GMS 6440 PRACTICE EXAM 2026/2027 QUESTIONS AND
SOLUTIONS RATED A+
✔✔Parts of a channel: pore, selectivity filter, electric field sensor, gate - ✔✔Pore: spans
the whole membrane
Selectivity filter: allows specific charges or shapes through
Electric field sensors: sense the change in voltage or electric potential across the
membrane
gate: unlocks due to ligand-receptor binding
✔✔What are the four main ion channel types? - ✔✔Ligand-gated (lock-and-key),
voltage-gated (change in potential changes the field sensor to modulate gate), leak
(continuously open), and stretch-activated (perturbation of size and pore stretch)
✔✔Na+/K+ ATPase - ✔✔Carries out primary active transport. Made up of four subunits.
Upon hydrolysis of ATP, 3 Na+ out and 2 K+ in. Happens 100+ times a minute.
✔✔What are some of the functions of Primary Active Transporters? - ✔✔-pump
electrolytes out of one compartment into another
-solute gradients for osmotic stability
-ion gradients for bioelectricity
-ion gradients for secondary active transport
✔✔What is an example of a secondary active transporter? - ✔✔Na+/Glucose
transporter. Coupled to Na+/K+ ATPase. Movement of glucose is secondary to primary
active transporter.
✔✔pump-leak model - ✔✔key to remember: simultaneous but independent of each
other.
✔✔When is the concentration gradient equal and opposite to the electrical gradient? -
✔✔At equilibrium
✔✔What controls an electrolyte's movement across a membrane? - ✔✔Voltage and
concentration gradient (electrical + chemical)
✔✔What controls an electrolyte's electrochemical equilibrium potential? -
✔✔Concentration and degree of permeability of the membrane to that species
✔✔What is the equilibrium potential of K+ and Na+? - ✔✔-100 mV and +65 mV
✔✔What is the equilibrium potential of a cell and where does it come from? - ✔✔-90 mV
and comes mostly from that of K+
, ✔✔What is metabolic acidosis? - ✔✔excessive pH drop in the extracellular fluid which
results in a buildup of K+ in the ECF --> hyperkalemia ( >6.5mM K+).
To correct: enhance Na+/K+ ATPase by injecting insulin
✔✔What is rhabdomyolysis? - ✔✔A breakdown of muscle tissue that releases excess
K+ in the ECF leading to hyperkalemia ( >6.5mM K+). K+ then influxes into the cell and
causes the potential to depolarize to -20 mV.
✔✔How much of body weight is water?How much is found in ICF and ECF? - ✔✔60%
of body weight is water.
40% of that is in ICF and 20% is in ECF (75% of ECF is interstitial fluid and 25% is
plasma)
✔✔Can proteins travel through the capillary wall? - ✔✔NO
✔✔What is the protein content intracellular, in the interstitium, and in plasma? -
✔✔Intracellularly about 30g/dl
Interstitium about 1g/dl
Plasma about 7g/dl
✔✔Dilution principle - ✔✔V = X (quantity of substance added) / C (concentration at
equilibrium)
In vivo, have to account for amount removed by body so numerator would be X -
quantity excreted
✔✔Criteria for measurement of volume of a particular fluid compartment - ✔✔must be
freely distributed, nontoxic, not metabolized, and easily measured
✔✔How to measure plasma volume - ✔✔Use something that cannot cross capillary wall
so use albumin or evans blue dye
✔✔How to measure total ECFV - ✔✔Use something that will equilibriate across
capillary wall but not enter cell so inulin or radiolabeled Na+ or Cl-
✔✔How to measure total body H2O - ✔✔want something that will move freely across
both membranes so want tritiated water or D2O
✔✔How to measure ICFV - ✔✔Have to have TB H2O - ECFV = ICFV
✔✔What is the capillary wall? - ✔✔It is the barrier between plasma and interstitial fluid.
It is a semipermeable membrane where exchange occurs. ONLY PASSIVE
MOVEMENT.
