Quiz #1: Neurons and Action Potentials (6) Flashcards

1
Q

What are the components of total body fluid?

A
  1. Intracellular fluid (2/3)
  2. Extracellular fluid (1/3)
    a. Plasma (1/5)
    b. Interstitial fluid (4/5)
    c. Minor ECF (lymph/transcellular fluid)
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2
Q

What are the factors influencing the rate of net diffusion in a substance across a plasma membrane?

A
  1. concentration gradient
  2. distance
  3. surface area of membrane
  4. lipid solubility
  5. molecular weight
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3
Q

What happens to the net diffusion when you increase the distance?

A

Decreased rate of net diffusion

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3
Q

What happens to the net diffusion when you increase concentration gradient of a substance?

A

Higher rate of net diffusion

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4
Q

What happens to the net diffusion when you increase the surface area of a membrane?

A

Higher rate of net diffusion

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5
Q

What happens to the net diffusion when you increase lipid solubility

A

Higher rate of net diffusion

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6
Q

What is tonicity?

A

the effect a solution has on cell volume

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7
Q

What happens to the net diffusion when you increase molecular weight of a substance?

A

Decreased rate of net diffusion

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8
Q

What is the osmolarity of ECF when it is isoosmotic?

A

Equal to RBC

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9
Q

What is the osmolarity of ECF when it is hyperosmotic?

A

Higher than RBC

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10
Q

What is the osmolarity of ECF when it is hypoosmotic?

A

Lower than RBC

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11
Q

What is the net diffusion of water in isoosmotic solution?

A

zero

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12
Q

What is the net diffusion of water in hypoosmotic solution?

A

into the RBC

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13
Q

What is the net diffusion of water in hyperosmotic solution?

A

Out of the RBC

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14
Q

What is the shape of the RBC in isoosmotic solution?

A

normal

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15
Q

What is the shape of the RBC in hypoosmotic solution?

A

swells

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16
Q

What is an isoosmotic effect on a RBC?

A

Isotonic

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16
Q

What is the shape of the RBC in hyperosmotic solution?

A

shrinks

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17
Q

What is an hypoosmotic effect on a RBC?

A

hypotonic

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18
Q

What is an hyperosmotic effect on a RBC?

A

hypertonic

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18
Q

What are the two types of transport of molecules across the plasma membrane?

A
  1. Simple diffusion
  2. Assisted membrane transport
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19
Q

What are the two types of assisted membrane transport?

A
  1. Carrier-mediated transport
  2. Vesicular transport
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20
Q

What are the two types of vesicular transport?

A
  1. Exocytosis
  2. Endocytosis
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20
Q

What are the two types of carrier-mediated transport?

A
  1. facilitated diffusion
  2. active transport
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21
Q

What are the two types of facilitated diffusion?

A
  1. channels
  2. carriers
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22
Q

Why is there the saturation of assisted membrane transport?

A

Due to the limited amount of carriers of facilitated diffusion

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22
Q

What are the two types of active transport?

A
  1. primary
  2. secondary
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22
Q

What are the changes to the membrane potential?

A
  1. Depolarization
  2. Repolarization
  3. Hyperpolarization
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23
Q

Where does K+ move and what does it do?

A

To the ECF
ECF becomes more positive
ICF becomes more negative because membrane is impermeable to A-

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24
Q

Where does Na+ move to and what does it do?

A

Na+ moves to ICF
ICF becomes more positive
The ECF becomes more negative due to negatively charged ions (like Cl-)

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25
Q

What is repolarization?

A
  • return to resting potential after depolarization
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25
Q

What is depolarization?

A
  • decrease in potential
  • membrane becomes less negative
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26
Q

What is hyperpolarization?

A
  • increase in potential
  • membrane more negative
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27
Q

What is resting potential?

A
  • potential at which the membrane doing nothing rests at
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28
Q

Are the voltage gate Na+ channels and K+ channels open or closed at resting potential?

A

Voltage gated Na+ channels: closed
Voltage gated K+ channels: closed

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29
Q

Are the voltage gate Na+ channels and K+ channels open or closed at depolarization (before threshold)?

