A&P 14: The Autonomic Nervous System

Question 1

Autonomic nervous system

Answer 1

although all body systems contribute, the stability of our internal environment depends largely on this system of motor neurons that innervates smooth and cardiac muscles and glands

Question 2

Involuntary nervous system

Answer 2

another name for the autonomic nervous system; reflects its subconscious control

Question 3

General Visceral Motor System

Answer 3

another name for the autonomic nervous system; indicates the location of most of its effectors

Question 4

Preganglionic neuron

Answer 4

the cell body of the 1st neuron in the ANS; resides in the brain or spinal cord

Question 5

Preganglionic axon

Answer 5

axon of the preganglionic neuron; synapses with the 2nd motor neuron; thin, lightly myelinated fibers

Question 6

Postganglionic (ganglionic) neuron

Answer 6

2nd motor neuron

Question 7

Autonomic ganglion

Answer 7

cell body of the 2nd motor neuron

Question 8

Postganglionic axon

Answer 8

axon of the 2nd motor neuron; extends to the effector neuron; thinner than preganglionic axons, nonmyelinated

Question 9

Acetylcholine (ACh)

Answer 9

all somatic neurons release this neurotransmitter at their synapses with skeletal muscle fibers; the effect is always excitatory; if stimulation reaches threshold, the muscle fibers contract; autonomic postganglionic fibers release this (secreted by parasympathetic fibers)

Question 10

Norepinephrine (NE)

Answer 10

autonomic postganglionic fibers release this neurotransmitter, which is secreted by most sympathetic fibers

Question 11

Dual innervation

Answer 11

while 1 division of the ANS stimulates certain smooth muscles to contract or a gland to secrete, the other division inhibits that action; the 2 divisions counterbalance each other to keep body systems running smoothly

Question 12

Parasympathetic division

Answer 12

“rest and digest system;” keeps body energy use as low as possible, even as it directs vital “housekeeping” activities like digesting food and eliminating feces and urine; blood pressure & heart rate are regulated at low normal levels, GI tract is actively digesting; pupils constrict and the lenses are accommodated for close vision

Question 13

Sympathetic division

Answer 13

“fight or flight” system; evident when we are excited or find ourselves in emergency or threatening situations; rapidly pounding heart, deep breathing, dry mouth, cold, sweaty skin, and dilated pupils

Question 14

Craniosacral division

Answer 14

another name for the parasympathetic division because its preganglionic fibers spring from opposite ends of the CNS (brain stem and the sacral region of the spinal cord)

Question 15

Terminal ganglia

Answer 15

the preganglionic axons extend from the CNS nearly all the way to the structures they innervate; there the axons synapse with postganglionic neurons located in ___ ___ that lie close to or within the target organs

Question 16

Oculomotor nerves (III)

Answer 16

innervate smooth muscles in the eyes that cause the pupils to constrict and the lenses to bulge - actions needed to focus on close objects

Question 17

Ciliary ganglia

Answer 17

the cell bodies of postganglionic neurons are in this within the eye orbits

Question 18

Facial nerves (VII)

Answer 18

the parasympathetic fibers of these nerves stimulate many large glands in the head

Question 19

Pterygopalatine ganglia

Answer 19

the preganglionic fibers synapse with postganglionic neurons in ___ ___ just posterior to the maxillae

Question 20

Glossopharyngeal nerves (IX)

Answer 20

the parasympathetics in these nerves originate in the inferior salivatory nuclei of the medulla and synapse in the otic ganglia

Question 21

Otic ganglia

Answer 21

where the glossopharyngeal nerves synapse; located just inferior to the foramen ovale of the skull

Question 22

Vagus nerves (X)

Answer 22

the two of these account for about 90% of all preganglionic parasympathetic fibers in the body; provide fibers to the neck and to nerve plexuses that serve virtually every organ in the thoracic and abdominal cavities

Question 23

Cardiac plexuses

Answer 23

supply fibers to the heart

Question 24

Pulmonary plexuses

Answer 24

serve the lungs and bronchi

Question 25

Esophageal plexuses

Answer 25

supply the esophagus

Question 26

Anterior/posterior vagal trunks

Answer 26

when the main trunks of the vagus nerves reach the esophagus, their fibers intermingle, forming these, each containing fibers from both vagus nerves

Question 27

Abdominal aortic plexus

Answer 27

formed by a number of smaller plexuses (celiac, superior mesenteric, and hypogastric) that run along the aorta

Question 28

Pelvic splanchnic nerves

Answer 28

axons of S2-4 run in the ventral roots of the spinal nerves to the ventral rami and then branch off to form these nerves, which pass through the inferior hypogastric (pelvic) plexus in the pelvic floor

Question 29

Inferior hypogastric (pelvic) plexus

Answer 29

Pelvic splanchnic nerves pass through this plexus in the pelvic floor

Question 30

Thoracolumbar division

Answer 30

another name for the sympathetic division because all of its preganglionic fibers arise from cell bodies of preganglionic neurons in spinal cord segments T1 - L2

Question 31

Lateral horns

Answer 31

the numerous preganglionic sympathetic neurons in the gray matter of the spinal cord form these structures that are just posterolateral to the ventral horns that house somatic motor neurons; there are none of these in the sacral region of the spinal cord

Question 32

White ramus communicans (pl = rami communicantes)

