Autonomic Nervous System
Order by
49 terms
Terms | Definitions |
|---|---|
 somatic nervous system | voluntary motor system: motorneuron + skeletal muscle fiber |
| CNS | brain stem or spinal cord |
| ACh and motorneurons | ACh the neurotransmitter and activates nicotinic receptors on motor end plates of skeletal muscle |
| AP in motorneuron | AP in motorneuron=>AP in muscle fiber=>muscle contraction |
| autonomic nervous system | involuntary system that controls and modulates fxns primarily of visceral organs 2 motorneurons: 1) preganglionic in CNS -synapse on postganglions 2) postganglionic in ganglia outside CNS -synapses on visceral effector organs |
| preganglionic neurons | axons are short synapse on postganglions all cholinergic bc release ACh that interact with nicotinic receptors |
| postganglionic neurons | axons are long synapses on visceral effector organs release either ACh or norepinephrine or neuropeptides |
| origins of preganglionic neurons -sympathetic -parasympathetic | sympathetic division: thoracolumbar spinal cord (T1-L3) parasympathetic division: craniosacral=>brain stem and sacral spinal cord (CN III, VII, IX, X; S2-S4) |
| adrenergic neurons | release norepinephrine |
| cholinergic neurons | release ACh |
| adrenoreceptor activation | activated by norepinephrine or epinephrine |
| NMJ vs NEJ | 1) NMJ has discrete arrangement: one motorneuron to one muscle fiber; NEJ postganglionic neurons innervate tissue in diffuse branching networks 2) NEJ target tissues can be innervated by multiple postganglionic neurons 3) in ANS postsynaptic receptors widely distributed unlike motor end plate of skeletal muscle in somatic nervous system |
| SNS overall fxn | mobilize body for activity: modulate fxns of organ systems (heart, blood vessels, GI tract, bronchi, sweat glands "fight or flight": ↑ arterial press/blood flow to active muscles/metabolic rate/blood glucose concentration/mental activity and alertness |
| varicosities | site of neurotransmitter synthesis, storage, and release in postganglionic branching networks of ANS |
| SNS organization | preganglionic neurons in thoracolumbar spinal cord=>ventral motor roots and white rami=>project to paravertebral ganglia of sympathetic chain or series of prevertebral ganglia |
| prevertebral ganglia | supplies visceral organs, glands, and enteric nervous system of GI tract celiac, superior mesenteric, inferior mesenteric |
| superior cervical ganglion projections | organs in the head, eyes, and salivary glands |
| celiac ganglion projections | stomach and small intestines |
| superior mesenteric ganglion projections | small and large intestines |
| inferior mesenteric ganglion projections | lower large intestines, anus, bladder, genitalia |
| adrenal medulla | specialized sympathetic ganglion=>preganglionic neurons located in thoracic spinal cord=>travel in greater splanchnic nerve=>synapse on chromaffin cells=>release ACh=>activate nicotinic receptors=>secrete catecholamines (*epinephrine 80%/norepinephrine 20%) |
| sympathetic postganglionic neurons | all adrenergic and act on adrenergic receptors in all effector organs EXCEPT sweat glands which are cholinergic and act on muscarinic cholinoreceptors |
| sympathetic adrenergic neurotransmitters | ATP: stored in small dense-core vesicles, binds to purinergic receptors=>acts before others norepinephrine: stored in small dense-core vesicles, causes second prolonged contraction NYP: stored in large dense-core vesicles, released with intense or higher frequency stimulation=>causes a third slower phase of contraction |
| pheochromocytoma | tumor of adrenal medulla located on or near adrenal medulla mainly secretes norepinephrine |
| fight or flight response | coordinated activation of SNS and adrenal medulla body's response to fear, extreme stress, and intense exercise ↑ HR/CO/BP/blood glucose concentration/ventilation with dilation of airways; redistributes blood flow away from skin and splanchnic regions towards skeletal muscles; ↓ GI motility and secretions |
| PNS overall fxn | restorative: to conserve NRG |
| Edinger-Westphal nucleus | located in midbrain where parasympathetic innervation of eye muscles originate=>travels to periphery through CNIII |
| CN X and parasympathetic innervation | originates in nuclei of medulla and innervates heart, bronchioles, and GI |
