  Frontal lobe      b) Parietal lobe     c)  Temporal lobe    d) Occipital lobe

• The fissure that separates the frontal lobe from the parietal lobe is called CENTRAL SULCUS or    FISSURE OF ROLANDO. The fissure that separates frontal lobe from temporal lobe is called LATERAL SULCUS  or FISSURE OF SYLVIAN.

• The fissure that separates parietal lobe and occipital is called PARIETO OCCIPITAL FISSURE. . FUNCTIONS:
  

1. It is the centre for voluntary movements.

2.  It is the centre for sensation such as taste, smell, pain sound, vibration and vision.

3.  It is the centre for intelligence, remembrance, recognition, learning etc.

4.  It is responsible for the function of speech which is found only in man.

DIENCEPHALON:

THALAMUS: It is called RELAY CENTRE.
HYPOTHALAMUS:

FUNCTIONS:

1. Controls autonomic nervous system

2.  Centre for homeostasis.

3.  Regulates body temperature (Thermoregulation).

4.  It controls sodium ion concentration

5.  Influences anterior pituitary

6.  It is the centre for hunger, thirst and sexual behaviour.

7. Controls water concentration (Osmoregulation)

8. Centre for involuntary movements.

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