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Physiology > Unit 1 - Membrane Pysiology > Flashcards

Unit 1 - Membrane Pysiology Flashcards

1
Q

All plasma membranes contain:

A
  1. lipids
  2. proteins
  3. carbohydrates

2-layers of phosolipids
Hydrophilic heads - polar
Hydrophobic tails - nonpolar

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2
Q

What substance maintains the fluidity of a plasma membrane?

A

cholestoral

fluidity allows movement of proteins

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3
Q

Peripheral proteins - where

A

appendages loosely bound to the surface of the membrane

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4
Q

Integral proteins

A
  • penetrate the hydrophobic core of the lipid bilayer

- often are transmembranous

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5
Q

Who proposed the Fluid Mosaic Model of membrane structure?

A

S. Singer & G. Nelson in 1972

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6
Q

glycolipids

A
  • formed by carbohydrate groups that join with lipids
  • on external surface
  • function as identity markers
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7
Q

glycoproteins

A
  • formed by carbohydrates that join with proteins
  • on external surface
  • function as identity markers
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8
Q

Functions of Cell Membranes

A
  1. regulate passage of substances into & out of cell & between cell organelles & cytosol
  2. detect chemical messengers arriving at surface
  3. link adjacent cells together by membrane junctions
  4. anchor cells to EC matrix
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9
Q

Major functions of proteins in plasma membrane:

A
  1. transport solutes across membrane
  2. enzymatic activity
  3. signal transduction
  4. cell-to-cell recognition
  5. intercellular joining
  6. attachment to cytoskeleton & ECM
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10
Q

osmotic pressure

A
  • a “pulling” pressure
  • measure of a tendency for flow of water into a solution b/c of its relative concentration of non penetrating solutes & water
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11
Q

hydrostatic pressure

A
  • pressure exerted by a standing (or stationary) fluid on an object.
  • when osmotic & hydrostatic pressure are equal, osmosis will stop
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12
Q

hyperpolarization

A

a change in a cell’s membrane potential that makes it more negative. It is the opposite of a depolarization.

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13
Q

tonicity

A

measure of whether water will enter or leave a cell

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14
Q

What contributes to the Resting Membrane Potential (RMP)?

A
  1. 20% - Na+/K+ pump
  2. 80% - membrane’s great permeability (Pk+) to K+
    - non-diffusibility of proteins (A-)
    [diffusion!]
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15
Q

Na+/K+ pump

A
  • pumps 2 Na+ out & brings in 2 K+ cells

- unequal pumping makes outside of cell more positive than inside

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16
Q

Nernst Equation

A
  • calculates Equilibrium Potentials for cells

* E = 61 * log [concentration of outside/concentration of inside)

17
Q

Equilibrium Potential of:

  1. Na+
  2. K+
A
  1. +61 mv

2. - 90 mv

18
Q

Where are leak channels found on a neuron?

A

cell body
dendrites
axon
They operate at resting membrane potential

19
Q

Where are CHEMICALLY GATED channels found on a neuron?

A

cell body
dendrites
They operate during a graded potential.

20
Q

Where are VOLTAGE-GATED channels found on a neuron?

A

axon

They operate during an action potential.

21
Q

suprathreshold stimulus

A

Is stronger than the threshold stimulus

22
Q

subthreshold stimulus

A

a stimulus that fails to take the MP to the TP

23
Q

Characteristics of voltage-gated Na+ channels

A
  1. found along axon
  2. important for action potential
  3. opened and closed gates
24
Q

What are the states that a VG Na+ channels could be in?

A
  1. inactivated, but capable
  2. open/activated
  3. inactivated & incapable
25
Q

What channels are open when the membrane is at -70 mv?

A

only leak channels

26
Q

polarization

A

any time there is a - or + charge on a membrane

27
Q

depolarization

A

membrane becoming less negative, as in an action potential

28
Q

repolarization

A

the cell becoming more negative as it re-establishes the polarization of its membrane

29
Q

hyperpolarization

A

membrane becoming more polarized; the inside becoming more negative than at its RMP

30
Q

Which cells form the myelin sheath in the:
PNS?
CNS?

A

PNS - Schwann cells

CNS - oligodendrocytes

31
Q

Two types of synapses. Which is there more of?

A
  1. Electrical - charge carrying ions pass between them.
  2. Chemical - chemical messenger transmits information one way

95% of synapses are CHEMICAL

32
Q

EPSP

A

Excitatory Post-Synaptic Potential

- due to increased Na+ permeability

33
Q

IPSP

A

Inhibitory Post-Synaptic Potential

- due to increased K+ or Cl- permeability

34
Q

GABA

A
  • the brains main’s inhibitory neurotransmitter

- Gamma amino butyric acid

35
Q

grand postsynaptic potential (GPSP)

A

a composite of all EPSPs and IPSPs occurring around the same time

36
Q

temporal summation

A

Caused by increasing the number of action potentials on an axon in a given period of time

37
Q

spatial summation

A

Increasing the number of synapses from different neurons

38
Q

absolute refractory period

A
  • Caused by closure & inactivation of the VG Nq+ channels that opened to depolarize the membrane.

Physiology (15 decks)

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