Lecture 17

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Cell and Systems Biology
Melanie Woodin

CSB332H1S L17; March. 19, 2012  Nearly all organs innervated by ANS ANS o Innervates many glands that act on structures not directly innervated  Most often antagonistic  Non-antagonistic actions = ability of either system to: o increase glandular secretion o cause contraction of smooth muscle  depending on type of neurotransmitter released & recs present  Reading: Ch.17 Sympathetic Responses Parasympathetic Responses  Unconscious  heart rate ↑  heart rate ↓  blood pressure ↑  blood pressure ↓ Most characteristic response of ANS:  pupils dilate  protects retina from excessive  Involuntary, fight or flight responses o  see better light  Feel superhuman  empties bowel & bladder  blood is shunted to skeletal Divisions of the ANS muscles that need it  gastrointestinal motility ↑ o ex.  run faster  absorption of nutrients ↑ 1. Sym: “fight/flight” response tending to  blood glucose ↑ o reduce digestive secretions o  have more energy o speeding up the heart o contracting blood vessels  ↑blood pressure  bronchioles dilate 2. Parasym: o  larger surface area to o opposes actions of sym division ↑ O2 & CO2 transfer 3. Enteric NS: Stimulation by Sym System o controls gut (stomach) – highly complex  Fight/flight stimulation: ANS doesn’t just deal w flight-or-fight response, deals w all housekeeping o Heart – stimulated maintenance work of body: o Blood vessels – vasoconstrict o Lungs – Dilate bronchi  Exercise (divert blood to muscles, stimulate sweat glands) o Generalized responses of other body systems  Emotion (thinking of a test, trying not to panic)  Divert blood flow to vital areas, ↓ to non vital organs  Changes in body position (regulate blood pressure)  don’t pass out  Eating (reroute blood to stomach & intestines) o When have a lot of fluid intake, eaten large meal SNS  Most active when body needs to react to changes internal (ex. sit up & o  feel lethargic change blood pressure) or external envt  During rage or fright, can discharge as a unit-affecting multi-organ ANS regulates organs/processes not under conscious control including:  Circulation, digestion, respiration, temp, sweating, metabolism systems  Some endocrine gland secretions o If put into action, normally all responses occur  Sympathetic preganglionic neurons located in spinal segments T1-L3 o Myelinated axons pass thru ventral roots & form synapses in ganglia running alongside:  vertebral column (paravertebral ganglia)  peripheral ganglia  adrenal medulla o Unmyelinated axons run from these ganglia to tissue  Tends to be thrown into action as a whole, w widespread generalized conseqs for body Adrenal Medulla  Chromaffin cells in adrenal medulla receive cholinergic input (ACh) from preganglionic axons – directly from ventral roots  Secrete epinephrine, NE, peptides, ATP as hormones into bloodstream  Effect of hormonal action tends to augment sym ANS response o Can reach regions that don’t receive direct neuronal innervations  Ex. smooth muscle of bronchi  S & P are anatomically separated PNS  Read in book  More focused in its activity  Sym: axons come out of ventral roots from T1-L3  Outflow: o Paravertebral ganglia chain – relay connection, synapse onto o CN III, VII, IX, X postganglionic axons o Sacral roots S2 - S4
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