VISCERAL FUNCTION REGULATED BY NERVOUS SYSTEM Nervous system Ⅴ

Autonomic Nervous System Parasympathetic nerve Sympathetic nerve Enteric divisions: independent nervous in GIT

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

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

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 S 2 -S 4  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

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 vessels Sweat 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 Sweat glands Striated muscle ACh SOMATIC NERVOUS SYSTEM Heart Sm. mus. Glands ACh Parasympathetic ACh E, NE Ad. M.  Heart Sm. 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: a 1, a 2, b 1 Epinephrine  Adrenal medulla, CNS  Receptors: a 1, a 2, b 1, b 2 Dopamine  Autonomic ganglia, CNS  Receptors: D (1-5), a 1, b 1 (also causes NE release)

Organ sympathetic stimulation parasympathetic stimulation Heart β 1 HR ↑ contraction ↑ HR ↓ atria contraction ↓ Blood vessel αconstriction dilation in penis and clitoris β 2 (heart and SM vessels)dilation Lungs β 2 (airway) dilation constriction GIT α, β 2 (organ) motility ↓ ↑ motility α (sphincters) contraction relaxation Urinary bladder β 2 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 cord Brain stem Hypothalamus Limbic cortex

Spinal cord Visceral reflexes  Micturition reflex  Defecation reflex

Lower brain stem

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

hunger

hypothalamus

Summary Stress response of the sympathetic system The neurotransmitter in ANS,their receptor and function Cholinergic fiber