Chapter 15 review questions

Question 1

Level one reviewing
The first priority of blood pressure homeostasis is to maintain adequate perfusion to which two organs?

Answer 1

brain and heart

Question 2

Match the types of systemic blood vessels with the terms that describe them. Each vessel type may have more than one match, and matching items may be used more than once.

a. arterioles
b. arteries
c. capillaries
d. veins
e. venules

1. store pressure generated by the heart
2. have walls that are both stiff and elastic
3. carry low-oxygen blood
4. have thin walls of exchange epithelium
5. act as a volume reservoir
6. their diameter can be altered by neural input
7. blood flow slowest through these vessels
8. have lowest blood pressure
9. are the main site of variable resistance

Answer 2

(a) 6, 9; (b) 1, 2; (c) 4, 7; (d) 3, 5, 6, 8; (e) 3, 4

Question 3

List the four tissue components of blood vessel walls, in order from inner lining to outer covering. Briefly describe the importance of each tissue.

Answer 3

endothelium (capillary exchange and paracrine secretion); elastic tissue (recoil); smooth muscle (contraction); fibrous connective tissue (resistance to stretch).

Question 4

Blood flow to individual tissues is regulated by selective vasoconstriction and vasodilation of which vessels?

Answer 4

arterioles

Question 5

Aortic pressure reaches a typical high value of        (give both numeric value and units) during       , or contraction of the heart. As the heart relaxes during the event       , aortic pressure declines to a typical low value of       . This blood pressure reading would be written as       /      .

Answer 5

120 mm Hg; systole; diastole; 80 mm Hg; 120/80

Question 6

The rapid pressure increase that occurs when the left ventricle pushes blood into the aorta can be felt as a pressure wave, or       . What is the equation used to calculate the strength of this pressure wave?

Answer 6

pulse. pulse pressure = systolic P - diastolic P.

Question 7

List the factors that aid venous return to the heart.

Answer 7

One-way valves in the veins, skeletal muscle pump, and low pressure in the thorax during breathing

Question 8

What is hypertension, and why is it a threat to a person’s health?

Answer 8

Elevated blood pressure can cause a weakened blood vessel to rupture and bleed.

Question 9

When measuring a person’s blood pressure, at what point in the procedure are you likely to hear Korotkoff sounds?

Answer 9

Korotkoff sounds occur when cuff pressure is lower than systolic pressure but higher than diastolic pressure.

Question 10

List three paracrine molecules that cause vasodilation. What is the source of each one? In addition to paracrine signals, list two other ways to control smooth muscle contraction in arterioles.

Answer 10

See Tbl. 15.2. Sympathetic neurons
vasoconstrict, and epinephrine on
beta2-receptors in certain organs vasodilates.

Question 11

What is hyperemia? How does active hyperemia differ from reactive hyperemia?

Answer 11

A region of increased blood flow. Active—increased blood flow is in response to an increase in metabolism. Reactive—increase in flow follows a period of decreased blood flow.

Question 12

Most systemic arterioles are innervated by the        branch of the nervous system. Increased sympathetic input will have what effect on arteriole diameter?

Answer 12

Sympathetic innervation causes vasoconstriction.

Question 13

Match each event in the left column with all appropriate neurotransmitter(s) and receptor(s) from the list on the right.

a. vasoconstriction of intestinal arterioles
b. vasodilation of coronary arterioles
c. increased heart rate
d. decreased heart rate
e. vasoconstriction of coronary arterioles

1. norepinephrine
2. epinephrine
3. acetylcholine
4. beta1-receptor
5. alpha-receptor
6. beta2-receptor
7. nicotinic receptor
8. muscarinic receptor

Answer 13

(a) 1, 5; (b) 2, 6; (c) 1, 2, 4; (d) 3, 8; (e) none of the above

Question 14

Which organs receive more than two-thirds of the cardiac output at rest? Which organs have the highest flow of blood on a per unit weight basis?

Answer 14

Digestive tract, liver, kidneys, and skeletal muscles. Kidneys have the highest flow on a per unit weight basis.

Question 15

By looking at the density of capillaries in a tissue, you can make assumptions about what property of the tissue? Which tissue has the lowest capillary density? Which tissue has the highest?

