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Biology 201 > Topic F > Flashcards

Topic F Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What are the four proteins needed for an action potential to occur?

A
  • Na+ and K+ pumps
  • K+ Leak Channels
  • Voltage-gated K+ Channels
  • Voltage gated Na+ Channels
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2
Q

What are the parts of a neuron?

A
  • cell body
  • dendrites
  • axon (less than 1mm to more than 1m long)
  • terminal branches of axons
  • nerve terminal
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3
Q

What is the “usual” resting membrane potential

A

-70.0mV

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4
Q

An axon at resting membrane potential is more _____ on the inside and more ____ on the outside

A

negative; positive`

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5
Q

What is the resting membrane potential maintained by?

A
  • Na+ & K+ pumps

- K+ Leak channels

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6
Q

Potassium channels are ______

A

Homotetramers

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7
Q

Sodium channels are ____ with ___ number of domains

A

monomers; 4

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8
Q

K+/Na+ channels in a neuron axon – Characteristics

A

shape: Channel
Energy - passive
Direction - uniport
Regulation: gated

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9
Q

Na+ channels open _____ in comparison to K+ channels when the membrane potential changes

A

Quicker

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10
Q

K+/ Na+ channels open at a membrane potential of ____

A

above -40 mv
(+) at the cytosol
(-) inside the neuron
Plasma membrane is depolarized

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11
Q

K+/ Na+ channels close at a membrane potential of ____

A

below -40 mv
(-) at the cytosol
(+) at inside the neuron
Plasma membrane is at rest

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12
Q

how do K+/ Na+ channels open

A

Gates of channels are wings that can rotate; (+) part of the wing moves towards (-) environment

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13
Q

What are the three phases of a sodium channel

A
  • Closed: Plasma membrane at rest
  • open: Membrane ois depolarized
  • inactivated: Membrane is at refractory
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14
Q

What is the inactived stage of a voltage gated Na+ channel

A

(-) inside the neuron
(+) at inside the cytosol
membrane Refractory

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15
Q

Activity of Na+/K+ pumps

A

(few)

Always working

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16
Q

Activity of K+ leak channels

A

Open and close randomly (few)

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17
Q

Activity of Voltage gated K+ channels

A

close, open, close

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18
Q

Activity of Voltage gated Na+ channels

A

close, open, inactivate, close

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19
Q

What are the stages of an action potential

A

1) Subthreshold depolarization
2) Threshold depolarization
3) Depolarization Phase
4) Repolarization Phase
5) Refractory Period

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20
Q

Subthreshold depolarization

A

@ resting membrane potential

1 Na+ channel opens nothing happens b/c of the K+ leak channels thats already open

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21
Q

Threshold depolarization

A

Several Na+ channels open, an influx of Na+ overcomes the outflow of K+ allowing the threshold membrane potential to be reached (-40mV).

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22
Q

Depolarization phase

A

Once threshold membrane potential is reached (-40mV), all the Na+ channels open, Membrane potential rises to +40mV.

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23
Q

Repolarization Phase

A

Na+ channels inactivate, K+ channels open, this drives the membrane pot. back down

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24
Q

Refractory Period

A

nothing can happened b/c Na+ channels are inactive, K+ channels open
After Membrane potential is below -40mV for a time Na+ and K+ channels close

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25
Q

How does an AP travel on a regular axon

A
  • voltage gated sodium channels allow Na+ to go into axon deploarizing the membrane causing passive depolarization to spread, which is followed by an outflow of K+ ions into the cytosol
    Speed of travel – ~5m/s
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26
Q

How does an AP travel on a giant axon

A

Larger diameters of axons – quicker APs
Found in large invertebrates
Speed – ~100m/s

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27
Q

How does an AP travel on a myelinated axon

A

myelinated cells (myelin sheath) that wrap around the neurons axon insulating it
AP “jumps” between nodes of ranvier
speed ~100m/s

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28
Q

what is the function of SNAREs in Presynaptic Neurones

A

Activated by Ca+ (indirectly)

fusses synaptic versicle with presynaptic membrane

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29
Q

what is the function of Vesicles in Presynaptic Neurones

A

Carry neurotransmitters to presynaptic membrane

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30
Q

what is the function of SNAREs in Presynaptic Neurones

A

Activated by Ca+ (indirectly)

fusses synaptic versicle with presynaptic membrane to release neurotransmitters

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31
Q

what is the function of Acetylcholine receptors (AChR) in Postsynaptic Neurones

A

Ion channels or open adjacent ion channels
Made of negatively charged amino acid side chains
Open when neurotransmitters bind to it.

32
Q

Electrical Synapses

A

Na+ moves through gap junctions

Advantages: speed

33
Q

Chemical synapses

A

Neurotransmitters export from cell

Advantages: integration of multiple signals

34
Q

what is the function of Acetylcholinesterase (AChE) in Postsynaptic Neurones

A

Degradation of ACh
removed Neurotransmitters from synaptic cleft
(break down with enzymes)

35
Q

what is the function of Excitatory synapses in Postsynaptic Neurones

A

CASUES AN AP

synapse in which an action potential in a presynaptic neuron increases the probability of an action potential occurring in a postsynaptic cell

36
Q

what is the function of inhibitory synapses in Postsynaptic Neurones

A

opposite to Excitatory synapses

37
Q

what is the function of postsynaptic potentials in Postsynaptic Neurones

A

Each active synapse generates a tiny post synaptic potential (PSP) from excitatory and inhibitory synapses which then combine

38
Q

what is the function of spatial summation in Postsynaptic Neurones

A

The combination of PSPs from DIFFERENT presynaptic neurons

39
Q

what is the function of temporal summation in Postsynaptic Neurones

A

the combination of PSPs from ONE presynaptic neurons

40
Q

what is the function of combined PSPs in Postsynaptic Neurones

A

TS and SS combined which then change the membrane potential of neurones

41
Q

what is the function of encoding at the axon hillock in Postsynaptic Neurones

A

generates output of postsynaptic neurones
Magnitude of combined PSP –> frequency of axon potentials
low, medium, high combined PSPs

42
Q

Cl- enters the postsynaptic neuron —>

A

Hyperpolairzation

43
Q

Neurotransmitters are removed from synaptic cleft by..

