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Human Physiology > CH 5: Membranes > Flashcards

CH 5: Membranes Flashcards

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1
Q

Interstitial fluid

A

Should have little to no proteins

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2
Q

Compartments in body

A

Are in a state of chemical disequilibrium
- ultimately what the body wants

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3
Q

Plasma membrane

A

Control of material exchanges
- mediation of cell-environment interactions
- membrane permeability/impermeability

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4
Q

Diffusion

A

The movement of a substance from an area of high substance con. to an area of low substance con. due to RANDOM THERMAL MOLECULAR MOTION
NO ENERGY, HAPPENS NATURALLY

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5
Q

Diffusion can occur in?

A
  • air
  • solids
  • liquids
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6
Q

Absolute zero

A

Molecules no longer move
- never rlly reached
- bodies constantly are using diffusion
- randomness net of diffusion

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7
Q

Homeostasis is?

A

Chemical disequilibrium

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8
Q

Rate of diffusion: factor & relationship

A

Temp is directly proportional

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9
Q

Rate of diffusion: factor & relationship

A

Molecular weight is inversely proportional

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10
Q

Rate of diffusion: factor & relationship

A

Surface area is directly proportional

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11
Q

Rate of diffusion: factor & relationship

A

Gradient is directly proportional

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12
Q

Rate of diffusion: factor & relationship

A

Membrane permeability is directly proportional

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13
Q

Rate of diffusion: factor & relationship

A

Distance is inversely proportional
- due to diffusion using NO ENERGY

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14
Q

Flux

A

Amount of a substance that crosses a defined surface area PER UNIT TIME

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15
Q

Diffusion equilibrium

A

State in which the diffusion fluxes in opposing directions are equal, resulting in a NET FLUX OF ZERO

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16
Q

Methods of passage through a lipid bilayer

A
  1. Passive transport
  2. Active Transport
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17
Q

Passive transport

A

NO ENERGY INPUT
2 ways:
1. Diffusion directly thru the membrane
2. Diffusion thru membrane protein

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18
Q

Diffusion through membrane protein

A
  1. Channels
  2. Carrier-mediated transport
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19
Q

Other types of channels are gated/regulated by the cell

A
  1. Stimulus-gated
  2. Voltage-gated
  3. Mechanosensitive
    *Open for milliseconds
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20
Q

Stimulus-gated

A

Respond to ligand binding
- closes channel when ligand dislodges
ex: neurotransmitters, hormones

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21
Q

Voltage-gated

A

Respond to changes in voltage (membrane potential)
ex: action potentials

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22
Q

Mechanosensitive

A

Respond to physical distortion
ex: tactile (receptors in our skin)

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23
Q

Channels can be very specific…

A

Can be:
- anion only
- cation only
- even specific for a particular ion

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24
Q

Active Transport

A

REQUIRES ENERGY
2 diff ways:
1. Primary active transport
2. Secondary active transport
3. Vesicular transport

