PHYSIOEX Lab 3 - Experiments 1-9

Question 1

nervous system contains two types of cells

Answer 1

neurons and neuroglia (or glial cells)

Question 2

the receptor potential can trigger another electrical signal (called action potential) which travels where?

Answer 2

along the membrane of the sensory neurons axon to the brain

Question 3

Action potential causes the release of what

Answer 3

chemical neurotransmitters

Question 4

T/F: interneurons respond to chemical neurotrasmitters released by other neurons

Answer 4

TRUE

Question 5

Neuron has three function regions:

Answer 5

receiving region
conducting region
output region or secretory region

Question 6

cell body and dendrites of interneurons receive stimulation by neurotransmitters at structures called? and produce what?

Answer 6

chemical synapses and produce synaptic potentials

Question 7

the conducting region is usually an _______ which ends in an output region where neurotransmitter is released

Answer 7

axon

Question 8

define neuron

Answer 8

single cell surrounded by continous plasma membrane

each region contains distinct membrane proteins that provide the basis for the function differences

Question 9

Dscribe the receiving end of the neuron:

Answer 9

has receptor proteins and proteins that generate the receptor potential

Question 10

Describe the conducting region of the neuron

Answer 10

has proteins that generate and conduct action potentials

Question 11

describe the output region of the neuron

Answer 11

has proteins to package and release neurotransmitters

Question 12

T/F: ions cannot easily pass through the lipid bilayer of the plasma membrane and must pass through ion channels

Answer 12

TRUE

Question 13

Describe membrane potential:

Answer 13

it is more common to measure the potential difference, or voltage, across the membrane this membrane voltage is usually called the membrane potential

Question 14

what are the units of the membrane potential called?

Answer 14

millivolts (mV)

Question 15

Describe polarized:

Answer 15

plasma membrane can store a charge and has a relatively positive side and a relatively negative side. the membrane is polarized.

Question 16

what occurs when two sides (intracellular and extracelluar) are connected through open ion channesl?

Answer 16

current in the form of ions can flow in or out across the membrane and thus change the membrane voltage.

Question 17

For many neurons, ____ and ____ are the most important ions

Answer 17

Na+ and K+

Question 18

What is the approximate concentration of K+ inside a typical cell (intracellular concentration

Answer 18

150mM

Question 19

What is the approximate concentration of K+ outside a cell (extracellular concentration

Answer 19

5mM

Question 20

What is the approximate concentration of Na+ inside a cell (intracellular concentration

Answer 20

5mM

Question 21

What is the approximate concentration of Na+ outside a cell (extracellular concentration

Answer 21

150mM

Question 22

the sensory receptor is the ____________________________________

Answer 22

receiving end of a sensory neuron

Question 23

the sensory receptor has receptor proteins that general a signal called the

Answer 23

receptor potential

Question 24

describe sensory transduction:

Answer 24

the energy in the stimulus is changed into an electral response that involves the opening or closing of a membrane ion channel

Question 25

describe depolarization

Answer 25

if the response (receptor potential) is a change in membrane potential from the negative resting potential to a less negative level

Question 26

which of the following is a sensory modality:

Answer 26

touch, smell, sight, pain

Question 27

which of the following is a sensory stimulus

Answer 27

pressure, chemical odorants, light

Question 28

which of the ofllowing is true of the response of a sensory neuron to the appropriate sensory stimulus

Answer 28

it can be called a receptor potential, it is graded potential, it is a change in the resting membrane potential

Question 29

Describe Axon

Answer 29

long, thin structures that conduct a signal called the action potential

Question 30

in a typical multipolar neuron the axon extends from the cell body at a regionaled called:

Answer 30

axon hillock

Question 31

in a myelinated axon, the first region is called the ______

Answer 31

initial segment

Question 32

an action potential is usually initiaated at the junction of the axon hillock and the initial segment; therefore, this region is called

Answer 32

trigger zone

Question 33

in a sensory neuron, the depolarizing receptor potential spreads _______ to the __________ and produces the depolarization needed to evoke the _________

Answer 33

passively axon hillock action potential

Question 34

once an action potential is generated, it is regenerated down the membrane of the axon. the action potential is________________ or conducted, down the axon

Answer 34

propagated

Question 35

a nerve is _

Answer 35

a bundle of axons

Question 36

axons are

Answer 36

long, thin structures that extend from a neuronal cell body

Question 37

which of the following is easier:

Answer 37

extracellular recordings of the action potential

Question 38

an action potential is usually initiaed in an axon at or near:

Answer 38

the axon hillock, the initial segment, the trigger zone

Question 39

the initiation of an action potential in a sensory neron in the body normally:

Answer 39

follows a sufficiently large depolarizing receptor potential

Question 40

voltage-gated sodium channels open when

Answer 40

the membrane depolarizes

Question 41

each _____ channel that opens allows ______ to diffuse in the cell down their electrochemical gradient

Answer 41

sodium channel | Na+ ions

Question 42

voltage-gated Na+ channels are membrane channels that open:

Answer 42

when the membrane depolarizes

Question 43

when open, Na= channels allow:

Answer 43

Na+ ions to diffuse into the cell

Question 44

which of the following is true of an action potential:

