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Physiology > Ch.5 membranes > Flashcards

Ch.5 membranes Flashcards

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1
Q

ECF

A

outside the cell,
- plasma and interstitial fluid

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2
Q

ICF

A

fluid inside the cell

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3
Q

describe the relationship of ECF and ICF

A

-both reach osmotic equilibrium due to the free movement of water
-some solutes are more concentrated in one compartment over the other

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4
Q

homeostasis does not equal

A

equilibrium
-ICF and ECF only share osmotic equilibrium, not chemical or electrical

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5
Q

chemical disequilibrium

A

-high amounts of potassium in ICF, low in ECF
-high amounts of sodium in ECF, low in ICF
- body strives to be in chemical disequilibrium

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6
Q

gradient

A

difference between concentrations

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7
Q

what is the plasma membrane and what does it control

A

composed of hydrophobic interactions
-controls the movement between the cell and its environment

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8
Q

diffusion

A

the movement of a substance from an area of high concentration to low concentration due to random thermal molecular motion
- no energy input
- substances are always in motion, above absolute zero
-occurs in all environments ; ex. air, some solids, primarily water
- chemical equilibrium can be reached, but still in movement

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9
Q

factors that affect diffusion and their relationship

A
  • temp: directly proportional
    -molecular weight: indirectly proportional
    -surface area: directly proportional
    -gradient: directly proportional
    -membrane permeability: directly proportional
    -distance: indirectly proportional
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10
Q

flux

A

amount of substance that crosses a defined surface area per unit of time
-rate of diffusion

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11
Q

net flux

A

includes diffusion from both sides

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12
Q

diffusion equilibrium

A

state of flux in both directions is equal and results in a net flux of zero

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13
Q

passive transport

A

no energy input, diffusion directly through membrane

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14
Q

passive transport
-substances need to be

A

small, charged, and nonpolar

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15
Q

most substances in the body are

A

lipophobic/ charged, so will not readily pass through bilayer

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16
Q

passive transport
facilitated diffusion

A

diffuse through a membrane protein

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17
Q

passive transport
what are the types of facilitated diffusion

A

through a channel or carrier

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18
Q

passive transport
facilitated diffusion
1. channel:

A

channel: transmembrane protein, contacts the ECF and ICF. creates an open cavity through which substances pass through.
-exterior: hydrophobic
-interior: hydrophilic; interacts with charged and polar substances
-limited to smaller atoms
-proteins: have the ability to flex and change shape. noncovalent interactions cause ability to change shape

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19
Q

passive transport
facilitated diffusion
1. channel
what are the types of channels and describe them

A

-open channels: create a water filled pore. known as leak channels. remain open most of the time although can occasionally close for brief periods. evens out gradients.
-gated channels: majority present in body. remain closed and open for a few milliseconds

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20
Q

passive transport
facilitated diffusion
1. channel
describe the types of gated channels

A
  • stimulus/ligand gated channels: respond to ligand bonding. binding substances causes weaker bonds to break and new bonds to form (noncovalent)
  • voltage gated channels: respond to changes in membrane potential ( action potential)
    -mechanically gated channels: respond to physical distortion
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21
Q

channels can be specific

A

anion only, cation only, even a specific ion

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22
Q

passive transport
facilitated diffusion
2. carrier mediated transport

A

never provide a continuous pathway (not open to both sides at the same time)
-transmembrane protein
-can carry larger substances like glucose
-binds noncovalently

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23
Q

passive transport
facilitated diffusion
2. carrier mediated transport
list the types of carriers and describe them

A

-uniport carrier: transports one kind of substrate (ie. glucose)
-symport carrier: move two or more substrates in the same direction across a membrane.
-antiport carrier: move substrates in opposite directions

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24
Q

passive transport
facilitated diffusion
channel vs carrier

A

-carrier: doesn’t open to both sides. reaches a max flux (saturation)
-channel: opens to both sides. rates of flux are higher

