Cell Membrane, Membrane Transport and Membrane Potential Flashcards
1
Q
structural proteins form
A
cell to cell attachments that hold adjacent epithelial cells together
2
Q
structural proteins sometimes anchors
A
cells to ECM
3
Q
tight junctions
A
prevents intercellular movement of fluid and dissolved substances
4
Q
desmosomes
A
structural support
5
Q
gap junctions
A
cell to cell communication via ions
6
Q
enzymes
A
integral membrane, transmembrane, or peripheral membrane proteins that catalyze specific chemical reactions either on the extracellular surface of cell oe inside cell
7
Q
properties of enzymes (3)
A
specificity
saturation
competition
8
Q
how long does it take to synthesize proteins
A
2 hours
9
Q
when are most proteins synthesized?
A
in advance and stored in an inactive form, activated when needed
10
Q
proteins provide a means for
A
immediate protein regulation
11
Q
interaction between substance and protein binding site follows the
A
mass action model
12
Q
glycococalyx
A
attached to EC surface of membrane lipids and proteins
13
Q
glycocalyx plays an important role in
A
enabling cells to identify and interact with each other
14
Q
characteristics of membrane structure (4)
A
selectively permeable barrier
mosaic
dynamic
fluid
15
Q
which concentrations are higher outside of the cell (5)
A
Na+ Ca++ Cl- HCO3- Glucose
16
Q
which concentrations are higher inside the cell (6)
A
K+ Mg++ Phosphates Animo acids pH Proteins
17
Q
passive transport (3)
A
no energy required
down gradients (high to low; deltaC, deltaP, or deltaE)
diffusion, osmosis, bulk flow
18
Q
active transport (3)
A
energy required
up gradients (low to high)
active transporters, bulk (vesicular) transport
19
Q
random thermal motion
A
molecules in a fluid are continuously and randomly bouncing around
20
Q
rate of movement is proportional to
A
(temp)/(mass)
21
Q
diffusion
A
movement of substances other than water down a gradient (deltaC; deltaE or deltaP; how to low)
22
Q
net movement stops at
A
equilibrium
23
Q
random movement is
A
continuous
24
Q
diffusion is — specific
A
substance
25
passive transport moves the system towards
equilibrium
26
mass and heat flow model
concentration gradient (higher energy, lower energy)
driving force
mass or energy flow
resistance
27
what can the mass and heat flow model be used to describe? (5)
```
diffusion
osmosis
blood flow through blood vessels
air flow through airways
capillary exchange
```
28
type of substances
simple diffusion:
facilitated diffusion:
hydrophobic/lipophilic substances
hydrophilic/lipophobic substances
29
movement
simple diffusion:
facilitated diffusion:
move directly through phospholipid bilayer
require membrane channels or carriers
30
speed
simple diffusion:
facilitated diffusion:
slower
faster
31
regulation
simple diffusion:
facilitated diffusion:
unregulated
regulated (specificity, saturation, competition)
32
plasma membrane?
simple diffusion:
facilitated diffusion:
does not require
requires
33
simple diffusion rate (SDR) equation
((gradient)(temp)(surface area))/((resistance)(diffusion distance))
34
facilitated diffusion rate (FDR) IONS equation
(gradient)(temp)(#channels)(probability channels are open)
35
facilitated diffusion rate (FDR) MOLECULES equation
(gradient)(temp)(#carriers)
36
why are the kinetics of simple and facilitated diffusion different?
facilitated diffusion results in saturated carriers, would need more carriers to to increase rate of diffusion
37
osmosis
movement of water across a plasma membrane down a free [h2o] gradient
38
water movement via osmosis is facilitated by
awuaporins
39
water permeability can be
regulated
40
[free h2o] is proportional to
1/[solute]
41
how will water molecules move?
passively down a free water gradient (toward the area with a higher solute concentration)
42
which 3 values change during osmosis?
solute conc
water conc
container volume
43
is osmosis substance specific?
no
44
what determines h2o movement via osmosis?
