Answers to Review Questions - Chapter 42
1. What are the functions of red blood cells (erythrocytes)? Of white blood cells
(leukocytes)? Of platelets (thrombocytes)?
Red blood cells are involved in gas transport (oxygen, carbon dioxide). White
blood cells play a role in the body's immune defenses. Platelets are involved in
blood clotting.
2. What are the three types of granular leukocytes? Describe the characteristics and
one significant function of each.
Neutrophils have granules that appear neutral when stained. They are the
principal phagocytic cells in the blood.
Eosinophils have granules that stain bright red. They function in detoxifying
foreign proteins and other substances - involved in allergic reactions and parasitic
infections. (any one of those functions…)
Basophils have deep blue granules when stained. They play a role in allergic
reactions - release histamine in injured tissues and in allergic responses. Also can
produce heparin to prevent blood from clotting. (any one of those functions…)
3. What are the two types of agranular leukocytes? Describe the characteristics and
one significant function of each.
Lymphocytes do not have granules - have round nuclei. Produce antibodies,
destroy foreign cells. (any one of those functions…)
Monocytes are the largest WBC - leaves the circulation to become a macrophage.
Major function is phagocytosis of foreign cells/materials.
4. Describe the flow of blood through the heart, beginning with where the
deoxygenated blood enters the heart and ending with where the newly oxygenated
blood leaves the heart to be delivered to the body tissues.
Right atrium → right ventricle → pulmonary trunk → lungs → pulmonary veins
→ left atrium → left ventricle → aorta
5. Describe the pathway of electrical activity through the conducting system of the
heart.
The sinoatrial node initiates the heartbeat, causing an action potential to spread
through the atria to the atrioventricular node; this action potential causes the atria
to contract. The action potential then spreads from the atrioventricular node
through specialized muscle fibers (bundle branches, purkinje fibers) into the
ventricles, and the ventricles contract.
6. What are the names of the four valves within the heart? Where is each located?
Be specific for each of the four valves.
Right atrioventricular valve (tricuspid) - located between the right atrium and
right ventricle.
Left atrioventricular valve (bicuspid or mitral) - located between the left atrium
and left ventricle.
Pulmonary semilunar valve - located between the right ventricle and the
pulmonary trunk.
Aortic semilunar valve - located between the left ventricle and the aorta.
7. What prevents backflow of blood through the atrioventricular valves?
The leaflets of the valves are anchored to the floor of the ventricles via string-like
structures called chordae tendineae.
8. What prevents backflow of blood through the semilunar valves?
The cup-shaped cusps of the semilunar valves collect with blood as it begins to be
pulled back toward the ventricle - this causes the cusps to snap tightly together.