HUMAN NERVOUS SYSTEM

1. NERVOUS SYSTEM
-ASHISH BUDHWAR

2. NERVOUS SYSTEM
 The nervous system is that part of living organisms
which coordinates its actions by transmitting signals
to and from different parts of the body.
 The nervous system detects change in the
environment that impacts the body and then works
in tandem with the endocrine system to respond to
such events.
 In vertebrates the nervous system is divided into the
Central & the Peripheral Nervous System.
 The nervous system consists fundamentally 2 types
of cells: Neurons and Glial Cells.

3. NERVOUS
SYSTEM

4. NERVOUS SYSTEM

5. CENTRAL NERVOUS SYSTEM
 It is that part of the nervous system in vertebrates
that consists of the brain and the spinal cord.
 It is named so because it integrates the received
information and coordinates and influences the
activity of all parts of the body and contains majority
of the nervous system.
 The nerves of the Peripheral Nervous System project
from the CNS. 12 nerves project from the brain
(called CRANIAL NERVES) and the rest from the
spine.

6. CRANIAL NERVES

8. CENTRAL NERVOUS SYSTEM
 The central nervous system is divided in GREY &
WHITE matter.
 The white matter (located near the sub-cortical and
the inner region of the brain & the outer area of the
spine) consists of the myelinated axons and
oligodendrocytes.
 The grey matter (located near the cortical region of
the brain and the inner region of the spine) consists
of the neurons.
 It is the MYELIN that gives he glossy white sheen to
the white matter.

9. PERIPHERAL NERVOUS SYSTEM
 The peripheral nervous system is that part of
nervous system which contains nerve cells outside
the brain and the spinal cord.
 The main function of the peripheral nervous system
is to connect the CNS to the limbs and the organs,
serving as a relay between the CNS and the rest of
the body of an organism.
 The PNS has 2 divisions namely;
1. THE SOMATIC NERVOUS SYSTEM, &
2. THE AUTONOMIC NERVOU SYSTEM.

10. SOMATIC NERVOUS SYSTEM
 The somatic nervous system is that part of the
peripheral nervous system which interacts with the
external environment.
 The somatic nervous system is composed of
1. AFFERENT(SENSORY) NERVES - which carry
sensory signals from the skin, skeletal muscles,
joints, eyes, ears, etc.. to the CNS.
2. EFFERENT(MOTOR) NERVES – which carry
signals from the CNS to the skeletal muscles.

11. AUTONOMIC NERVOUS SYSTEM
 It is that part of the peripheral nervous system that
regulates the body’s internal environment and the
organs.
 It is composed of;
1. AFFERENT (SENSORY) NERVES – which carry
sensory signals from the organs to the CNS, &
2. EFFERENT (MOTOR) NERVES – which carry
motor signals from the CNS to the internal organs
of the body.

13. AUTONOMIC NERVOUS SYSTEM
 The autonomic nervous system consists of 2 types of
EFFERENT (MOTOR) NERVES.
1. SYMPATHETIC NERVES : Autonomic motor
nerves that project from the lumbar and thoracic
region of the spine.
2. PARASYMPATHETIC NERVES : Autonomic motor
nerves that project from the brain and the sacral
region of the spine.
Both these nerves synapse on 2nd stage neurons
before reaching their target organ.

14. Sympathetic v/s Parasympathetic Nerves
 SYMPATHETIC NERVES
1. Originate from the lumbar
and thoracic region of the
spine.
2. They synapse on 2nd stage
neurons at a distance from
the target organ.
3. Stimulate, organize &
mobilize energy in conditions
of threat.
4. Indicate state of
psychological arousal.
PARA-SYMPATHETIC NERVES
1. Originate from the brain and
sacral region of the spinal
cord.
2. They synapse on 2nd stage
neurons at a closer distance
from the target organ.
3. These nerves act to conserve
energy of the organs and the
body.
4. Indicate state of
psychological relaxation.