QBank TB 1 Flashcards
A fluid that is composed of 120 mmol/L K, 12 mmol/L
Na, and 15 mmol/L Cl but is virtually Ca2 free (1
mol/L) would best approximate which body fluid compartment?
A. Transcellular
B. Plasma
C. Interstitial
D. Intracellular
E. Extracellular
d
Dye indicators are important physiologic tools used to
calculate unknown volumes or concentrations within
the body. If a dye is membrane permeable, which of
the following changes will most likely increase dye diffusion
rate?
A. Lowering dye concentration
B. Increasing membrane surface area
C. Increasing membrane thickness
D. Decreasing fl uid temperature
E. Lowering the dye partition coeffi cient
b
A 66-year-old male is treated with the loop diuretic
furosemide (Na-K-2Cl cotransport inhibitor) to reduce
symptoms associated with congestive heart failure.
Which of the following best describes this cotransporter’s
mode of action?
A. It is a primary active transporter.
B. It is electrogenic.
C. A rise in intracellular K would decrease transport
rate.
D. It transports Na and K into the cell and 2 Cl out
of the cell.
E. It transports Na against its electrochemical gradient.
c
Serum electrolytes levels are ordered on a 12-yearold
boy with a gastrointestinal infection, which induced
prolonged and severe vomiting episodes. Plasma K
concentrations were found to be abnormally low (2
mmol/L). Which of the following might be expected to
result from mild hypokalemia?
A. Resting potentials would shift positive.
B. K equilibrium potential would shift negative.
C. Neuronal action potentials would be inhibited.
D. Na channels would inactivate.
E. K-channel activation would yield K infl ux.
b
A 35-year-old man carries an epilepsy gene. The gene
mutation affects the neuronal voltage-dependent Na
channel, causing it to inactivate more slowly (50%).
How might expression of this epilepsy gene affect
nerve function?
A. Resting potential would settle close to 0 mV.
B. Action potentials would no longer overshoot 0 mV.
C. Action potentials would be prolonged.
D. Action potentials would rise very slowly.
E. There would be no action potentials.
c
An agricultural worker is packing hot chili peppers for
transport. He removes his protective mask and becomes
incapacitated with a sensation of nasal burning
caused by capsaicin from the peppers. What receptor
type is capsaicin stimulating?
A. Transient receptor-potential channels
B. Purinergic receptors
C. Ionotropic glutamate receptors
D. Cys-loop family receptors
E. Voltage-gated Na channels
a
During a serological analysis, red blood cells (RBCs)
were transferred from blood to a solution containing
100 mmol/L CaCl2 and 100 mmol/L urea and then
monitored using light microscopy. How would you expect
this transfer to affect RBC volume?
A. The solution is isosmotic, so no long-term effect.
B. The solution is isotonic, so no long-term effect.
C. Transient swelling would occur.
D. Swelling to the point of lysis would occur.
E. The cell would shrink by 50%.
b
Liver damage may result in decreased synthesis of
plasma proteins such as albumin. What is the most
signifi cant effect of low plasma albumin on osmosis or
fluid transport?
A. Interstitial fluid volume increases.
B. Vascular fluid volume increases.
C. Plasma colloid osmotic pressure increases.
D. Plasma osmolality increases.
E. Plasma osmolality decreases.
a
A 95-year-old man with widely metastatic cancer is
receiving morphine to help alleviate pain. Brainstem
respiratory center function has been depressed as a
result, causing hypoventilation. Which of the following
might be expected to result from reducing ventilation?
A. Alkalemia
B. Decreased plasma HCO3
levels
C. Decreased renal HCO3
reabsorption
D. Increased interstitial pH
E. Increased urinary H excretion
e
A researcher investigating the properties of intestinal
epithelium from a patient with inflammatory bowel disease
noted that the diseased areas have a low electrical
resistance, whereas the healthy areas have a high
resistance. What might be inferred about the properties
of the healthy epithelium?
A. It forms weak transepithelial ionic gradients.
B. It is specialized for isosmotic transport.
C. It has a thick basement membrane.
D. The tight junctions are highly impermeable.
E. It lacks a basolateral Na-K ATPase.
d
A 52-year-old woman presents with heart palpitations
and lightheadedness. An electrocardiogram shows her
to be in atrial fibrillation, which has been linked to increased
connexin 43 expression. Which of the following
best describes connexins normally?
A. They open during membrane depolarization.
B. They are highly ion selective.
C. They mediate Ca2 influx from the cell exterior.
D. They allow electrical propagation through tissues.
E. They are found only in the heart.
d
Hypokalemia is relatively rare in healthy individuals,
but which of the following would favor increased K uptake
by a transport epithelium for transfer to the circulation?
A. Lumen-negative potential difference
B. Increased paracellular water uptake
C. Increased Na-K ATPase activity
D. High interstitial K concentrations
E. Apical glucose cotransport
b
Autoimmune diseases such as multiple sclerosis cause
neurological impairment by affecting axon conduction
velocity. Which of the following would slow axonal signal
propagation to the greatest extent?
A. Increasing axon diameter
B. Increasing axon length
C. Increasing myelin thickness
D. Decreasing leak-channel density
E. Decreasing depolarization rate
e
Epilepsy is a common neurologic disorder characterized
by spontaneous episodic neuronal fi ring and seizures.
Research indicates that a glial spatial buffering
dysfunction may be involved. Spatial buffering’s role
includes which of the following?
A. Limiting K buildup and nerve hyperexcitability
B. Preventing acidifi cation of brain extracellular fl uid
C. Increasing axonal conduction velocity
D. Synaptic neurotransmitter recycling
E. Transferring nutrients from blood to neurons
a
Cerebrospinal fluid (CSF) loss reduces buoyancy, allowing
the brain to sag and triggering a “low CSF pressure
headache” through loss of buoyancy. In addition
to buoyancy, what other protective feature does CSF
provide?
A. It contains mucin to lubricate the brain.
B. Cerebrospinal fluid volume 15 mL that forms a
cohesive film between brain and cranium.
C. It is enriched in HCO3
to buffer pH changes.
D. It is K free to enhance neuronal K efflux.
E. It drains along the olfactory nerve to moisturize the
olfactory epithelium.
c
A 45-year-old woman complains of pain in her fingertips
and toes during cold exposure or emotional stress.
This “Raynaud phenomenon” is caused by exaggerated
sympathetic vasoconstriction in the extremities,
producing ischemic pain. Which of the following statements
best applies to her condition?
A. Sympathetic ganglia serving the fingers are located
in the hand.
B. The sympathetic postganglionic nerve is myelinated.
C. The patient may gain relief from an -adrenergic
inhibitor.
D. Pain may be relieved by an acetylcholinesterase
inhibitor.
E. The vascular neuromuscular junction contains nicotinic
acetylcholine receptors.
c
