Neurons

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CLASSIFICATION OF NEURON

 1. Depending upon the number of poles

 • unipolar

 • Bipolar

 • Multipolar

 2. Depending upon the function

 • Motor

 • Sensory

 3. Depenidng upon the length of Axon

 • Golgi Type I (Long axon)- to reach remote peripheral organ

 • Golgi Type II (Short Axon)- present in cerebral cortex and spinal cord.

Autonomic Nervous System (ANS)

 • Autonomic nervous system (ANS) is primarily concerned with regulation of visceral or vegetative functions of the body. So, it is also called vegetative or involuntary nervous system.

 • divided into

 1. Sympathetic division

 2. Parasympathetic division.

SYMPATHETIC DIVISION

 • It is also called thoracolumber outflow because , the preganglionic neurons are situated in lateral gray horn of 12 thoracic and first two lumber segments of spinal cord.

 • Fibers arising from here are called preganglionic fibres.

 • Preganlionic fibres leave the spinal cord through Anterior nerve root.

 • Sympathetic division supplies smooth muscles fibres of all visceral organ such as blood vessls ,heart , lung ,etc.

 SYMPATHETIC GANGLIA

 Sympathetic ganglia is classified as following:-

 A. paravertebral ganglia

 • Cervical ganglia-8 in number

 • Thoracic ganglia - 12 in number

 • Lumber ganglia - 5 in number

 • Sacral ganglia - 5 in number

 B. prevertebral ganglia

 They are situated in thorax , abdomen, and pelvis, in relation to aorta and its branches.

 Prevertebral ganglia are:-

 • Celiac ganglion

 • Superior mesentric ganglion

 • Inferior mesentric ganglion

 C. terminal ganglia

 they are situated within or close to structures invervated by them such as heart , bronchis, pancreas , urinary bladder, etc

PARA-SYMPATHETIC DIVISION:-

It is also called Craniosacral outflow because the fibres arise from brain and sacral segments of spinal cord.

 A. Midbrain Outflow

 Group of cells forming Edinger-Westphal nucelus of III cranial nerve gives rise to these fibers

 B. Bulber Outflow

 these fibres are fibres of VII, IX and X cranial nerves , which arises from nuclei present in the medulla oblongata.


Written by: RB Sah (MBBS)

Reference: K. Sembulimgan Physiology Book; Guyton and Hall Medical physiology 

Location: Kathmandu 44600, Nepal

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