| parasympathetic ganglia location vs. sympathetic ganglia location | parasympathetic ganglia: near, on, or in effector organs=>preganglion axons long sympathetic ganglia: located near CNS=>preganglion axons short |
| muscarinic receptors | receptors for ACh in the effector organs of PNS |
| parasympathetic cholinergic varicosities | release ACh, VIP and NO ACh stored in small, clear vesicles VIP stored in large dense-core vesicles and released with intense or high intensity stimulation NO synthesized on demand |
| organs with only sympathetic innervation | sweat glands vascular smooth muscle pilomotor muscles of skin liver adipose tissue kidney |
| alpha-1 and alpha-2 receptor fxn | cause contraction of smooth muscles: vascular smooth muscle GI and bladder spinchters pilomotor muscles radial muscle of iris alpha-1 more common than alpha-2 (found in walls of GI and presynaptic adrenergic nerve terminals) alpha-1 relatively insensitive to catecholamines compared to beta receptors=>higher concentrations required |
| beta-1 receptor fxn | involved in metabolic fxns: glucogenesis lipolysis renin secretion all fxns of heart norepinephrine and epinephrine are equipotent agonists |
| beta-2 receptor fxn | cause relaxation of smooth muscles: bronchioles wall of GI and bladder preferentially activated by epinephrine |
| autonomic centers in hypothalamus and brain stem | hypothalamus: temp regulation, thirst, food intake midbrain: micturition center pons: pneumotaxic center (inhibits inspiration) medulla: vasomotor center (cardiovascular), respiratory center, swallowing, coughing, vomiting centers |
| alpha-1 receptor agonists/antagonists | agonists: NE, phenylephrine antagonists: phenoxybenzamine, prazosin |
| alpha-2 receptor agonists/antagonists | agonists: clonidine antagonists: yohimbime |
| beta-1 receptor agonists/antagonists | agonists: norepinephrine, isoproterenol antagonists: propanolol, metoprolol |
| beta-2 receptor agonists/antagonists | agonists: epinephrine, isoproterenol, albuterol antagonists: propanolol, butoxamine |
| nicotinic receptor agonists/antagonists | agonists: ACh, nicotine, carbachol antagonists: curare, hexamethonium (blocks ganglionic receptor NOT NMJ) |
| muscarinic receptor agonists/antagonists | agonists: ACh, muscarine, carbachol antagonists: atropine |
| G protein and autonomic receptors | autonomic receptors are coupled to G proteins G proteins are heterodimer: alpha, beta, gamma=>G protein activity resides in alpha subunit=>active when bound to GTP and inactive when bound to GDP=>has intrinsic GTPase |
| alpha-1 receptor mechanism | 1) alpha subunit of G protein binds and activates PLC 2) phopholipase C catalyzes release of diacylglycerol and IP3 from phosphatidylinositol 4,5-diphosphate 3) IP3 cause Ca2+ release from endoplasmic or sarcoplasmic reticulums=>↑ intracellular [Ca2+] 4) Ca2+ and diacylglycerol activate protein kinase C=>phosphorylate proteins that execute final physiologic actions |
| alpha-2 receptor mechanism | alpha subunit of G protein binds and inhibits adenylyl cyclase=>leads to ↓ in cAMP |
| beta receptor mechanism | alpha subunit of G protein binds and activates adenylyl cyclase=>catalyzes conversion of ATP to cAMP=>activates protein kinases=>phosphorylate proteins that execute final physiologic actions |
| epinephrine | major catecholamine released from adrenal medulla slightly more potent than norepineprhine |
| nicotinic receptor mechanisms | receptor is also a Na+ and K+ channel=>channel opens when activated by ACh=>depolarizes membrane potential has five subunits: two alpha, one beta, one delta, one gamma that form mouth around central core=>opens when ACh binds to each alpha subunit |
| muscarinic receptor mechanisms | 1) some receptors G protein-linked similar to alpha-1: binding of ACh activates alpha subunit=>activates phospholipase C=>catalyzes release of IP3 (causes release of Ca+ from endoplasmic or sarcoplasmic reticulum) and diacyglycerol=>Ca2+ and diacylglycerol activates protein kinase C=>phosphorylate proteins that execute final physiologic actions 2) some receptors act via direct action of G protein=>no 2nd messenger |
First Time Here?
Welcome to Quizlet, a fun, free place to study. Try these flashcards, find others to study, or make your own.