INTROANSvF_Bb_Arnot

Excites platelets to become activated and release

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Unformatted text preview: rgic post ganglionic neurons • Inhibits release of ACh and thus parasympathetic output – Inhibitory in the GI track • Via presynaptic mechanisms? • Excites platelets to become activated and release granules • VSM contraction – PLC & ↑Ca • VSM relaxation – CNS &/or NO Note: & receptors respond to Epi, but 2 receptors do not respond well to NE What are the consequences of this ? IV A/B. 5. Regulation of ANS Function • Dual innervation of organs • Balance between parasympathetic and sympathetic activity Dual Control: i.e. pupil diameter & control of iris muscles • Contraction of radial muscles by 1 receptors opens iris (dilates pupils) – Excitation!! • Contraction of circular muscles by muscarinic receptors closes iris (constricts pupils) Note: as one set of these muscles is stimulated and contracts, the opposing set is not stimulated and relaxes Visceral Reflexes Maintain Homeostasis Efferent branch of reflex arc is the autonomic nervous system Baroreceptor reflex IX glossopharyngeal X vagus Human Physiology, Silverthorn 15-20 The rate of baroreceptor firing depends on pressure From Berne and Levy SYMPATHETIC NT & RECEPTOR EXCEPTIONS • Some blood vessels to skeletal muscles: – ACh onto muscarinic R (dilate and increase blood flow) • Sweat glands: – ACh onto muscarinic • Adrenal Medulla –? ACh onto nicotinic R SYMPATHETIC PREGANGLIONIC FIBER ACh RECEPTOR ? ADRENAL MEDULLA nicotinic EPI INTO BLOOD Why have three different receptors on blood vessels to skeletal muscle? • Muscarinic to respond to ACh from sympathetic nerves during fight - flight – Dilation to increase blood flow • 2 to respond to Epi from adrenal medulla in fight - flight – Dilation to increase blood flow • 1 to respond to sympathetic nerves to adjust blood flow throughout the body – Constricts to decrease flow and shunt it to other areas Presynaptic Inhibition of opposing branch of the ANS Inhibition by Ach or NE On Presynaptic Receptors Presynaptic Inhibition Sympathetic nerve Effector Parasympathetic nerve Presynapt...
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