A

Voltage gated Na+ channels: closed
Voltage gated K+ channels: closed

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30
Q

Are the voltage gate Na+ channels and K+ channels open or closed at depolarization (after threshold)?

A

Voltage gated Na+ channels: OPEN
Voltage gated K+ channels: closed

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31
Q

Are the voltage gate Na+ channels and K+ channels open or closed at repolarization?

A

Voltage gated Na+ channels: closed
Voltage gated K+ channels: OPEN

32
Q

Are the voltage gate Na+ channels and K+ channels open or closed at hyperpolarization?

A

Voltage gated Na+ channels: closed
Voltage gated K+ channels: OPEN (for first half)

33
Q

What is the membrane permeability during resting potential?

A

close to zero

33
Q

What is the membrane potential throughout an action potential?

A

Resting: -70mV
Depolarization (to thres.): >-70 to -50
Depolarization (after thres): >-50 to +30
Repolarization: <+30 to -70
Hyperpolarization: <-70

34
Q

What is the membrane permeability during depolarization (to threshold)?

A

high for Na+

35
Q

What is the membrane permeability during depolarization (after threshold)?

A

high for Na+

36
Q

What is the membrane permeability during repolarization?

A

high for K+

37
Q

What is the membrane permeability during hyperpolarization

A

high for K+

38
Q

What is the one stage the voltage gated Na+ channels are open?

A

Depolarization (after threshold)

39
Q

What is the 1.5 times the voltage gated K+ channels are open?

A

repolarization
hyperpolarization (1st half)

40
Q

What are the steps of a neuron receiving a signal?

A
  1. input zone
  2. trigger zone
  3. conducting zone
  4. output zone
41
Q

What is the input zone of a neuron

A

receives incoming signals from other neurons through dendrites

42
Q

What is the trigger zone?

A

Initiates action potentials in axon hillock

43
Q

What is the conducting zone?

A

conducts action potentials in undiminishing fashion over long distances
axon

44
Q

What is the output zone?

A

Where neurotransmitters are released from axon terminals that influences other cells

45
Q

A stronger stimuli will generate:

A

a higher frequency of action potentials

46
Q

A stronger stimuli in a region causes more neurons to reach _________.

A

threshold

47
Q

What is contiguous conduction?

A

An action potential moves step-by-step along an UNMYELINATED axon, depolarizing each successive segment of the axonal membrane

48
Q

What is the process of continuous conduction?

A
  1. previous active ares are returned to resting potential (in refractory period)
  2. adjacent area that was brought to threshold by local current flow now active at peak of action potential
  3. new adjacent inactive area into which depolarization is spreading will soon reach threshold
  4. remainder of axon remains at resting potential
49
Q

What are the two parts of the refractory period?

A
  1. absolute refractory period
  2. relative refractory period
50
Q

What is the absolute refractory period?

A

Brief period of time after an action potential when a neuron is unable to send more action potentials, no matter how strong the stimulus

51
Q

What is the relative refractory period?

A

Period of time that occurs after an action potential when a cell membrane changes to an unexcitable state and gradually returns to its resting state

52
Q

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

A

During the absolute refractory period, a new action potential cannot be elicited. During the relative refractory period, a new action potential can be elicited under the correct circumstances.

53
Q

What specifically happens in the ion influx during the absolute refractory period?

A

Na+ enters

54
Q

What happens to the ion influx during the relative refractory period?

A

K+ leaves

55
Q

What is saltatory conduction?

A

Process that allows action potentials to travel quickly down myelinated axons by jumping from one node of Ranvier to the next

56
Q

What is myelination?

A
  • axons covered with myelin
  • formed by glial cells
  • CNS: oligodendrocytes
  • PNS: schwann cells
57
Q

What are some common neurotransmitters?

A

Achetylcholine
Norepinephrine
Dopamine
Serotonin
Glutamate
GABA
Glycine

58
Q

What the the things that carry NT called?

A

synaptic vesicles

59
Q

What is the gap between the axon terminal presynaptic neuron and dendrite of the postsynaptic neuron called?

A

synaptic cleft

60
Q

What causes the release of neurotransmitters?

A

Calcium influx

61
Q

What are the types of neurotransmitter receptors?