SOLUTIONS RATED A+
✔✔Parts of a channel: pore, selectivity filter, electric field sensor, gate - ✔✔Pore: spans
the whole membrane
Selectivity filter: allows specific charges or shapes through
Electric field sensors: sense the change in voltage or electric potential across the
membrane
gate: unlocks due to ligand-receptor binding
✔✔What are the four main ion channel types? - ✔✔Ligand-gated (lock-and-key),
voltage-gated (change in potential changes the field sensor to modulate gate), leak
(continuously open), and stretch-activated (perturbation of size and pore stretch)
✔✔Na+/K+ ATPase - ✔✔Carries out primary active transport. Made up of four subunits.
Upon hydrolysis of ATP, 3 Na+ out and 2 K+ in. Happens 100+ times a minute.
✔✔What are some of the functions of Primary Active Transporters? - ✔✔-pump
electrolytes out of one compartment into another
-solute gradients for osmotic stability
-ion gradients for bioelectricity
-ion gradients for secondary active transport
✔✔What is an example of a secondary active transporter? - ✔✔Na+/Glucose
transporter. Coupled to Na+/K+ ATPase. Movement of glucose is secondary to primary
active transporter.
✔✔pump-leak model - ✔✔key to remember: simultaneous but independent of each
other.
✔✔When is the concentration gradient equal and opposite to the electrical gradient? -
✔✔At equilibrium
✔✔What controls an electrolyte's movement across a membrane? - ✔✔Voltage and
concentration gradient (electrical + chemical)
✔✔What controls an electrolyte's electrochemical equilibrium potential? -
✔✔Concentration and degree of permeability of the membrane to that species
✔✔What is the equilibrium potential of K+ and Na+? - ✔✔-100 mV and +65 mV
✔✔What is the equilibrium potential of a cell and where does it come from? - ✔✔-90 mV
and comes mostly from that of K+
, ✔✔What is metabolic acidosis? - ✔✔excessive pH drop in the extracellular fluid which
results in a buildup of K+ in the ECF --> hyperkalemia ( >6.5mM K+).
To correct: enhance Na+/K+ ATPase by injecting insulin
✔✔What is rhabdomyolysis? - ✔✔A breakdown of muscle tissue that releases excess
K+ in the ECF leading to hyperkalemia ( >6.5mM K+). K+ then influxes into the cell and
causes the potential to depolarize to -20 mV.
✔✔How much of body weight is water?How much is found in ICF and ECF? - ✔✔60%
of body weight is water.
40% of that is in ICF and 20% is in ECF (75% of ECF is interstitial fluid and 25% is
plasma)
✔✔Can proteins travel through the capillary wall? - ✔✔NO
✔✔What is the protein content intracellular, in the interstitium, and in plasma? -
✔✔Intracellularly about 30g/dl
Interstitium about 1g/dl
Plasma about 7g/dl
✔✔Dilution principle - ✔✔V = X (quantity of substance added) / C (concentration at
equilibrium)
In vivo, have to account for amount removed by body so numerator would be X -
quantity excreted
✔✔Criteria for measurement of volume of a particular fluid compartment - ✔✔must be
freely distributed, nontoxic, not metabolized, and easily measured
✔✔How to measure plasma volume - ✔✔Use something that cannot cross capillary wall
so use albumin or evans blue dye
✔✔How to measure total ECFV - ✔✔Use something that will equilibriate across
capillary wall but not enter cell so inulin or radiolabeled Na+ or Cl-
✔✔How to measure total body H2O - ✔✔want something that will move freely across
both membranes so want tritiated water or D2O
✔✔How to measure ICFV - ✔✔Have to have TB H2O - ECFV = ICFV
✔✔What is the capillary wall? - ✔✔It is the barrier between plasma and interstitial fluid.
It is a semipermeable membrane where exchange occurs. ONLY PASSIVE
MOVEMENT.