Answer 32

after leaving the cord through the ventral root, preganglionic sympathetic fibers pass through this

Question 33

Sympathetic trunk ganglion

Answer 33

after leaving the cord through the ventral root, preganglionic sympathetic fibers pass through white rami communicantes to enter this adjoining cluster

Question 34

Sympathetic trunk/chain

Answer 34

looks like strands of glistening white beads; flanks each side of the vertebral column; consist of the sympathetic ganglia and fibers running from 1 ganglion to another

Question 35

Collateral (prevertebral) ganglia

Answer 35

the preganglionic axon passes through the trunk ganglion and emerges from the sympathetic trunk without synapsing; these preganglionic fibers help form several splanchnic nerves and synapse in these clusters located anterior to the vertebral column; neither paired nor segmentally arranged, unlike sympathetic trunk ganglia; occur only in the abdomen and pelvis

Question 36

Gray rami communicantes

Answer 36

when synapses are made in sympathetic trunk ganglia, the postganglionic axons enter the ventral (or dorsal) ramus of the adjoining spinal nerves by way of these communicating branches; from there they travel via branches of the rami to their effectors, including sweat glands and arrector pili muscles of the skin

Question 37

Superior cervical ganglion

Answer 37

sympathetic preganglionic fibers serving the head emerge from spinal cord segments T1-4 and ascend the sympathetic trunk to synapse with postganglionic neurons in this cluster; contributes sympathetic fibers that run in several cranial nerves and in the upper 3 or 4 cervical spinal nerves; serve the skin and blood vessels of the head, stimulate the dilatory muscles of the irises of the eyes, inhibit the nasal and salivary glands, and innervate smooth (tarsal) muscle that lifts the upper eyelid; also sends direct branches to the heart

Question 38

Middle/inferior cervical ganglia

Answer 38

postganglionic fibers emerging from these clusters enter cervical nerves C4-8; some of these fibers innervate the heart via the cardiac plexus, some innervate the thyroid gland, most serve the skin

Question 39

Splanchnic nerves

Answer 39

includes thoracic ___ nerves (greater, lesser, and least), & lumbar and sacral ___ nerves; contribute to a number of interweaving nerve plexuses known collectively as the abdominal aortic plexus, which clings to the surface of the abdominal aorta

Question 40

Celiac ganglia

Answer 40

most superior of the ganglia serving the abdominopelvic viscera

Question 41

Superior mesenteric

Answer 41

middle of the ganglia serving the abdominopelvic viscera

Question 42

Inferior mesenteric

Answer 42

most inferior of the ganglia serving the abdominopelvic viscera

Question 43

Visceral sensory neurons

Answer 43

send info concerning chemical changes, stretch, and irritation of the viscera; 1st link in autonomic reflexes

Question 44

Visceral reflex arcs

Answer 44

have essentially the same components as somatic reflex arcs (receptor, sensory neuron, integration center, motor neuron, effector); however, a key difference is that a it has 2 neurons in its motor component

Question 45

Cholinergic fibers

Answer 45

fibers that release ACh

Question 46

Adrenergic fibers

Answer 46

most sympathetic postganglionic axons release NE and are called this (exception is sympathetic postganglionic fibers that secrete ACh onto sweat glands)

Question 47

Nicotinic receptors

Answer 47

type of cholinergic (ACh-binding) receptors that respond to nicotine

Question 48

Muscarinic receptors

Answer 48

type of cholinergic receptors that can be activated by the mushroom poison muscarine

Question 49

Alpha & beta adrenergic receptors

Answer 49

2 major classes of adrenergic (NE-binding) receptors

Question 50

Sympathetic (vasomotor) tone

Answer 50

with few exceptions, the vascular system is entirely innervated by sympathetic fibers that keep the blood vessels in this continual state of partial constriction

Question 51

Vasomotor fibers

Answer 51

when blood pressure is too low to maintain blood flow, the sympathetic fibers fire more rapidly, causing blood vessels to constrict (and raising blood pressure); when blood pressure becomes to high, sympathetic fibers fire less rapidly and the vessels dilate; alpha-blockers (drugs that block the response in these fibers) are sometimes used to treat hypertension

Question 52

Parasympathetic tone

Answer 52

the heart and the smooth muscle of digestive and urinary tract organs exhibit this

Question 53

Autonomic neuropathy

Answer 53

damage to autonomic nerves; common complication of diabetes mellitus; early/troubling symptom = sexual dysfunction

Question 54

Biofeedback

Answer 54

way of becoming aware of physiological conditions (such as heart rate and blood pressure) with the goal of being able to influence them consciously

Question 55

Biofeedback training

Answer 55

during this training, subjects are connected to monitoring devices that detect and amplify changes in physiological processes; feedback comes in the form of flashing lights or audible tones

Question 56

Neural crest

Answer 56

ANS structures in the PNS - postganglionic neurons, the adrenal medulla, and all autonomic ganglia - derive from this developmental structure

Question 57

Nerve growth factor (NGF)

Answer 57

protein that promotes survival and development of neurons; secreted by their target cells and many other cell types

Question 58

Orthostatic hypotension

Answer 58

fainting episodes when one stands up (low blood pressure following changes in position); occurs because aging pressure receptors become less responsive to changes in blood pressure, and aging cardiovascular centers fail to maintain healthy blood pressure