Question 1

The part of the circulation involved with carrying blood to and from the lungs is the:

Accepted Answer

In the pulmonary circuit,the path of blood can be traced as follows.O₂-poor blood from all regions of the body collects in the right atrium and then passes into the right ventricle,which pumps it into the pulmonary trunk.The pulmonary trunk divides into the right and left pulmonary arteries,which carry blood to the lungs.As blood passes through pulmonary capillaries,carbon dioxide is given off and oxygen is picked up.O₂-rich blood returns to the left atrium of the heart,through pulmonary venules that join to form pulmonary veins.See figure 30.4.

Question 2

The pacemaker of the heart is termed the:

Accepted Answer

The SA (sinoatrial)node,located in the dorsal wall of the right atrium causes the atria to contract and initiates the heartbeat every 0.85 seconds.Therefore,the SA node is called the cardiac pacemaker.

Question 3

-This figure shows the anatomy of a capillary bed.What does "e" represent?

Accepted Answer

"e" represents a vein.See figure 30.3B.

Question 4

The "lub" heart sound is due to the:

Accepted Answer

When the heart beats,the familiar "lub-dub" sound is heard as the valves of the heart close.The longer,lower-pitched lub is caused by vibrations of the heart when the atrioventricular valves close due to ventricular contraction.The shorter,sharper dub is heard when the semilunar valves close due to back pressure of blood in the arteries.

Question 5

When an individual suffers a cut,what structures will initially attempt to seal the break in the blood vessel?

Accepted Answer

When a blood vessel in the body is damaged,platelets clump at the site of the puncture and partially seal the leak.

Question 6

Blood traveling from the intestines to the liver is traveling in the:

Accepted Answer

The hepatic portal system takes blood from the intestines to the liver.See figure 30.4.

Question 7

-This figure shows the anatomy of a capillary bed.What does "d" represent?

Accepted Answer

"d" represents a venule.See figure 30.3B.

Question 8

What are the consequences of having a low level of calcium when the body is trying to form a blood clot?

Accepted Answer

When a blood vessel in the body is damaged,platelets clump at the site of the puncture and partially seal the leak.Platelets and the injured tissues release a clotting factor,called prothrombin activator,that converts prothrombin to thrombin.This reaction requires calcium ions (Ca₂⁺).

Question 9

What is the relationship between blood pressure and the velocity of blood flow?

Accepted Answer

As blood flows from the aorta into the various arteries,arterioles,and capillaries,blood pressure falls,as does blood velocity.See Figure 30.3A.

Question 10

Blood flow in capillaries is:

Accepted Answer

As blood flows from the aorta into the various arteries,arterioles,and capillaries,blood pressure falls.Also,the difference between systolic and diastolic pressure gradually diminishes.The fall of blood pressure and blood velocity in the capillaries may be related to the very high total cross-sectional area of the capillaries.It has been calculated that if all the blood vessels in a human were connected end-to-end,the total distance would reach around the Earth at the equator two times.A large portion of this distance would be due to the quantity of capillaries.

Question 11

-This figure shows the anatomy of a capillary bed.What does "a" represent?

Accepted Answer

"a" represents an artery.See figure 30.3B.

Question 12

If you are studying the blood vessel(s)that serve the heart muscle oxygen and nutrients,which of the following would you be studying?

Accepted Answer

The coronary arteries are extremely important because they serve the heart muscle itself.Failure of the coronary arteries to perform this function results in a heart attack because the heart is not nourished by the blood in its chambers.

Question 13

During a single heartbeat,first the ____________ contracts,and then the _____________ contracts.

Accepted Answer

Each heartbeat can be divided into three phases: (1)The atria contract (while the ventricles relax); (2)The ventricles contract (while the atria relax); (3)All chambers rest.

Question 14

A biologist is studying blood vessels which have valves to prevent the backflow of blood.Based on this information you would conclude that he or she is studying:

Accepted Answer

Veins have valves that prevent the backward flow of blood.This is necessary because blood pressure in the veins is low and cannot move blood back to the heart,especially from the limbs.

Question 15

Which component of plasma is the largest?

Accepted Answer

Plasma is composed mostly of water (90-92%)and proteins (7-8%),but it also contains smaller quantities of many types of molecules,including nutrients,wastes,and salts.

Question 16

-This figure shows the anatomy of a capillary bed.What does "c" represent?

Accepted Answer

"c" represents a precapillary sphincter.See figure 30.3B.

Question 17

"Artery" and "vein" are defined by whether they take blood away or toward the heart.If they were defined by whether they carry oxygenated or deoxygenated blood,how would we have to change the names of certain vessels?

Accepted Answer

Pulmonary arteries contain O₂-poor blood and the pulmonary veins contain O₂-rich blood.See Figure 30.4.

Question 18

Which blood vessels have walls that are only one cell thick?

Accepted Answer

Capillaries are extremely narrow-about 8-10 mm wide-and have thin walls composed of a single layer of endothelium (a simple squamous epithelium)with a basement membrane.

Question 19

Which blood vessels carry blood away from the heart?

Accepted Answer

The cardiovascular system has three types of blood vessels: arteries (and arterioles),which carry blood away from the heart to the capillaries;capillaries,which permit exchange of material with the tissues;and veins (and venules),which return blood from the capillaries to the heart.

Question 20

Which of the following is not a correct association?

Accepted Answer

Blood pressure in the veins is low and cannot move blood back to the heart,especially from the limbs.Instead,venous return depends upon three factors: skeletal muscle contraction,the presence of valves in veins,and respiratory movements.

Quiz 30: Circulation and Cardiovascular Systems