- The central nervous system consists of brain and spinal cord.
- The peripheral nervous system consists of sensory and motor nerves. Motor nerves are further
divided into anotomous nervous system and somatic nervous system.
- The anotomous nervous system works independently to regulate smooth muscles, cardiac muscles
and glands.
The central nervous system:
The central nervous system is made up of brain and spinal cord.
The brain and the spinal cord is submerged in a fluid called cerebrospinal fluid for protection.
The CSF: About 150cc of cerebrospinal fluid is present in an adult. It is secreted from anterior
and posterior choroids plexus. Total volume of
CSF is 150ml. The rate of formation is 20ml/
hr. CSF can be obtained by lumber puncture.
It consists of salts, glucose, and small amount
of albumin, globulin and few traces of urea
and creatinine. It is secreted by anterior and
posterior choroid plexus in ventricles of
brain, central canal of spinal cord and space
around the brain and spinal cord. It performs
following functions.
- Acts as cushion shock absorber.
- Acts as medium for exchange of different
materials through the blood vessels.
- Keeps the brain and spinal cord moist and
exchange of substances between CSF and
nerve cells.
- It makes the brain weight less through
buoyancy. It maintains uniform pressure
around these delicate structures.
5. It nourishes the nerve cells and also acts as
buffer.
The main component of the brain and spinal
cord is the nerve cells or the neurons.
Neuron structure & classification Structure:
A neuron is an electrically excitable cell that
processes and transmits information through
electrical and chemical signals. Neurons are
the major components of the brain and spinal
cord of the central nervous system (CNS),
and of the autonomic ganglia of the peripheral
nervous system.
A neuron is a microscopic structure composed
of three major parts, namely, cell body,
dendrites and axon.
Cell Body: The cell body contains cytoplasm
with typical cell organelles and certain
granular bodies called Nissl’s granules.
