CH 5: Membranes Flashcards by Dahlia Hernandez | Brainscape

Q

Interstitial fluid

A

Should have little to no proteins

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Q

Compartments in body

A

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

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Q

Plasma membrane

A

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

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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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Q

Diffusion can occur in?

A

air
solids
liquids

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Q

Absolute zero

A

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

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Q

Homeostasis is?

A

Chemical disequilibrium

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Q

Rate of diffusion: factor & relationship

A

Temp is directly proportional

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Q

Rate of diffusion: factor & relationship

A

Molecular weight is inversely proportional

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Q

Rate of diffusion: factor & relationship

A

Surface area is directly proportional

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Q

Rate of diffusion: factor & relationship

A

Gradient is directly proportional

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Q

Rate of diffusion: factor & relationship

A

Membrane permeability is directly proportional

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Q

Rate of diffusion: factor & relationship

A

Distance is inversely proportional
- due to diffusion using NO ENERGY

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Q

Flux

A

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

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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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Q

Methods of passage through a lipid bilayer

A

Passive transport
Active Transport

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Q

Passive transport

A

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

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Q

Diffusion through membrane protein

A

Channels
Carrier-mediated transport

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Q

Other types of channels are gated/regulated by the cell

A

Stimulus-gated
Voltage-gated
Mechanosensitive
*Open for milliseconds

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Q

Stimulus-gated

A

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

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Q

Voltage-gated

A

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

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Q

Mechanosensitive

A

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

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Q

Channels can be very specific…

A

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

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Q

Active Transport

A

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

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Q

Primary active transport

A

utilizes transmembrane protein (a physical pump)
non-covalent bonds are no longer sufficient…use covalent bonds (PO4-)
4 types of ion ATPase (primary active)

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Q

4 types of ion ATPase (primary active)

A

Na+ – K+
Ca++
H+
H+ – K+

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Q

Sodium Potassium pump

A

maintains membrane potential

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Q

Calcium pump

A

Plasma membrane & organelles
- cardiac muscle cells & smooth ER

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Q

Hydrogen pump

A

Mitochondria & plasma membranes
- kidney

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Q

Hydrogen Potassium pump

A

Plasma membranes
- stomach

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Q

Secondary active transport

A

Using gradients from primary active transport

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Q

Vesicular transport

A

Uses ATP
- looking at > 1 molecule “much more magnified”
- cytoskeleton uses ATP
- moves BIGGER substances (hormones/neurotransmitters)
2 diff types:
1. Endocytosis
2. Exocytosis

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Q

Endocytosis

A

Phagocytosis “cell eating”
Pinocytosis “cell drinking”

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Q

Exocytosis

A

Contents of cell are released

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Q

Osmosis

A

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

Q

Osmotic pressure

A

Measurement of potential force w/in osmosis
- amount of force needed to oppose osmosis

Q

Osmolarity

A

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)

Q

Hypotonic

A

A solution that has lower concentration

Q

Hyperosmotic

A

A solution that has higher concentration than another solution
- exert greater osmotic force

Q

Isoosmotic

A

Solutions that have equal concentration

Q

Tonicity

A

Describes the volume change of a cell placed in a solution
- very specific
- must refer to 2 things

Q

Tonicity must refer to 2 things…

A

Talk ab a cell & compare to a cell
Must be dealing w/ NON-PENETRATING solutes

Q

Crenate

A

“shrinking”

Q

RBC normal shape

A

Biconcave disc

Q

Basic principles of electricity

A

How things get across a membrane

Q

Opposites attract…

A

Oppositely charged particles come together to perform work
- separating (+) charge from (-) charge REQUIRES ENERGY

Q

Electricity: ECF vs ICF

A

ECF is more positive
ICF is more negative

Q

Electrical potential (E)

A

Voltage difference b/t 2 points
“separation of charge”

Q

Voltage (V)

A

Measure of potential (separated charge) to do work (units of potential)
“how much power you have to work with”

Q

Membrane potential (Vm or Em)

A

Voltage difference b/t the inside & outside of the cell

Q

Current (I)

A

Movement of an electrical charge
- can be H, Na, Etc.

Q

Ohm’s law

A

I = E/R (electrical potential/resistance)

Q

Resistance

A

Is membrane permeability

Q

What happens to a cell in a hypertonic solution?

A

Cell shrinks
Crenates

Q

What happens to a cell in a hypotonic solution?

A

Cell swells

Q

What happens to a cell in an isotonic solution?

A

Cell doesn’t change size

Q

Normal intracellular concentration

A

300 mOsm
- NON-penetrating solutes

Q

Membranes are not necessarily permeable…

A

But facilitated through CHANNELS & carriers

Q

g = conductance

A

= 1/R
then,
I = gE

Q

Equilibrium potential (Ex)

A

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

Q

Net flux (driving force) is present if not at?

A

Equilibrium potential
- one gradient is larger than the other

Q

Separation of charge

A

Aka gradient
- more gradient, more current (flow of ions)

Q

Normal physiological concentration: Na+

A

ECF: 150 mOsm
ICF: 15 mOsm
Ratio: 10:1
E: +60 mV
- body will never reach +60…there will always be a gradient

Q

Normal physiological concentration: K+

A

ECF: 5 mOsm
ICF: 150 mOsm
Ratio: 1:30
E: -90 mV
- skeletal muscles will reach -90

Q

Normal physiological concentration: Cl-

A

ECF: 110 mOsm
ICF: 7 mOsm
Ratio: 15:1
E: -70 mV

Q

Homeostasis fluctuates around?

A

Normal physiological values of equilibirum potential

Q

Nernst Equation

A

Ex = RT/zF * log [X]o/[X]i
- o = outside cell
- i = inside cell

Q

R

A

Universal gas constant
(8314.9 J/KgmolK)

Q

T

A

Absolute temperature (K)

Q

F

A

Farday’s number
(96,485 C/mol of charge)

Q

z

A

Charge of ion
(+1/-1)

Q

For sodium at normal body temp…

A

RT/zF simplifies to the constant 61

Q

By convention, outside of the cell equals?

A

zero

Q

Inside of the cell is stated as?

A

Excess charge relative to the outside of the cell
*whatever # we are using is referring to INSIDE the cell

Q

At rest, all cells have _______ membrane potential

A

Negative

Q

Resting membrane potential

A

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

Q

Separation of charge

A

Electrical gradient
- the greater the separation of charge, the larger the electrical gradient
- less separation of charge, the smaller the electrical gradient

Q

Vm = 0mV

A

No separation of charge

Q

Changes happening in electrical gradients are significantly relative to changes in?

A

Concentration gradient

Q

“Relative distribution of ions”: 2 questions

A

Is the membrane PERMEABLE?
Is there a GRADIENT?
—-opposites attract

Q

Membrane potential (Vm) is influenced by?

A

Permeability of membrane to an ion
Ion gradient

Q

Proportionate ion flux maintains what?

A

Steady-state

Q

Ion flux and membrane potential play an important role in?

A

Cellular & organismal function
- Changes in Vm cause cellular responses in excitable & non-excitable tissues

Q

The beta cells of pancreas produce & secrete what?

A

Insulin

Q

Insulin is required by most cells to absorb what?

A

Glucose from the plasma (and interstitial fluid)

Q

How can beta cells monitor blood glucose concentrations?

A

Through changes in membrane potential

Q

Glucose range (normal)

A

70-100