Membrane Transport Flashcards
1
Q
cell membrane is a bilayer of
A
phopholipids
2
Q
the major function of the cell membrane
A
create a barrier for diffusion
3
Q
hormone –> receptor –> ( ) –> cellular response
A
second messenger
4
Q
diffusion occurs with a rate depending on what?
A
permeability
5
Q
membranes are permeable to
A
- gasses (oxygen, CO2, nitric oxide)
- lipophilic substances (fatty acids and steroids)
- water
6
Q
membranes are not permeable to
A
- ions (Na+, K+, Ca2+, Cl-)
- small charges or hydrophilic molecules (aminoacids, nucleoacids, sugars, neurotransmitters), proteins, & DNA
7
Q
rate of diffusion: 1 micron
A
0.5 ms
8
Q
what pushes water backwards?
A
solutes
9
Q
force required to prevent osmosis
A
force required to prevent osmosis
10
Q
osmosis direction
A
lower solute concentration to higher solute concentration
11
Q
osmolality of solution=
A
total # of solute molecules/# of water molecules in the same volume of solution
12
Q
osmolality of plasma in body
A
300 mOsm
13
Q
osmotic pressure of plasma=
A
osmotic pressure of istonic soln
14
Q
A
hyptonic
15
Q
> osmotic pressure of plasma (shrink)
A
hypertonic
16
Q
dehydration effect on plasma volume
A
decreases
17
Q
decreased plasma volume leads to
A
increased plasma osmolality
18
Q
increased plasma osmolality leads to
A
increased osmoreceptors activity
19
Q
increased osmoreceptors activity leads to
A
secretion of ADH by posterior pituitary
20
Q
secretion of ADH by posterior pituitary leads to
A
water retention in kidneys
21
Q
water retention in kidneys leads to
A
increased plasma volume
22
Q
facilitated diffusion is characterized by
A
- specificity
- competition
- saturation
23
Q
uncharged/charged: the electrochemical gradient is determined by the relative concentrations of the substance on both sides of the membrane
A
uncharged
24
Q
uncharged/charged: the electrochemical gradient is determined by the relative concentrations of the substance on both sides of the membrane AND the membrane potential across the membrane
A
charged
25
if hydrolysis of ATP is the source of energy, this is called ( )
primary active transport (Ca2+ pump, Na+/K+ exchanger)
26
if energy comes from moving another substance down the electrochemical gradient this is called ( )
secondary active transport/cotransport (Na+-glucose cotransporter in kidneys, Na+/Ca2+ exchanger)
27
Na+ out
140mM
28
K+ out
5mM
29
Cl- out
120mM
30
HCO3- out
20-26mM
31
Na+ in
5-10mM
32
K+ in
150mM
33
Cl- in
5-40mM
34
types of channels
- water channels
| - ion channel
35
types of carriers
- uniporters (facilitated diffusion)
- symporters (contransporters)
- Antiporters (exchangers)
- pumps
36
function similarly to uniporters except that two subrates must bind for the transport step to take place
cotransporters
37
binding sites re-orient only when substrates are bound and NOT when binding sites are empty
antoporters (exchangers)
38
proton pumps that are relatives of the ATP synthase of mitochondria
V-pumps
39
super-family of genes that encode the ABS transporter proteins
ATP-binding cassette transporters
40
epithelial transport: ( ) physically connect epithelial cells in a tight layer
tight junctions
41
what do tight junctions allow to pass?
water
42
epithelial transport: cells are ( )
polarized
43
epithelial transport: Na/K pumps are located on the ( ) side
basolateral
44
epithelial transport: ( ) minimizes osmotic gradients
water flux
45
epithelial transport: most physiological secretions are ( )
hypotonic
46
epithelial transport: ( ) is maintained
electric neutrality
47
body attempts to absorb all nutrients from the ( ) and to do so the body uses both ( )
- gut
| - cotransporters & uniporters
48
how hypotonic sweat produced
1) salt secreted and water follows
| 2) salt reabsorbed
49
why is the skin of a baby with CFTR salty?