Answer 15

Capillary density is proportional to the tissue’s metabolic rate. Cartilage—lowest; muscles and glands—highest.

Question 16

What type of transport is used to move each of the following substances across the capillary endothelium?
a. oxygen
b. proteins
c. glucose
d. water

Answer 16

(a) diffusion, (b) diffusion or transcytosis, (c) facilitated diffusion, (d) osmosis

Question 17

With which three physiological systems do the vessels of the lymphatic system interact?

Answer 17

immune, circulatory, and digestive systems

Question 18

Define edema. List some ways in which it can arise.

Answer 18

Edema is excess fluid in the interstitial space. Causes include lower capillary colloid osmotic pressure due to decreased plasma proteins or blockage of the lymphatic vessels by a tumor or other pathology.

Question 19

Define the following terms and explain their significance to cardiovascular physiology.
a. perfusion
b. colloid osmotic pressure
c. vasoconstriction
d. angiogenesis
e. metarterioles
f. pericytes

Answer 19

(a) blood flow though a tissue; (b) the contribution of plasma proteins to the osmotic pressure of the plasma; (c) a decrease in blood vessel diameter; (d) growth of new blood vessels, especially capillaries, into a tissue; (e) small vessels between arterioles and venules that can act as bypass channels; (f) cells surrounding the capillary endothelium that regulate capillary leakiness

Question 20

The two major lipoprotein carriers of cholesterol are        and       . Which type is bad when present in the body in elevated amounts?

Answer 20

HDL and LDL. LDL-C is harmful in elevated amounts.

Question 21

Level Two review concept
Calcium channel blockers prevent Ca2+ movement through Ca2+ channels. Explain two ways this action lowers blood pressure. Why are neurons and other cells unaffected by these drugs?

Answer 21

Preventing Ca2+ entry decreases ability of cardiac and smooth muscles to contract. Decreasing Ca2+ entry into autorhythmic cells decreases heart rate. Neurons and other cells are unaffected because they have types of calcium channels not affected by the drugs.

Question 22

Compare and contrast the following sets of terms:
a. lymphatic capillaries and systemic capillaries
b. roles of the sympathetic and parasympathetic branches in blood pressure control
c. lymph and blood
d. continuous capillaries and fenestrated capillaries
e. hydrostatic pressure and colloid osmotic pressure in systemic capillaries

Answer 22

(a) Pores of lymphatic capillaries are larger. Lymphatic capillaries have contractile fibers to help fluid flow; systemic capillaries depend on systemic blood pressure for flow. (b) Sympathetic division raises blood pressure by increasing cardiac output and causing vasoconstriction. Parasympathetic division can decrease heart rate. (c)Lymph fluid is similar to blood plasma minus most plasma proteins. Blood also has nearly half its volume occupied by blood cells. (d) Continuous capillaries have smaller pores and regulate the movement of substances better than fenestrated capillaries. Fenestrated can open large gaps to allow proteins and blood cells to pass. (e)Hydrostatic pressure forces fluid out of capillaries; colloid osmotic pressure of plasma proteins draws fluid into capillaries.
23.Use Fig. 15.8 as the starting point.

Question 23

Map all the following factors that influence mean arterial pressure. You may add terms.
aorta
arteriole
baroreceptor
blood volume
cardiac output
carotid artery
contractility
heart rate
medulla oblongata
parasympathetic
peripheral
SA node
sensory neuron
stroke volume
sympathetic
vein
venous return
ventricle

Answer 23

Use Fig. 15.8 as the starting point

Question 24

Define myogenic autoregulation. What mechanisms have been proposed to explain it?

Answer 24

The ability of vascular smooth muscle to regulate its own contraction. Probably results from Ca2+ influx when the muscle is stretched.

Question 25

Left ventricular failure may be accompanied by edema, shortness of breath, and increased venous pressure. Explain how these signs and symptoms develop.

Answer 25

Left ventricular failure causes blood to pool in the lungs, increasing pulmonary capillary hydrostatic pressure. This may cause pulmonary edema and shortness of breath when oxygen has trouble diffusing into the body. Blood backing up into the systemic circulation increases venous pressure.

Question 26

Level three problem solving:
Robert is a 52-year-old nonsmoker. He weighs 180 lbs and stands 5’9 tall, and his blood pressure averaged 145/95 on three successive visits to his doctor’s office. His father, grandfather, and uncle all had heart attacks in their early 50s, and his mother died of a stroke at the age of 71.

