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BIOL 223 > Membrane Systems > Flashcards

Membrane Systems Flashcards

1
Q

Intracellular fluid is

A

cytosol

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2
Q

Extracellular fluid is

A

Interstitial fluid

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3
Q

The ions of higher concentration inside the cell are

A

K+ and anionic proteins

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4
Q

The ions of higher concentration outside the cell are

A

Na+
Cl-
Ca2+

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5
Q

Define permeability

A

The ease with which substances can cross the cell membrane

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6
Q

A cell membrane is selectively permeable and that selectivity is due to

A

different transport mechanisms

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7
Q

A passive transport mechanism

A

does not expend energy

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8
Q

An active transport mechanism

A

expends energy

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9
Q

Diffusion is

A

passive

random motion of ions and molecules down their concentration gradient

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10
Q

Carrier mediated transport

A

Can be passive or active

requires transport protein in membrane

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11
Q

When an ion moves from high to low concentration, it is said to be

A

passive

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12
Q

When an ion moves from low to high concentration, it is said to be

A

active

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13
Q

Diffusion is define as

A

the movement of a substance from an area of high concentration to low

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14
Q

Molecules with no electrical charges diffuse

A

down the chemical concentration gradient

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15
Q

Charged ions and molecules diffuse

A

based on electro-chemical gradient

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16
Q

What are the four examples of diffusion in body fluids?

A

O2 moves from lungs to blood
CO2 moves from cells to lungs
Water moves across digestive tract
Anesthetics diffuse into cells

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17
Q

For diffusion to occur, the membrane must be

A

permeable

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18
Q

The lipid bilayer portion of cell membranes is permeable to

A

O2
CO2
Hydrophobic molecules

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19
Q

The lipid bilayer portion of the cell membrane is not permeable to

A

large molecules

hydrophilic molecules

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20
Q

Membrane proteins provide channels for what type of diffusion?

A

Passive

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21
Q

Define osmosis

A

Diffusion of water across a semi-permeable membrane in response to solute differences

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22
Q

Water moves

A

via diffusion down its concentration gradient

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23
Q

In osmosis, water wants to move

A

from low to high solute concentration

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24
Q

Define osmotic pressure

A

force of water movement into a solution

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25
Define tonicity
The effects of extracellular solutions on cells
26
Define isotonic
No net osmosis, no net gain or loss of water
27
Define hypotonic
Net gain of water into cells
28
Hypotonic states of cells can result in
Cytolysis (hemolysis in RBCs)
29
Define hypertonic
Net water flow out of the cell
30
Hypertonic states of cells can result in
crenation
31
What is a hypotonic extracellular solution and how will water behave?
Less solutes, more water than intracellular solution Water will flow into the cell
32
What is hypertonic extracellular solution and how will water behave?
More solutes, less water than intracellular solution Water will flow out of the cell
33
What factors influence diffusion?
Distance Size Temperature Concentration gradient
34
Diffusion is an effective means of transport from 0- _____ micrometers
123
35
Diffusion will occur faster if
molecule is smaller temp is higher concentration gradient is higher
36
For charged ions, the 2 driving forces influencing their rate of diffusion are
electrical gradient | concentration gradient
37
What would happen if a cell suddenly became very permeable to Na+ ions?
Na+ ions would move into the cell
38
Describe diffusion
Passive Random motion of substances down their gradient Channel proteins allow hydrophilic substances through
39
Describe carrier mediated transport
Passive or active | Requires a transport protein in membrane
40
Carrier mediated transport relies on what three factors?
specificity saturation limits regulation
41
Define specificity in terms of carrier mediated transport
carrier proteins are generally specific for a particular substance
42
Define Saturation limits
Rate of transport is subject to number of transport proteins available
43
Define Regulation
Various control factors exist that effect the activity of carrier proteins
44
To increase your saturation limit, you can use a
enzyme
45
Define co-transport
both substances being transported go same directions across the membrane
46
Define counter-transport
both substances being transported go opposite directions across the memrane
47
Is facilitated diffusion passive or active?
Passive
48
Describe facilitated diffusion
Substance moves down conc. gradient Requires transport protein Differs from simple diffusion (can reach saturation)
49
Describe facilitated diffusion with co transport against concentration gradient
One substance moves down gradient Another moves against gradient Requires transport protein
50
Describe active transport
Consumes ATP | Independent of conc gradients
51
What are the two examples of active transport??
Ion pumps | Secondary active transport
52
What is trans-membrane potential?
Difference in electrical potential between inside and outside of a cell?
53
At rest, cells have more negative charge ____ than _____
inside than outside
54
What is higher in concentration inside a cell at rest?
K+ | Proteins (negatively charged anions)
55
What is higher in concentration outside a cell at rest?
Na+ Cl- Ca2+
56
What is the electro-chemical gradient?
Sum of all forces of all chemical and electrical gradients acting across the cell membrane
57
The resting trans-membrane potential in nerve cells is
-70mV
58
The resting trans-membrane potential in muscle cells is
-85mV
59
What is the driving force of ion flow across a membrane?
Diffusion along a electro-chemical gradient
60
Chemically regulated channels
Open or close when they bind specific chemicals
61
Voltage-regulated channels
Open or close in response to level of trans-membrane potential
62
____ is released by motor neurons and tell muscles to contract
ACh
63
Define neuromuscular junction
synapse between nerve cell and muscle cell
64
Nerve cell process releases acetylcholine by
exocytosis
65
Define depolarization
trans-membrane potential becomes less negative
66
Define hyperpolarization
trans-membrane potential becomes more negative
67
Define repolarization
trans-membrane potential returns toward resting potential after being depolarized

BIOL 223 (9 decks)

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