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D1 Spring - Physiology > 1/23: Cell Membrane, Membrane Transport, and Membrane Potential III > Flashcards

1/23: Cell Membrane, Membrane Transport, and Membrane Potential III Flashcards

1
Q

What are the two mechanisms of membrane transport?

A
  1. Passive transport
  2. Active transport
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2
Q

Does passive transport have energy?

A

No

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3
Q

How do substances move on a gradient in passive transport?

A

Down gradients (high to low; ΔC, ΔP, or ΔE)

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4
Q

Does active transport require energy?

A

Yes

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5
Q

How do substances move on a gradient in active transport?

A

Up gradients (low to high)

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6
Q

What are types of passive transport?

A

Diffusion
Osmosis
Bulk flow

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7
Q

What are types of active transport?

A

Active transporters
Bulk (vesicular) transport

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8
Q

What are things to consider when discussing passive transport?

A

Random thermal motion
Rate of movement

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9
Q

What is random thermal motion?

A

Molecules in a fluid are continuously and randomly bouncing around

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10
Q

What is rate of movement directly/inversely proportional to?

A

Directly: T (temperature)
Inversely: M (mass)

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11
Q

What is diffusion?

A

Movement of substances other than water down a gradient (ΔC, ΔP, or ΔE; high to low)

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12
Q

When does net movement stop in diffusion?

A

At equilibrium

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13
Q

During diffusion, random movement is ______

A

Continuous & substance specific

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14
Q

Passive transport moves the system towards ________

A

Equilibrium

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15
Q

Describe how the mass and heat flow model works

A

↑ driving force; – resistance: ↑ mass/energy flow
↓ driving force; – resistance: ↓ mass/energy flow

– driving force; ↑ resistance = ↓ mass or energy flow
– driving force; ↓ resistance = ↑ mass or energy flow

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16
Q

What can the mass and heat flow model be used to describe?

A

Diffusion
Osmosis
Blood flow through blood vessels
Air flow through airways
Capillary exchange
etc

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17
Q

Which line represents the net flux across the membrane with higher permeability?

A

Purple -
More net flux = ↓ resistance, ↑ membrane permeability = can cross membrane at a higher rate

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18
Q

What are the two different types of diffusion?

A
  1. Simple diffusion
  2. Facilitated diffusion
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19
Q

What substances use simple diffusion?

A

Hydrophobic/lipophilic substances
ex: fatty acids, ethanol

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20
Q

What substances use facilitated diffusion?

A

Hydrophilic/lipophobic substances

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21
Q

How do substances move when using simple diffusion?

A

Directly through phospholipid bilayer
- slower
- unregulated

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22
Q

How do substances move when using facilitated diffusion?

A

Require membrane channels or carriers because can’t pass bilayer
- faster
- unregulated (specificity, saturation, competition)

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23
Q

Does simple or facilitated diffusion require a plasma membrane?

A

Facilitated diffusion

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24
Q

What substances are directly/indirectly related to the simple diffusion rate?

A

Directly: temperature, gradient, surface area
Indirectly: resistance (viscocity of fluid; size of molecule), diffusion distance

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25
Q

What substances are directly related to the facilitated diffusion rate (FDR) of ions?

A

Gradient, temperature, # of channels, probability the channels are open

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26
Q

What substances are directly related to the facilitated diffusion rate (FDR) of hydrophilic building blocks?

A

Gradient, temperature, # of carriers, probability the channels are active

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27
Q

What is simple diffusion regulated by?

A

Changing concentration gradient

28
Q

What is facilitated diffusion regulated by?

A

Changing resistance

29
Q

Why are the kinetics different?

A

Facilitated diffusion has saturation due to membrane carriers
Simple diffusion moves directly though a bilayer so there is nothing to saturate

30
Q
  1. Which way will dots move via diffusion?
  2. Which way will triangles move via diffusion?
  3. What type of substance could the triangles represent?
  4. If the stars represent a hydrophobic substance, what would increase the diffusion rate of stars?
A
  1. Net movement into cell
  2. No net movement because the membrane isn’t permeable to the triangles
  3. triangle is impermeable to membrane so must represent hydrophilic substance (glucose, potassium, etc)
  4. ↑ΔC, ↑SA, ↑T, ↓R, ↓D
31
Q

What is another type of passive transport?

A

Osmosis

32
Q

What is osmosis?

A

Movement of H2O across a plasma membrane down a [free H2O] gradient

33
Q

Water movement via osmosis is facilitated by?

A

Aquaporins

34
Q

Can water permeability be regulated?

A

Yes

35
Q

What is free water inversely related to?

A

Solute concentration

36
Q

How do water molecules move down a free water gradient?

A

Passively (toward the area with a higher solute concentration)

37
Q

Which direction do we have water movement between the tanks?

