Chapter 60 - Guyton

Question 1

Portion of the nervous system that controls most visceral functions of the body.

Answer 1

autonomic nervous system (control arterial pressure, gastrointestinal motility, gastrointestinal secretion, urinary bladder emptying, sweating, body temperature, etc.)

Question 2

Organization of the Autonomic Nervous System

Answer 2

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

Question 3

Location of sympathetic ganglia vs. parasympathetic ganglia.

Answer 3

sympathetic - close to the spinal cord (short preganglionic, long postganglionic); parasympathetic - close to the visceral effector tissues (long preganglionic, short postganglionic)

Question 4

Sympathetic System - Axon Paths (3)

Answer 4

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

Question 5

Where do parasympathetic nerves originate?

Answer 5

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)`

Question 6

Sympathetic nerves release ____________ and we call these nerves ___________.

Answer 6

norepinephrine, adrenergic

Question 7

Parasympathetic nerves release ____________ and we call these nerves ___________.

Answer 7

acetylcholine, cholinergic

Question 8

Norepinephrine and epinephrine are synthesized from the amino acid ________.

Answer 8

tyrosine (tyrosine –> DOPA –> dopamine –> NE/EPI)

Question 9

What occurs after sympathetic nerves release norepinephrine?

Answer 9

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

Question 10

What occurs after parasympathetic nerves release acetylcholine?

Answer 10

Ach activates nicotinic (between pre- and post-ganglionic receptors) and muscarinic (found on all effector cells and stimulated by post-ganglionic parasympathetic fibers) receptors

Question 11

Effect of Autonomic Nervous System on the Eye

Answer 11

sympathetic - pupillary dilation; parasympathetic - pupillary restriction and accommodation of the lens (focusing)

Question 12

Effect of Autonomic Nervous System on the Glands

Answer 12

sympathetic - sweat glands; parasympathetic - nasal, lacrimal, salivary, GI glands

Question 13

Effect of Autonomic Nervous System on the GI Tract

Answer 13

sympathetic - very little effect; parasympathetic - overall activity including GI smooth muscle

Question 14

Effect of Autonomic Nervous System on the Heart

Answer 14

sympathetic - increase HR and contractility; parasympathetic - decrease HR

Question 15

Effect of Autonomic Nervous System on the Blood Vessels

Answer 15

sympathetic - vasoconstriction; parasympathetic - some vasodilation

Question 16

Function of the Adrenal Medulla

Answer 16

large sympathetic ganglion, releases EPI (80%) and NE (20%) when stimulated, stimulates cardiovascular function and metabolism, helps body deal with stress

Question 17

What is meant by sympathetic and parasympathetic tone?

Answer 17

sympathetic - normally accounts for 50% vasoconstriction; parasympathetic - provides background GI activity

Question 18

What occurs during a stress response?

Answer 18

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”)

Question 19

How do drugs affecting the sympathetic nervous system work?

Answer 19

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)

Question 20

How do drugs affecting the parasympathetic nervous system work?

Answer 20

parasympathomimetic drugs activate nicotinic (nicotine) or muscarinic receptors, potentiate effect of Ach (cholinesterase inhibitors) or block Ach (atropine)