A

diffusion – Wonder away
degradation – Break down w/ enzymes
Reuptake – import back into a cell

44
Q

Low combined PSP

A

No action potential
Voltage Gated Na+ and K+ channels are closed
Minimal axon membrane potential (mV)

45
Q

High combined PSP

A

Lots of action potential
Voltage gated Na+ and K+ channels are open
Many axon membrane potential (mV)

46
Q

Moderate combined PSP

A

action potentials are possible but iinfrequent

47
Q

____ refractory periods when combined PSP is ___ above threshold

A

extend; Slightly

48
Q

What are the steps in activating a skeletal muscle cell?

A

1) Voltage Gated Ca+2 open with the activation of the nerve impulse resulting in a release of ACh
2) ACh binds to AChR —> localized memb. depolarization
3) Voltage gated Na+ opens –> entire surface including T-tubules depolarizes
4) Voltage Gated Ca+2 open
5) Mechanically gates Ca+2 –> Ca+2 enter cytosol

49
Q

The Binding of ___ to the troponin complex exposes the ____ ____ site.

A

Ca+2; myosin binding

50
Q

What are the steps in activating a skeletal muscle cell?

A

1) Voltage Gated Ca+2 open with the activation of the nerve impulse resulting in a release of ACh
2) ACh binds to AChR —> localized memb. depolarization
3) Voltage gated Na+ opens –> entire surface including T-tubules depolarizes
4) Voltage Gated Ca+2 open
5) Mechanically gates Ca+2 –> Ca+2 enter cytosol

51
Q

steps for recovery of an activated skeletal muscle cell…

A
  • ACh removed from synapse
  • Channels close
  • Ca+2 removed from cytosol
  • Tropomyosin block myosin binding sites
52
Q

Ca+2 removed from cytosol with ____ & ____ Ca+2 transporters

A

ATP powered; Na+ gradient powered

53
Q

How are skeletal muscles controlled

A

Need multiple signals/APs (temporal summation) to contract a muscle

54
Q

Do muscle cells also do spatial summation?

A

No, only temporal

55
Q

What is one motor unit?

A

1 motor neuron and several muscle cells

56
Q

cardiac muscle cells vs skeletal muscle cell

A
  • cardiac muscle cells are controlled by pacemaker cell not motor neuron – sends pulses of (+) ions
  • wave of contractions to heart muscle cells – spreads across heart
  • Connected with electrical synapses –gap junctions
  • Brain and adrenaline control the heart rate
  • cardiac muscle cells contract for a longer time
57
Q

steps for recovery of an activated skeletal muscle cell…

A
  • ACh removed from synapse
  • Channels close
  • Ca+2 removed from cytosol
  • Tropomyosin block myosin binding sites
58
Q

Agonist

A

Activates

59
Q

Antagonist

A

Blocks

60
Q

Activator toxin

A

normal binding to site of enzyme; Increases activity

61
Q

Competitive inhibitor toxin

A

Binds to active site of enzyme to decreases activity

62
Q

Noncompetitive inhibitor

A

decreases activity

63
Q

Noncompetitive inhibitor

A

binds at an allosteric site separate from the active site of substrate binding to decreases activity

64
Q

Toxin: BoNT/A

A

Enzyme that cleaves SNAREs – cuts SNARE thats necessary for release of ACh vesicles
(Prevents release of neurotransmitters)

65
Q

Toxin: Sarin

A

Competitive inhibitor – mimics ACh and Inhibits AChE
Involuntary muscle contractions
(Prevents removal of neurotransmitters)

66
Q

Toxin: Charybdotoxin

A

AChR Antagonist – Blocks certain AChRs
Muscle paralysis
(prevents activation of receptors)

67
Q

Toxin: Nicotine

A

AChR Agonist – mimics ACh and activates certain AChRs
Increases activity in brains pleasure center – produces euphoria feeling and adrenaline response
(inappropriate activation of receptors)

68
Q

Humans have __ different AChRs

A

11

69
Q

Toxin: BoNT/A

The effect?

A
  • Enzyme that cleaves SNAREs – cuts SNARE thats necessary for release of ACh vesicles
  • Muscle paralysis; Treat people who have uncontrolled muscle contractions; Botox
    (Prevents release of neurotransmitters)
70
Q

Toxin: Sarin

The effect?

A
  • Competitive inhibitor – mimics ACh and Inhibits AChE
  • Involuntary muscle contractions
    (Prevents removal of neurotransmitters)
71
Q

Toxin: Charybdotoxin

The effect?

A
  • AChR Antagonist – Blocks certain AChRs
  • Muscle paralysis
    (prevents activation of receptors)
72
Q

Toxin: Nicotine

The effect?

A
  • AChR Agonist – mimics ACh and activates certain AChRs
  • Increases activity in brains pleasure center – produces euphoria feeling and adrenaline response
    (inappropriate activation of receptors)
73
Q

most dangerous neurotoxin? why?

A

BoNT/A; enzyme–> 1 molecule within a cell of the toxin can get rid of all the SNAREs

74
Q

Nicotine activates AChRs on ____ and ___ cells

A

brain; adrenal

75
Q

Nicotine activates AChRs which Causes voltage gates Ca+2 channels to ____ and ____ exocytosis of adrenaline

A

open; causes

Biology 201 (8 decks)

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