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NPLEX - Physiology > Cellular physiology > Flashcards

Cellular physiology Flashcards

1
Q

Name two hormones that use cGMP as a second messenger.

A

ANF (antrial natriuretic factor) and Nitric Oxide

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2
Q

Do secondary active transport proteins use ATP?

A

no, but ATP may be expended elsewhere in the cell to maintain concentration gradients that permit secondary active transport

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3
Q

How do electrical forces affect the rate of diffusion?

A

the slight negative charge on the inside of a cell membrane increases the rate of diffusion of positive species and reduces the rate of diffusion of negative species

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4
Q

Which active transport process consumes up to 40% of all ATP produced in the body and is a significant source of heat?

A

sodium-potassium ATPase (aka exchange pump)

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5
Q

ACh released through exocytosis diffuses across the synaptic cleft and causes a ________ depolarization which may or may not result in an action potential.

A

graded depolarization

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6
Q

T/F: ACh released into the synapse is quickly repackaged and reabsorbed into the synaptic knob so that it can be reused.

A

False. The ACh is broken down by acetylcholinesterase into choline and acetate. The choline is reabsorbed and used to synthesize de novo ACh.

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7
Q

The chemical gradient for potassium ions tends to drive them out of the cell, but this movement is opposed by the _______ gradient.

A

electrical

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8
Q

Name some important hormones that activate adenylate cyclase (ie: use the cAMP second messenger system). (10)

A

glucagon, epinephrine and norepinephrine (beta receptors), calcitonin, PTH, ADH, ACTH, FSH, LH, TSH

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9
Q

What triggers the release for neurotransmitters at the synaptic nob?

A

the arrival of the action potential

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10
Q

Name the key second messengers. (3)

A

cATP, cGTP, calcium ions

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11
Q

Which is faster: continuous or saltatory conduction of action potentials?

A

saltatory

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12
Q

Which type of intracellular connection results in a narrow passageway that lets small ions pass from cell to cell?

A

gap junction

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13
Q

As a result of the rapid depolarization caused by sodium channels opening, _________ channels open, causing a sudden movement of positive ions ________ of the cell.

A

voltage gated potassium channels; outside of the cell

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14
Q

What would happen to the resting membrane potential if the cell suddenly became freely permeable to sodium?

A

sodium would enter the cell until the equilibrium potential for sodium is reached (+66mV)

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15
Q

As a result of opening voltage gated sodium channels, sodium rushes ______ the cell, raising the membrane potential from -70mV to _____mV.

A

Into the cell, +30mV

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16
Q

In osmosis, water flows across a membrane toward a solution that has a _____concentration of solutes, because that is where the concentration of water is lowest.

A

higher

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17
Q

Name two places where ACh is always used as a neurotransmitter.

A

all neuron-to-neuron junctions in the PNS; All neuroeffector junctions of the sympathetic division of the ANS

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18
Q

How does temperature affect the rate of diffusion?

A

higher temperatures increase the rate of diffusion

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19
Q

A typical threshold for an action potential is between ______ mV and _____ mV.

A

-60mV and -55mV

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20
Q

Name six functional types of membrane proteins

A

anchors, identifiers, enzymes, receptors, carriers and channels

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21
Q

Name two important hormones that inhibit adenylate cyclase.

A

epinephrine and nonepinephrine (alpha 2 receptors).

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22
Q

Name the chief molecular component of the ‘intercellular’ cement that holds intermediate junctions together.

A

hyaluronic acid

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23
Q

Regarding polarization: Exitatory neurotransmitters cause ______ wheras inhibitory neurotransmitters cause ______.

A

depolarization (promote action potentials); Hyperpolarization (depress action potentials)

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24
Q

T/F: It is easier for a potassium ion to leave a cell than it is for a sodium ion to enter a cell

A

true

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25
Q

How does lymphatic blockage lead to edema?

A

increased fluid colloid osmotic pressure

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26
Q

Does active transport rely on the concentration gradient of the solute being transported?

A

no

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27
Q

What would happen to the resting membrane potential if the cell suddenly became freely permeable to potassium?

