The document provides an overview of the nervous system, detailing its organization into the central nervous system (CNS) and peripheral nervous system (PNS) and their respective components. It discusses the classifications and functions of neurons, the roles of supportive neuroglia cells, and the synaptic communication processes between neurons. The content emphasizes the essential functions of sensory and motor neurons, as well as the various types of synapses in nerve communication.

1. INTRODUCTION TO
NERVOUS SYSTEM
Prepared by,
Abhay Shripad Joshi
Assistant Professor
Yash Institute of Pharmacy, Aurangabad
abhay.joshirss@gmail.com

2. NERVOUS SYSTEM
Organization of nervous system
• CNS: (central nervous system)
- brain
- spinal cord
• (PNS) Peripheral Nervous System
- cranial nerves (12 pairs)
- spinal nerves (31 pairs)
Communication lines between CNS and the rest of body

3. NERVOUS SYSTEM
• Divisions:
- Sensory (afferent) division
• Somatic (skin, muscle, joints) and visceral (organs) sensory
neurons
• Conducts impulses from receptors to the CNS
- Motor (efferent) division
• Motor neurons
• Conducts impulses from the CNS to effectors (muscles and glands)

4. NERVOUS SYSTEM
• Motor Divisions:
• Somatic Nervous System
- Voluntary
- Conducts impulses from CNS to skeletal muscles
• Autonomic Nervous System
- Involuntary
- Conducts impulses from CNS to cardiac muscles, smooth
muscles, and glands.
- Divisions:
- Sympathetic
- Parasympathetic

5. ORGANIZATION OF NERVOUS SYSTEM

6. Nervous Tissue
• Comprise of 2 types of cells
• Neuroglia = supporting cells
• The insulators, adhesive, protectors and nourishers
• Neurons = nerve cells that transmit impulses

7. Nervous Tissue: Support Cells (Neuroglia)
• Astrocytes :
– Abundant, star-shaped cells
– Brace neurons
– Form barrier
between capillaries
and neurons
– Control the chemical
environment of
the brain

8. Nervous Tissue: Support Cells (Neuroglia)
• Microglia
- Spider-like phagocytes
- Dispose of debris
• Ependymal cells
- Line cavities of the
brain and spinal cord
- Circulate
cerebrospinal
fluid

9. Nervous Tissue: Support Cells (Neuroglia)
• Oligodendrocytes:
• Produce myelin sheath around nerve fibers in the central
nervous system

10. Figure 7.3e
Nervous Tissue: Support Cells (Neuroglia)
• Satellite cells:
• Protect neuron cell bodies
• Schwann cells:
• Form myelin sheath in the peripheral nervous system

11. NEURON
•The nervous system is
made up of more cells
than any other system.
•For instance, the brain
has about 100 billion
cells.
• There are also a
number of different
cell types, the most
important is the
neuron.

12. NEURON
• A neuron is a cell shaped like a
starfish with a long tail called an
axon. The axon of each neuron is
surrounded by a sheath called
the endoneurium. Some axons
have an additional sheath called
myelin.
• A bundle of neurons travel
together in a fascicle, and are
surrounded by perineurium.
• A bundle of fascicles is
surrounded by epineurium

13. NEURON
• All neurons do three things:
• Receive a signal: Can be any type of stimulus, depending on
what type of neuron it is (touch, vibration, light, sound,
chemicals, signal from another neuron, etc).
• Transmit a signal to another location: E.g. finger touching
something  signal to spinal cord or brain.
• Stimulate another cell:
• Another neuron  transmit signal
• Muscle  contraction
• Gland  secretion
• Blood vessel  constriction

14. Functional Classification of Neurons
• Sensory (afferent) neurons:
•Carry impulses from the sensory receptors
•Cutaneous sense organs
•Proprioceptors – detect stretch or tension
• Motor (efferent) neurons:
•Carry impulses from the central nervous system

15. Functional Classification of Neurons
• Interneurons (association neurons) :
• Found in neural pathways in the central nervous
system
• Connect sensory and motor neurons

16. Structural Classification of Neurons
• Multipolar neurons: – many extensions from the cell
body
Figure 7.8a

17. Structural Classification of Neurons
• Bipolar neurons: – one axon and one dendrite
Figure 7.8b

18. Structural Classification of Neurons
• Unipolar neurons: – have a short single process leaving the
cell body
Figure 7.8c

19. SYNAPSE
• The connection between 2 or more nerves and they are
separated by a space or cleft.

20. SYNAPTIC TERMINOLOGY
• Synapse – site where two nerves communicate with each
other.
• Presynaptic neuron – neuron that is conducting information
toward the next neuron
• Postsynaptic neuron – transmits information away from
synapse
• Most synaptic communication is via chemical messengers
(e.g. acetylcholine, serotonin, norepinephrine, dopamine,
endorphins, GABA, glycine, glutamic acid, etc.)

21. TYPES OF SYNAPSES
• Axodendritic = axon to dendrite
• Axosomatic = axon to cell body
• Axoaxonic = axon to axon

22. TYPES OF SYNAPSES

23. THANK YOU