神經(jīng)系統(tǒng)對軀體運動的調(diào)節(jié)(編輯修改稿)
2025-04-16 19:56 本頁面
【文章內(nèi)容簡介】 lionic neurons Spinal Cord 腎上腺髓質(zhì) ② Parasympathetic Nervous System ? Preganglionic fibers originate in midbrain, medulla, and pons。 and in the 24 sacral levels of the spinal cord. ? Preganglionic fibers synapse in ganglia located next to or within ans innervated. ? Do not travel within spinal nerves ? Do not innervate blood vessels, sweat glands,and arrector pilli muscles (豎毛肌 ). ? 4 of 12 pairs of cranial nerves contain preganglionic parasympathetic fibers. ? Preganglionic fibers are long, postganglionic fibers are short. ? Vagus: Innervate heart, lungs, esophagus, stomach, pancreas, liver, small intestine and upper half of the large intestine. ? Preganglionic fibers from the sacral level innervate the lower half of large intestine, the rectum, urinary and reproductive systems. Parasympathetic Origin ? Nerve fibers emerge from brain amp。 sacrum 睫狀神經(jīng)節(jié) 翼腭神經(jīng)節(jié)下頜下神經(jīng)節(jié) 耳神經(jīng)節(jié) ? Ganglia close to or on target ans ? Preganglionic neurons long ? Post ganglionic neurons short ③ Sympathetic Effects ? Fight or flight response. ? Release of norepinephrine from postganglionic fibers and epinephrine from adrenal medulla. ? Mass activation prepares for intense activity. ? Heart rate increases. ? Bronchioles dilate. ? [glucose] increases. ④ Parasympathetic Effects ? Stimulation of separate parasympathetic nerves. ? Release ACh. ? Relaxing effects: ? Decrease heart rate (HR). ? Dilate blood vessels. ? Increase GI(胃腸 ) activity. ? “Fight or Flight” ? Activated during emergencies, exercise or vigorous physical activity ? Revs up body to respond to situations that upset homeostasis ? “Rest amp。 Digest” ? Reduces energy use ? Promotes: ? digestion of food ? storage of energy ? elimination of wastes ? homeostasis Sympathetic Parasympathetic 3. Organs with Dual Innervation ? Most visceral ans receive dual innervation (innervated by both sympathetic and parasympathetic fibers). ? Antagonistic effects: ? Actions counteract each other. ? Heart rate. ? Complementary: ? Produce similar effects. ? Salivary gland secretion. ? Cooperative: ? Cooperate to produce a desired effect. ? Micturition排尿 . 4. Neurotransmitters and NT Receptors ① Neurotransmitters ? ACh is NT for all preganglionic fibers of both sympathetic and parasympathetic nervous systems. ? ACh is NT released by most postganglionic parasympathetic fibers. ? Transmission at these synapses is termed cholinergic(膽堿能 ). Sympathetic Parasympathetic ? NT released by most postganglionic sympathetic nerve fibers is norepinephrine(NE,去 甲腎上腺素 ). ? Transmission at these synapses is called adrenergic(腎上腺素能 ). ? Epinephrine(E,腎上腺素 ) released by the adrenal medulla is synthesized from the same precursor as norepinephrine. ? Collectively called catecholamines(兒茶酚胺 ). 酪氨酸 二羥 (基 ) 苯丙氨酸 , 左旋多巴 多巴胺 Sympathetic ? Adrenal medulla: releases epinepherine amp。 norepinepherine into blood. ? Postganglionic neurons: release norepinepherine at target ans. ? Attention:支配汗腺、骨骼肌的交感節(jié)后舒血管纖維為膽堿能纖維。 ?Other Autonomic NTs ? Certain postganglionic autonomic axons produce their effects through other NTs. ? ATP ? VIP ? NO ② Receptors ? Found on dendrites amp。 cell bodies of postganglionic neurons of both sympathetic and parasympathetic divisions of ANS. ? Found on parasympathetic target ans. ? Found on skeletal muscle cells regulated by motor neurons. ?Cholinergic Receptors(膽堿能受體 ) A. Muscarinic receptors(M型受體，毒蕈堿型受體 ) ? On all target ans of parasympathetic ? Ach binds to receptor. ? Requires the mediation of Gproteins. ? Betagamma plex binds to chemical K+ channel, opening the channel. ? May excite or decrease activity depending on target ? Decrease HR. ? Decrease force of contraction of the heart. ? Produce bronchiole constriction. ? Increases digestive activity including secretions amp。 peristalsis. ? Causes constriction of Iris(虹膜 ) ? Blocking Agents ? Blocking agents are chemicals which bind to the receptors on target ans and prevent the normal neurotransmitter from binding. ? Blockers: Atropine(阿托品 ). B. Nicotinic receptors(N型受體，菸堿型受體 ) ? On skeletal muscle cells(N2) ? On postganglionic dendrites amp。 cell bodies in both sympathetic amp。 parasympathetic(N1) ? ACh binds to 2 nicotinic receptor binding sites. ? Opens a Na+/ K+ channel. ? Almost always excite ? Blockers: Tubocurarine(筒箭毒 ) ? Interfere with stimulatory or depressing effects of neurotransmitters by blocking the
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