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25
Primary active transport
- utilizes transmembrane protein (a physical pump) - non-covalent bonds are no longer sufficient...use covalent bonds (PO4-) - 4 types of ion ATPase (primary active)
26
4 types of ion ATPase (primary active)
1. Na+ -- K+ 2. Ca++ 3. H+ 4. H+ -- K+
27
Sodium Potassium pump
maintains membrane potential
28
Calcium pump
Plasma membrane & organelles - cardiac muscle cells & smooth ER
29
Hydrogen pump
Mitochondria & plasma membranes - kidney
30
Hydrogen Potassium pump
Plasma membranes - stomach
31
Secondary active transport
Using gradients from primary active transport
32
Vesicular transport
Uses ATP - looking at > 1 molecule "much more magnified" - cytoskeleton uses ATP - moves BIGGER substances (hormones/neurotransmitters) 2 diff types: 1. Endocytosis 2. Exocytosis
33
Endocytosis
1. Phagocytosis "cell eating" 2. Pinocytosis "cell drinking"
34
Exocytosis
Contents of cell are released
35
Osmosis
The movement of water from an area of high water (low solute) concentration to an area of low water (high solute) concentration due to random thermal molecular motion - diffusion of water - membrane permeability is essential *all factors that apply to diffusion also apply to osmosis
36
Osmotic pressure
Measurement of potential force w/in osmosis - amount of force needed to oppose osmosis
37
Osmolarity
Concentration of a solution expressed as number of solutes per liter (REGARDLESS OF SOLUTE TYPE) - moles = 6.022 x 10^23 molecules/atoms (Avogadro's number)
38
Hypotonic
A solution that has lower concentration
39
Hyperosmotic
A solution that has higher concentration than another solution - exert greater osmotic force
40
Isoosmotic
Solutions that have equal concentration
41
Tonicity
Describes the volume change of a cell placed in a solution - very specific - must refer to 2 things
42
Tonicity must refer to 2 things...
1. Talk ab a cell & compare to a cell 2. Must be dealing w/ NON-PENETRATING solutes
43
Crenate
"shrinking"
44
RBC normal shape
Biconcave disc
45
Basic principles of electricity
How things get across a membrane
46
Opposites attract...
Oppositely charged particles come together to perform work - separating (+) charge from (-) charge REQUIRES ENERGY
47
Electricity: ECF vs ICF
- ECF is more positive - ICF is more negative
48
Electrical potential (E)
Voltage difference b/t 2 points "separation of charge"
49
Voltage (V)
Measure of potential (separated charge) to do work (units of potential) "how much power you have to work with"
50
Membrane potential (Vm or Em)
Voltage difference b/t the inside & outside of the cell
51
Current (I)
Movement of an electrical charge - can be H, Na, Etc.
52
Ohm's law
I = E/R (electrical potential/resistance)
53
Resistance
Is membrane permeability
54
What happens to a cell in a hypertonic solution?
Cell shrinks *Crenates*
55
What happens to a cell in a hypotonic solution?
Cell swells
56
What happens to a cell in an isotonic solution?
Cell doesn't change size
57
Normal intracellular concentration
300 mOsm - NON-penetrating solutes
58
Membranes are not necessarily permeable...
But facilitated through CHANNELS & carriers
59
g = conductance
= 1/R then, I = gE
60
Equilibrium potential (Ex)
The voltage that would exist across a membrane if it were exclusively permeable to one ion in which a voltage force is equal & opposite to concentration force - if membrane potential is at equilibrium potential, then there is no driving force for that ion - as membrane potential deviates from Ex, then an increased driving force is created
61
Net flux (driving force) is present if not at?
Equilibrium potential - one gradient is larger than the other
62
Separation of charge
Aka gradient - more gradient, more current (flow of ions)
63
Normal physiological concentration: Na+
ECF: 150 mOsm ICF: 15 mOsm Ratio: 10:1 E: +60 mV - body will never reach +60...there will always be a gradient
64
Normal physiological concentration: K+
ECF: 5 mOsm ICF: 150 mOsm Ratio: 1:30 E: -90 mV - skeletal muscles will reach -90
65
Normal physiological concentration: Cl-
ECF: 110 mOsm ICF: 7 mOsm Ratio: 15:1 E: -70 mV
66
Homeostasis fluctuates around?
Normal physiological values of equilibirum potential
66
Nernst Equation
Ex = RT/zF * log [X]o/[X]i - o = outside cell - i = inside cell
67
R
Universal gas constant (8314.9 J/Kg*mol*K)
68
T
Absolute temperature (K)
69
F
Farday's number (96,485 C/mol of charge)
70
z
Charge of ion (+1/-1)
71
For sodium at normal body temp...
RT/zF simplifies to the constant 61
72
By convention, outside of the cell equals?
zero
73
Inside of the cell is stated as?
Excess charge relative to the outside of the cell *whatever # we are using is referring to INSIDE the cell
74
At rest, all cells have _______ membrane potential
Negative
75
Resting membrane potential
Voltage difference between the inside & outside of the cell when the cell is not active (-70 mV in neurons) - "at rest" - will vary for different cell/tissue
76
Separation of charge
Electrical gradient - the greater the separation of charge, the larger the electrical gradient - less separation of charge, the smaller the electrical gradient
77
Vm = 0mV
No separation of charge
78
Changes happening in electrical gradients are significantly relative to changes in?
Concentration gradient
79
"Relative distribution of ions": 2 questions
1. Is the membrane PERMEABLE? 2. Is there a GRADIENT? ----opposites attract
80
Membrane potential (Vm) is influenced by?
1. Permeability of membrane to an ion 2. Ion gradient
81
Proportionate ion flux maintains what?
Steady-state
82
Ion flux and membrane potential play an important role in?
Cellular & organismal function - Changes in Vm cause cellular responses in excitable & non-excitable tissues
83
The beta cells of pancreas produce & secrete what?
Insulin
84
Insulin is required by most cells to absorb what?
Glucose from the plasma (and interstitial fluid)
85
How can beta cells monitor blood glucose concentrations?
Through changes in membrane potential
86
Glucose range (normal)
70-100

Human Physiology (8 decks)

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