7. 3-7.5 in plasma 7. 2 in cell

B1W1: Physio Flashcards by Becky Gehrmann

Na+ conc.

In plasma: 138-146 mM

In cell: 15 mm

How well did you know this?

Not at all

Perfectly

Cl- conc.

In plasma: 103-112 mM

In cell: 20 mM

How well did you know this?

Not at all

Perfectly

Glucose conc.

In plasma: 75-95 mg/dl

In cell: VERY LOW

How well did you know this?

Not at all

Perfectly

Ca2+ conc.

In plasma: 1-1.4 mg/dL

In cell: .0001 mM

How well did you know this?

Not at all

Perfectly

K+ conc.

4.4 mM in plasma

120 mM in cell

How well did you know this?

Not at all

Perfectly

3-7.5 in plasma

7. 2 in cell

How well did you know this?

Not at all

Perfectly

Cystic fibrosis

mutation in CFTR Cl- channel

How well did you know this?

Not at all

Perfectly

Lipophillic molecules

resp. molecules (O2, CO2, N2)
organic molecules (alcohols, ketones)
anesthetics

How well did you know this?

Not at all

Perfectly

Hydrophillic molecules

Urea, glycerol

How well did you know this?

Not at all

Perfectly

What is permeability dependent on?

Px=DB/L

D=ease of mvt within cell membrane; determined by size, shape, charge of solute

B=how easily solute crosses one layer; diff. in force attraction for diffusing molecules within and outside membrane

*when with electrochemical gradient, also dependent on # channels open

How well did you know this?

Not at all

Perfectly

B>1 and B<1; B equation

B=[X]i’/[X]i

B>1=lipophillic
B<1=hydrophillic

How well did you know this?

Not at all

Perfectly

sum/net electrical difference across plasma membrane of each permeable ion

–only at steady state, not when ions are at equilibrium

How well did you know this?

Not at all

Perfectly

Steady state

When no net change is occurring in cell and it is maintained by energy (not at equilibrium, though!)

Current zero

How well did you know this?

Not at all

Perfectly

Equillibrium potential

When ion down diffusion gradient is counteracted by force of electrical potential

Value each ion wants to bring the membrane potential
–would not be under steady state; permeability does not matter

EACH ION WANTS TO DO WHAT IT CAN TO BRING CELL TO EQUILLIBRIUM, even if it means leaving it

How well did you know this?

Not at all

Perfectly

Myotonia congenita

Usually Cl- helps repolarize skeletal muscle
BUT Cl- channel inhibited genetically
Cl- not allowed in, prolongued depolarization of flexor muscles, clasped hand won’t relax, abnormal walking gait

How well did you know this?

Not at all

Perfectly

Increase in [K+]o

Depolarization of cell
iK outwardly decreases due to less gradient

less K+ leaving, cell stays more positive

How well did you know this?

Not at all

Perfectly

Clinical issue with increase in [K+]o

Too much means hyper excitability (huge depolarization), arrythmias, abnormal breathing, loss neural control

How well did you know this?

Not at all

Perfectly

Decrease in Pk

depolarization occurs

less K+ is coming out, less separation of + and - charge

How well did you know this?

Not at all

Perfectly

Increase in Pk

causes hyperpolarization

How well did you know this?

Not at all

Perfectly

Decrease in PNa

little change in cell
In resting cell, PNa small already
Making it smaller does nothing

How well did you know this?

Not at all

Perfectly

Increase in PNa

Deplarization large iNa

Increasing permeability in general

pushes membrane towards ion’s equilibrium

Structure of carrier proteins

4 or more membrane spanning protein subunits

Each subunit is 6 segments

Each segment=helical polypeptide sequence

S4 domain

Opens up channels

S5, S6 domain in Na+ channel

inactivates Na+ channel

Terminal intracellular chain of K+ channel

inactivation

3 properties of protein channels

1. chemical specificity (D glucose only) 2. Saturation 3. competitive/noncompetitive inhibition

Ouabain

competitive inhibitor that blocks K+ from binding to Na/K pump

Variables in GHK Current Equation

assumptions are that the cell membrane is homogenous, PM is thin so the electrical field is constant, ions are independent and Px is const. Vm, [X] and Px of each ion determine current

What are ATPases inhibited by?

Blockers of metabolism because need energy from ATP i.e. cyanide, dinitrophenol, azide

Steps of binding of facilitated proteins

1. Carrier open to outside 2. Solute binds 3. Outer gate closes 4. Inner gate opens 5. Solute leaves

Example of facilitated diffusion carrier protein

SLC family of transmembrane glucose transporters (GLUT) 12 sequences connected; 7, 8, 11 make pore Mobilization by insulin

Na/K pump

Alpha subunit: hydrolyzes ATP and has pore for Na/ (10 polypeptide seg.) Beta subunit: 1 segment, targets pump to membrane

Cardiac glycosides

Oubain, digoxin and digitalis Bind to side of alpha subunit of Na/K, causing conformational change that blocks K+

What is the Na/K pump regulated by?

1. intracellular ATP 2. extracellular K 3. intracellular Na

H/K Pump

Primary transport In gastric glands, kidney 2K+ in, two H+ out HCl production, acid/base balance

Ca2+ ATPase

Primary transport aka SERCA 2 Ca2+ into SR from cytoplasm in exchange for 2 H+

Ca2+/Na+ pump

Primary transport One Ca2+ from cell for one Na+ want low intracellular Ca2+

Ca2+/H+ pump

Primary Transport 1 Ca2+ from cell for one H+ Want low intracellular Ca2+

Na/Glucose pump

Co Transport In smal intestine epithelium/proximal tubule of kidney Glucose in cell, Na+ in Saturation=diabetes

Na/K/Cl Pump

Co transport In non-epithelial, apical membrane Cl- and Na+ down concentration gradient inward, K+ up inward Blockage means increased water loss (water diuresis) --furosemide water pill blocks channel

Na Ca Pump

Exchange transport 3 Na+ in, down gradient 1 Ca 2+ ion out, up gradient Raising [Na+]i=depolarization

Cl/HCO3 pump

Exchange transport Acid base regulation, CO2 transport In RBC, brings HCO3 out for one Cl- in

Na/H pump

Exchange transport

Calculating osmolarity

Conc. x # particles

What affect does manipulating Na, Ca or Cl have on resting membrane potential?

Little because usually at rest the channels for these ions are closed anyway A change in K is he only thing that changes resting membrane potential

Isotonic

conc. of cell and outside of cell is equal No volume change Won't increase, decrease in size

isomotic

``` # of particles inside and outside of cell are equal Won't necessarily stop a hange in size ```

Hypotonic extracellular solution

ECF concentration is less than that in cytoplasm | Water goes into cell (lysis)

Hypertonic extracellular solution

ECF has concentration greater than cytoplasm | Water goes out of cell (crenation)

Hypokalemia

Decrease in K+ outside causes K+ on the inside to leave, the water following

What direction does water flow from?

Low osmolarity to high osmolarity | The higher value of osmolarity is hypertonic