448 Chapter 13
- The activation of factor X occurs in
a. the intrinsic pathway only.
b. the extrinsic pathway only.
c. both the intrinsic and extrinsic pathways.
d. neither the intrinsic nor extrinsic pathway.- Platelets
a. form a plug by sticking to each other.
b. release chemicals that stimulate vasoconstriction.
c. provide phospholipids needed for the intrinsic pathway.
d. serve all of these functions.- Antibodies against both type A and type B antigens are
found in the plasma of a person who is
a. type A. c. type AB.
b. type B. d. type O.
e. any of these types. - Production of which of the following blood cells is
stimulated by a hormone secreted by the kidneys?
a. Lymphocytes c. Erythrocytes
b. Monocytes d. Neutrophils
e. Thrombocytes - Which of these statements about plasmin is true?
a. It is involved in the intrinsic clotting system.
b. It is involved in the extrinsic clotting system.
c. It functions in fibrinolysis.
d. It promotes the formation of emboli.- During the phase of isovolumetric relaxation of the
ventricles, the pressure in the ventricles is
a. rising.
b. falling.
c. first rising, then falling.
d. constant. - Peristaltic waves of contraction move fluid within which of
these vessels?
a. Arteries
b. Veins
c. Capillaries
d. Lymphatic vessels
e. All of these
Test Your Understanding
- Describe how the pacemaker cells produce a spontaneous
diastolic depolarization, and how this leads to the production
of action potentials. - What characteristic of the SA node distinguishes it from
other possible pacemaker regions and allows it to function
as the normal pacemaker? How do action potentials from the
SA node reach the atria and the ventricles? - Compare the duration of the heart’s contraction with the
myocardial action potential and refractory period. Explain
the significance of these relationships.
21. Step by step, describe the pressure changes that occur in
the ventricles during the cardiac cycle. Explain how these
pressure changes relate to the occurrence of the heart
sounds.
22. Can a defective valve be detected by an ECG? Can a
partially damaged AV node be detected by auscultation
(listening) with a stethoscope? Explain.
23. Describe the causes of the P, QRS, and T waves of an ECG,
and indicate at which point in the cardiac cycle each of
these waves occurs. Explain why the first heart sound occurs
immediately after the QRS wave and why the second sound
occurs at the time of the T wave.
24. The lungs are the only organs that receive the entire output
of a ventricle. Explain this statement, and describe how this
relates to the differences in structure and function between
the right and left ventricles.
25. Explain the process of Ca^2 1 -induced Ca^2 1 release in the
myocardium. How does this process differ from excitation-
contraction coupling in skeletal muscles? - Explain how a cut in the skin initiates both the intrinsic and
the extrinsic clotting pathways. Which pathway is shorter?
Why? - Explain how aspirin, coumarin drugs, EDTA, and heparin
function as anticoagulants. Which of these are effective
when added to a test tube? Which are not? Why? - Explain how blood moves through arteries, capillaries, and
veins. How does exercise affect this movement? - Explain the processes involved in the development of
atherosclerosis. How might antioxidants help retard the
progression of this disease? How might exercise help? What
other changes in lifestyle might help prevent or reduce
atherosclerotic plaques?
Test Your Analytical Ability- Hematopoietic stem cells account for less than 1% of the
cells in the bone marrow. These cells can be separated from
the others prior to bone marrow transplantation, but it is
better to first inject the donor with recombinant cytokines.
Identify the cytokines that might be used and describe their
effects. - A patient has a low red blood cell count, and microscopic
examination of his blood reveals an abnormally high
proportion of circulating reticulocytes. Upon subsequent
examination, the patient is diagnosed with a bleeding ulcer.
This is surgically corrected, and in due course his blood
measurements return to normal. What was the reason
for the low red blood cell count and high proportion of
reticulocytes? - A chemical called EDTA, like citrate, binds to (or
“chelates”) Ca^2 1. Suppose a person had EDTA infused into
their blood. What effect would this have on the intrinsic and
extrinsic clotting pathways? How would these effects differ
from the effects of aspirin on blood clotting? - During the course of a physiology laboratory, a student finds
that her PR interval is 0.24 second. Concerned, she takes
her own ECG again an hour later and sees an area of the
ECG strip where the PR interval becomes longer and longer.