Flashcards in Chapter 60 - Guyton Deck (20):
Portion of the nervous system that controls most visceral functions of the body.
autonomic nervous system (control arterial pressure, gastrointestinal motility, gastrointestinal secretion, urinary bladder emptying, sweating, body temperature, etc.)
Organization of the Autonomic Nervous System
cell body of preganglionic axon located in the brain stem or spinal cord, axon of the visceral motor neuron is thinly myelinated and projects to an autonomic ganglia, cell body of postganglionic neuron in the autonomic ganglia projects to visceral effector cell
Location of sympathetic ganglia vs. parasympathetic ganglia.
sympathetic - close to the spinal cord (short preganglionic, long postganglionic); parasympathetic - close to the visceral effector tissues (long preganglionic, short postganglionic)
Sympathetic System - Axon Paths (3)
1) enter the sympathetic chain via the white ramus and terminate there; 2) enter the sympathetic chain via the white ramus and ascend or descend a few segments before terminating there; 3) enter via the white ramus and exit via a splanchnic nerve and terminate in prevertebral ganglia
Where do parasympathetic nerves originate?
CN III (pupillary sphincter and ciliary muscle), CN VII (nasal, lacrimal, and submandibular glands), CN IX (parotid gland), CN X (motor to visceral organs), sacral segments (descending colon, rectum, bladder, and genitalia)`
Sympathetic nerves release ____________ and we call these nerves ___________.
Parasympathetic nerves release ____________ and we call these nerves ___________.
Norepinephrine and epinephrine are synthesized from the amino acid ________.
tyrosine (tyrosine --> DOPA --> dopamine --> NE/EPI)
What occurs after sympathetic nerves release norepinephrine?
stimulates alpha and beta adrenergic receptors, alpha receptors on blood vessels cause vasoconstriction, beta1 increases heart rate and contractility, beta2 causes bronchial dilation, dilation of blood vessels in skeletal muscles, calorigenesis, glycogenolysis
What occurs after parasympathetic nerves release acetylcholine?
Ach activates nicotinic (between pre- and post-ganglionic receptors) and muscarinic (found on all effector cells and stimulated by post-ganglionic parasympathetic fibers) receptors
Effect of Autonomic Nervous System on the Eye
sympathetic - pupillary dilation; parasympathetic - pupillary restriction and accommodation of the lens (focusing)
Effect of Autonomic Nervous System on the Glands
sympathetic - sweat glands; parasympathetic - nasal, lacrimal, salivary, GI glands
Effect of Autonomic Nervous System on the GI Tract
sympathetic - very little effect; parasympathetic - overall activity including GI smooth muscle
Effect of Autonomic Nervous System on the Heart
sympathetic - increase HR and contractility; parasympathetic - decrease HR
Effect of Autonomic Nervous System on the Blood Vessels
sympathetic - vasoconstriction; parasympathetic - some vasodilation
Function of the Adrenal Medulla
large sympathetic ganglion, releases EPI (80%) and NE (20%) when stimulated, stimulates cardiovascular function and metabolism, helps body deal with stress
What is meant by sympathetic and parasympathetic tone?
sympathetic - normally accounts for 50% vasoconstriction; parasympathetic - provides background GI activity
What occurs during a stress response?
mass sympathetic discharge, increase in arterial pressure, HR and contractility, blood flow to muscles, blood glucose, metabolic rate, muscle strength, mental activity, blood coagulation (preparing the body for vigorous activity aka "fight or flight")
How do drugs affecting the sympathetic nervous system work?
adrenergic or sympathomimetic drugs act like EPI or NE, much more prolonged effect than real thing, drugs can increase release (albuterol, phenylephrine, ephedrine, amphetamine) or block the effect (beta blockers)