Modules 9 & 10 Neuron, Nervous Systems, Endocrine System

Question 1

neuron

Answer 1

a nerve cell; the basic building block of the nervous system.

Question 2

dentrite

Answer 2

a neuron’s bushy, branching extensions that receive messages and conduct impulses toward the cell body.

Question 3

axon

Answer 3

the neuron extension that passes messages through its branches to other neurons or to muscles or glands.

Question 4

myelin sheath

Answer 4

a fatty tissue layer segmentally encasing the axons of some neurons; enables vastly greater transmission speed as neural impulses hop from one sausage-like node to the next.

Question 5

action potential

Answer 5

a neural impulse; a brief electrical charge that travels down an axon.

Question 6

thresehold

Answer 6

the level of stimulation required to trigger a neural impulse

Question 7

synapse

Answer 7

the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or synaptic cleft.

Question 8

neurotransmitters

Answer 8

chemical messengers that cross the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.

Question 9

refractory period

Answer 9

a period of inactivity after a neuron has fired.

Question 10

all-or-none response

Answer 10

a neuron’s reaction of either firing (with a full-strength response) or not firing.

Question 11

nervous system

Answer 11

the body’s speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems.

Question 12

central nervous system (CNS)

Answer 12

the brain and spinal cord.

Question 13

peripheral nervous system (PNS)

Answer 13

the sensory and motor
neurons that connect the central nervous system (CNS) to the rest of the body.

Question 14

nerves

Answer 14

bundled axons that form neural “cables” connecting the central nervous system with muscles, glands, and sense organs.

Question 15

sensory (afferent) neurons

Answer 15

neurons that carry incoming information from the sense receptors to the central nervous system.

Question 16

motor (efferent) neurons

Answer 16

neurons that carry outgoing information from the central nervous system to the muscles and glands.

Question 17

interneurons

Answer 17

neurons within the brain and spinal cord that communicate internally and intervene between the sensory inputs and motor outputs.

Question 18

somatic nervous system

Answer 18

Sub system of the Peripheral Nervous System (PNS). Primary function is to regulate the actions of the skeletal muscles.

Question 19

autonomic nervous system (ANS)

Answer 19

the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms.

Question 20

sympathetic nervous system

Answer 20

the division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations.

Question 21

parasympathetic nervous system

Answer 21

the division of the autonomic nervous system that calms the body, conserving its energy.

Question 22

Adrenal glands

Answer 22

a pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress.

Question 23

pituitary gland

Answer 23

the endocrine system’s most influential gland.
Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands.

Question 24

endocrine system

Answer 24

the body’s “slow” chemical communication system; a set of glands that secrete hormones into the bloodstream.

Question 25

hormones

Answer 25

chemical messengers that are manufactured by the endocrine glands travel through the bloodstream and affect other tissues.

Question 26

Reuptake

Answer 26

a neurotransmitter’s reabsorption by the sending neuron.

Question 27

endorphins

Answer 27

“morphine within” -natural, opiate-like neurotransmitters linked to pain control and to pleasure.

Question 28

agonist

Answer 28

a molecule that, by binding to a receptor site, stimulates a response.

Question 29

antagonist

Answer 29

a molecule that, by binding to a receptor site, inhibits or blocks a response.