A

From tank 2 to tank 1

38
Q

What values are dependent on osmosis to occur?

A
  1. Solute concentration
  2. Water concentration
  3. Container volume
39
Q

Which direction will there be net movement of H2O?
*membrane permeable to H2O only
*dots and stars are not permeable

A

No net water movement, it is not substance specific

40
Q

Which direction will there be net movement of H2O?
*membrane is permeable to water and stars NOT dots

A

Tank 2 to tank 1
- you could ignore the substances permeable to the membrane (stars)
- take home: only the impermeable substances influence the movement via osmosis

41
Q

Which way will water move via osmosis?

A

Out of the cell
- since the membrane is permeable to water, dots, stars, and squares, they can be ignored. From there, the things move out the cell because the solute concentration is higher outside the cell so thats where water will go

42
Q

What is osmolarity?

A

The total (free) solute concentration of a solution (permeable and impermeable solute)

43
Q

What is 1 osmol equal to?

A

1 mol of solute particles
So a 1 M solution of glucose has a concentration of 1 Osm (1 osmol per liter), whereas 1 M solution of sodium chloride is 2 Osm (2 osmol of solute per liter of solution)
NaCl (1) -> Na+(1) + Cl-(1)

44
Q

Cells bathing solution is defined by its Osm:

A
  1. Isosmotic
  2. Hyposomotic
  3. Hyperosmotic
45
Q

What is isosmotic?

A

Bathing solution Osm = cytosolic Osm

46
Q

What is hyposmotic?

A

Bathing solution Osm < cytosolic Osm

47
Q

What is hyperosmotic?

A

Bathing solution Osm > cytosolic Osm

48
Q

What is tonicity defined by?

A

Impermeable substances only

49
Q

What does tonicity determine?

A

The direction of H2O movement via osmosis

50
Q

Cell’s bathing solution can be defined by its tonicity:

A
  1. Isotonic solution
  2. Hypotonic solution
  3. Hypertonic solution
51
Q

What is an isotonic solution?

A
  1. Concentration of impermeable solute = cell cytosol
  2. Cells in an isotonic bathing solution will have no net volume
52
Q

What is a hypotonic solution?

A
  1. Concentration of impermeable solute < cell cytosol
  2. Cells in a hypotonic bathing solution will gain water and swell
53
Q

What is a hypertonic solution?

A
  1. Concentration of impermeable solute > cell cytosol
  2. Cells in a hypertonic bathing solution will lose water and shrink
54
Q

What is the osmolarity and tonicity of the bathing solution?

A

Hyposomotic
Hypotonic

55
Q

Which direction will water flow via osmosis?

A

Right

56
Q

What are permeable solutes?

A

Ethanol
Fatty acids
O2
CO2
Steroids
Urea - passive transporters
Glucose (dextrose) - actions of insulin dependent on diabetes can move to impermeable category

57
Q

What are impermeable solutes?

A

Na
K
Cl
HCO3
Protein

58
Q

What does permeability depend on?

A

Cell type (ex: RBC always permeable to urea and glucose)
Chemical signals present at the time (ex: liver and muscle cells only permeable to glucose if insulin present)

59
Q

If asking about a single cell AND identity not provided, what can we assume regarding permeability regarding glucose and urea?

A

Glucose and urea may be impermeable

60
Q

If asking about the body over time, what can we assume regarding permeability regarding glucose and urea?

A

Glucose and urea are permeable

61
Q

Define the osmolarity, tonicity, and direction of water movement

A

Hyperosmotic
- 400 outside, 300 inside
isotonic
- NaCl is the only thing impermeable
- 300 outside, 300 inside
No volume change
- cells in an isotonic solution don’t have a change in volume

62
Q

Define the osmolarity, tonicity, and direction of water movement

A

Hyperosmotic
- 400 outside, 200 inside
Hypertonic
- 400 outside, 200 inside
Water moves out of the cell due to higher concentration outside the cell

63
Q

Define the osmolarity, tonicity, and direction of water movement

A

Isoosmotic
- 300 outside, 300 inside
Hypotonic
- 100 outside, 300 inside
Water moves into the cell due to a higher concentration inside the cell

64
Q

What happens when a RBC is placed in a hypertonic, isotonic, and hypotonic solution?

A

Hypertonic: shriveled cell
Isotonic: normal
Hypotonic: cells swell and eventually burst

65
Q

A

A

Osmolarity: Hyperosmotic
Tonicity: Isotonic
Volume: No change in cell volume

66
Q

B

A

Osmolarity: Isoosmotic
Tonicity: Hypotonic
Volume: Flow into cell, increase volume

67
Q

C

A

Osmolarity: Hyperosmotic
Tonicity: Hypertonic
Volume: Cells decrease volume and shrink

D1 Spring - Physiology (17 decks)

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