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AU14 Physiology > EX1; Excitable Cells; Ions/Transport > Flashcards

EX1; Excitable Cells; Ions/Transport Flashcards

1
Q

What three types of cells are considered excitable cells

A

neurons
sensory cells
most muscle cells

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2
Q

What categorizes an excitable cell

A

their physiologic functions rely critically on electrical events in their plasma membrane

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3
Q

What three things categorize a mechanism of cell-to-cell (intercellular) communication

A

very rapid
allow precise timing of signals between cells
allow complex patterns of communication between cells

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4
Q

This is a mechanism for sensing environmental changes (light, sound, temp, etc.)

A

stimuli from environment; electrical events in receptor cells

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5
Q

This is a mechanism for triggering intracellular events

A

electrical events in cells; intracellular changes that are either rapid or can accumulate over time

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6
Q

This is the activation to initiate an event

A

excitation

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7
Q

What are the three major components of excitation

A

extracellular fluid
intracellular fluid
membrane

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8
Q

What is the composition of extracellular fluid

A

primarily ions, proteins, and other molecules

high NaCl concentration

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9
Q

What is the composition of intracellular fluid

A

ions, much higher concentrations of proteins, other molecules
high KCl concentration

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10
Q

This allows cells to communicate with one another

A

the differences between the inside (KCl) and outside (NaCl) of cells

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11
Q

What is the composition of the membrane

A

phospholipid bilayer and proteins (equal amount), small (~5%) carbohydrates

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12
Q

This characteristic of cell membranes is essential to excitation

A

permeability

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13
Q

What is the permeability of a membrane to an ion an index of

A

the ability of the ion to cross the membrane; if the ions can readily cross the membrane, then the membrane has a high ion permeability

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14
Q

Changes in the permeability that are these two things are essential to excitation in cells

A

ion-specific

exquisitely timed

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15
Q

This is random diffusion down an electrical or concentration gradient; organic molecules or ions

A

simple diffusion

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16
Q

These type of molecules diffuse rapidly through the membrane which is 50% lipid; solubility in lipid is high

A

non-polar organic molecules; O2, CO2, fatty acids, steroids

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17
Q

Does the diffusion of non-polar organic molecules require energy?

A

No; no energy is required

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18
Q

These type of molecules cross membranes via channels which are proteins, often several subunits and generally specific for that molecule

A

ions

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19
Q

This is the amount of a substance crossing a surface per unit of time

A

flux

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20
Q

Diffusion between two compartments is always what

A

bi-directional; 1 to 2 and 2 to 1

21
Q

This is the difference between the two unidirectional fluxes

A

net-flux

22
Q

When net-flux is zero, the system is referred to be in a state of what

A

diffusion equilibrium

23
Q

What are the two types of mediated transport

A

facilitated diffusion

active transport

24
Q

This type of mediated transport has no energy requirement; a membrane protein serves as a carrier to translocate a molecule across a membrane

A

facilitated diffusion

25
Q

This type of mediated transport requires energy; a molecule is bound to a transporter (pump) and it moves up the concentration and/or electrical gradient

A

active transport

26
Q

What two things does energy effect involving active transport

A

the affinity of the transporter for the ligand on one side of the membrane more than the other
rate of transporter conformational change

27
Q

What is the energy source of the primary active-transport model

A

hydrolysis of ATP

28
Q

What is the primary-active transport model

A

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

29
Q

What is the secondary-active transport model

A

uses energy in ion concentration gradient across membrane

transporter has 2 binding sites

30
Q

What three factors determine the rate of flux

A

number of transporters in the membrane
extent of transporter saturation
rate of transporter conformational change

31
Q

What are three types of channels

A 
ligand-sensitive (chemically regulated)
voltage sensitive (voltage regulated)
mechanosensitive
32
Q

What are the three basic steps in mediated transport

A

ligand binds to transporter
transporter undergoes conformational change
ligand is released on other side of membrane

33
Q

This is the bulk flow of water across a membrane; shrinking or swelling

A

osmosis

34
Q

Water is polar and therefore diffused down its concentration gradient through these channels

A

aquaporins

35
Q

This is the total solute concentration in a solutaion

A

osmolarity

1. 0 osmol = 1.0 mol solute
1. 0 mol NaCl = 2.0 osmols

36
Q

What is the osmolarity of extracellular fluid

A

300 mOsm

37
Q

300 mOsm of non-penetrating solutes; no change in cell volume is what type of solution

A

isotonic

38
Q

< 300mOsm of non-penetrating solutes; cell swells, is what type of solution

A

hypotonic

39
Q

> 300 mOsm of non-penetrating solutes; cell shrinks, is what type of solution

A

hypertonic

40
Q

300 mOsm of non penetrating solutes plus penetrating solutes is what type of solution

A

isoosmotic

41
Q

< 300 mOsm of non penetrating solutes plus penetrating solutes is what type of solution

A

hypoosmotic

42
Q

> 300 mOsm of non penetrating solutes plus penetrating solutes is what type of solution

A

hyperosmotic

43
Q

True or False

A solution can be hyper osmotic and isotonic at the same time

A

True

44
Q

This is engulfment of fluid and particles from the extracellular space

A

endocytosis

45
Q

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

A

pinocytosis

46
Q

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

A

phagocytosis

47
Q

This is the export of material from a cell

A

exocytosis

48
Q

What is the purpose of exocytosis

A

replaces membrane patches internalized through endocytosis

49
Q

What is the mechanism of release of molecules synthesized within cells

A

secretion

AU14 Physiology (24 decks)

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