impermeable substances
45
osmolarity
the total (free) solute concentration of a solution (permeable and impermeable)
46
one osmol is equal to
1 mol of solute particles
47
a 1M solution of glucose has a concentration of ---, whereas a 1 M solution of NaCl is ---
1 Osm (1 osmol/L)
2 Osm (2 Osm of solute/1 L of solution)
48
isosmotic
bathing solution Osm=cytosolic Osm
49
hyposmotic
bathing solution Osm
50
hyperosmotic
bathing solution Osm>cytosolic Osm
51
tonicity
defined by the number of impermeable substances only
52
tonicity determines the
direction of h2o movement via osmosis
| bc only impermeable substances determine the movement
53
isotonic solution (2)
concentration of impermeable substance=cell cytosol
| cells in an isotonic bathing solution will have no net change in volume
54
hypotonic solutions (2)
concentration of impermeable substance
55
hypertonic solutions (2)
concentration of impermeable substance>cell cytosol
| cells in an isotonic bathing solution will lose water and shrink
56
normal ECF is -- mosm of nonpenetrating solute
300
57
normal cytosol is -- mosm of nonpenetrating solute
300
58
under normal circumstances, ECF Osm, is --- to cell cytosol
isotonic
59
cells do not have a net change in
volume
60
what exists to maintain ECF Osm. isotonic?
homeostatic processes
61
pressure is required to -- the flow of water into a compartment
stop
62
permeable solutes (7)
```
ethanol
FA
O2
CO2
steroids
urea
glucose (dextrose)
```
63
impermeable solutes (6)
```
Na+
K+
Cl-
CHO3-
protein
others
```
64
any given cell, at any given moment may or may not be permeable to
glucose or urea
65
any given cell, at any given moment may or may not be permeable to glucose or urea. this depends on (2)
cell type (ex. RBC always permeable to urea/glucose)
chemical signals present at the time (ex. liver and muscle cells only permeable to glucose if insulin present)
66
if asked about a single cell and cell identity is not provided, assume
glucose and urea may be impermeable
67
if asked about whole water over time, assume
glucose and urea are permeable
68
how abundant is water in the body
most abundance molecule, accounts for 60% of body weight
69
think about water as either
intracellular or extracellular
70
the volume of water in the intracellular vs extracellular spaces is
unequal
71
the osmolarity of the extracellular and intracellular spaces is
equal
72
blood plasma accounts for
5% ECF
73
interstitial fluid accounts for
15% ECF
74
intracellular fluid accounts for
40%
75
active transport requiers an
input of energy
76
two types of active transport
1. active transport with membrane proteins (typically what is meant)
2. bulk (vesicular) transport
77
active transporters
transmembrane protein that moves ions and hydrophilic building blocks across the plasma membrane up a deltaC (requires energy)
78
classification of active transporters is based on (3)
1. number of substances being transported
2. directions substances are transported
3. source of energy for transport
79
types of active transporters are based on (2)
number and direction of movement
80
uniporter
moves only one substance
81
symptorters/cotransporters
all substances moving in same directions
82
antiporter/countertransporter
substances moving in different directions
83
primary active transporters
energy comes directly from breakdown of ATP
84
secondary active transporters
energy released from one substance moving down a gradient is used to pump a second substance up a gradient
85
examples of active transport (3)
sodium potassium pump
calcium pump
hydrogen pump
86
sodium potassium pump functions (2)
maintain Na+ and K+ concentration differences
| electrogenic- establishes negative membrane potential
87
cotransporteres (symporters) examples (2)
Na/glucose symporter
| Na/aa symptorter
88
countertransporters (antiporters) ex
Na/Ca exchanger
89
Through a H+ channel (diffusion; DOWN concentration gradient), H+ moves
outside of
| the cell
90
However, if H+ is moving via active transport
| (against its concentration gradient), then it will be moving
into the cell
91
What type of H+ transporter is found in the
| apical epithelium of the stomach??
92
vesicular transport/bulk transport
moves large substances across the PM
93
vesicular transport/bulk transport is --- dependent
gradient
94
vesicular transport/bulk transport requires
energy
95
two types of vesicular transport/bulk transport
endocytosis
| exocytosis
96
endocytosis (3)
brings substances into cell
forms vesicle
removes membrane from PM
97
exocytosis (3)
removes substances from cell
vesicle fuses to membrane
adds membrane to PM
98
vesicular transport/bulk transport is how the cell modifies....
composition of the PM
99
membrane potentials (Vm)
charge difference across the PM
100
membrane potentials (Vm) is created by
unequal distribution of anions and cations across the cell membrane
101
charge separation =
source of energy
102
resting membrane potential
the charge difference across the plasma membrane when the cell us ate rest
103
normal resting Vm
!-70mV (varies by cell type)
104
-- represents the charge inside the cell
sign
105
membrane potential creates the electrical gradients for
movement of ions into/out of cells
106
membrane potential opens or closes
gated ion channels
107
membrane potential regulates
exocytosis