A

potassium would leave the cell until the equilibrium potential for potassium is reached. (-90mV)

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28
Q

Name four places where ACh may be used as a neurotransmitter.

A

all neuromuscular junctions involving skeletal muscle; many synapses inside the CNS; all neuron-to-neuron synapses in the PNS; all neuroeffector junctions of the parasympathetic division of the ANS

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29
Q

T/F: The fastest reflexes have just one synapse. As synapses increase, so does delay.

A

true

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30
Q

The electrical gradient for sodium tends to push them into the cell, and this enhanced by the ____ gradient.

A

chemical

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31
Q

Name some important hormones that activate phospholipase C (use calcium as a second messenger). (5)

A

epinephrine and non epinephrine (alpha 1 receptors), oxytocin, regulatory hormones of the hypothalamus, several elcosanoids.

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32
Q

What is required to activate protein kinases?

A

second messenger

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33
Q

What is the main way that a cell maintains its resting potential?

A

sodium-potassium exchange pump

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34
Q

Is ATP required for facilitated diffusion?

A

no

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35
Q

Type _____ fibers are smaller myelinated axons.

A

type B

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36
Q

Which form of endocytosis is the most specific?

A

receptor mediated endocytosis is the most selective process, bringing in only molecules that the cell specifically needs.

37
Q

The extracellular fluid contains relatively ______ concentrations of sodium ions and chloride ions.

A

high

38
Q

How many molecules of sodium and potassium enter/exit the cell in each cycle of the sodium-potassium exchange pump?

A

two potassium in, three sodium out

39
Q

The depolarization of the synaptic knob causes the opening of _____ channels.

A

voltage gated calcium channels

40
Q

Why is glucose added to sodium in oral rehydration formulas? What specific form of cellular transport is being exploited?

A

these proteins use the energy from a downhill sodium gradient to transport glucose across the apical membrane against an uphill glucose gradient. Therefore, these co-transporters are an example of secondary active transport.

41
Q

T/F: The passive channels and active transporters ensure an equal distribution of positive and negative charges across the cell membrane.

A

false

42
Q

Type ___ fibers are the smallest and slowest axons. Unlike the other two types they are not myelinated?

A

type C

43
Q

Describe the tonicity of a solution that creates an osmotic force that pulls water out of a cell.

A

hypertonic

44
Q

Type __ fibers are the largest and fastest axons.

A

type A

45
Q

The resting potential primarily reflects the relatively high membrane permeability to ____ions.

A

potassium

46
Q

T/F: Catecholamines, peptide hormones and eicosanoids do not exert their effects directly, but by acting as first messengers that cause the appearance of second messengers in the cytoplasm.

A

true

47
Q

Describe the tonicity of a solution that does not generate an osmotic force in or out of a cell

A

isotonic

48
Q

The cytosol contains relatively ______ concentrations of potassium ions and negatively charged proteins.

A

high

49
Q

Do all cells maintain resting potentials?

A

yes. the range is between -10mV and -100mV

50
Q

How does the size of the concentration gradient affect rate of diffusion?

A

the larger the concentration gradient, the faster the rate of diffusion

51
Q

Which enzyme “turns off” the cAMP second messenger system?

A

phospodiesterase

52
Q

What would happen to the resting membrane potential if the cell were freely permeable to sodium?

A

the membrane potential would become more positive (approach zero).

53
Q

Which intracellular protein must second messenger calcium ions bind in order to have an effect on target enzymes?

A

calmodulin

54
Q

Which type of intercellular connection uses a very thin proteoglycan layer reinforced by a network of intermediate filaments to lock two cells together?

A

desmosomes

55
Q

What does osmolarity measure?

A

the number of moles of solute particles per unit volume of solution.

56
Q

Many substances like iron and cholesterol are attached to transport proteins that are too large to pass through membrane pores. How do they enter the cell?

A

receptor mediated endocytosis.

57
Q

What happens to neurons as pH rises? As pH falls?

