Physiology Flashcards
Which of the following does not cause a right shift in the hemoglobin-O2 dissociation curve?
A. Increase in pCO2
B. Decrease in 2,3-DPG
C. Increase in temperature
D. Decrease in pH
B. Decrease in 2,3-DPG
A right shift in the hemoglobin-O2 dissociation curve is when the affinity of hemoglobin for O2 is decreased. This increases the unloading of O2 from arterial blood into tissues. 2,3-DPG is a byproduct of glycolysis that decreases oxygen affinity when it binds to hemoglobin.
Right shift: Increased: temperature, 2,3-DPG, [H+]
Left shift: CO, decreased: temperature, 2,3-DPG, [H+]
Which of the following is true of CO2 transport in the blood?
A. Most CO2 is transported from the tissues to the lungs in the dissolved molecular form
B. Reversible dissociation of carbonic acid into hydrogen and bicarbonate ions accounts for 70% of the transport of CO2 from tissues to the lungs
C. Normal blood PCO2 is 70mm Hg in venous blood
D. Increase in CO2 results in greater affinity of oxygen and hemoglobin
E. The primary mechanism of transport is carbaminohemoglobin
B. Reversible dissociation of carbonic acid into hydrogen and bicarbonate ions accounts for 70% of the transport of CO2 from tissues to lungs
Influx of which ion into the sarcomere results in release of calcium to the sarcoplasm of skeletal muscle?
Sodium
Sodium moves into the sarcomere to cause depolarization. This results in activation of voltage-sensor proteins in the T-tubules, opening gated calcium channels in adjacent sarcoplasmic reticulum. As a result, calcium is released to the sarcoplasm.
Which of the following is accurate concerning acid-base homeostasis?
A. pH is directly proportionate to H+ ion concentration
B. H+ is determined by the ratio of PCO2 and HCO3-
C. A buffer is a strong acid and its associated base
D. Most CO2 is transported in the blood dissolved in plasma
E. A base excess less than -5 is associated with metabolic alkalosis
B. H+ is determined by the ratio of PCO2 and HCO3-
In an EKG, what pathological state do increases in PR intervals signify?
Decreased AV nodal conduction velocity
PV interval is the interval from the beginning of the P wave to the beginning of the Q wave. It is the time is takes for the impulse to conduct through the atria and reach the ventricles through the AV node. Therefore, if this interval is increased, it indicates there is a decreased conduction velocity through the AV node. Ie it is taking longer for the impulse to reach the ventricles, which occurs in heart block.
In an EKG, what does QRS complex signify?
Ventricular conduction
In an EKG, what does T wave signify?
Ventricular repolarization
Which of the following is true of sinus node fibers?
A. The resting membrane potential is more negative than ventricular muscle fibers
B. Fast sodium channels cause the action potential
C. L-type voltage-gated calcium channels are activated by an increase in the membrane potential
D. Influx of potassium results in hyperpolarization of the membrane
E. The action potential is terminated by efflux of sodium and potassium
C. L-type voltage-gated calcium channels are activated by an increase in membrane potential
