The nervous system is made up of the central nervous system and the peripheral nervous system. The central nervous system (CNS) is made up of the brain and spinal cord. The brain controls most body functions, including awareness, movements, sensations, thoughts, speech and memory.

1. Topic- The Nervous System, Anatomy & Neuronal
Communication
Online Classes
Course
Biomedical Instrumentation
Presented by
Mr. Gaurav Pandey

2. Definition and Basic Structure of Nervous System
•The nervous system is believed to have ten thousand million
of such cells, called neurons and glia, the glia being present
in greater numbers than neurons.
•From a functional standpoint, the nervous system can be
divided into two major compartments-
(a)The somatic nervous system conveys sensory information
(touch, temperature, pain and limb position-even when
the eyes are closed) from the body segments and carries
the neural pathways that innervate and control the
movement of skeletal muscles, such as those of the arms,
fingers, legs and toes.

3. (b) The visceral nervous system controls internal organs
that are not normally under the influence of blood
vessels, the dilation and constriction of the pupils of the
eyes and so on.
•From an anatomical viewpoint, four main components
need to be identified:
(a)The Central nervous system
(b) The Peripheral nervous system including cranial
nerves, the autonomic system and the
neuroendocrine system.

4. The Neuron

5. The dendrites are finely branched processes arising near the cell
body of a neuron.
The dendrites receive excitatory or inhibitory effects via
chemical messengers called neurotransmitters.
 The cytoplasm is the material of the cell body in which the
organelles-including the cell nucleus-and other inclusions are
found . The nucleus contains the cell's chromatin, or genetic
material.
The nucleus is rich in ribonucleic acid (RNA), which is necessary
for the synthesis of protein.

6. Functions of Neuron
The normal functions of the neuron include-
protein synthesis
 axonal transport
 generation and conduction of the action potential
 synaptic transmission
formation and maintenance of the myelin.
Myelin is an insulating layer that forms around nerves,
including those in the brain and spinal cord. It is made up of
protein and fatty substances. This myelin sheath allows
electrical impulses to transmit quickly and efficiently along
the nerve cells

7. Neurotransmitter
A neurotransmitter is a chemical substance which, when released
from axon terminals by the action potential, produces the
momentary change in electrical potential when another nerve fibre
is stimulated.
Neurotransmitters stimulate or inhibit adjacent neurons or
effector organs such as muscle and glands.
Some neurological and psychiatric disorders-myasthenia gravis,
Parkinson's disease, depression, severe distortion of thought
processes such as in schizophrenia, and Alzheimer's disease.
Acetylcholine, Norepinepharine, Serotonin, Gama Amino Butyric
acid are the common neurotransmitters.

10. Reflex Arc

11. Components of a Reflex Arc
A. Receptor - reacts to a stimulus
B. Afferent pathway (sensory neuron) - conducts impulses to
the CNS
C. Interneuron - consists of one or more synapses in the CNS
(most are in the spine)
D. Efferent pathway (motor neuron) conducts impulses from
CNS to effector.
E. Effector - muscle fibers (as in the Hamstring muscle) or glands
responds by contracting or secreting a product.
Spinal reflexes - initiated and completed at the spinal cord level.
Occur without the involvement of higher brain centers.

12. Neuronal Communication
1. Within a single neuron, information is relayed
through electric signals. Ions of either positive or negative charge
cross the cell membrane, creating a potential across the cell
membrane.
2. When a neuron is resting, the charge created across the membrane
is called the resting potential, and is usually about -70 mV. This
means that the inside of the neuron is negative compared to the
outside.
3. Signals from other neurons will cause a shift in ions, or a movement
of charge. Thus, the neuron will veer away from its resting potential
to become depolarized— less negative— or hyperpolarized— more
negative.
4. When a neuron depolarizes sufficiently, it sends signals onto the next
neuron. This is the nervous system’s check – a neuron will not
propagate information until it is sufficiently depolarized.

13. 5. Communication between neurons is achieved primarily
through neurotransmitters, or small molecules that are
released into the synapse.