A

they are facilitated: at pH near 7.8 , action potentials are spontaneously generated, producing deadly convulsions. As pH falls, neurons are inhibited. At pH 7.0 the nervous system all but shuts down

58
Q

Is the sodium potassium-pump a form of active transport?

A

yes

59
Q

T/F: The release of ACh causes the generation of an action potential across a synapse in an all-or-none fashion.

A

false

60
Q

The sudden influx of calcium in the synaptic knob triggers ____ of vesicles and release of neurotransmitter.

A

exocytosis

61
Q

The equilibrium potential for ___ is about -90mV.

A

potassium

62
Q

How does distance affect diffusion?

A

longer distances require more time for diffusion to occur.

63
Q

What effect does a 10% nasal salt solution have on the cells lining the nasal cavity?

A

nasal cell will shrink and release water, thus loosening mucus and relieving congestion.

64
Q

T/F: The greater the degree of sustained depolarization at the axon hillock, the higher the frequency of action potential generation.

A

true

65
Q

Which forms of endocytosis require ATP? (receptor-mediated, pinocytosis, phagocytosis)

A

all of them

66
Q

Does active transport require ATP?

A

yes

67
Q

Can facilitated diffusion move molecules against their concentration gradient?

A

no

68
Q

What is required to activate protein kinases?

A

second messenger

69
Q

Which have faster and more immediate effects- water soluble or lipid soluble hormones?

A

water soluble hormones can have immediate (seconds to minutes) effects in cells. Lipid soluble hormones have an effect by changing gene expression (hours to days)

70
Q

T/F: Postsynaptic potentials may be summated in spatially, but not temporally.

A

false. both spatial and temporal summation are possible

71
Q

The inside of a cell membrane has a slight ___ charge with respect to the outside.

A

negative

72
Q

Where are desmosomes abundant? (2)

A

superficial skin layers, cardiac muscle tissue

73
Q

Which type of intercellular connection involves partial fusion of the lipid portions of two cell membranes?

A

tight junction

74
Q

Voltage gated sodium channels open at __mV, and voltage gated potassium channels open at __mV.

A

-60mV; +30mV

75
Q

Why does facilitated transport proceed slower than diffusion?

A

carrier proteins are saturable.

76
Q

Although acetylcholine typically has a ___effect on the postsynaptic membrane, it has a ___ effect when released at neuromuscular junctions in the heart.

A

depolarizing; inhibitory (hyperpolarizing)

77
Q

Name the force that pushes water and dissolved solutes into tissues of the body.

A

hydrostatic pressure

78
Q

Which channels open when voltage reaches the threshold for n action potential?

A

voltage gated sodium channels open first, causing rapid depolarization.

79
Q

Is osmotic pressure a force that pushes water into a compartment, or is it a force that pushes water out of a compartment?

A

the osmotic pressure is a force that pushes water into a compartment.

80
Q

T/F: Norepinephrine often has an exitatory depolarizing effect on post synaptic membranes that is similar to ACh

A

false. The exitatory, depolarizing effect of NE has a distinct mechanism from ACh.

81
Q

Describe the tonicity of a solution that creates an osmotic force that pushes water into a cell.

A

hypotonic

82
Q

How does molecular size affect rate of diffusion?

A

ions and smaller molecules like glucose diffuse much faster than larger molecules (like proteins).

83
Q

Where are gap junctions most common? (2)

A

cardiac muscle and smooth muscle tissue

84
Q

The equilibrium potential for ___ is about +66mV.

A

sodium

85
Q

Osmosis is the diffusion of ___ through a semi-permeable membrane.

A

water

86
Q

T/F: Continuous propagation cannot occur in a myelinated axon.

A

true

87
Q

Where are tight junctions most common? (1)

A

near the exposed surfaces of cells lining the digestive tract, thus preventing stomach acids, enzymes etc from damaging underlying tissues.

88
Q

Will lowering the resting membrane potential to -65mV produce an action potential?

A

no, the potential must be raised to at least -60mV, which is the threshold for most axons.

NPLEX - Physiology (10 decks)

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