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Med310A > Lecture 1: Membrane Physiology And Transport > Flashcards

Lecture 1: Membrane Physiology And Transport Flashcards

1
Q

Fluid portion of the blood

A

Plasma

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2
Q

Fluid outside cells is__

A

Extracellular fluid (ECF)

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3
Q

The fluid surrounding and bathing cells

A

Interstitial fluid

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4
Q

Fluid within cells is __

A

Intracellular fluid (ICF)

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5
Q

Separates the ICF from the ECF

A

Physical barrier

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6
Q

Controls entry/exit of ions, nutrients and other products to/from the cell

A

Gateway for exchange

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7
Q

Plasma membrane:
The function of Containing proteins that enable cell to recognize and respond to changes in the extracellular environment

A

Communication

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8
Q

Plasma membrane:
Function of Membrane proteins that can create specialized barriers between adjacent cells or between cells and the extracellular matrix. These junctions can stabilize tissue structures

A

Cell structure

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9
Q

Hydrophilic polar end can interact with ___ molecules

A

Aqueous

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10
Q

Hydrophobic polar end can interact with ___ molecules

A

Lipid soluble

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11
Q

Aqueous molecules are excluded from passing through the __. Unless they use ___, ___, or ___

A

Lipid membrane.
Channels
Carriers
Transporters

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12
Q

Ion channels, carrier molecules, membrane-bound enzymes, receptors and cell adhesion molecules are different forms of ____

A

Membrane proteins

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13
Q

Separates intracellular fluid from extracellular fluid

A

Lipid bilayer

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14
Q

The head of a phospholipid is __, __, and ___

A

Negatively charged, polar, and hydrophilic

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15
Q

The tail of a phospholipid is __, __, and ___

A

Uncharged, no polar, and hydrophobic

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16
Q

Anything that passes between a cell and the surrounding extracellular fluid must be able to penetrate the ___

A

Plasma membrane

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17
Q

If a substance can cross the membrane, then the membrane is said to be ___ to it

A

Permeable

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18
Q

If a substance cannot pass, then the membrane is ____ to it

A

Impermeable

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19
Q

Plasma membrane is selectively permeable, which is when the membrane __

A

allows some particles to pass while excluding others

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20
Q

What are the 2 general types of forces that produce the movement of a particle across the membrane ?

A

Passive, active

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21
Q

Forces that don’t require cell to expend energy to produce moment across membrane

A

Passive forces

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22
Q

Forces that do require the cell to expend energy (ATP)

A

Active

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23
Q

_____ OR ___ molecules are highly soluble and readily cross

A

Uncharged or nonpolar

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24
Q

__ or __ molecules have low lipid solubility

A

Charged particles(ions) and polar

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25
Q

Lipid bilayer is impermeable to ____ molecules but protein channels can allow passage of ___

A

water-soluble. Ions

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26
Q

Molecules that can permeate the plasma membrane on their own are passively driven by 2 forces – ___ and ___

A

Chemical and electrical

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27
Q

______ - Positively charged ions tend to move toward the more negatively charged area and vice versa

A

Electrical gradient

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28
Q

______ - when both electrical and concentration gradients act
simultaneously

A

Electrochemical gradient

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29
Q

If a substance can permeate the membrane, ___ occurs

A

Diffusion

30
Q

If the membrane is impermeable to a substance, no ___ occurs

A

Diffusion

31
Q

Diffusion across a lipid bilayer is called _____

A

Simple diffusion

32
Q

The rate of simple diffusion depends on the ability of the diffusing molecule to____ in the lipid bilayer

A

Dissolve

33
Q

only non-polar, lipophilic molecules can cross the _______ by diffusion

A

Lipid bilayer

34
Q

The rate of simple diffusion is directly proportional to the ______ of the membrane

A

Surface area

35
Q

The rate of simple diffusion is inversely proportional to the ___ of the membrane

A

Thickness

36
Q

when concentration gradient of substance increases, rate of net diffusion ___

A

Increases

37
Q

when permeability of membrane to substance increases, rate of net diffusion ___

A

Increases

38
Q

when surface area of membrane increases, rate of net diffusion ___

A

Increases

39
Q

when molecular weight of substance increases, rate of net diffusion ___

A

Decreases

40
Q

when distance (thickness) increases, rate of net diffusion ___

A

Decreases

41
Q

The net diffusion of water down its concentration gradient

A

Osmosis

42
Q

_____ tells you what happens to cell volume when a cell is placed into a solution

A

Tonicity

43
Q

____ solutions have the same concentration of nonpenetrating solutes as normal body cells and will result in cell volume remaining constant