A
  1. ligand-gated ion channels
  2. g-protein coupled receptors
62
Q

Ligand-gated ion channel example

A
  • NT (ACh) released from presynaptic neuron activated nicotinic ACh receptors on the postsynaptice cell (msucle fiber)
    activation = increase permeability to Na+ and K+
  • cell depolarizes
  • muscle contraction
63
Q

G protein-coupled receptor example

A
  • ACh binds muscarinic ACh receptors which activated G protein-coupled receptors on the postsynaptic membrane
  • Opens K+ channels
  • Posysynaptic membrane hyperpolarizes
  • excitation of cells is inhibited
64
Q

_____________ receptors are classified as ligand-gated ion channels while ____________ receptors are G-protein-coupled receptors.

A
  1. nicotinic
  2. muscarinic
65
Q

Activation of nicotonic receptors does what?

A

increase Na+ and K+ permeability

66
Q

Activation of muscarinic receptors does what?

A

increases K+ permeability

67
Q

What is the outcome of a nicotinic receptor?

A

depolarize membrane potential
muscle contraction

68
Q

What is the outcome of a muscarinic receptor?

A

hyperpolarize membrane potential
reduce force and rate of contraction

69
Q

What is convergence of input?

A

one cell is influenced by many others

70
Q

What is divergence of output?

A

one cell influences many others

71
Q

What is grand postsynaptic potential?

A

the total potential in the postsynaptic neuron is a sum of all EPSPs and IPSPs occurring approximately at the same time

72
Q

What does EPSP stand for and what does it mean?

A

excitatory postsynaptic potential (EPSP)
postsynaptic potential that makes the postsynaptic neuron more likely to fire an action potential

73
Q

What is IPSP?

A

Inhibitory postsynaptic potentials (IPSPs)
Type of synaptic potential that make it less likely for a postsynaptic neuron to generate an action potential

74
Q

What are the types of grand postsynaptic potential?

A
  1. no summation
  2. temporal summation
  3. spacial summation
  4. EPSP-IPSP cancellation
75
Q

What is no summation?

A

Addition of all potentials is not enough for action potential
nothing cancels out just not enough to reach threshold potential

76
Q

What is temporal summation?

A

Temporal summation involves a single presynaptic neuron rapid-firing signals to a single postsynaptic neuron’s synapse.
Because the signals are received in rapid succession, they compound into a greater signal

77
Q

What is spatial summation?

A

Spatial summation involves multiple presynaptic neurons simultaneously sending signals to a single neuron

78
Q

What is EPSP-IPSP cancellation?

A

One excitatory and one inhibitory signal cancel each other out for no summation

79
Q

What is a graded potential?

A

Small change in the membrane potential of a neuron that occurs in response to sensory input or stimuli
Magnitude of the graded potential is determined by the strength of the stimulus, and can be either excitatory or inhibitory
Every stimulus (big or small) elicits a response

80
Q

What is a neuromuscular junction?

A

Specialized synapse that connects the end of a motor nerve to a muscle

81
Q

SLIDE QUESTION: Select the TWO conditions in which the rate of net diffusion across a cell membrane of a substance would be highest.

A. Decrease in the concentration gradient of the substance
B. Increase the thickness of the membrane
C. Increase the surface area of the membrane that is available for diffusion
D. Increase the lipid solubility of the substance
E. Increase the molecular weight of the substance

A

C/D

82
Q

SLIDE QUESTION: What happens to the charge of the cell when the cell membrane is more permeable to Na+?

A

Depolarization (charge increases and becomes more positive)

83
Q

SLIDE QUESTION: What happens to the charge of the cell when the cell membrane is more permeable to Na+?

A. Reverse polarize
B. Hyperpolarizes
C. Depolarizes
D. Repolarize 39

A

C

84
Q

SLIDE QUESTION: Excitatory postsynaptic potentials are considered as ___ potentials.

A. Action
B. Graded

A

B. Graded

85
Q

SLIDE QUESTION: Excitatory postsynaptic potentials causes membrane ___.

A. Depolarization
B. Repolarization
C. Hyperpolarization

A

A. Depolarization