02a: Fluids and Transport Flashcards
TBW stands for (X) and is (Y)% BW.
X = Total body water Y = 60
TBW can be divided into (X) and (Y).
X = ECF Y = ICF
ECF is (X)% of (Y) and (Z)% of BW.
X = 33 Y = TBW Z = 20
ICF is (X)% of (Y) and (Z)% of BW.
X = 67 Y = TBW Z = 40
Fluid in circulatory system is called (X). Amount of fluid is (Y)% of (Z).
X = plasma Y = 20 Z = ECF
Interstitial fluid is (X)% of (Y).
X = 80 Y = ECF
Osmolality of intracellular water is about (X). And of extracellular water is about (Y).
X = Y = 300 mOsmol/L H20
Same in all compartments!
Osmolality is a measure of:
Solute (salt/ion) per kg solvent
Normal Na concentration in ECF and ICF.
ECF: 140 mEq/L H20
ICF: 12 mEq/L H20
Normal K concentration in ECF and ICF.
ECF: 4 mEq/L H20
ICF: 150 mEq/L H20
Normal Ca concentration in ECF and ICF.
ECF: 2 mEq/L H20
ICF: .00010 mEq/L H20
Normal HCO3 concentration in ECF and ICF.
ECF: 24 mEq/L H20
ICF: 10 mEq/L H20
Normal protein concentration in ECF and ICF.
ECF: 16 mEq/L H20
ICF: 60 mEq/L H20
In which specific compartments in ECF can proteins be found?
Plasma; very very little in interstitial fluid
The (X) and (Y) of ECF are separated by (Z) membrane. Speak to its permeability.
X = plasma Y = interstitia Z = endothelium
Very permeable
ECF and ICF separated by (X). Speak to its permeability.
X = plasma membrane
Selective permability
Macroscopic electroneutrality states:
In each compartment, positive charges equal the negative charges on a macroscopic level
Permeability equation
P = (D)(beta)/(deltaX)
Which characteristic(s) of solute affect permeability?
- Size (smaller MW, larger diffusion coefficient)
2. Its solubility in lipids (more soluble, larger partition coefficient)
How is the partition coefficient calculated?
Concentration of solute in lipid/Concentration of solute in water
Net flux equation.
J = P(C1-C2)
Net flux equation.
J = P(C1-C2)
Which type of molecules can pass through PM via simple diffusion?
- Hydrophobic molecules
2. Small, uncharged, polar molecules
List some ions that can pass PM via simple diffusion.
None!
List some small, polar molecules that can pass PM via simple diffusion.
Water, urea, glycerol, CO2
O2 (can/can’t) pass PM via simple diffusion, because it is what type of molecule?
Can; hydrophobic
N2 (can/can’t) pass PM via simple diffusion, because it is what type of molecule?
Can; hydrophobic
Benzene (can/can’t) pass PM via simple diffusion, because it is what type of molecule?
Can; hydrophobic
The electrochemical potential takes into account:
- Concentration differences
2. Membrane potential
What’s the typical membrane potential of a cell?
-60 mV (more negative inside)
Under what conditions is an ion said to be in electrochemical equilibrium?
When the chemical and electrical gradients are equal in magnitude
Define the equilibrium potential.
The membrane potential that is established at equilibrium for an ion under the existing concentration gradient.
The Nernst equation exists to allow for the calculation of:
the equilibrium potential (Ei)
The net driving force equation (taking into account equilibrium potential):
Vm - Ei
What are the requirements to establish Gibbs-Donan Equilibrium?
- Macroscopic electroneutrality
- Concentration of permeant cations must be greater (and permeant anions less) on side with protein (electrical potential negative on side with protein)
- Osmolality greater on side with protein
Is flux affected by transport proteins? How/why or why not?
Yes; permeability factor in determining flux is altered by proteins
Which key things differ between channels and carriers?
- Translocation rate
2. Accessibility of binding sites
(Carriers/channels) have selectivity filter. Provide example.
Channels; carboxyl ions in K channel act as selectivity filter
List different types of gating in channel proteins.
- Voltage-gated
- Ligand-gated
- Stretch-activated
- Leak (spontaneous)
Channels are accessible form (intra/extra)-cellular side.
Both
T/F: One difference between channels and carriers is that, unlike carriers, net flux is always downhill in channels.
False - facilitated diffusion by carrier proteins is also always downhill flux
(Intra/extra)-cellular side of carrier protein has greater affinity for substrate.
Both sides have same affinity!
P-Type ATPases rely on (primary/secondary) active transport. Give examples.
Primary (phosphorylation);
- Ca-ATPase
- Na/K Pump
- H-ATPase
Ca-ATPase is responsible for:
High extracellular Ca concentrations
Describe movement of ions by Na/K pump.
2 K ions pumped into cell; 3 Na ions pumped out
H-ATPase responsible for:
pH maintenance
ABC transporters rely on (X) to function. Give examples of these transporters.
X = ATP
- MDR1
- CFTR
What’s MDR1?
Multi-drug resistant ABC Transporter; pumps drugs out of cell
What’s CFTR?
CF transmembrane regulatory; a Cl channel that opens upon binding ATP
Give example of secondary active transport.
Na/glucose cotransport
In the Na/glucose cotransport model, Na moves (uphill/downhill).
Downhill
Define osmotic pressure.
Pressure required to prevent fluid movement into compartment, if concentration gradient exists.
Osmotic pressure equation.
P = (sigma)RT(Cs)
In osmotic pressure equation, what does sigma represent?
Reflection coefficient (how permeable is the solute)
A solute as permeable as water will have a reflection coefficient value of:
0
A completely impermeable solute will have reflection coefficient value of:
1
What is responsible for oncotic pressure
The proteins present in plasma (and not in interstitia)
