CARDIOVASCULAR PHYSIOLOGY CONCEPTS
contraction, vascular smooth muscle
contraction is slow and sustained.
Cardiac muscle contraction is regulated
by various substances that bind to
receptors coupled to G-proteins.
Vascular smooth muscle contraction/
relaxation is additionally regulated
by NO/cGMP-dependent pathways.
All these pathways largely affect
contraction/relaxation primarily by
regulating intracellular calcium.
The vascular endothelium synthesizes
nitric oxide and prostacyclin, both of
which relax vascular smooth muscle.
Endothelin-1, which is also synthesized
by the endothelium, contracts vascular
For each question, choose the one best answer:
Which of the following is common to
both cardiac myocytes and vascular
smooth muscle cells?
a. Dense bodies
b. Myosin light chain kinase
c. Terminal cistemae
d. T tubules
Thick filaments within cardiac myocytes
During excitation-contraction coupling
in cardiac myocytes,
a. Calcium binds to myosin causing ATP
b. Calcium binds to troponin-I.
c. Myosin heads hind to actin.
d. SERCA pumps calcium out of the
Cardiac inotropy is enhanced by
a. Agonists coupled to Gi-protein.
b. Decreased calcium binding to
c. Decreased release of calcium by
d. Protein kinase A phosphorylation of
L-type calcium channels.
Vascular smooth muscle contraction is
a. Activation of myosin light chain
h. Activation of myosin light chain
c. Calcium binding to troponin-C.
d. Dephosphorylation of myosin light
Angiotensin II causes contraction of
vascular smooth muscle by
a. Activating Gs-protein.
b. Increasing cAMP
c. Increasing IP3.
d. Inhibiting release of calcium by
A patient in circulatory shock is
treated with norepinephrine to raise
arterial pressure by stimulating the
heart through ß-adrenoceptor activa-
tion and constricting blood vessels
through oq-adrenoceptor activation.
The cardiac and vascular effects can be
a. Increased cardiac cAMP and increased
h. Increased cardiac cAMP and increased
c. Increased cardiac and vascular cAMP
d. Increased cardiac IP3 and increased