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Exam 1 Notes > Membrane and Gas Transport > Flashcards

Membrane and Gas Transport Flashcards

1
Q

What kind of molecules can pass directly through the phospholipid bilayer?

A

Lipid soluble molecules

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2
Q

What molecules have to be transported across the phospholipid bilayer?

A

Charged, polar molecules or large molecules

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3
Q

What are the three main types of membrane transport?

A

Simple diffusion, facilitated diffusion, and active transport

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4
Q

simple diffusion

A

Diffusion of molecules through the cell membrane or through an open channel. Goes down the concentration gradient until system reached equilibrium.

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5
Q

In general, what is Fick’s law?

A

Fick’s law is an equation that describes the rate at which a substance can flow down its gradient. (I.e., how quickly it move from one compartment to another or how easily a solute can pass through a membrane).

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6
Q

What factors can influence net flux?

A

Electrical gradient, temperate, surface area, mass, and membrane permeability.

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7
Q

What kind of relationship does Fick’s law represent?

A

A linear relationship. As the permeability of the membrane increases, the flux increases.

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8
Q

Partition Coefficient

A

relates how well a substance will partition itself between two I miscible substances. Basically, will it stay between them or does it prefer water or lipid?

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9
Q

How do you calculate the partition coefficient?

A

Concentration of substance in oil/concentration of substance in water

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10
Q

Partition coefficient=1

A

Exists equally in water and oil

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11
Q

Partition coefficient>1

A

Lipophilic (soluble in oil) and can pass easily through the membrane.

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12
Q

Partition coefficient

A

Only soluble in water and will not easily pass through the membrane

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13
Q

Pore

A

Non gated transmembrane protein channel that is always open. Transports according to the concentration gradient.

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14
Q

Channel

A

Gates transmembrane protein that can open and close

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15
Q

Transporter

A

Transmembrane protein that undergoes a conformational change and facilitates the transport of a “packet of substrate across the membrane.

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16
Q

What do ion channels do?

A

They increase the permeability of the membrane for that ion species.

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17
Q

What are the three types of ion channels?

A

Ligand gated-activated with a specific molecules binds to the binding site causing a conformational change.

Voltage gated-a change in the membrane potential causes the molecules to move within the channel.

Mechanosensitve-whole stretch of the membrane that may affect the channel conformation by either opening or closing the channel.

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18
Q

What are the four major factors that determine the rate of transport across a membrane?

A

Saturation of transporter
Number of transports
Conformational change (takes time to change shape)
Gradient

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19
Q

Facilitated Diffusion

A

Solute is moved across a membrane down its electrochemical gradient. Transporters are specific for a substrate.

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20
Q

Active Transport

A

requires an energy source to move a solute against its electrochemical gradient (which can generate voltage). that energy source is usually ATP

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21
Q

what is the difference between primary active transport and secondary active transport?

A

In primary, the concentration gradient is used to move a solute against its own gradient, n secondary it moves another solute against its concentration gradient.

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22
Q

Co-transporter

A

In secondary active transport in which both substrates are moved in the same direction

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23
Q

Exchanger

A

In secondary active transport in which the two substrates move in opposite directions.

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24
Q

Anti porters

A

Another name for secondary active exchangers, these utilize the electrochemical gradient of one substrate to drive another substrate in the opposite direction.

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25
Q

What is the major role of epithelial cells?

A

the secretion and/or absorption of solutes and fluid, does this by setting up an osmotic gradient that water can flow down

26
Q

Absorption

A

Movement of solutes/fluid from lumen to blood (uses eNAC)

27
Q

Secretion

A

Movement of solutes/fluid from blood into the lumen

28
Q

Apical membrane

A

Membrane in contact with the luminal space

29
Q

Basolateral membrane

A

membrane in contract with the interstitium and blood

30
Q

Cardiolipin

A

Fatty acid that is the most common component of the inner mitochondrial membrane (about 20%)

31
Q

What kind of transport do the GLUT transporters utilize? Do they depend on sodium?

A

they do facilitated diffusion and do not rely on sodium

32
Q

GLUT 1

A

Brain, RBC

33
Q

GLUT 2

A

Liver kidney, beta cell, intestine

34
Q

GLUT 3

A

Neurons, brain

35
Q

GLUT 4

A

Muscle and fat

36
Q

GLUT 5

A

Intestine, seminal vesicles (high affinity for fructose)

37
Q

What makes the GLUT 4 transporter unique?

A

It is insulin dependent as insulin mobilizes its transport

38
Q

Osmoles

A

Number of particles of solute that contribute to osmotic pressure

39
Q

Osmolality

A

Osmosis/L

40
Q

Osmolarity

A

Total number of solute particles/L

41
Q

Tonicity

A

concentration of only the osmotically active particles (those that can’t penetrate the barrier)-control cell volume

42
Q

Concentration

A

Mass of substance in a known volume

43
Q

Chemical potential difference

A

Concentration gradient between two compartments

44
Q

what are the two driving forces for water movement within the body?

A

Osmotic pressure (concentration of solutes within the water-water moves to area of high concentration) and hydrostatic driving forces (effect of gravity on the fluid across capillary endothelial cells)

45
Q

what causes osmosis?

A

difference in solute concentration, causing water to flow from area of low osmolarity to high osmolarity (less solute to more solute)

46
Q

How does reflection coefficient relate to osmotic pressure?

A

You can’t have osmotic pressure without reflection. The inability of solutes to cross the membrane is what drives the flow of water

47
Q

Penetrating Solutes

A

can enter the cell (glucose, urea) and will distribute until equilibrium is reached

48
Q

Non-penetrating solutes

A

Cannot enter the cell (sucrose, things that dissociate into ions) and water will move to dilute solutes

49
Q

Isoosmotic

A

total osmotic pressure of solution=osmotic pressure of cell

50
Q

Hyperosmotic

A

Solution has a greater osmotic pressure than the cell

51
Q

Hypoosmotic

A

Is the solution has less osmotic pressure than the cell

52
Q

Isotonic

A

A solution is isotonic if, at equilibrium, it causes the cell to neither shrink nor swell (non-penetrating solute concentration is equal on both sides of cell membrane)

53
Q

Hypertonic

A

Causes cell to shrink (non-penetrating solute is greater outside the cell)

54
Q

Hypotonic

A

Causes cell to swell (non-penetrating solute concentration is greater inside the cell than outside)

55
Q

Trans cellular

A

Movement of water across epithelial cells

56
Q

Paracellular

A

Movement of water between cells-determined by how “tight” or “leaky” the cells are

57
Q

What determines membrane potential?

A

which ion has a greater conductance at rest (usually potassium) and the magnitude of the concentration gradient for the ion

58
Q

When does a membrane potential result in zero net flux?

A

Net flux will be zero when the electrical energy is equal and opposite to the chemical energy

59
Q

What is the main purpose of the Nernst equation?

A

It tells you the membrane potential that keeps the ions in equilibrium

60
Q

What has the greatest effect upon membrane potential in a cell?

A

the most permeant ion has the greatest effect, so most cell membrane potentials are close to the potassium equilibrium potential (most cells have high K permeability)

61
Q

Membrane potential

A

Potential difference between the inside and outside of the cell

62
Q

Equilibrium Potential

A

Potential at which there is no flux of ion

Exam 1 Notes (10 decks)

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