Exam I Answer Key

Question 1

If a person’s systolic pressure is 120 mm Hg and his mean arterial pressure is 90 mm Hg, what is his diastolic pressure?

Answer 1

Mean pressure = diastolic pressure + 1/3 pulse pressure; and pulse pressure (P) = systolic pressure (S) - diastolic (D) so
Mean = D + 1/3 (S-D)

Question 2

If a person has a cardiac output of 4.9 liters/min, a heart rate of 70 beats/min, and an end-diastolic volume of 130 milliliters/beat, what is his end-systolic volume?

Answer 2

CO = (HR)(SV) = (HR)(EDV - ESV)

Question 3

Ventricular ejection occurs when

Answer 3

The AV valves are closed and Semilunar valves are open

Question 4

The drop in pressure from one end of a vessel to the other end of that same vessel is directly proportional to

Answer 4

The resistance in that vessel. ABSOLUTE pressure would be related to how far from the pump the vessel is. The cross-sectional area of that part of the circulatory tree only influences the velocity of the blood.

Question 5

What is always true about large diameter blood vessels?

Answer 5

They have thicker walls than small diameter vessels in which the blood pressure is similar

Question 6

A local reduction of pH in the tissues of the gut cause

Answer 6

Vasodilation of gut arterioles. Relaxation of precapillary sphincters in capillaries of gut tissue.

Question 7

As you go from rest to exercise what happens to your heart?

Answer 7

End-diastolic volume stays the same or could decrease if the HR is very high. Stroke volume rises. End-systolic volume falls b/c greater ejection due to increased contractility.

Question 8

Metarterioles

Answer 8

Are part of channels that connect arterioles to venules, and provide a pathway for blood to bypass a capillary bed if the precapillary sphincters are closed

Question 9

What assists in the return of blood to the heart?

Answer 9

Skeletal muscles that squeeze veins during their contraction. Differences in abdominal and thoracic pressures during the respiratory cycle. One-way valves in the veins. Gravity in those veins that lie Above the heart.

Question 10

As your metabolism increases

Answer 10

The average velocity of your blood increases b/c cardiac output rises (more blood moves through circuit/min) so it has to go faster. The production of lymph increases b/c blood pressure rises. The flow (ml/min) of blood increases.

Question 11

Name the double-layered serous membrane that surrounds the heart

Answer 11

Pericardial sac (Pericardium)

Question 12

This plasma protein, produced by the liver, becomes a structural component of blood clots

Answer 12

Fibrinogen

Question 13

Fibers that attach between the AV valves and the papillary muscles, which serve to anchor the valves and keep them for everting during systole

Answer 13

Chordae Tendinae

Question 14

Name the chemical released by thrombocytes that causes vasoconstriction

Answer 14

Seratonin

Question 15

Name the internal lining of the heart which is continuous with the heart valves

Answer 15

Endocardium

Question 16

In the fetus, umbilical veins are part of the _____ circuit, and they carry blood that is relatively _____ in oxygen content

Answer 16

Systemic & High

Question 17

In which tissue does blood flow (ml/min) remain unaltered as you move from rest to heavy exercise

Answer 17

Brain

Question 18

Lymph is identical to

Answer 18

Interstitial fluid

Question 19

T/F: Lipid soluble solutes such as oxygen and carbon dioxide diffuse through the cells membranes of capillaries, whereas water soluble solutes such as glucose and amino acids diffuse through fenestrations and clefts (e.g. pores) in the capillary wallls

Answer 19

T

Question 20

T/F: At any point in time, the volume of blood in the systemic circuit exceeds the blood volume in the pulmonary circuit, but the stroke volumes of the left and right ventricles are equal

Answer 20

T

Question 21

T/F: In the contractile cells of the heart, the influx of calcium through slow, voltage-dependent calcium channels is matched by the outflow of potassium causing a plateau in the action potential and creating a prolonged refractory period

Answer 21

T

Question 22

T/F: Plaque buildup can reduce the effective diameter of coronary arteries by as much as 60% without effecting flow very much, because the major source of resistance in the coronary circulation is downstream of the arteries

Answer 22

T

Question 23

T/F: Starling’s Law of the Heart states that the strength of contraction is proportional to the number of cross bridges formed

Answer 23

F; it’s about the degree of stretching

Question 24

T/F: Because veins interconnect much more freely than do arteries (i.e. venous anastomoses are common), the occlusion of a venous channel rarely blocks flow from a tissue

Answer 24

T

Question 25

T/F: A sudden drop in blood pressure will be sensed by baroreceptors in the aortic arch and carotid arteries, and via the vasomotor area of the medulla will lead to an increase in venous tone

Answer 25

T

Question 26

T/F: Pulse pressure is highest in the blood vessels with the greatest diameter, because they offer less resistance to flow than small vessels

Answer 26

F; ones closest to the heart do. Large veins have no pulse

Question 27

T/F: There is no longer a distinction between systolic and diastolic pressure (i.e. there is no pulse) by the time the blood has reached the venules

Answer 27

T

Question 28

The relatively-long length of the systemic circuit, compared to the pulmonary, is reflected in

Answer 28

Relatively-thin walls of the right ventricle compared to the left ventricle b/c it must exert more pressure to overcome greater resistance in long circuit

Question 29

The left atrium acts

Answer 29

As a reservoir to collect blood during ventricular systole

Question 30

The site for the pacemaker for cardiac contractions

Answer 30

Right atrium

Question 31

Red blood cells (test)

Answer 31

Are destroyed after their approximate 3 to 4 month life span
Lack a nucleus
Are produced in the red bone marrow when progenitor cells are stimulated by the hormone erythropoietin (sometimes called hemopoietin)

Question 32

Name the correct order of structures in the electrical conduction pathway in the heart

Answer 32

SA node, AV node, AV bundle (of His), bundle branches, Purkinje fibers