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Physiology > Movement of Molecules (Topic 4) > Flashcards

Movement of Molecules (Topic 4) Flashcards

1
Q

What is diffusion? (2)

A

The movement of molecules from one location to another as a result of their random thermal motion

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2
Q

What happens if a solution with molecules on one side sits for a while? (2)

A

The random thermal motion will cause the molecules to move to the other side till saturation is reached

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3
Q

What is flux? (3)

A

the amount of material crossing a surface per unit time

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4
Q

What is net flux? (3)

A

difference between fluxes in each direction

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5
Q

What is net flux at equilibrium? (3)

A

zero

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6
Q

If net flux is 0, is one-way flux 0? (3)

A

No, it means that they are equal to each other

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6
Q

If net flux is 0, is one-way flux 0? (3)

A

No, it means that they are equal to each other

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7
Q

What does diffusion rate depend on? (4)

A
  • temperature
  • mass of molecule
  • surface area
  • type of medium
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8
Q

What affect does temp have on diffusion? (4)

A

As it increases, rate increases

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9
Q

What affect does mass of the molecule have on diffusion? (4)

A

as it increases, rate decreases

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10
Q

What affect does surface area have on diffusion? (4)

A

as it increases, rate increases

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11
Q

What affect does the type of medium have on diffusion? why? (4)

A

ex: faster in air than in water
- water is more dense than air
(dependent on density)

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12
Q

time for diffusion is proportional to what? (4)

A

distance squared

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13
Q

If you have a call (20um) and a basketball (23cm) how long would it take to reach equilibrium? (4)

A
  • 20um = 15 msec
  • 23cm = 265 days
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14
Q

Why is diffusion through a membrane slower than water? (5)

A

The job of a membrane is to literally block things (be a barrier)

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15
Q

What moves through a membrane easier? non-polar (hydrophobic) or polar (hydrophilic)? why? (5)

A

non-polar because the inside of a membrane is hydrophobic (contains the hydrophobic tails)

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16
Q

What are examples of non-polar things that can move through a membrane easily? (5)

A
  • oxygen
  • carbon
  • fatty acids
  • steroids
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17
Q

Why is oxygen non-polar? (5)

A

there is no difference in electronegativity because they are the same atom

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18
Q

What are examples of polar things that can not move through a membrane easily? (5)

A
  • ions
  • water
  • charged things
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19
Q

Flux (J) through membrane: (5)

A
  • Difference in concentrations (C)
  • Surface Area (A)
  • Permeability coefficient (P)
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20
Q

J = ? (5)

A

J = PA (Co-Ci)

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21
Q

What effect does permeability, surface area, and concentration have on flux? (5)

A

They are all equal
- as one increases, flux increases

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22
Q

What is facilitated diffusion? (6)

A

like simple diffusion, but uses a protein

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23
Q

Does facilitated diffusion require energy? (6)

A

No

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24
Q

What is the direction of movement in facilitated diffusion? (6)

A

high conc. -> low conc.
- With the gradient

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25
Q

What is a channel? (7)

A

integral proteins that span the lipid bilayer

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26
Q

Why do ions need a channel? (7)

A

because they are charged and cannot pass through the hydrophobic (tails) inside of the protein

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27
Q

Would every amino acid in a channel have the same type of R-group? (7)

A

No, because of the hydrophilic and hydrophobic regions, the R-groups will change to match their regions
(different R-groups in different parts of the protein, allow it to function the way its supposed to)

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28
Q

What does flux depend on? (8)

A

electrochemical gradient

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29
Q

What does it mean when you say channels are specific? (7)

A

They are specific to each ion
(ex: calcium channel vs potassium channel)

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30
Q

What does “electro” refer to? (8)

A

charge difference across the membrane

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31
Q

What does “chemical” refer to? (8)

A

concentration difference

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32
Q

Channels that have gates that can open and close are called what? (9)

A

gated channels

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33
Q

What are 3-types of gated channels? (9)

A
  • ligand-gated
  • voltage-gated
  • mechanically-gated
34
Q

What is a ligand-gated channel? (9)

A

binding of a chemical messenger (allosteric or covalent)

35
Q

What is a voltage-gated channel? (9)

A

change in membrane potential

36
Q

What is a mechanically-gated channel? (9)

A

physical deformation of the membrane

37
Q

How are molecules that are too large or charged transported across a membrane? (10)

A

transported one-by-one across the membrane
(ex: glucose, amino acids)

38
Q

What do protein transporters do? (10)

A

change conformation to move solute (one or few at a time)

39
Q

What are similarities and differences between ion channels and transporters? (10)

A

similarities:
- transmembrane proteins
- chemical specificity
differences:
- Ion channels open continuous stream (like bridge)
- Transporters change shape to move each molecule (like ferry boat)

40
Q

What are three factors that affect the rate of mediated-transport? (11)

A
  • degree of saturation of transports
  • number of transports in the membrane
  • time it takes to transport one solute (speed of shape change)
41
Q

as extracellular solute concentration increases, ? (11)

A

flux of the cell increases

42
Q

What is maximal flux? (11)

A

All carriers are saturated and the max is reached (plateau)

43
Q

Movement through a channel when graphed looks like what? why? (11)

A

Diffusion (constant incline)
- because they cannot get saturated

44
Q

What is passive transport?