A

Isotonic

44
Q

____ solutions have a lower concentration of nonpenetrating solutes and tend to swell the cell (water enters by osmosis)

A

Hypotonic

45
Q

___ solutions which have a higher concentration of nonpenetrating solutes tend to shrink the cell, as water moves out of the cell

A

Hypertonic

46
Q

Cell must provide mechanisms for transporting these poorly lipid-soluble molecules in and
out of cell
◦ Two different mechanisms:_____ and _____

A

Carrier-mediated transport, vesicular transport

47
Q

____ transport uses a carrier molecule facilitate the transfer of a substance across the membrane from high to low concentration (downhill)

A

Passive

48
Q

___ transport requires the carrier to use energy to transfer substance against the concentration gradient (uphill)

A

Active

49
Q

____ diffusion: uses a carrier molecule facilitate the transfer of a substance
across the membrane from high to low concentration (“downhill”)

A

Facilitated

50
Q

transport of glucose into cells:
• [Glucose(ex) > [Glucose(in)]
• Cells metabolize glucose as fast as it enters
• So there is always a gradient for net diffusion
• But – glucose is _____, not ___ soluble and is too
large for channels

A

Polar, lipid

51
Q

Carrier protein takes conformation in which solute binding site is exposed to region of __ concentration

A

Higher

52
Q

Order Steps of carrier proteins:
(A)- Solute molecule binds to carrier protein
(B)-Transported solute is released and carrier protein returns to conformation.
(C)- Carrier protein changes conformation so that binding site is exposed to region of lower concentration
(D)- carrier proteins takes conformation in which solute binding site is exposed to region of higher concentration

A

D, A, C, B

53
Q

With____ diffusion of a
molecule down its
concentration gradient, the
rate of transport of the
molecule into the cell is
directly proportional to the
extracellular concentration of
the molecule.

A

Simple

54
Q

With ____
transport of a molecule down its concentration gradient, the rate of transport of the molecule into the cell is directly proportional to the extracellular concentration of the molecule until the carrier is saturated, at which time the rate of transport reaches a maximum value

A

Carrier mediated

55
Q

Na+–K+ pump transports Na ___ of
the cell against its concentration
gradient and K ___ the cell

A

Out. In

56
Q

Pump has __ high-affinity sites for Na+ and __ low-affinity sites for k+ when exposed to ICF

A
  1. 2
57
Q

When 3 Na+ from ICF bind to pump. It splits ATP into ____ plus phosphate group binds to pump.

A

ADP

58
Q

____ causes pump to change conformation so that Na+ binding sites are exposed to opposite side of membrane and 3 Na+ are released to ECF as affinity of Na+ binding sites greatly decreases.

A

Phosphorylation

59
Q

Change in shape also exposes pump’s binding sites for K+ TO ECF and greatly ___ affinity for K+

A

Increases

60
Q

When 2 K+ from ECF bind to pump, it releases ____ ___. ___ causes pump to revert to its original conformation.

A

Phosphate group. Dephosphorylation

61
Q

2__ are released to ICF as affinity of K+ binding sites markedly ___ during change in shape. At same time, affinity of Na+ binding sites greatly increases, returning process to step 1.

A

K+. Decreases.

62
Q

Na+–K+ pump transports ___ out of
the cell against its concentration gradient and __ into the cell
• Not a direct exchange – __ __ out for __ __ in

A

Na. K.
3 Na
2 K

63
Q

When Actin-mediated process by which a cell engulfs a particle into a large membrane bound vesicle called a phagosome

A

Phagocytosis

64
Q

Vesicular transport of materials into the cell

A

Endocytosis

65
Q

Vesicular transport of materials out of the cell

A

Exocytosis

66
Q

Exocytosis:
Membrane-enclosed vesicle fuses with _______ then opens up and releases its contents to the ___

A

Plasma membrane.
Exterior

67
Q

Exocytosis:
Materials for secretion are produced and packaged by ___ and ____ complex

A

ER
Golgi

68
Q

Exocytosis:
Secretion of large ____ molecules (i.e., hormones or enzymes) that cannot cross plasma membrane – regulated by specific ____ events

A

Polar
Signalling

69
Q

Release of secretory vesicles is generally regulated by intracellular ___

A

Ca++

70
Q

What method of transport ?
◦ Through lipid bilayer
◦ Through channels (ie ions)
◦ Special case of osmosis (water only)

A

Diffusion

71
Q

What method of transport?

◦ Facilitated diffusion – passive
◦ Primary active transport – requires energy

A

Carrier-mediated transport

72
Q

What method of transport?
Endocytosis-active
Exocytosis - active

A

Vesicular transport

Med310A (29 decks)

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