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Physio > Chapter 4 > Flashcards

Chapter 4 Flashcards

1
Q

Symptoms of Epilepsy

A

Aura: a “feeling” or sensation
Abnormal movements
loss of consciousness

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2
Q

Electrical Stimulation

A

passing an electrical current from the uninsulated tip of an electrode onto a nerve produces behavior–> muscle contractoin

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3
Q

Voltmeter

A

device that measures the flow and the strength of electrical voltage by recording the difference in electrical potential between two bodies

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4
Q

Electroencephalogram (EEG)

A

can detect fluctuations in voltmeter recordings by placing electrodes on the skull

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5
Q

North Atlantic Squid

A

has “giant” axons–millimeter in diameter

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6
Q

Oscilloscope

A

device that serves as a sensitive voltmeter by registering the flow of electrons to measure voltage

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7
Q

Microelectrode

A

microscopic insulated wire or a salt-water filled glass tube of which the uninsulated tip is used to stimulate or record from neurons

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8
Q

Na

A

Sodium; positively charged

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9
Q

K

A

potassium; positively charged

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10
Q

Cl

A

chloride; negatively charged

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11
Q

A

A

protein molecules; negatively charged

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12
Q

Cations

A

positively charged ions

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13
Q

anions

A

negatively charged ions

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14
Q

Diffusion

A

movement of ions from an area of higher concentration to an area of lower concentration through random motion

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15
Q

Concentration Gradient

A

differences in concentration of a substance among regions of a container that allow the substance to diffuse from an area of higher concentration to an area of lower concentration

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16
Q

Voltage Gradient

A

difference in charge between two regions that allows a flow of current if the two regions are connected

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17
Q

Efflux

A

outward flow

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18
Q

influx

A

inward flow

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19
Q

Resting potential

A

store of potential energy in a membrane; -70mV

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20
Q

Ions in intracellular fluid

A

K+ and A-

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21
Q

Ions in the extracellular fluid

A

Na+ and Cl-

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22
Q

Maintaining Resting Potential

A
  1. membrane is mostly impermeable, leaving A- inside
  2. Ungated K+ and Cl- channels allow ions to pass freely, but gates keep Na+ out
  3. Na+ -K+ pump extrude Na+ from inside and inject K+
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23
Q

A-

A

large protein anions; manufactured inside cells; too large to leave; alone sufficient to produce a transmembrane voltage or resting potential

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24
Q

How do cells balance A-?

A

K+ cross through channels; 20:1 inside to outside to balance the A- charge; K+ gets drawn out because of the concentration gradient; not enough K+ can enter to balance it

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25
Q

Outside the cell

A

Na+ is gated outside

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26
Q

Sodium-Potassium Pump

A

protein molecule embedded in the cell membrane that escorts out Na+ ions that leak into the cell; exchange three intercellular Na+ for two K+ ions

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27
Q

Cl-

A

move in an out of the cell freely; contribute little to resting potential;

28
Q

Graded Potentials

A

small voltage fluctuations that are restricted to the vicinity on the axon where ion concentration change

29
Q

Hyperpolarization

A

increases in electrical charge across a membrane, usually due to the inward flow of Cl- or Na+ or the outward flow of K+ ions; ex. -73 mV

30
Q

Depolarization

A

decrease in electrical charge across a membrane, usually due to the inward flow of sodium ions; ex. -65 mV

31
Q

Where does hyperpolarization/depolarization take place?

A

soma (cell-body) and dendrites; these areas contain channels that can open and close

32
Q

Potassium Channels

A

for a membrane to become hyperpolarized, outside must become more positive–> efflux of K+. there is resistance to outward flow of K+–> reduce resistance for hyperpolarization

33
Q

Chloride Channels

A

hyperpolarization–> influx of Cl-. Can pass through, but more remain outside. Thus, decreased resistance to Cl- can result in brief increases of Cl- inside

34
Q

Sodium Channels

A

depolarization–> influx of Na+ by opening of normally gated Na+ channels

35
Q

Action Potential

A

large, brief reversal in the polarity of an axon; summed current changes of inflow of Na+ and outflow of K+