when CFTR channels are lost, sweat becomes salty because NaCl is not effectively reabsorbed
50
in Na/K pumps, the ( ) is used to drive Cl0 out across the basolater side through CFTR Cl- channels --> cytoplasmic Cl- low
negative potential
51
the apical membrane contrains both CFTR ( ) channels
Cl- and Na+
52
Na+ channels used by epithelia that are highly selectrive for Na but very different from voltage gated Na+ channels used to make AP
Epithelial Na+ Channels (ENAC)
53
the major function of the cell membrane
create a barrier for diffusion
54
hormone --> receptor --> ( ) --> cellular response
second messenger
55
diffusion occurs with a rate depending on what?
permeability
56
membranes are permeable to
- gasses (oxygen, CO2, nitric oxide)
- lipophilic substances (fatty acids and steroids)
- water
57
membranes are not permeable to
- ions (Na+, K+, Ca2+, Cl-)
| - small charges or hydrophilic molecules (aminoacids, nucleoacids, sugars, neurotransmitters), proteins, & DNA
58
rate of diffusion: 1 micron
0.5 ms
59
what pushes water backwards?
solutes
60
force required to prevent osmosis
force required to prevent osmosis
61
osmosis direction
lower solute concentration to higher solute concentration
62
osmolality of solution=
total # of solute molecules/# of water molecules in the same volume of solution
63
osmolality of plasma in body
300 mOsm
64
osmotic pressure of plasma=
osmotic pressure of istonic soln
65
hyptonic
66
> osmotic pressure of plasma (shrink)
hypertonic
67
dehydration effect on plasma volume
decreases
68
decreased plasma volume leads to
increased plasma osmolality
69
increased plasma osmolality leads to
increased osmoreceptors activity
70
increased osmoreceptors activity leads to
secretion of ADH by posterior pituitary
71
secretion of ADH by posterior pituitary leads to
water retention in kidneys
72
water retention in kidneys leads to
increased plasma volume
73
facilitated diffusion is characterized by
- specificity
- competition
- saturation
74
uncharged/charged: the electrochemical gradient is determined by the relative concentrations of the substance on both sides of the membrane
uncharged
75
uncharged/charged: the electrochemical gradient is determined by the relative concentrations of the substance on both sides of the membrane AND the membrane potential across the membrane
charged
76
if hydrolysis of ATP is the source of energy, this is called ( )
primary active transport (Ca2+ pump, Na+/K+ exchanger)
77
if energy comes from moving another substance down the electrochemical gradient this is called ( )
secondary active transport/cotransport (Na+-glucose cotransporter in kidneys, Na+/Ca2+ exchanger)
78
Na+ out
140mM
79
K+ out
5mM
80
Cl- out
120mM
81
HCO3- out
20-26mM
82
Na+ in
5-10mM
83
K+ in
150mM
84
Cl- in
5-40mM
85
types of channels
- water channels
| - ion channel
86
types of carriers
- uniporters (facilitated diffusion)
- symporters (contransporters)
- Antiporters (exchangers)
- pumps
87
function similarly to uniporters except that two subrates must bind for the transport step to take place
cotransporters
88
binding sites re-orient only when substrates are bound and NOT when binding sites are empty
antoporters (exchangers)
89
proton pumps that are relatives of the ATP synthase of mitochondria
V-pumps
90
super-family of genes that encode the ABS transporter proteins
ATP-binding cassette transporters
91
epithelial transport: ( ) physically connect epithelial cells in a tight layer
tight junctions
92
what do tight junctions allow to pass?
water
93
epithelial transport: cells are ( )
polarized
94
epithelial transport: Na/K pumps are located on the ( ) side
basolateral
95
epithelial transport: ( ) minimizes osmotic gradients
water flux
96
epithelial transport: most physiological secretions are ( )
hypotonic
97
epithelial transport: ( ) is maintained
electric neutrality
98
body attempts to absorb all nutrients from the ( ) and to do so the body uses both ( )
- gut
| - cotransporters & uniporters
99
how hypotonic sweat produced
1) salt secreted and water follows
| 2) salt reabsorbed
100
why is the skin of a baby with CFTR salty?
when CFTR channels are lost, sweat becomes salty because NaCl is not effectively reabsorbed
101
in Na/K pumps, the ( ) is used to drive Cl0 out across the basolater side through CFTR Cl- channels --> cytoplasmic Cl- low
negative potential
102
the apical membrane contrains both CFTR ( ) channels
Cl- and Na+
103
Na+ channels used by epithelia that are highly selectrive for Na but very different from voltage gated Na+ channels used to make AP
Epithelial Na+ Channels (ENAC)
