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Biology 102 > Ch 48 pt B > Flashcards

Ch 48 pt B Flashcards

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1
Q

Action potential sequence (4)

A

1) Begins with graded potential depolarizes to threshold potential (-50mV)
2) Voltage-gated Na channels open triggering action potential
3) Na+ rapidly diffuses into the cell causing the characteristic spike
4) Inactivation- gate in Na channel swing shuts once membrane is polarized

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2
Q

What are voltage gated K channels opened by?

A

threshold potential but 1 msec later than Na Channels

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3
Q

When does the membrane become negative again

A

When the K+ leaves
membrane hyperpolarizes

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4
Q

What happens when K+ channels close

A

The resting membrane potential is restored

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5
Q

What are the 2 types of refractory periods?

A

1) absolute refractory period
2) relative refractory period

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6
Q

When does the Absolute refractory period occur?

A

When the Na+ Gate is closed and become unresponsive

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7
Q

What does the absolute refractory period do? (2)

A

1) Places limits on the frequency of action potentials
2) Also ensures action potential doesn’t move backward

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8
Q

When does the relative refractory period occur?

A

while K+ channels still open

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9
Q

What happens during the relative refractory period?

A

Membrane hyperpolarizes

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10
Q

What is the difference between the absolute refractory period and the relative refractory period?

A

Absolute refractory period is completely unresponsive to stimulus
Relative refractory period may respond to stimulus if graded potential is big enough

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11
Q

What does speed of info depend on (2)

A

1) Axon diameter
2) Myelination

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12
Q

How does axon diameter effect speed?

A

Broad axons provide less resistance and action potential moves faster

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13
Q

How does myelination affect speed? (2)

A

1) Faster than unmyelinated
2) Saltatory conduction- action potential seems to jump from node to node

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14
Q

What are the parts of synapses? (3)

A

Presynaptic (send signals) synaptic cleft and postynaptic cell (receives signal)

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15
Q

What are the 2 types of synapses?

A

Electrical: electric charge flows through junction
Chemical: neurotransmitter acts as signal

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16
Q

Describe the Chemical Synapse process (6)

A

1) Presynaptic nerve cells contains vesicles of neurotransmitter
2) Exocytosis releases neurotransmitter into synaptic cleft
3) Neurotransmitters diffuse across cleft
4) Binds to channels or receptors in postsynaptic cell membrane
5) Binding of neurotransmitter changes membrane potential of postsynaptic cell
6) signal ends when neurotransmitters are broken down by enzymes or taken back by presynaptic cell

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17
Q

What are the 2 types of changes in postsynaptic potential?

A

1) excitatory postsynaptic potential
2) inhibitory postsynaptic potential

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18
Q

What is Excitatory postsynaptic potential (EPSP)? (2)

A

1) Brings membrane closer to threshold potential
2) Sodium Channels opening

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19
Q

What is Inhibitory postsynaptic potential (IPSP)? (2)

A

1) Takes membrane farther from threshold potential
2) Opening of chlorine channels Cl enters the cells

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20
Q

What causes the synaptic signal to end?

A

When neurotransmitter broken down by enzymes or taken back into presynaptic cell for reuse

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21
Q

A single EPSP is usually too small to trigger what?

A

Action potential in a postsynaptic neuron

22
Q

What is Summation?

A

combination of multiple individual postsynaptic potentials

23
Q

If two EPSP are produced in rapid succession called

A

Temporal summation

24
Q

What is temporal summation?

A

2 EPSP’s produced in rapid succession on the same synapse

25
Q

EPSP produced nearly simultaneously by different synapses on the same postsynaptic neuron

A

Spatial summation

26
Q

What is spatial summation?

A

2 EPSP’s produced nearly simultaneously by different synapses on 1 postsynaptic neuron

27
Q

Combination of EPSP through spatial and temporal summation can trigger?

A

Action potential

28
Q

What counters EPSP

A

IPSP (through summation)

29
Q

The sum of EPSP’s and IPSP’s determine whether _______ reaches threshold to generate action potential at the _______?

A

stimulus; axon hillock

30
Q

After ____, a chemical synapse returns to resting state

A

response

31
Q

Where are neurotransmitter molecules cleared from

A

Synaptic cleft

32
Q

What causes severe effects that can lead to death

A

The inhibition of the enzyme that breaks down the neurotransmitter controlling skeletal muslces

33
Q

What is the gas that inhibits enzymes from breaking down neurotransmitters?

A

nerve gas (sarin)

34
Q

Explain how Metabotropic differs from Ionotropic

A

in Metabotropic, neurotransmitters activate signal transduction pathways
in Ionotropic, Neurotransmitters bind directly to gated channel

35
Q

An advantage of metabotropic signaling is

A

Many channels can be opened or closed

36
Q

What are the 5 types of neurotransmitters?

A

1) acetylcholine
2) amino acids
3) biogenic amines
4) neuropeptides
5) gases

37
Q

What is acetylcholine involved in? (3)

A

1) muscle stimulation
2) memory
3) learning

38
Q

What inhibits acetylcholine? (2)

A

sarin and botulism

39
Q

What are the 3 types of amino acids

A

1) glutamate
2) glycine
3) Gamma-aminobutyric acid (GABA)

40
Q

What does glutamate function as?

A

amino acid neurotransmitter in vertebrates and invertebrates

41
Q

What is the function of glycine?

A

acts at inhibitory synapses in the CNS outside of the brain

42
Q

What is the function of Gamma-aminobutyric acid?

A

neurotransmitter at most inhibitory synapses in brain

43
Q

What are the 4 types of biogenic amines?

A

1) norepinephrine
2) epinephrine
3) dopamine
4) serotonin

44
Q

What is the function of most biogenic amines?

A

central role in # of nervous system disorders
ex) Parkinson’s disease: lack of dopamine in brain

45
Q

What makes up neuropeptides?

A

short chains of amino acids

46
Q

What are the 2 types of neuropeptides? What is their function?

A

substance P and endorphins
both affect pain reception

47
Q

What inhibits substance P and endorphins?

A

opiates: used as pain killers

48
Q

What are the 2 gases?

A

1) NO
2) CO

49
Q

What are the characteristics of NO? (3)

A

1) local regulator in PNS
2) synthesized on demand
3) broken down within a few seconds of production

50
Q

What are the characteristics of CO? (2)

A

1) can be deadly
2) vertebrate body synthesizes in small amounts to be used as neurotransmitters

51
Q

what are orphan receptors?

A

receptors that have been identified but their ligands not found/discovered yet

Biology 102 (38 decks)

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