Autonomic and Somatic Control of Motor Systems PDF

Motor: Autonomic and Somatic Control (Ch. 11) You should be able to: Compare and contrast the parasympathetic and sympathetic divisions of the ANS Compare and contrast adrenergic, nicotinic and muscarinic receptors Walk through the steps of activation Fight-Or-...

Motor: Autonomic and Somatic Control (Ch. 11) You should be able to: Compare and contrast the parasympathetic and sympathetic divisions of the ANS Compare and contrast adrenergic, nicotinic and muscarinic receptors Walk through the steps of activation Fight-Or-Flight-Or-Freeze at the NMJ 1  The Autonomic Nervous System includes both the parasympathetic (normal) and sympathetic (stress) divisions Cras h cours 2 e9 Autonomic control in the brain does not involve the cerebral cortex Hypothalamus Pituitary Pons 3 The autonomic ganglion is a synapse outside of the CNS 4 The autonomic nervous system uses dual- innervation to maintain tonic control Sympathetic and parasympathetic divisions excite some, inhibit others when activated 5 Some processes require both sympathetic and parasympathetic activation for completion “Point and Shoot” (penis and semen; Parasympathetic v. Sympathetic; erection & ejaculation) 6 The first autonomic synapse receptor is cholinergic (ACh), 2nd may be cholinergic or adrenergic (Epi, NorEpi) Parasympathetic: Sympathet All ACh: ic: nicotinic @ ACh ganglion (nicotinic) muscarinic @ @ target ganglion  NorEpi (adrenergi c) @ target 7 Sympathetic receptors tend to be more sensitive to norepinephrine than epinephrine Remember Cannon’s Postulate! 8 The parasympathetic division uses receptors named for their toxic agonists Parasympathetic => Parasol => mushroom => muscarinic 9 Autonomic varicosities allow coordination of multiple effector units 10 The Sympathetic Nervous System emerges from the thoracolumbar region of the spine Sympathetic = Fight-Or- Flight: Chain ganglia Collateral ganglia Adrenal medullae Sympathetic chain ganglia: (1st synapses) most ganglia close to spinal cord 11  Sympathetic activation of the adrenal medulla causes the fight-or- flight response The adrenal cortex is endocrine, the medulla is neurosecretory (like pituitary) Chromaffin cells are axon-less post- ganglionic “neurons” 12 “E” situations: Emergency, Excitement, Exercise, Embarrassment Cocaine acts as an indirect adrenergic agonist, blocking the reuptake of norepinephrine Pulp Fiction Overdose  heart attack 13  Xylazine is a non-opioid that acts as an agonist on beta1-adrenergic receptors In PA, 50,000 samples of fentanyl-laced Vasoconstriction of local blood vessels urine samples were tested, ~40% causes hypoperfusion and skin ulceration contained xylazine. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10402246/ #:~:text=Xylazine%2Dinduced%20skin%20ulcers 14 %20may,progressive%2C%20large%2C%20and%20necrotic. The parasympathetic nervous system is responsible for rest-and-digest activities Craniosacral – Nerves leave the spinal cord at top and bottom SLUD – Salivation, lacrimation, urination, defecation Ganglia – Most lie near or in target tissue Vagus nerve – Significant feature of the Parasympathetic system 15 The vagus nerve carries 75% of traffic in the parasympathetic nervous system “Wanderer” (vagabond) 75% of PS traffic; Two-way conduction Visceral sensory info Motor heart, stomach, intestines, gallbladder Vasovagal syncope: One on each side Fainting due to undue of body stimulation of vagus (sight of blood, etc.) 16 https://www.physio-pedia.com/Vagus_Nerve The neuromuscular junction (NMJ) allows the nervous system to control skeletal muscles “Soma” = body Somatic  skeletal muscles, which move the 17 At the NMJ, cholinergic receptors are non- specific monovalent (Na+, K+) channels Channels must bind 2 ACh molecules for activation 18 Exogenous toxins can interfere with acetylcholine activity at the neuromuscular junction ACh Belladonna/Atropine (Nightshade) Nicotine Mimic in CNS and PNS, Why? Anti-ACh Atropine ingestion can be fatal, yet it can be used to treat muscarine poisoning. Why? Muscarine Mimic in PNS only, WHY? 19 Curare and botulinum toxin also affect ACh efficiency at the neuromuscular junction Botulinum toxin prevents ACh release, causing flaccid paralysis Curare is a non- depolarizing competitor 20 Different toxins affect different stages of the neuromuscular junction ACh ACh ACh ACh breakdo receptor channel release wn by binding opens AChE Botulinum Curare Muscarine Nightshade/Atropine 21  Questions ? should be able You to: 1. Compare and contrast the parasympathetic and sympathetic divisions of the ANS 2. Compare and ACh relea ACh recep tor ACh chan nel ACh break down contrast se bindi ng open s by AChE adrenergic, nicotinic and muscarinic Botulinum Curare Muscarine receptors Nightshade/Atropine 3. Walk through the 22