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Physiology > Movement of Molecules (Topic 4) > Flashcards

Movement of Molecules (Topic 4) Flashcards

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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
What is the direction of movement in facilitated diffusion? (6)
high conc. -> low conc. - With the gradient
25
What is a channel? (7)
integral proteins that span the lipid bilayer
26
Why do ions need a channel? (7)
because they are charged and cannot pass through the hydrophobic (tails) inside of the protein
27
Would every amino acid in a channel have the same type of R-group? (7)
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)
28
What does flux depend on? (8)
electrochemical gradient
29
What does it mean when you say channels are specific? (7)
They are specific to each ion (ex: calcium channel vs potassium channel)
30
What does "electro" refer to? (8)
charge difference across the membrane
31
What does "chemical" refer to? (8)
concentration difference
32
Channels that have gates that can open and close are called what? (9)
gated channels
33
What are 3-types of gated channels? (9)
- ligand-gated - voltage-gated - mechanically-gated
34
What is a ligand-gated channel? (9)
binding of a chemical messenger (allosteric or covalent)
35
What is a voltage-gated channel? (9)
change in membrane potential
36
What is a mechanically-gated channel? (9)
physical deformation of the membrane
37
How are molecules that are too large or charged transported across a membrane? (10)
transported one-by-one across the membrane (ex: glucose, amino acids)
38
What do protein transporters do? (10)
change conformation to move solute (one or few at a time)
39
What are similarities and differences between ion channels and transporters? (10)
similarities: - transmembrane proteins - chemical specificity differences: - Ion channels open continuous stream (like bridge) - Transporters change shape to move each molecule (like ferry boat)
40
What are three factors that affect the rate of mediated-transport? (11)
- degree of saturation of transports - number of transports in the membrane - time it takes to transport one solute (speed of shape change)
41
as extracellular solute concentration increases, ? (11)
flux of the cell increases
42
What is maximal flux? (11)
All carriers are saturated and the max is reached (plateau)
43
Movement through a channel when graphed looks like what? why? (11)
Diffusion (constant incline) - because they cannot get saturated
44
What is passive transport?
Transport that does not require ATP
45
What is active transport? (12)
Transport that requires energy
46
What can active transport do that passive cannot? (12)
can move molecules against the gradient (low to high concentration)
47
What are active transports often called? (12)
pumps
48
What are the two types of active transport? (12)
Primary and secondary active transport
49
What is primary active transport? (12)
direct use of ATP by the transporter to move the solute
50
What is secondary active transport? (12)
- ATP is used indirectly and used to form a gradient - transporter uses gradient to move the solute
51
How does a sodium-potassium pump work? (13)
(13)
52
How does secondary active transport work? (13)
A molecule is transported against the gradient while another is cotransported with an ion following the gradient
53
Where does ATP go during rest in secondary active transport? (14)
10-40% is used by pumps to maintain the electrochemical gradient
54
What is symport? (14)
solutes are moved in the same physical direction
55
What is antiport? (14)
solutes are moved in different physical directions
56
What is osmosis? (16)
diffusion of water
57
How does water cross the membrane? (16)
aquaporins
58
What is osmolarity? (16)
total solute concentration
59
1 osmol= (16)
1 Mol of solute particles
60
What is osmotic pressure? (16)
pressure needed to be applied to one side of a membrane to prevent pure water from flowing in
61
What is isotonic? (18)
solutions have the same concentration of nonpenetrating solutes as normal extracellular fluid.
62
What is hypotonic? (18)
solutions have a lower concentration of nonpenetrating solutes as normal extracellular fluid.
63
What is tonicity? (18)
isotonic, hypotonic, and hypertonic solutions
64
What is hypertonic? (18)
solutions have a higher concentration of nonpenetrating solutes as normal extracellular fluid.
65
Only penetrating or non penetrating solutes for tonicity? (18)
Only NON PENETRATING
66
Only penetrating or non penetrating solutes in osmolarity? (19)
penetrating solutes (osmolarity includes all solutes)
67
Would putting a cell in a hyperosmotic solution always make it shrink? (19)
No, because some of the solutes may penetrate the cell
68
Is MgCl2 and glucose penetrating or nonpenetrating? (19)
- MgCl2 is non penetrating - Glucose is penetrating
69
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)
- 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
What is exocytosis? (20)
transport of materials out of the cell via vesicles
71
What is endocytosis? (20)
stuff in the extracellular fluid moves into the cell membrane
72
What does a vesicle do? (21)
transport material into the cell
73
What are the three types of vesicles? (21)
- Pinocytosis - Phagocytosis - receptor-mediated
74
What are the functions of exocytosis? (22)
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
What triggers exocytosis? (22)
influx of calcium
76
What are epithelial cells? (23)
77
What are the two epithelial transport pathways? (23)
- paracellular - transcellular
78
What is the paracellular pathway? (23)
around/between cells - very limited because of tight junctions
79
What is a tight junction? (23)
proteins that enter cells together
80
What is the transcellular pathway? (23)
Diffusion or mediated transport through the cell - crosses both membranes (luminal and basolateral membrane)
81
How do apical and basolateral membranes differ? (24)
differ in ion channels and transporters
82
T/F Solutes can cross the whole epithelium against a gradient? (24)
True - Ex: absorption in intestines and kidneys

Physiology (15 decks)

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