Answer 44

the generation of an action potential uses voltage-gated Na+ channels, an action potential is a large, all or none change in membrane potential

Question 45

which of the following can reduce the likelihood of an action potential:

Answer 45

TTX, lidocaine, creasing the leak of K+ from a cell

Question 46

voltage-gated sodium channels in the plasma membrane of the excitable cell ______ when the membrane ________

Answer 46

open | depolarizes

Question 47

which of the following occurs after the peak of the action potential:

Answer 47

the membrane repolarizes voltage-gated K+ channels open some voltage-gated Na+ channels inactivate

Question 48

which is mean by Na+ channel inactivation

Answer 48

the Na+ channels no longer allows Na+ ions to pass through

Question 49

what happens when voltage-gated K+ channels open:

Answer 49

K+ ions can diffuse out of the cell the membrane repolarizes from the peak of the action potential it becomes harder for a subsequent stimulus to depolarize the membrane to threshold.

Question 50

it is harder to generate a second action potential soon after the first action potential because

Answer 50

some voltage-gated Na+ channels are inactivated voltage-gated K+ channels have opened the efflux of K+ ions opposes a depolarization towartd threshold

Question 51

the time after an action potential when a second action potential cannot be generated no matter how intentse the stimulus is called the

Answer 51

absolute refractory period

Question 52

the time after an action potential when a second action potential can be generated on:

Answer 52

if the stimulus intensiyt is increased is called the relative refractory period

Question 53

the term frequency refers to

Answer 53

the number of action potentials per second

Question 54

propagation/conduction occurse because

Answer 54

there are voltage-gated sodium and potassium channels located along the axon and the large depolarzation that constitues the action potential easily brings the next gion of the axon to threshold

Question 55

_________________can be easily calculated by knowing both the distance the action potential travels and the amount of time it takes

Answer 55

conduction velocity

Question 56

velocity has the units of distance per time, typically ______________

Answer 56

meters/second

Question 57

what parameters influence the conduction velocity in an axon?

Answer 57

axon diameter and amount of myelination

Question 58

myelination refers

Answer 58

to a special wrapping of tthe membrane from glial cells around the axon

Question 59

in the central nervous systems: ________ are the glial that wrap around the axon

Answer 59

oligodendorcyts

Question 60

in the peripheral nervous sytem: the ________ cells are the glial that wrap around the axon

Answer 60

schwann cells

Question 61

myelin sheaths are seperated by gaps called

Answer 61

nodes of ranvier

Question 62

an action potential can be propagated along an axon because there are

Answer 62

voltage-gated channels in the membrane

Question 63

the units of conduction velocity are

Answer 63

meters/second

Question 64

which of the following will affect axonal conduction velocity:

Answer 64

both the diameter of the axon and the amount of myelination

Question 65

which of the following describes an A fiber

Answer 65

large diameter, heavily myelinated

Question 66

which of the following describes a C fiber

Answer 66

small diameter, unmyelinated

Question 67

At the end of each axon brach there is a region called the

Answer 67

axon terminal

Question 68

describe the function ofthe axon terminal

Answer 68

to release packets of chemical neurotransmitters from small intracellular membrane-bound vesicles, called synaptic vesicles

Question 69

neuron releasing chemicals are released by exocytosis and diffuse across a small extracellular space called

Answer 69

synapic gap or synaptic deft

Question 70

region where the neurotransmitter is released from one neuron and binds to a receptor on a target cell is called

Answer 70

chemical synapse

Question 71

the change in membrane potential of the target is called a

Answer 71

synaptic potential or postsynaptic potential

Question 72

exocytosis of synaptic vesicles is normally triggered by the

Answer 72

increase in calcium ions in the axon terminal

Question 73

_____________ enters from the outside the cell through membrane calcium channels that are open dby the depolarization of an action potential

Answer 73

calcium enters

Question 74

the end of the axon where it contacts a target cell is called the

Answer 74

axon terminal

Question 75

neurotransmitter is released into the synapic gap by

Answer 75

exocytosis

Question 76

exocytosis of neurotransmitter from the axon terminal is triggered by

Answer 76

an increase in the intracellular concentration of Ca2+

Question 77

neurotransmitter released into the synaptic gap reaches the target cell by

Answer 77

diffusion

Question 78

at the target, neurotransmitter

Answer 78

binds to receptor proteins causes membrane channels to open or close causes a change in membrane potential

Question 79

Excitatory postsynapic potential is

Answer 79

graded amplitude, depending on teh amount of neurotransmitter and the number of channels it opens

Question 80

sensory neurons respond to an appropriate sensory stimulus with a change in membrane potential that is

Answer 80

graded with the stimulus intensity

Question 81

if the depolarization that reaches the axon is large and suprathreshold, the result in the axon is:

Answer 81

action potential at higher frequency

Question 82

at the axon terminal, each action potential causes the release of neurotransmitter. this neurotransmitter diffuses to the receiving end of an interneuron, where it binds to receptors and causes:

Answer 82

ion channels to open, so that the receiving end of the interneuron depolarizes

Question 83

interneurons respond to chemical stimulation with a change in membrane potential that is

Answer 83

graded with the stimulus intensity