VISCERAL FUNCTION REGULATED BY NERVOUS SYSTEM Nervous system Ⅴ.

VISCERAL FUNCTION REGULATED BY NERVOUS SYSTEM

Nervous system Ⅴ

Autonomic Nervous System

Parasympathetic nerveSympathetic nerve Enteric divisions: independent nervous in GIT

Somatic and Autonomic Nervous System

Somatic and Autonomic Nervous System

Somatic Skeletal muscle

Conscious and unconscious movement

Skeletal muscle contracts

One synapse Acetylcholine

Autonomic Smooth and cardiac

muscle and glands Unconscious regulation

Target tissues stimulated or inhibited

Two synapses

preganglionic neurons: ACh

postganglionic neurons: ACh or norepinephrine

Sympathetic Division

Sympathetic Division

Preganglionic cell bodies in lateral horns of spinal cord T1-L2:release ACh

Preganglionic axons pass through ventral roots to white ramus communicans to sympathetic chain ganglia

Parasympathetic Division

Parasympathetic Division

Ⅲ，Ⅶ ，Ⅸ，Ⅹ cranial nerve : Preganglionic cell bodies in nuclei of brainstem

(mid brain , pons and medulla)Sacral region of spinal cord:

Preganglionic cell bodies in lateral parts of spinal cord gray matter from S2-S4

Postganglionic axons pass to terminal ganglia within wall of or near organ innervated

Preganglionic fiber

Postganglionic fiber

Parasympathetic and sympathetic nerve distribution

Function property of ANS

Function property of ANS

Dual innervation Exception

Most sweat glands ， arrector pili muscle ， Adrenal medulla ，kidney (sympathetic , ACh )

Salivary gland (dual but not antagonistic

Sympathetic and para-sympathetic tone Ongoing action potential activity on the both nerves Under given circumstances : one division dominate another

Function property of ANS

ANS activity characteristics Mental and physical activity : oppose each

other Sympathetic nerve activity ↑ Para-Sympathetic nerve activity ↓

Quiet condition Sympathetic nerve activity↓ Para-Sympathetic nerve activity ↑

Just like the accelerator and brake of a car

Sympathetic stress response

Effect of sympathetic and para-sympathetic in specific organ

The eyes Sympathetic : increase pupillary opening para-sympathetic: focusing of the lens

blood vesselsSweat glands (sympathetic , ACh )Salivary gland (dual but not antagonistic)

Sympathetic : small volume of thick saliva rich in mucus

para-sympathetic : large volume of watery saliva rich in enzymes

GIT Heart (parasympathetic nerve on SA node)

Neurotransmitters and receptors

Acetylcholine and Norepinephrine All preganglionic neurons are cholinergic Parasympathetic post ganglionic neurons are

cholinergic Sympathetic post ganglionic neurons are adrenergic

except sweat glands, Some blood vessels

Neurotransmitters

ACh AChSweatglands

Striatedmuscle

AChSOMATIC NERVOUS SYSTEM

HeartSm. mus.Glands

ACh AChParasympathetic

ACh E, NE

Ad. M.

HeartSm. mus.Glands

ACh NE

AUTONOMIC NERVOUS SYSTEM

Sympathetic

Acetylcholine

Nicotinic receptors Nm: skeletal muscle Nn: autonomic ganglia, CNS

Muscarinic receptors Postganglionic parasympathetic and a few sympathetic

sites, CNS (also autonomic gang.) Receptor subtypes: M1-5

Catecholamines

Norepinephrine Postganglionic sympathetic, CNS, adrenal medulla Receptors: a1, a2, b1

Epinephrine Adrenal medulla, CNS Receptors: a1, a2, b1 , b2

Dopamine Autonomic ganglia, CNS Receptors: D(1-5), a1, b1 (also causes NE release)

Organ sympathetic stimulation parasympathetic stimulation

Heart β1 HR↑ contraction ↑ HR↓atria contraction ↓

Blood vessel αconstriction dilation in penis and clitoris

β2 (heart and SM vessels)dilation

Lungs β2 (airway) dilation constriction

GIT α, β2 (organ) motility↓ ↑ motility

α (sphincters) contraction relaxation

Urinary bladder β2 relaxation contraction (emptying)

Sweat gland cholinergic , stimulating stimulating

Saliva gland α , cholinergic, stimulating stmulating Adrenal medulla cholinergic stimulation of NE, E release none

Effect of the autonomic NS on various organs

CNS control of visceral activity

Spinal cordBrain stemHypothalamusLimbic cortex

Spinal cord

Visceral reflexes Micturition reflex Defecation reflex

Lower brain stem

Hypothalamus

Hypothalamus

Vegetative and endocrine control functions

: Influence the CVS control center

Hypothalamus

Regulation of body temperature PO/AH (the preoptic area)

hypothalamus

Regulation of body water AH:brain osmoreceptor

Supraoptic nucleus:ADH

hypothalamus

hypothalamus

hypothalamus

hypothalamus

hunger

hypothalamus

Summary

Stress response of the sympathetic systemThe neurotransmitter in ANS ,their receptor

and functionCholinergic fiber