3. At the end of this Lecture You should know
Organization of Nervous System
Structural & functional unit of CNS
Glial Cells & their functions

4. The Nervous System Components Responsible for Subdivisions
Receptors
spinal cord & nerves,
Brain & cranial nerves
Responsible for
Sensory perceptions,
Muscle Contraction & Posture
Secretions of glands
Higher Intellectual functions,
Subdivisions
Central nervous system (CNS)
Peripheral nervous system (PNS)

5. Central Nervous System
Consists of
Brain
Located in cranial vault of skull
Spinal cord
Located in vertebral canal
Brain and spinal cord are Continuous with each other at foramen magnum

6. Cells of Nervous System
1.Neurons; Structural & Functional Unit of Nervous System
Receive stimuli and transmit in the form of action potentials;
2. Neuroglia or glial cells
Support and protect neurons

7. Cells of Nervous System

8. Functional Component of Neuron
Cell body or soma
Dendrites:- Input
Axons: Output

9. Peripheral Nervous System

10. Types of Neurons

11. Types of Neurons Functional classification
Sensory or afferent: Action potentials toward CNS
Motor or efferent: Action potentials away from CNS
Interneuron : Within CNS from one neuron to another

12. Types of Neurons Depending upon the length of the axon
Golgi Type I: long axons.Cell body of these neurons is in different parts of CNS and their axons reach the remote peripheral organs.
Golgi Type II: Short axons. Present in cerebral cortex and spinal cord.

13. Structural classification
Multipolar,
bipolar,
unipolar
Pseudounipolar

14. Classification of Neurons on the Basis of Structure

15. Neuroglia of CNS
Astrocytes
Ependymal cells
Microglia
Oligodendrocytes

16. Neuroglia of PNS
Schwann cells
Stellate cells

17. Neuroglia of CNS (Astrocytes)
Fibrous
Protoplasmic

18. Functions of Astrocytes
They hold the neurons together in proper spatial relationships.
Act as a scaffold to guide neurons to their proper final destination during fetal brain development.
Regulate extracellular fluid composition in the brain Sp K+
Promote tight junctions to form blood-brain barrier (BBB)

19. FUNCTIONS:
Glycogen storage and lactate
Vasomodulation
Regulate transmission of AP
Provide repairing
Promote mylination activity by Oligodendrocytes
Long term potentiation in Hippocampus

20. Ependymal Cells -Line brain ventricles and spinal cord central canal
Ependymal Cells -Line brain ventricles and spinal cord central canal. -Help to form choroid plexuses that secrete CSF

21. Neuroglia of CNS Microglia Specialized macrophages Oligodendrocytes
Form myelin sheaths of surrounding axons
Upto 50 axons can by mylinated

23. Neuroglia of Peripheral NS
Schwann cells or neurolemmocytes
Wrap around portion of only one axon to form myelin sheath
Stellate cells
Surround neuron cell bodies in dorsal root ganglia,
provide support and nutrients

24. Myelinated and Unmyelinated Axons
Myelin protects and insulates axons from one another
Not continuous
Nodes of Ranvier
Unmyelinated axons