Chapter 2

Question 1

NEURON

Answer 1

a specialized cell transmitting nerve impulses; a nerve cell.

Question 2

DENDRITES

Answer 2

a short branched extension of a nerve cell, along which impulses received from other cells at synapses are transmitted to the cell body.

Question 3

CELL BODY

Answer 3

the nucleus-containing central part of a neuron exclusive of its axons and dendrites that is the major structural element of the gray matter of the brain and spinal cord, the ganglia, and the retina — called also perikaryon, soma.

Question 4

AXON

Answer 4

the long threadlike part of a nerve cell along which impulses are conducted from the cell body to other cells.

Question 5

MYELIN SHEATH

Answer 5

the insulating covering that surrounds an axon with multiple spiral layers of myelin,

Question 6

TERMINAL BUTTONS

Answer 6

Tiny bulblike structures at the end of the dendrites, which contain neurotransmitters that carry the neuron’s message into the synapse.

Question 7

NEUROTRANSMITTERS

Answer 7

a chemical substance that is released at the end of a nerve fiber by the arrival of a nerve impulse and, by diffusing across the synapse or junction, causes the transfer of the impulse to another nerve fiber, a muscle fiber, or some other structure.

Question 8

SYNAPSE

Answer 8

a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter.

Question 9

RECEPTOR

SITES

Answer 9

the part of a nerve that receives and reads chemical signals (neurotransmitters) from other nerves to transmit the electrical signals that transfer information through the brain and nervous system.

Question 10

THRESHOLD

Answer 10

the level of strength a stimulus must reach to be detected.

Question 11

ACTION POTENTIAL

Answer 11

threshold in a neuron is the point of depolarization at which the neuron fires, transmitting information to another neuron.

Question 12

ALL-OR-NONE

PRINCIPLE

Answer 12

law is a principle that states that the strength of a response of a nerve cell or muscle fiber is not dependent upon the strength of the stimulus.

Question 13

NEURAL FIRING

Answer 13

An action potential is part of the process that occurs during the firing of a neuron. During the action potential, part of the neural membrane opens to allow positively charged ions inside the cell and negatively charged ions out. … When the charge reaches +40 mv, the impulse is propagated down the nerve fiber.

Question 14

EXCITATORY

NEUROTRANSMITTERS

Answer 14

Excitatory neurotransmitters are neurotransmitters that increase the likelihood that a nerve cell will produce an action potential, an electrochemical impulse that nerve cells use to transmit signals

Question 15

INHIBITORY

NEUROTRANSMITTERS

Answer 15

A neurotransmitter that generally activates receptors that have reversal potentials more negative than threshold for action potential firing.

Question 16

ACETYLCHOLINE

Answer 16

a compound that occurs throughout the nervous system, in which it functions as a neurotransmitter.

Question 17

DOPAMINE

Answer 17

a compound present in the body as a neurotransmitter and a precursor of other substances including epinephrine.

Question 18

ENDORPHINS

Answer 18

any of a group of hormones secreted within the brain and nervous system and having a number of physiological functions. They are peptides that activate the body’s opiate receptors, causing an analgesic effect.

Question 19

SEROTONIN

Answer 19

a compound present in blood platelets and serum that constricts the blood vessels and acts as a neurotransmitter.

Question 20

AFFERENT

NEURONS

Answer 20

are pathways that carry sensory information from the body to the central nervous system (the brain and spinal cord).

Question 21

EFFERENT

NEURONS

Answer 21

are conducting cells that carry information from the central nervous system (the brain and spinal cord) to muscles and organs throughout the body.

Question 22

CENTRAL
NERVOUS
SYSTEM

Answer 22

the complex of nerve tissues that controls the activities of the body. In vertebrates it comprises the brain and spinal cord.

Question 23

SPINAL CORD

Answer 23

the cylindrical bundle of nerve fibers and associated tissue that is enclosed in the spine and connects nearly all parts of the body to the brain, with which it forms the central nervous system.

Question 24

PERIPHERAL
NERVOUS
SYSTEM

Answer 24

the nervous system outside the brain and spinal cord.

Question 25

SOMATIC NERVOUS SYSTEM

Answer 25

Major functions of the somatic nervous system include voluntary movement of the muscles and organs and reflex movements. In the process of voluntary movement, sensory neurons carry impulses to the brain and the spinal cord

Question 26

AUTONOMIC | NERVOUS SYSTEM

Answer 26

the part of the nervous system responsible for control of the bodily functions not consciously directed, such as breathing, the heartbeat, and digestive processes.

Question 27

SYMPATHETIC NERVOUS SYSTEM

Answer 27

the part of the autonomic nervous system that contains chiefly adrenergic fibers and tends to depress secretion, decrease the tone and contractility of smooth muscle, and increase heart rate — compare parasympathetic nervous system.

Question 28

PARASYMPATHETIC | NERVOUS SYSTEM

Answer 28

The part of the involuntary nervous system that serves to slow the heart rate, increase intestinal and glandular activity, and relax the sphincter muscles. The parasympathetic nervous system, together with the sympathetic nervous system, constitutes the autonomic nervous system

Question 29

LESIONS

Answer 29

a region in an organ or tissue that has suffered damage through injury or disease, such as a wound, ulcer, abscess, tumor, etc.

Question 30

ELECTROENCEPHALOGRAM

Answer 30

a test or record of brain activity produced by electroencephalography.

Question 31

COMPUTERIZED AXIAL TOMOGRAPHY

Answer 31

Tomography in which computer analysis of a series of cross-sectional scans made along a single axis of a bodily structure or tissue is used to construct a three-dimensional image of that structure.

Question 32

MAGNETIC RESONANCE IMAGING

Answer 32

a form of medical imaging that measures the response of the atomic nuclei of body tissues to high-frequency radio waves when placed in a strong magnetic field, and that produces images of the internal organs.

Question 33

POSITRON EMISSION | TOMOGRAPHY

Answer 33

positron emission tomography (PET) scan is an imaging test that helps reveal how your tissues and organs are functioning. A PET scan uses a radioactive drug (tracer) to show this activity. ... The tracer may be injected, swallowed or inhaled, depending on which organ or tissue is being studied.

Question 34

FUNCTIONAL MRI

Answer 34

Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled.

Question 35

HINDBRAIN

Answer 35

the lower part of the brainstem, comprising the cerebellum, pons, and medulla oblongata.

Question 36

MEDULLA

Answer 36

the inner region of an organ or tissue, especially when it is distinguishable from the outer region or cortex (as in a kidney, an adrenal gland, or hair).

Question 37

PONS

Answer 37

the part of the brainstem that links the medulla oblongata and the thalamus.

Question 38

CEREBELLUM

Answer 38

“Little brain” the part of the brain at the back of the skull in vertebrates. Its function is to coordinate and regulate muscular activity.

Question 39

MIDBRAIN

Answer 39

a small central part of the brainstem, developing from the middle of the primitive or embryonic brain.

Question 40

RETICULAR FORMATION

Answer 40

a diffuse network of nerve pathways in the brainstem connecting the spinal cord, cerebrum, and cerebellum, and mediating the overall level of consciousness.