THE AUTONOMIC NERVOUS SYSTEM

Nervous system divided in 1)CNS 2)PNS Peripheral Nervous sys. 

PNS: 1)Efferant division (brain to peripheral) 2)Afferant division(peripheral to brain) 

Efferant Division: Motor neurons 

1)ANS Autonomic Nervous Sys. 2)Somatic sys. 

ANS divided in

 1)ENS (Enteric nervous sys)

 2)PNS ( parasympathic nervous sys) 

3)SNS (sympathic nervous sys).

ANS : Involuntary/Visceral/Vegetative=regulates the everyday requirement of vital bodily 

function without conscious participation of mind 

Somatic SYS.: Voluntary control of functions such as contraction of skeletal muscle 

Sympathic Neurons:

👉Preganglionic neurons of sympathetic come from T1-L2 of spinal 
cord-------short compare to postganglionic neurons 

Response to stressful situation such as trauma,cold,hypoglycemia,exercise 

Fight or Flight response---release of adrenaline(epinephrine) & lesser amount of 

norepinephrinee.

Parasympathetic system: maintain the homeostatic sys in body---Rest & Digest 

Originate from Cranial nerve lll(oculomotor), Vll(facial), IX,X(vagus) and S2-S4

Reflex Arc: most of Afferent impulses involved into reflex response without involving

consciousness--- e.g Baroreceptor activate when fall in B.P 

Dual innervations: most organs of the body involves both innervations of sympathetic & 

parasympathetic division.

e.g Heart ; parasympathetic decrease heart rate sympathetic increase the heart rate

Neurotransmitter=Chemical signals involved in communication b/w nerve cells, and b/w

nerve cells & effector cells---Norepinephrine, Epinephrine, Acetylcholine, Dopamine, 

Serotonin, Histamine, GABA 

Co-transmitter: Adenosine 

Hormone : released from endocrine cells, into blood stream, travel throughout the body 

Local mediators: cells secrete the chemicals act locally in their immediate environment 

e.g Histamine, Prostaglandins 

Second Messenger: produced in response to neurotransmitter binding to receptors, 

translate the extracellular signal into response

e.g cAMP, IP3, DAG