3. BIOLOGICAL BASES OF BEHAVIOR

Question 1

Define: neuron

Answer 1

cells in the nervous system that communicate with one another to perform information processing skills=

Question 2

Purpose of the cell body

Answer 2

“control center”, coordinates information-processing tasks, keeps the cell alive

Question 3

Purpose of dendrites

Answer 3

receives information from other neurons and relays to the cell body

Question 4

Purpose of axon

Answer 4

transmits information to other neurons, muscles, glandsM

Question 5

Define: myelin sheath

Answer 5

insulating layer of fatty material

Question 6

Define: glial cell

Answer 6

support cells of the nervous system

Question 7

Define: synapse

Answer 7

junction between axon of one neuron and dendrites/cell body of another neuron

Question 8

Define: motor neurons

Answer 8

neurons that carry signals from CNS (spinal cord) to PNS (muscles) to produce movement

Question 9

Define: interneurons

Answer 9

neurons connecting sensory neurons, motor neurons, other interneurons, “bridge neurons”

Question 10

Define: sensory neurons

Answer 10

contain specialized dendrites for light, sound, touch, etc.

Question 11

Functions of glial cells

Answer 11

myelin sheath, supply nourishment to neurons, help remove neurons’ waste products, provide insulation around many axons.

Question 12

Summarize Hodgkin & Huxley’s discovery about neural impulses

Answer 12

Na+ and K- flow in and out the neurons across the cell membrane at different rates, resulting in a slightly net negative charge in the neuron (more negative ions inside the cell), which causes it to store potential energy like a tiny battery

Question 13

Define: resting potential

Answer 13

stable, negative charge when the cell is inactive

Question 14

Approximate resting potential of a neuron

Answer 14

around 70 millivolts

Question 15

Describe: action potential

Answer 15

very brief shift in neuron’s electrical charge when it is stimulated (Na+ gates open and K- gates close so Na+ rushes in to make the neuron positive)

Question 16

Define; absolute refractory period

Answer 16

minimum length of time after an action potential fires, during which another action potential cannot begin (1-2 milliseconds)

Question 17

Define: All-or-None law

Answer 17

either neuron fires or it doesn’t, action potentials are all the same size (size of action potential does not change based on size of stimuli)

Question 18

Explain how neurons convey information about the strength of a stimulus

Answer 18

variance in rate

Question 19

Define: synaptic cleft

Answer 19

a microscopic gap between terminal button of one neuron and cell membrane of another (neurons do not directly touch) that signals have to cross to permit communication between neurons

Question 20

Define: presynaptic neuron

Answer 20

neuron that sends the signal across synaptic cleft

Question 21

Define: postsynaptic neuron

Answer 21

neuron that receives the signal across the synaptic cleft

Question 22

Define: neurotransmitter

Answer 22

chemicals that transmit info from one neuron to another triggered by the arrival of an action potential at an axon’s terminal buttons

Question 23

Define: synaptic vesicles

Answer 23

small sacs where neurotransmitters are stored

Question 24

Describe the process of a signal crossing the synaptic cleft

Answer 24

When the synaptic vesicle fuses with the presynaptic cell membrane, the neurotransmitters inside are released and diffuse across the synaptic cleft to reach receptor sites on the outside of the postsynaptic cell membrane, where certain neurotransmitters are allowed in

Question 25

Describe: postsynaptic potential (PSP)

Answer 25

graded (variance in size) voltage change at a receptor site on a postsynaptic cell membrane that occurs when a neurotransmitter and receptor molecule combine

Question 26

Describe: excitatory PSP

Answer 26

positive voltage shift increasing likelihood that postsynaptic neuron will fire action potentials

Question 27

Describe: inhibitory PSP

Answer 27

negative voltage shift decreasing likelihood that postsynaptic neuron will fire action potentials

Question 28

What determines the direction of the voltage shift and nature of PSP

Answer 28

which receptor sites are activated in postsynaptic neuron

Question 29

Describe: reuptake

Answer 29

neurotransmitters are absorbed from synaptic cleft by the presynaptic membrane

Question 30

Significance of reuptake

Answer 30

allows synapses to recycle their materials

Question 31

Define: synaptic pruning

Answer 31

elimination of old or less-active synapses

Question 32

How many neurons can link with an individual neuron

Answer 32

1000s

Question 32

Significance of synaptic pruning

Answer 32

major role in formation and strengthening of neural networks crucial to communication in the nervous system

Question 33

Define: terminal buttons

Answer 33

knoblike structures that branch out from an axon

Question 34

Define: neurotransmitters

Answer 34

chemicals that transmit information across the synapse to a receiving neuron’s dendrites

Question 35

List three ways that neurotransmitters respond

Answer 35

reuptake, enzyme deactivation, auto receptor binding

Question 36

____ and ___ ___ act like a lock-and-key system.

Answer 36

Neurotransmitters, receptor sites

Question 37

How are neurons interlinked

Answer 37

in complex chains, pathways, circuits, and networks

Question 38

What shapes our perceptions, thoughts, and actions?

Answer 38

patterns of neural activity in elaborate, widely distributed neural networks