Answers to Illustration Questions 54311–7: The liver is a vital organ because it produces
many of the protein clotting factors.CHAPTER 1212–1: Serous fluid is found between the serous peri-
cardial layers; it prevents friction as the heart
beats.
12–2: The blue arrows represent blood that is low in
oxygen, returning to the RA from the body by
way of the caval veins. (Let’s go a step further:
What do the red arrows in the left atrium rep-
resent?)
12–3: The mitral and tricuspid valves close when the
ventricles contract, to prevent backflow of
blood from the ventricles to the atria. (A step
further: When do the arterial semilunar valves
close, and why is this important?)
12–4:The coronary vessels supply blood to the
myocardium.
12–5: The onset of ventricular systole makes the AV
valves close and the semilunar valves open.
12–6: The SA node is the pacemaker of the heart; it
depolarizes 60 to 80 times per minute, that is,
the normal resting heart rate. (A step further:
Define bradycardia and tachycardia.)
12–7: Sympathetic impulses increase the heart rate
and force of contraction. (A step further: Name
the parasympathetic nerves to the heart.)CHAPTER 1313–1: The tunica media is made of smooth muscle
and is thicker in an artery because it is needed
to help regulate blood pressure. (Let’s go a step
further: What structure found in veins is not
found in arteries, and why not?)
13–2: The highest pressure is BP at the arterial end of
the capillary network; it brings about the
process of filtration. (A step further: By what
process are gases exchanged?)
13–3: Many possible answers. For bones: radial, ulnar,
femoral, tibial, iliac, subclavian, occipital. For
organs: renal, celiac, hepatic, splenic.
13–4: Many possible answers: subclavian, axillary,
brachial, iliac, femoral, popliteal, tibial, renal,
splenic, intercostal.
13–5: The internal jugular vein is the counterpart of
the common carotid artery.13–6: The brain is always active and needs a large
supply of blood.
13–7: The blood in the portal vein is going to the
liver. The blood is coming from the capillaries
of the digestive organs and spleen.
13–8: Blood flows through the foramen ovale from
the RA to the LA, to bypass the fetal lungs. (A
step further: What other fetal structure helps
blood bypass the fetal lungs?)
13–9: As cross-sectional area increases, velocity of
blood flow decreases. Blood velocity is slowest
in the capillaries. (A step further: Why is this
slow flow important?)
13–10: Aldosterone increases the reabsorption of
sodium ions by the kidneys and ANP increases
the excretion of sodium ions. In both cases
water follows sodium to increase (aldosterone)
or decrease (ANP) blood volume and BP.
13–11: The skeletal muscles have the greatest
increase in blood flow, followed by the skin
and heart. The GI tract and kidneys have the
greatest decrease.
13–12: The kidneys produce renin when BP de-
creases. Angiotensin II causes vasoconstriction
and increases the secretion of aldosterone.
13–13: Changes in BP are the sensory information
used to keep BP within normal limits. The
pressoreceptors are located in the carotid and
aortic sinuses.CHAPTER 1414–1: Lymph is returned to the subclavian veins.
Return of lymph to the blood is important to
maintain normal blood volume and BP.
14–2: Before becoming lymph, the water is tissue
fluid.
14–3: Major paired groups of lymph nodes are the
cervical, axillary, and inguinal. (Let’s go a step
further: Why are these locations so impor-
tant?)
14–4: Plasma cells produce antibodies.
14–5: T cells (T lymphocytes) mature in the thymus.
14–6: There are many connections. Lysozyme is a
chemical, yet is found in some mucous mem-
branes; defensins are chemicals produced by
the epidermis. WBCs are part of each aspect:
barriers, cells, and chemicals. Langerhans cells
are part of the epidermis but are mobile.29Scanlon(p3) App-G 8/17/06 11:08 AM Page 543