Nervous system-Neuroglia and Synapse

1. Human Anatomy and Physiology-II
Nervous system
(Neuroglia, Synapse)
Mr N.JEGAN
Associate Professor
K.M.COLLEGE OF PHARMACY.
MADURAI.

2. Content
1.Neuroglia
2. Synapse

3. Neuroglia
Neuro - Nerve cell
Glial -Supporting cell
Cells that provide metabolic support and
immune protection for neurons
Neuroglia do not generate or conduct nerve
impulses.
Neuroglial cell present 10-15 times more than
neuron in our body.
Unlike neurons, glial cells can regenerate if injured

4. Types of neuroglial cell
There are two types neuroglial cell in our body
1.Central neuroglial cell- Present in central nervous system
a. Astrocytes
b.Ependymal Cells
c.Microglial Cells (microglia)
d.Oligodendrocytes
2.Peripheral neuroglial cell- Present in peripheral nervous system
a. Schwann cells
b. Satellite cells

6. Central neuroglial cell- Astrocytes
Structure
Astrocytes are star-shaped with fine branching
processes neuroglial cells.
It cover the cell body of neuron
Location- Brain and Spinal cord
Function
1.Supporting network in brain and spinal cord
2.play an important role in the formation of blood-brain
barrier
3. Provide calcium and potassium and regulate
neurotransmitter level in synapses.

7. Ependymal Cells
Structure
Epithelial (Cuboidal) like cell that form a single
lining layer.
Location
ventricles of the brain and the central canal
of the spinal cord.
Function
1. Production and regulation of CSF
2. Cilia in the cell circulate CSF around the CNS.

8. Microglial Cells
Structure
Microglia are the smallest neuroglial cells.
These cells are derived from monocytes and
enter the tissues of nervous system from blood
Location
Brain and spinal cord.
Function
Engulf and destroy the microorganisms and
cellular debris by means of phagocytosis in
CNS

9. Oligodendrocytes
Structure
It produce myelin sheath around the nerve
fibers in CNS.
It have only few processes, which are short.
Location
Brain and spinal cord.
Function
1. Provide myelination around the nerve fibers
in CNS
2. Provide support to the CNS neurons

10. Schwann cells
Structure
In myelinated axons of peripheral nerve, it form the
myelin sheath
Location
Axon of peripheral nerve
Function
1. Provide myelination around the nerve fibers in PNS
2. Remove cellular debris during regeneration

11. Satellite Cells
Structure
Satellite cells are small, flattened cells
Location
It is present in exterior surface of PNS
neurons.
Function
1. Provide physical support to the PNS neurons
2. Regulation of chemical environment of PNS
neurons

12. Synapse

13. Synapse
Synapse is the junction between two
neurons.
It is not an anatomical continuation.
But, it is only a physiological continuity
between two nerve cells

14. CLASSIFICATION OF SYNAPSE
Synapse is classified by two methods:
A. Anatomical classification
B. Functional classification.

15. Anatomical classification
It is formed by axon of one neuron ending on the cell body, dendrite or axon
of the next neuron.
1.Axoaxonic synapse
Axon of one neuron terminates on axon of another neuron
2. Axodendritic synapse
Axon of one neuron terminates on dendrite of another neuron
3. Axosomatic synapse
Axon of one neuron ends on soma (cell body) of another neuron

17. Functional classification
Functional classification of
synapse is on the basis of mode of
impulse transmission
1.Electrical Synapse
Physiological continuity between
the presynaptic and the postsynaptic
neurons is provided by gap junction
between the two neurons.

18. 2. Chemical synapse
It is the junction between a
nerve fiber and a muscle fiber
or between two nerve fibers,
through which the signals are
transmitted by the release of
chemical transmitter.

19. Properties Of Synapse
1.ONE WAY CONDUCTION
The impulses are transmitted only in one direction in synapse, i.e. from
presynaptic neuron to postsynaptic neuron
2. SYNAPTIC DELAY
It is a short delay that occurs during the transmission of impulses through
the synapse. It is due to the time taken for Release of neurotransmitter ,
Passage of neurotransmitter and open ion channel
3. Fatigue
Fatigue at synapse is due to the depletion of neurotransmitter substance,
acetylcholine

20. 4. SUMMATION
Summation is the fusion of effects or progressive increase in the
excitatory postsynaptic potential in post synaptic neuron when many
presynaptic excitatory terminals are stimulated simultaneously.
5. Electrical properties
Electrical properties of the synapse are the EPSP (Excitatory
postsynaptic potential)and IPSP(Inhibitory postsynaptic potential)

21. FUNCTIONS OF SYNAPSE
Main function of the synapse is to transmit the impulses, i.e. action potential
from one neuron to another.
However, some of the synapses inhibit these impulses. So the impulses
are not transmitted to the postsynaptic neuron.
Two types:
1. Excitatory synapses, which transmit the transmission impulses (excitatory
function)
2. Inhibitory synapses, which inhibit the transmission of impulses (inhibitory
function).

22. Excitatory function

23. Inhibitory function

24. Thank you