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Physio > Excitable Cells > Flashcards

Excitable Cells Flashcards

1
Q

____, ____, and most ____ are often referred to as “excitable cells” bc their physiologic functions rely critically on electrical events in their plasma (i.e. surface) membrane

A

neurons (single nerve cells)
sensory cells
muscle cells

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2
Q

3 mechanisms of electrical events

A
  • cell to cell (intercellular) communication
  • sensing environmental changes (light, sound, temp, etc.)
  • triggering intracellular events
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3
Q

three components of cell excitation

A 
extracellular fluid (ECF) or interstitial fluid
intracellular fluid (cytosol)
membrane
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4
Q

extracellular fluid has a high ____ concentration

A

NaCl

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5
Q

intracellular fluid is predominantly _____

A

KCl

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6
Q

cell membrane made up of ____ and ____

A

phospholipid bilayer ; proteins

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7
Q

a characteristic of cell membranes, essential to excitation, is _____

A

permeability

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8
Q

changes in permeability, that are ____ and ____, are essential to excitation in cells

A

ion-specific; exquisitely timed

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9
Q

random diffusion down an electrical or concentration gradient; done by organic molecules or ions

A

simple diffusion

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10
Q

examples of non-polar substances

A

O2, CO2, fatty acids, and steroid hormones

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11
Q

amount of a substance crossing a surface per unit of time

A

flux

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12
Q

diffusion between 2 compartments is always _____

A

bi-directional

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13
Q

the difference between the two unidirectional fluxes

A

net flux

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14
Q

when net flux=0, the system is referred to as being in a state of ______

A

diffusion equilibrium

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15
Q

two types of mediated transport

A

facilitated diffusion and active transport

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16
Q

primary active transport

A

energy source is hydrolysis of ATP > transporter becomes phosphorylated > changes affinity for solute (ligand) > increases transport rate

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17
Q

examples of primary active transport

A
  1. transport of Na ions out of cells

2. transport of K ions into cells

18
Q

secondary active transport uses energy in ____ across membrane; transporter has ____ binding sites

A

ion concentration gradient; two

19
Q

example of secondary active transport

A

transport of amino acids, uses [Na] gradient

20
Q

3 steps in mediated transport

A
  1. ligand binds to transporter
  2. transporter undergoes conformation change
  3. ligand is released on other side of membrane
21
Q

types of channels

A

ligand-sensitive
voltage-sensitive
mechanosensitive

22
Q

water is polar and diffuses through channels called ____; water diffuses ____ its concentration gradient

A

aquaporins; down

23
Q

the total solute concentration in a solution

A

osmolarity

24
Q

engulfment of fluid and particles from the extracellular space

A

endocytosis

25
Q

engulfment of small particles with or without small volume of ECF; performed by all cell types

A

pinocytosis

26
Q

engulfment of large particles or cellular debris; performed by specialized cells

A

phagocytosis

27
Q

electrical charge difference between the inside and outside of a cell

A

voltage (V)

28
Q

voltage (V) in a resting cell is ____. therefore, plasma membrane must have a ____

A

steady; resistance (R)

29
Q

when resistance changes, ions cross the plasma membrane, and this ion movement is a ____

A

current (I)

30
Q

conductance (g) is the ____ of resistance

A

reciprocal

31
Q

Ohm’s law

A

V = IR

32
Q

____ and ____ are both membrane properties

A

conductance; resistance

33
Q

the nernst equation yields the ____ of a single ionic species

A

equilibrium potential (or equilibrium voltage)

34
Q

the equilibrium potential is the voltage across a cell membrane that exactly balances the force in the ____ of a ____ ion

A

concentration gradient; permeable

35
Q

diffusion potentials can be ____; they are due to an ____ ion flow- an imbalance in the flow of an ion or several ions between two compartments

A

transient (disappear over time); asymmetric

36
Q

a diffusion potential can also be ____ at a ____ level over time

A

maintained; steady

37
Q

toward 0 mV

A

depolarization (hypopolarization)

38
Q

toward resting potential

A

repolarization

39
Q

increase in membrane potential (i.e. more negative)

A

hyperpolarization

40
Q

equilibrium is reached when the force in the ____ for K+ ions to move out of the cell is balanced by opposing force in the ____ which favors keeping K+ ions inside the cell

A

concentration gradient; electrical gradient

41
Q

membrane potential at equilibrium

A

-70-90 mV

42
Q

equilibrium potential for K+

A

-100 mV

Physio (9 decks)

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