BIO 360 - Exam 3 - Chapter 11 Summary Questions

Question 1

The efferent division of the peripheral nervous system consists of ______ ______ ______, which control skeletal muscles, and ______ ______, which control smooth muscle, cardiac muscle, many glands, lymphoid tissue, and some adipose tissue.

Answer 1

somatic motor neurons / autonomic neurons

Question 2

The autonomic division is subdivided into a ______ ______ and a ______ ______.

If you are resting quietly after a meal, the parasympathetic branch is dominant, taking command of the routine, quiet activities of day-to-day living, such as digestion. Consequently, parasympathetic neurons are sometimes said to control “rest and digest” functions.

In contrast, the sympathetic branch dominates in stressful situations, such as the potential threat from the snake. One of the most dramatic examples of sympathetic action is the fight-or-flight response, in which the brain triggers massive simultaneous sympathetic discharge throughout the body.

Answer 2

sympathetic branch / parasympathetic branch.

Question 3

The maintenance of homeostasis within the body is a balance of what three things?

Answer 3

autonomic control, endocrine control, and behavioral responses.

Question 4

The autonomic division is controlled by centers in the ______, ______, and ______. Some autonomic reflexes are spinal reflexes. Many of these can be modulated by input from the brain.

Answer 4

hypothalamus / pons / medulla

Question 5

The two autonomic branches demonstrate Cannon’s four properties of homeostasis:

Answer 5

(1) maintenance of the internal environment
(2) antagonistic control
(3) tonic control
(4) tissue responses

Question 6

In some autonomic pathways, the neurotransmitter receptor determines the response of the target tissue. For instance, most blood vessels contain one type of adrenergic receptor[p. 253] that causes smooth muscle contraction (vasoconstriction). However, some blood vessels also contain a second type of adrenergic receptor that causes smooth muscle relaxation (vasodilation). Both receptors are activated by the ______, ______ and ______[p. 204]. In these blood vessels, the ______ ______, not the chemical signal, determines the response[p. 179].

Answer 6

catecholamines / norepinephrine / epinephrine / adrenergic receptor

Question 7

All autonomic pathways are composed of a ______ ______ from the CNS that synapses with a ______ ______ in an ______ ______. Autonomic ganglia can modulate and integrate information passing through them.

Answer 7

preganglionic neuron / postganglionic neuron / autonomic ganglion

Question 8

______ is an important feature of autonomic pathways.

Answer 8

Divergence

Question 9

Most sympathetic pathways originate in the ______ and ______ regions of the spinal cord.

Most sympathetic ganglia lie either close to the spinal cord or along the ______ ______.

Answer 9

thoracic and lumbar / descending aorta

Question 10

Parasympathetic pathways originate in the ______ ______ or the ______ ______ of the spinal cord.

Parasympathetic ganglia are located on or near their ______ ______.

The major parasympathetic tract is the ______ ______ (cranial nerve X), which contains about 75% of all parasympathetic fibers. This nerve carries both sensory information from internal organs to the brain and parasympathetic output from the brain to organs.

Answer 10

brain stem / sacral region / target organs / vagus nerve

Question 11

The primary autonomic neurotransmitters are ______ and ______.

All preganglionic neurons secrete ACh onto ______ ______ receptors.

Postganglionic sympathetic neurons secrete norepinephrine onto ______ ______.

Postganglionic parasympathetic neurons secrete ACh onto ______ ______ receptors.

Answer 11

acetylcholine / norepinephrine / nicotinic cholinergic / adrenergic receptors / muscarinic cholinergic

Question 12

What is the neuroeffector junction?

Answer 12

The synapse between an autonomic neuron and its target cells.

Question 13

Neurotransmitter release follows the pattern found in other cells: ______-______-______.

Once neurotransmitters are released into the synapse, they either do one of two things…

Answer 13

depolarization—calcium signal—exocytosis

(1) diffuse through the interstitial fluid until they encounter a receptor on the target cell
(2) drift away from the synapse

Question 14

The concentration of neurotransmitter in the synapse is a major factor in autonomic control of a target: more neurotransmitter means a longer or stronger response.

The concentration of neurotransmitter in a synapse is influenced by its rate of _________ or ______ (Fig. 11.7b).

Neurotransmitter activation of its receptor terminates when the neurotransmitter…(3 things)…

The uptake of neurotransmitter by ______ allows neurons to reuse the chemicals.

Answer 14

breakdown or removal

(1) diffuses away
(2) is metabolized by enzymes in the extracellular fluid
(3) is actively transported into cells around the synapse

varicosities

Question 15

All adrenergic receptors are G protein-coupled receptors rather than ion channels[p. 173]. This means that the target cell response is slower to start and can persist for a longer time than is usually associated with the nervous system.

Question 16

Postganglionic autonomic axons end with ______ from which neurotransmitter is released.

Answer 16

varicosities

Question 17

In general, activation of ______ causes muscle contraction or secretion by exocytosis.
______ decrease intracellular cyclic AMP and cause smooth muscle relaxation (gastrointestinal tract) or decreased secretion (pancreas).

______ all increase cyclic AMP and trigger the phosphorylation of intracellular proteins. The target cell response then depends on the receptor subtype and the specific downstream pathway in the target cell.

For example, activation of ______ enhances cardiac muscle contraction, but activation of ______ relaxes smooth muscle in many tissues.

Answer 17

a1-receptors / a2-receptors / B-receptors / B1-receptors / B2-receptors

Question 18

The ______ ______ secretes epinephrine and is controlled by sympathetic preganglionic neurons.

Answer 18

adrenal medulla

Question 19

Adrenergic receptors are G protein-coupled receptors.
Alpha receptors respond most strongly to norepinephrine.

______ respond equally to norepinephrine and epinephrine.

______ are not associated with sympathetic neurons and respond most strongly to epinephrine.

______ respond most strongly to norepinephrine.

Answer 19

B1-receptors / B2-receptors / B3-receptors

Question 20

______ ______ ______, which control skeletal muscles, have a single neuron that originates in the CNS and terminates on a skeletal muscle. Somatic motor neurons are always excitatory and cause muscle contraction.

Answer 20

Somatic motor pathways

Question 21

A single _____ ______ ______ controls many muscle fibers at one time.

Somatic pathways are always excitatory, unlike autonomic pathways, which may be either excitatory or inhibitory.

The cell bodies of somatic motor neurons are located either in the ventral horn of the spinal cord[p. 282] or in the brain, with a long single axon projecting to the skeletal muscle target

Answer 21

somatic motor neuron

Question 22

The synapse of a somatic motor neuron on a muscle fiber is called the ______ ______.

The muscle cell membrane is modified into a _____ ______ ______ that contains a high concentration of nicotinic ACh receptors.

Answer 22

neuromuscular junction / motor end plate

Question 23

ACh binding to nicotinic receptor opens cation channels. Net ______ entry into the muscle fiber depolarizes the fiber. Acetylcholine in the synapse is broken down by the enzyme ______.

Answer 23

Na+ / acetylcholinesterase

Question 24

______ ______, a disease characterized by loss of ACh receptors, is the most common disorder of the neuromuscular junction.

Answer 24

Myasthenia gravis