PRACTICE QUESTIONS
1. Vasovagal syncope:
a. Involves decreased blood pressure and heart rate.
b. Involves increased sympathetic activity.
c. Involves decreased cardiac parasympathetic activity.
d. Prepares an animal for “fight or flight.”
e. Involves constriction of splanchnic arterioles.
2. The dilation of arterioles that occurs during steady-state exercise in active skeletal muscles could be eliminated by:
a. Pharmacological blockade of all sympathetic and parasympathetic nerves
b. Complete surgical removal of sympathetic innervation of the skeletal muscles
c. Administration of a muscarinic cholinergic-blocking agent
d. Administration of a β-adrenergic receptor-blocking agent
e. None of the above
3. A drug is injected intravenously into a dog and causes a transient increase in mean arterial pressure and a transient decrease in heart rate. The baroreceptor nerves are cut; the drug is reinjected and now causes a greater increase in blood pressure but no change in heart rate. Which choice most likely explains the results caused by the first injection of the drug?
a. It caused activation of muscarinic cholinergic (M3) receptors of arterioles.
b. It caused a reflex slowing of the heart.
c. It caused activation of β∣-adrenergic receptors of the pacemaker cells of the atrium.
d. It blocked α-adrenergic receptors of arterioles.
e. It decreased the activity of arterial baroreceptors.
4. A dog has had a hemorrhage. The heart rate is increased above normal, and the skin is cold. The mucous membranes are pale. In this situation (compared with normal):
a. The baroreceptor nerves are firing at a higher rate.
b. 'Γhe sympathetic nerves to the heart are firing at a decreased rate.
c. The sympathetic nerves to the blood vessels of the skin and mucous membranes are firing at an increased rate.
d. The parasympathetic fibers to the blood vessels are firing at an increased rate.
e. I he release of renin by the kidney is decreased.
5. Blood (250 mL) is taken from a vein of a dog. Mean arterial pressure does not decrease measurably. Nevertheless, it is likely that:
a. Stimulation of atrial stretch receptors has decreased.
b. Stroke volume has increased.
c. Stimulation of aortic arch baroreceptors has increased.
d. Total peripheral resistance has decreased.
e. Secretion of ADH by the pituitary has decreased.