36
Q

Threshold Potential

A

voltage on a neural membrane at which an action potential is triggered by the opening of Na+ and K+ voltage-sensitive channels; about -50 mV relative to extracellular surroundings

37
Q

Voltage Sensitive Channels

A

closed during resting potential; open briefly when the threshold voltage is met

38
Q

How voltage sensitive channels work

A
  1. Na+ and K+ have a threshold voltage of -50 mV–> channels open if this is met
  2. Na+ open first because they are more sensitive
  3. Na+ have two gates: once membrane depolarizes to +30 one gate closes
  4. K+ open more slowly but stay open longer–> efflux reverses depolarization caused by Na+ influx
39
Q

Absolutely Refractory

A

State of an axon in the repolarizing period during which a new action potential cannot be excited because gate 2 of Na, which is not voltage sensitive, is closed

40
Q

Relatively Refractory

A

state of an axon in the later phase of an action potential during which increased electrical current is required to produce another action potential; K+ channels are still open

41
Q

of Na+ gates

A

2

42
Q

of K+ gates

A

1

43
Q

During resting potential

A

gate 1 of Na+ is closed with gate 2 open–>threshold–>gate 1 opens and gate 2 quickly closes. When BOTH are open and when 2 is closed–> absolutely refractory

44
Q

When a membrane is hyperpolarizing it is….

A

relatively refractory

45
Q

Nerve Impulse

A

propagation of an action potential on the membrane of an axon

46
Q

Refectory periods prevent…

A

action potentials from reversing direction on an axon

47
Q

Largest human axons

A

30 micrometers wide and thus are not quick to transmit information

48
Q

Glial Cells

A

speed up nerve impulses by forming meyling

49
Q

Schwann Cells

A

Glial cells in the PNS; form meylin

50
Q

Oligodendroglia

A

Glial cells in CNS; form meyling

51
Q

Node of Ranvier

A

part of axon not covered by meylin; action potential occurring at one node can trigger the opening of voltage-sensitive gates at an adjacent node

52
Q

Saltatory Conduction

A

propagation of an action potential at successive nodes of ranvier

53
Q

Excitatory Postsynaptic Potentials (EPSPs)

A

reduce the charge of the membrane toward the threshold level and increase the probability that an action potential will result

54
Q

Inhibitory Postsynaptic Potentials (IPSPs)

A

increase the charge of the membrane away from the threshold level and decrease the probability that an action potential will result

55
Q

EPSPs

A

open Na+ channels and allow an influx of Na+ ions

56
Q

IPSPs

A

open K+ channels, allow for an efflux of K+ ions OR the opening of Cl- channels and the influx of Cl-

57
Q

Temporal Summation

A

graded potentials that occur at approximately the same time on a membrane are summed

58
Q

Spatial Summation

A

graded potentials that occur at approximately the same location and time on a membrane are summed

59
Q

Will a cell fire?

A

membrane indicates the summed influences of multiple inputs (temporal and spatial summation). Neuron analyzes inputs before determining what to do–> decision made at the axon hillock

60
Q

Axon Hillock

A

region that initiates the action potential; inputs close are more influential than those further away

61
Q

To produce an action potential

A

summed graded potentials must depolarize the membrane at the axon hillock to -50 mV

62
Q

Hippocampus

A

can produce additional action potentials (depolarizing potentials) when the cell would typically be refractory

63
Q

Back Propagation

A

movement of an action potential from the axon hillock into the dendritic field; signals that the neuron is sending an action potential over the axon and may influence learning

64
Q

Stretch Sensitive Channel

A

Ion channel on a tactile sensory neuron that activates in response to stretching of the membrane, initiating a nerve impulse

65
Q

End Plate

A

on a muscle, the receptor-ion complex that is activated by the release of the neurotransmitter acetylcholine from the terminal of a motor neuron

66
Q

Transmitter-sensitive Channels

A

receptor complex that has both a receptor site for a chemical and a pore through which ions can flow

Physio (20 decks)

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