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Physiology 208 > Membrane Dynamics > Flashcards

Membrane Dynamics Flashcards

1
Q

What fraction of total body water volume does intracellular fluid take up?

A

2/3 (ECF 1/3)

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2
Q

Where is the interstitial fluid found?

A

Between the circulatory system and the cells.

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3
Q

What percent of the body is water?

A

60%

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4
Q

What does it mean when the extracellular and intracellular compartments are in osmotic equilibrium?

A

Their fluid concentrations, or the amount of solute per volume solution are equal.

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5
Q

What is osmosis?

A

The movement of water across a membrane in response to a solute concentration gradient.

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6
Q

What is the purpose of aquaporin channels?

A

Allows water to cross the membrane faster. Involved in short term and long term water regulation.

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7
Q

Where does water move by osmosis?

A

From an area of low solute concentration to high solute concentration (trying to dilute it).

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8
Q

What is osmotic pressure?

A

The pressure that would have to be applied to oppose and prevent osmosis.

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9
Q

What is osmolarity?

A

Describes the number of particles in solution.

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10
Q

What is the normal osmolarity in the human body?

A

280-296 mOsm.

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11
Q

What does isosmotic mean?

A

Solutions have identical osmolarities (equal).

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12
Q

What does hyperosmotic describe?

A

The solution with the higher osmolarity (greater than).

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13
Q

What does hyposmotic describe?

A

The solution with the lower osmolarity (less than).

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14
Q

What is tonicity?

A

Describes a solution and how that solution would affect cell volume if that cell were placed in the solution and allowed to come to equilibrium.

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15
Q

What happens to a cell when the solution is hypotonic?

A

The cell will swell/burst.

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16
Q

What happens to a cell when the solution is hypertonic?

A

The cell will shrink.

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17
Q

What is the main difference between osmolarity and tonicity?

A

Osmolarity can be used to compare two solutions (and has units), tonicity always compares a solution and a cell and describes the solution.

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18
Q

What does tonicity depend on?

A

The concentration of non-penetrating solutes.

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19
Q

What two factors are considered in allowing a substance to cross a cell membrane?

A
  1. The properties of the cell membrane (lipid and protein composition).
  2. The substance (size and lipid solubility).
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20
Q

What is diffusion?

A

The movement of molecules from an area of higher concentration to an area of lower concentration. Does not require energy.

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21
Q

What sort of molecules can move from simple diffusion?

A

Small uncharged molecules or lipids.

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22
Q

What 4 factors make the rate of diffusion through a membrane faster?

A
  1. The membrane’s surface area is larger.
  2. The membrane is thinner.
  3. The concentration gradient is larger.
  4. The membrane is more permeable to the molecule.
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23
Q

What does membrane permeability to a molecule depend on?

A
  1. The molecule’s lipid solubility.
  2. The molecule’s size.
  3. The lipid composition of the membrane.
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24
Q

What is Fick’s Law of Diffusion?

A

Rate of Diffusion = surface area x concentration gradient x membrane permeability

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25
Q

What are channel proteins?

A

They are made of membrane spanning protein subunits that create a cluster of cylinders with a pore through the center.

26
Q

How can channel proteins be classified?

A
  1. Open channels - Leak channels.

2. Gated channels - Chemically, voltage, mechanically

27
Q

What are carrier proteins?

A

Large complex proteins that change conformation to move molecules.

28
Q

What do channel proteins and carrier proteins move?

A

Channel - Mainly smaller substances (ions and water)

Carrier - Small organic molecules that cannot pass through channels.

29
Q

What is facilitated diffusion?

A

Uses carrier proteins to move down their concentration gradients with no energy required. Stops once equilibrium is reached.

30
Q

What is active transport?

A

Moves molecules against their concentration gradients (low to high concentration).

31
Q

What is primary active transport?

A

Molecules are moved using energy from hydrolyzing ATP.

32
Q

What is secondary active transport?

A

Uses the potential energy stored in the concentration gradient of one molecule to push another molecule against their concentration gradient.

33
Q

What is the difference between symporters and antiporters?

A 
Symport = Same direction 
Anitport = Opposite direction
34
Q

What is specificity in terms of both active and passive carrier mediated transport?

A

The ability of a transporter to move one molecule or a closely related group of molecules.

35
Q

What is competition in terms of both active and passive carrier mediated transport?

A

A carrier may move severeal members of a related group of substances, but these substances compete with one another (carriers may have a preference).

36
Q

What is saturation in terms of both active and passive carrier mediated transport?

A

When a group of carrier proteins is operating at its max rate (all of the carriers are being used).

37
Q

What is vesicular transport used for?

A

Macromolecules that cannot fit through a carrier or channel.

38
Q

What is phagocytosis?

A

Creates vesicles using the cytoskeleton. Requires ATP.

39
Q

What is the inner vesicle termed after phagocytosis?

A

Phagosome.

40
Q

What is endocytosis?

A

Transport into the cell by membrane indentation and APT.

41
Q

What is the non-selective form of endocytosis?

A

Pinocytosis - Allows ECF to enter.

42
Q

What is the selective form of endocytosis?

A

Receptor mediated transport.

43
Q

What two proteins induce endocytosis?

A

Clathrin and caveolae.

44
Q

What is exocytosis?

A

Transport out of the cell.

45
Q

How can exocytosis be regulated?

A

By Ca2+. Can occur continuously or intermittently.

46
Q

What is epithelial transport?

A

Movement of substances across an entire epithelium (digestive tract, airways, etc.)

47
Q

What is absorption?

A

From the lumen of the organ to ECF.

48
Q

What is secretion?

A

From ECF to lumen of organ.

49
Q

What is transcellular transport?

A

Across epithelial cell - Substances cross the apical layer, and then the basolateral layer.

50
Q

What is paracellular transport?

A

Between the cells between tight junctions that usually don’t allow substances to pass.

51
Q

What is transcytosis?

A

It is a combination of endocytosis, vesicle transport and exocytosis.

52
Q

What are the two types of passive transport?

A

Simple and facilitated diffusion.

53
Q

What are the two types of active transport?

A

Primary and secondary.

54
Q

What are the three types of vesicular transport?

A

Phagocytosis, endocytosis, and exocytosis.

55
Q

What are the three types of epithelial transport?

A

Paracellular, transcellular and transcytosis.

56
Q

What is the membrane potential?

A

The electrical disequilibrium that exists between the ECF and ICF.

57
Q

What is the electrochemical gradient?

A

The combination of electrical and concentration gradients.

58
Q

What is the equilibrium potential?

A

For any given concentration gradient of a single ion, the membrane potential that exactly opposes the concentration gradient.

59
Q

What is the resting membrane potential?

A

The membrane potential of a cell when it is not active.

60
Q

What is the resting membrane potential due to mostly?

A

Potassium ions. Permeable to both Na+ and K+ but 40X more to K+.

Physiology 208 (3 decks)

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