Diffusion, Ionic Concentration, Electrochemical Potential, and Excitable Tissue

Question 1

movement of solute down its concentration gradient until concentrations are equal

Answer 1

simple diffusion

Question 2

Na+, K+, Cl-, Ca++

Answer 2

important physiological ions

Question 3

glucose, amino acids, lipids

Answer 3

important physiological nutrients

Question 4

O2, CO2

Answer 4

important physiological gases

Question 5

diffusion of water down its concentration gradient
water moves from more dilute to more concentrated solute solutions

Answer 5

osmosis

Question 6

the force that would need to be applied on a compartment to prevent the migration of water into that apartment, due to unequal solute concentrations

Answer 6

osmotic pressure

Question 7

a solution with high solute load would have a high osmotic pressure relative to a pure water solution

Answer 7

osmotic pressure ex.

Question 8

1 mole of solute dissolved in 1 liter of water
(solute concentration)

Answer 8

molality

Question 9

the total molality of a water solution

Answer 9

osmolality

Question 10

1m glucose + 1 m fructose = 2 osmol/L

Answer 10

osmolality of non-ionic substances

Question 11

1m NaCl yields 2 osmol/L

Answer 11

osmolality of ionic substances

Question 12

describes the effect of net movement of water due to osmosis into or out of the cell
(what happens to cell volume when exposed to a solution)

Answer 12

tonicity

Question 13

no net movement of water

Answer 13

isotonic solution

Question 14

Blood plasma = 300 mOsm
0.3 m glucose = 300 mOsm (5g glusoce/100mL H2O)
0.15m NaCl = 300 mOsm (0.9g NaCl/100mL H2O)

Answer 14

standard solutions, (isotonic)

Question 15

higher solute load than inside the cell, water will move from cell to solution, causing the cell the shrink (crenation)

Answer 15

hypertonic solution

Question 16

lower solute load inside the cell, water will move into the cell from the solution causing the cell to expand and burst (Hemolysis)

Answer 16

hypotonic solution

Question 17

(carrier mediated transport) involves a membrane carrier molecule
could become saturated (all carrier molecules are used)

Answer 17

facilitated diffusion

Question 18

defines the distribution of ions in two aqueous compartments separated by membrane, where membrane is impermeable to at least one ionic species

Answer 18

Gibbs Donnan Equilibrium

Question 19

determined by charge and concentration gradients

Answer 19

movement of ions

Question 20

Gibbs Donnan Equilibrium equation

Answer 20

[K+]i[Cl-]i = [K+]o[Cl-]o

Question 21

osmotic hydrostatic pressure calculation

Answer 21

P = 22.4 atm(delta[K+] + delta[Cl-] + delta[A-]

Question 22

brain ischemia, low O2 shuts down Na+/K+ ATPase pump, ion balance is disturbed, water flows into cells, neurons swell and are damaged

Answer 22

Gibbs Donnan Equilibrium ex.

Question 23

movement of an ion against its concentration gradient, requires ATP

Answer 23

Primary active transport

Question 24

kinetic energy of a molecule moving downs its concentration gradient is coupled to move another molecule against its concentrating gradient (hitching a ride)

Answer 24

Secondary active transport

Question 25

electrogenic (moves charge across a membrane) located in the plasma membrane, ATP is the source, moves 3 Na+ out of the cell and 2 K+ in establishes charge and concentration differences across the membrane

Answer 25

NA+/K+ ATPase pump

Question 26

Na+/K+ ATPase pump steps

Answer 26

1. 3 Na+ bind to transporter, ATP binds 2. phosphate is cleaved, bind the pump 3. confirmational change results, Na+ is released 4. K+ now binds to outside of transporter 5. Phosphate is released 6. confirmation change results, K+ is released in the cell

Question 27

a way to calculate equilibrium potential for individual ions

Answer 27

Nernst equation

Question 28

Nernst equation

Answer 28

E = (61.5/Z) log([ion]out/[ion]in) Z is ion valence

Question 29

establishes equilibrium potential for cell, simultaneously using all ions

Answer 29

Goldmann Field equation

Question 30

Goldmann Field Equation

Answer 30

61.5log((PK[ion]out + PNa[Ion]out + PCl[Ion]in)/(PK[ion]in + PNa[ion]in + PCl[Ion]out)) P = permeability coefficient

Question 31

Permeability coefficients for a resting cell

Answer 31

PK = 1.0 PCl = 0.45 PNa = 0.04

Question 32

Permeability coefficients for an excited state cell

Answer 32

PK = 1.0 PCl = 0.45 PNa = 20.0

Question 33

ionic potential creates an electrical potential across the membrane

Answer 33

why nerve tissue is excitable

Question 34

quantitative measure of irritability

Answer 34

the strength duration curve

Question 35

the four important values derived from the strength duration curve

Answer 35

1. Rheobase: minimum intensity in mV that still produces response 2. Utilization time: the time necessary to produce Rheobase response 3. Chronaxie: the duration in msec which a stimulus 2x Rheobase needs to produce a response 4. Excitability: 1/Chronaxie

Question 36

determinants of the charge and excitability of a cell (4)

Answer 36

1. Phospholipid bilayer (permeable to water, impermeable to ions) 2. Na+/K+ ATPase pump (ion inequality across the membrane) 3. Nongated channels (channels that are always open to ions) 4. Gated channels (channels that open or close depending on cell charge)

Question 37

resting potential is established by

Answer 37

Nongated channels and the Na+/K+ ATPase pump negative potential difference compared to extracellular fluid -70 mV

Question 38

passive channels, determine ion permeabilities, "leaky," more permeable to K+ than Na+

Answer 38

Nongated channels

Question 39

found in membrane, uses ATP, 3 Na+ out, 2K+ in, uses 60% of the cells energy

Answer 39

Na+/K+ ATPase pump

Question 40

extracellular Na+ gate

Answer 40

M gate

Question 41

intracellular Na+ gate

Answer 41

H gate

Question 42

single extracellular gate

Answer 42

N gate

Question 43

The time after an action potential when a neuron cannot be activated by another stimulus, controlled by Na+ gates

Answer 43

absolute refractory period

Question 44

threshold for action potential is elevated because of hyperpolarization overshoot, requires strong stimulus

Answer 44

relative refractory period

Question 45

pufferfish, tetrodotoxin, block Na+ channels, nerves cannot produce action potential, results in cardiac and respiratory failure

Answer 45

Fugu

Question 46

inhibits the Na+/K+ ATPase pump

Answer 46

the role of Ouabain