Answer 26

(a) Uncontrollable: male, middle-aged, family history of cardiovascular disease on both sides of his family. Controllable: elevated blood pressure. (b) Yes, because blood pressure was
or diastolic pressure >90 on several occasions. It would be useful to confirm that this was not “white coat hypertension” by having him take his blood pressure for a week or so at locations away from the doctor’s office, such as at a drug store. (c) Beta-blockers block beta1-receptors in the heart, thus lowering cardiac output and MAP.

Question 27

The following figure is a schematic representation of the systemic circulation. Use it to help answer the following questions.

a. If resistance in vessels 1 and 2 increases because of the presence of local paracrine signals but cardiac output is unchanged, what happens to MAP? What happens to flow through vessels 1 and 2? Through vessels 3 and 4?
b. Homeostatic compensation occurs within seconds. Draw a reflex map to explain the compensation (stimulus, receptor, and so on).
c. When vessel 1 constricts, what happens to the filtration pressure in the capillaries downstream from that arteriole?

Answer 27

(a) MAP increases, flow through vessels 1 and 2 decreases, flow through 3 and 4 increases. (b) Pressure increase —> arterial baroreceptor —> cardiovascular control center —> arteriolar vasodilation and decreased
CO —-> decreased pressure (c) decreases

Question 28

The following graphs are recordings of contractions in an isolated frog heart. The intact frog heart is innervated by sympathetic neurons that increase heart rate and by parasympathetic neurons that decrease heart rate. Based on these four graphs, what conclusion can you draw about the mechanism of action of atropine? (Atropine does not cross the cell membrane.)

Answer 28

Atropine is an ACh antagonist, possibly by binding to an ACh receptor.

Question 29

Draw a reflex map that explains Anthony’s vasovagal syncope at the sight of blood. Include all the steps of the reflex, and explain whether autonomic pathways are being stimulated or inhibited.

Answer 29

sight of blood –> cerebral cortex —> CVCC in the medulla oblongata —? increased parasympathetic and decreased sympathetic output —-> decreased heart rate and vasodilation –> decrease blood pressure

Question 30

A physiologist placed a section of excised arteriole in a perfusion chamber containing saline. When the oxygen content of the saline perfusing (flowing through) the arteriole was reduced, the arteriole dilated. In a follow-up experiment, she used an isolated piece of arteriolar smooth muscle that had been stripped away from the other layers of the arteriole wall. When the oxygen content of the saline was reduced as in the first experiment, the isolated muscle showed no response. What do these two experiments suggest about how low oxygen exerts local control over arterioles?

Answer 30

Cells (endothelium) in the intact wall detect changes in oxygen and communicate these changes to the smooth muscle.

Question 31

In advanced atherosclerosis, calcified plaques cause the normally elastic aorta and arteries to become stiff and noncompliant. (a) What effect does this change in the aorta have on afterload? (b) If cardiac output remains unchanged, what happens to peripheral resistance and mean arterial pressure?

Answer 31

(a) increases (b) resistance increases and pressure increases

Question 32

During fetal development, most blood in the pulmonary artery bypasses the lungs and goes into the aorta by way of a channel called the ductus arteriosus. Normally, this fetal bypass channel closes during the first day after birth, but each year, about 4000 babies in the United States maintain a patent (open) ductus arteriosus and require surgery to close the channel.

a. Use this information to draw an anatomical diagram showing blood flow in an infant with a patent ductus arteriosus.
b. In the fetus, why does most blood bypass the lungs?
c. If the systemic side of the circulatory system is longer than the pulmonary side, which circuit has the greater resistance?
d. If the flow is equal in the pulmonary and systemic circulations, which side of the heart must generate more pressure to overcome resistance?
e. Use your answer to (d) to figure out which way blood will flow through a patent ductus arteriosus.

Answer 32

(a) In Fig. 14.1, draw a connection from pulmonary artery to aorta. In Fig. 14.5f, you can see a remnant of the closed ductus as a small ligament connecting the aorta and pulmonary artery. (b) The lungs are not functioning. (c) systemic, (d) left side, (e) from the aorta into the pulmonary artery