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25
active transport
uses energy, moves substance from low to high concentration -commonly uses ATP
26
active transport 1. primary active transport
use energy that is found on an ATP
27
active transport 1. primary active transport list the 4 types of ion ATPase:
-break down ATP, move ions -NA-K: maintains membrane potential, transmembrane protein pumps. 3 Na out and 2 K in. use of covalent bond phosphorylates, creates energy to flex. causes it to change shape. primary outcome: contribute to gradient: high K inside and high Na outside. antiport -Ca (calcium): found in plasma membranes and organelles. uniport. 3. H+ ATPase or proton pump: mitchondria and plasma membranes. uniport 4. H+-K+: plasma membranes. stomach acid
28
active transport what are the three subdivisions of active transport
-primary active transport -secondary active transport -vesicular transport
29
active transport 2. secondary active transport
cotransporters, similar to carrier pumps out an ion from high conc to low which gives energy. while doing so it pushes another ion up its gradient, moving low to high conc. -energy source: ex. sodium moving down its gradient drawback: sodium will even out. first needs primary active transport to make gradient. constantly needs to pump sodium out but needs ATP
30
active transport 3. vesicular transport
uses ATP to move cytoskeleton, creates vessicles.can bring larger contents.
31
active transport 3. vesicular transport: describe the types
1. exocytosis: bring in -phagocytosis: cell eating -pinocytosis: cell drinking 2. exocytosis: exits cell
32
osmosis
the movement of water from an area of high conc (low solute) to low conc (high solute) due to random thermal molecular motion -all factors that apply to diffusion also apply to osmosis -exception: molecular weight
33
solution
solute + solvent
34
osmotic pressure
pressure that must be applied to enforce diffusion of water
35
osmolarity
concentration of a solution expressed as a number of solutes per L
36
tonicity:
describes the volume change in a cell placed in a solution -always comparing a solution to a cell -solutes have to be impermeable
37
hypertonic
cell shrinks
38
hypotonic
cell swells
39
isotonic
doesn't change size
40
normal cell concentation
300 m osm
41
electrical potential: (E)
separation of charge, voltage difference between two points -more separation= more potential
42
voltage (V):
measure of potential (separation of charge) to do work (units of potential)
43
membrane potential (Vm or Em)
voltage difference between the inside or outside of the cell
44
current (I)
movement of an electrical charge (ion)
45
ohms law
I= E/R g= conductance I/R then I= gE. permeability -movement is inversely proportional to distance
46
synonym of conductance
permeability
47
as the membrane deviates from Ex, then
an increasing driving force is created
47
if the membrane potential is at equilibrium then
there is no driving force for that ion
47
equilibrium potential
the voltage that would exist across a membrane if it were exclusively permeable to one ion in which the voltage force is = and opposite to the concertation force -different directions -between the chemical and electrical gradient
48
Ex of Na+
60mV
49
Ex of K+
-90mV
50
Ex of Cl-
-70mV
51
equilibrium potential is dependent on
the separation of charge
52
the outside of the cell is typically referred to as
0 charge
53
equilibirum potential inside the cell
stated as excess charge relative to the outside, always (-) relative to the outside
54
equilibirum potential at rest, all cells have what kind of membrane potential
negative membrane potential
55
resting membrane potential
voltage difference between the inside and outside of the cell when the cell is NOT active
56
what is the resting membrane potential of neurons
-70 mV
57
disproportional ion flux
deviations in membrane potentiald
58
depolarization
move (-) to 0
59
repolarization
moves towards resting membrane potential
60
hyperpolarization
below resting membrane potential
61
polarize
not at 0, there is a separation of charge present
62
describe the elements of a beta pancrease cell at rest
-stimulus: there is low glucose in the blood. glucose travels through GLUT transporter protein which results in low metabolism and low ATP -katp channel: remains open and allows K+ to leak. causes the inside of the cell to become more (-), not depolarizing. so premade insulin stays in vesicles because there is no signal
63
beta cell secreting insulin
-stimulus: there is a high glucose gradient present which travels through GLUT transporter by simple diffusion into the beta cell -glucose undergoes glycolysis, citric acid cycle, and oxidative phosphorylation which creates ATP -production of ATP, binds to the kATP channel (allosteric modulation) and closes the k+atp and K+ does not leak out of the betal cell. -keeping the K+ ions inside the cell causes depolarization -change in membrane potential causes Ca+ channel to open up (voltage gated channel) -Ca+ travels from high concentration to outside of the cell to low concentration inside of the cell. -Ca+ interacts with cytoskeleton proteins and triggers exocytosis of vesicles and secretes insulin -insulin binds to stomach and liver cells, which then trigger a signal to break down glucose.

Physiology (8 decks)

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