A

Transport that does not require ATP

45
Q

What is active transport? (12)

A

Transport that requires energy

46
Q

What can active transport do that passive cannot? (12)

A

can move molecules against the gradient (low to high concentration)

47
Q

What are active transports often called? (12)

A

pumps

48
Q

What are the two types of active transport? (12)

A

Primary and secondary active transport

49
Q

What is primary active transport? (12)

A

direct use of ATP by the transporter to move the solute

50
Q

What is secondary active transport? (12)

A
  • ATP is used indirectly and used to form a gradient
  • transporter uses gradient to move the solute
51
Q

How does a sodium-potassium pump work? (13)

A

(13)

52
Q

How does secondary active transport work? (13)

A

A molecule is transported against the gradient while another is cotransported with an ion following the gradient

53
Q

Where does ATP go during rest in secondary active transport? (14)

A

10-40% is used by pumps to maintain the electrochemical gradient

54
Q

What is symport? (14)

A

solutes are moved in the same physical direction

55
Q

What is antiport? (14)

A

solutes are moved in different physical directions

56
Q

What is osmosis? (16)

A

diffusion of water

57
Q

How does water cross the membrane? (16)

A

aquaporins

58
Q

What is osmolarity? (16)

A

total solute concentration

59
Q

1 osmol= (16)

A

1 Mol of solute particles

60
Q

What is osmotic pressure? (16)

A

pressure needed to be applied to one side of a membrane to prevent pure water from flowing in

61
Q

What is isotonic? (18)

A

solutions have the same concentration of nonpenetrating solutes as normal extracellular fluid.

62
Q

What is hypotonic? (18)

A

solutions have a lower concentration of nonpenetrating solutes as normal extracellular fluid.

63
Q

What is tonicity? (18)

A

isotonic, hypotonic, and hypertonic solutions

64
Q

What is hypertonic? (18)

A

solutions have a higher concentration of nonpenetrating solutes as normal extracellular fluid.

65
Q

Only penetrating or non penetrating solutes for tonicity? (18)

A

Only NON PENETRATING

66
Q

Only penetrating or non penetrating solutes in osmolarity? (19)

A

penetrating solutes (osmolarity includes all solutes)

67
Q

Would putting a cell in a hyperosmotic solution always make it shrink? (19)

A

No, because some of the solutes may penetrate the cell

68
Q

Is MgCl2 and glucose penetrating or nonpenetrating? (19)

A
  • MgCl2 is non penetrating
  • Glucose is penetrating
69
Q

you place a RBC (300mOsM) in a solution of 0.1M MgCl2 and 0.1M glucose. Assume all solutes are non-penetrating. What would happen to the cell? (19)

A
  • in terms of tonicity, the cell is Isotonic, because they are non penetrating. MgCl2 is 0.3 OsM which is the same as 300mOsM
  • in terms of osmolarity, it is hyperosmotic. Inside the cell has 0.3 OsM, outside of the cell it is 0.4 Osm (MgCl2 + glucose) so the solution is hyperosmotic (need more information to determine if the cell will shrink to swell because we need to know what’s penetrating)
  • glucose goes in and some water will follow into the cell
70
Q

What is exocytosis? (20)

A

transport of materials out of the cell via vesicles

71
Q

What is endocytosis? (20)

A

stuff in the extracellular fluid moves into the cell membrane

72
Q

What does a vesicle do? (21)

A

transport material into the cell

73
Q

What are the three types of vesicles? (21)

A
  • Pinocytosis
  • Phagocytosis
  • receptor-mediated
74
Q

What are the functions of exocytosis? (22)

A

1.Provides a way to replace portions of the plasma membrane that endocytosis has removed
2. Adds new membrane components to the membrane
3. Provides a route by which membrane-impermeable molecules (such as protein hormones) the cell synthesizes can be secreted into the extracellular fluid

75
Q

What triggers exocytosis? (22)

A

influx of calcium

76
Q

What are epithelial cells? (23)

A
77
Q

What are the two epithelial transport pathways? (23)

A
  • paracellular
  • transcellular
78
Q

What is the paracellular pathway? (23)

A

around/between cells
- very limited because of tight junctions

79
Q

What is a tight junction? (23)

A

proteins that enter cells together

80
Q

What is the transcellular pathway? (23)

A

Diffusion or mediated transport
through the cell
- crosses both membranes (luminal and basolateral membrane)

81
Q

How do apical and basolateral membranes differ? (24)

A

differ in ion channels and transporters

82
Q

T/F Solutes can cross the whole epithelium against a gradient? (24)

A

True
- Ex: absorption in intestines and kidneys

Physiology (15 decks)

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