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ANS
Autonomic nervous system: sympathetic and parasympathetic
| Question | Answer |
|---|---|
| Effectors of Somatic NS | skeletal muscle |
| Effectors of ANS | cardiac muscle, smooth muscle, glands |
| Somatic NS efferent pathways | motor neurons in CNS, axons extend in spinal nerve to effector |
| Efferent pathways in ANS | motor unit is a 2 neuron chain: preganglionic neuron sends its preganglionic axon to synapse with the ganglionic neuron in an autonomic ganglion, the postganglionic axon then extends to effector |
| Somatic neurotransmitters | All neurotransmitters are acetylcholine, all are excitatory |
| Neurotransmitters of the ANS | All preganglionic fibers release ACh, and excitatory. Postganglionic fibers release NE and ACh: they may be either inhibitory or excitatory depending on receptor type bound to |
| Parasympathetic division | "resting and digesting" D division: digestion, defacation, diuresis. Housekeeping system keeps body energy use low |
| Sympathetic division | "Fight or Flight" E division: exersize, excitement, emergency, embarrasement. Promotes optimal conditions for appropriate response to threats. Much broader, longer lasting effects. |
| Some effects of sympathetic division | dialated pupils, cold skin, sweaty palms, clammy skin |
| Most differences between somatic and ANS | besides effectors served, most are physiological |
| Ganglia | nerve cell bodies outside of CNS |
| Second neuron components | ganglionic neuron and postganglionic axon |
| Parasympathetic origin sites | craniosacral |
| Sympathetic origin sites | thoracolumbar |
| Parasympathetic length of fibers | long preganglionic, short postganglionic |
| Sympathetic length of fibers | short preganglionic, long postganglionic |
| Parasympathetic location of ganglia | visceral effector organ |
| Sympathetic location of ganglia | close to spinal cord |
| Parasympathetic cranial outflow | preganglionic fibers run in oculomotor, facial, glossopharyngeal, and vagus nerves. Only preganglionic fibers serving these areas lie in cranial nerves-- postganglionic fibers travel in trigeminal nerves to face |
| Parasympathetic oculomotor outflow | constricts pupils (for close vision), eye lenses bulge |
| Parasympathetic facial outflow | secretion by nasal glands, lacrimal glands (tears), submandibular and sublingual salivary glands |
| Parasympathetic glossopharyngeal outflow | secretion by parotid salivory glands |
| Where do postganglionic fibers of parasympathetic division travel? | They travel in trigeminal nerves to the face |
| Parasympathetic vagus outflow | Forms three plexuses. 90% of all preganglionic fibers of this division leave as a part of this nerve. Serves every organ in abdominal cavity from neck to pelvis. Including to liver, gallbladder, stomach, kidneys, pancreas, small intestine, proximal large |
| Parasympathetic sacral outflow | axons run in ventral roots of spinal nerves to ventral rami. They branch to form pelvic splanchnic nerves. Some preganglionic fibers synapse w/ganglia in plexus. Most synapse w/ganglia in walls of-- distal large intestine, bladder, ureters, reproductive o |
| Preganglionic fibers origin of sympathetic division | arise from T1- L2 (thoracolumnar division) |
| Splanchnic nerve | any ANS nerve tracks to different organs in pelvic cavity |
| Sympathetic division supplies (general): | visceral organs in internal cavities and all visceral structures in somatic parts of body |
| Visceral motor zones | preganglionic sympathetic neurons (bodies) produce lateral horns in spinal cord |
| How preganglionic fibers of sympathetic divison leave spinal cord | By ventral root, pass through a white ramus communicans to enter chain (paravertebral) ganlion. They then become part of a sympathetic chain (trunk) |
| Paravertebral ganlion | chain ganglion, this is where preganglionic fibers go after passing through white rami communicans |
| What can happen to preganglionic sympathetic axon once it reaches the chain ganglion? | 1 it can synapse w/ganglionic neuron in same chain ganglion 2 it can ascend or descend the chain to synapse in another chain ganglion 3 it can pass through chain ganglion and emerge from chain w/out synapsing |
| What happens when a preganglionic sympathetic axon passes through chain ganglion and emerges w/out synapsing? | form splanchnic nerves in pelvic region, and synapse in prevertebral or collateral ganglia |
| 5 STEPS OF SYMPATHETIC PREGANGLIONIC FIBERS PATH | 1 preganglionic fibers leave spinal cord by ventral root 2 they pass through a white ramus communicantes 3 they enter chain (paravertebral) ganglion 4 they become part of the sympathetic chain (trunk) 5 once reaching this they can do one of three things: |
| Parasympathetic ganglia | terminal ganglia |
| Sympathetic ganglia | paravertebral ganglia |
| White rami communicantes | made of preganglionic fibers (which are myelinated) |
| Gray rami communicantes | No cell bodies, just postganglionic fibers (which are unmyelinated) |
| Sympathetic division: pathways that synapse in collateral ganglia | They have dual innervation; enter and leave chain w/out synapsing, form thoracic, lumbar, and sacral splanchnic nerves and interweave abdominal aortic plexus |
| Sympathetic division: pathways that synapse in adrenal medulla | No dual innervation; some fibers of the thoracic splanchnic nerve synapse w/modified neurons in ________. Secretes NE and epinephrine |
| Visceral sensory neurons | monitor chemical changes, stretch, irritation |
| Visceral reflex arcs | same components as somatic, except they always have a two neuron motor chain |
| Visceral pain afferents travel | travel the same pathways as somatic, which creates referred pain |
| Cholinergic fibers | ACh releasin fibers. The two types are nicotinic and muscarinic receptors. |
| Adrenergic fibers | most sympathetic postganglionic axons that release NE |
| ACh and NE | not consistently excitatory or inhibitory |
| ACh release | all ANS preganglionic axons and all parasympathetic postganglionic axons at effector |
| Cholinergic receptors | bind ACh |
| Nicotinic receptors | a type of cholinergic receptor. All ganglionic neurons. Adrenal medulla. ACh binding is stimulatory. |
| Muscarinic receptors | type of cholinergic receptor. All effector cells stimulated by postganglionic cholinergic fibers. All parasympathetic targets and some sympathetic. ACh binding is excaitatory or inhibitory, depending on target. |
| Adrenergic receptors | bind NE, Alpha and Beta. Alpha binding stimulatory. Beta binding inhibitory. |
| Where lateral horns are found and why | Only in thoracic and lumbar regions, this is bc ONLY cell bodies of preganglionic motor neurons of Sympathetic division rest here |
| Parasympathetic preganglionic axons synapse ____ | in terminal ganglia |
| Blood vessel innervation | ONLY by sympathetic division |
| Postganglionic sympathetic axons travel | they enter the ventral ramus of adjoining spinal nerves by gray rami communicantes. Travel from rami to sweat glands and skin (innervate blood vessel smooth muscle as they travel). Pathways to the head travel w/cranial nerves and cervical spinal nerves. P |
| some other effects of sympathetic division | dialate pupils (see better in low light) turn off salivory and nasal glands. Innervate all sweat glands and all arector pili musles of skin. |
Created by:
hanalin2
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