Deck 23: Circulation

Question 1

The largest blood vessel in the human body is the

A) superior vena cava.
B) pulmonary vein.
C) aorta.
D) pulmonary artery.

Answer 1

C

Question 2

Which of the following animals has a single circuit of blood flow and two heart chambers?

A) salamander
B) salmon
C) snake
D) squirrel

Answer 2

B

Question 3

Which of the following statements about mammalian circulatory systems is false?

A) The pulmonary circuit carries blood between the heart and the lungs.
B) The systemic circuit carries blood between the heart and the rest of the body.
C) Mammals have two atria and two ventricles in their hearts.
D) The left side of a mammal's heart sends blood to the lungs.

Answer 3

D

Question 4

Which of the following is a function of the circulatory system?

A) transporting nerve impulses throughout the body
B) governing nutrient concentration in the blood
C) transporting nutrients to body cells
D) mounting a response to invading microorganisms

Question 5

During which phase of the heartbeat do the ventricles fill with blood?

A) diastole
B) systole

Question 6

Using a stethoscope, you listen to a beating heart and hear "lub-dup, lub-dup." These sounds are created by

A) muscles in the left ventricle.
B) blood flowing through the aorta.
C) blood pressure differentials from chamber to chamber.
D) blood recoiling against the closed valves.

Question 7

You are dissecting a "mystery animal" in biology lab and discover that it has a series of closed blood vessels, a pair of lungs, two atria, and a single ventricle. What animal are you dissecting?

A) fish
B) frog
C) crocodile
D) bird

Question 8

From the left ventricle, oxygen-rich blood flows through the

A) superior vena cava.
B) aorta.
C) pulmonary artery.
D) pulmonary vein.

Question 9

Which of the following is characteristic of the circulatory system of arthropods?

A) lack of a heart
B) lack of blood
C) lack of blood vessels
D) lack of distinction between blood and interstitial fluid

Question 10

Adaptation to terrestrial life involved major evolutionary changes. The change from gill breathing to lung breathing was accompanied by important changes in the

A) reproductive system.
B) cardiovascular system.
C) manufacture of blood cells.
D) association of blood and interstitial fluid.

Question 11

Which of the following statements regarding circulatory systems is true?

A) The smallest blood vessels in the body are veins.
B) A circulatory system is necessary in any animal whose body is too large or too complex for vital chemicals to reach all parts of the body by diffusion.
C) Materials are exchanged directly between the blood and body cells.
D) Veins carry blood away from the heart to body organs and tissues.

Question 12

Which of the following animals has a three-chambered heart?

A) snake
B) crocodile
C) human
D) bird

Question 13

In mammals, which of the following vessels transports oxygenated blood from the lung back to the heart?

A) pulmonary artery
B) pulmonary vein
C) superior vena cava
D) coronary artery

Question 14

Cardiac output is defined as the volume of blood pumped by a(n) ________ each time it contracts.

A) heart
B) atrium
C) atrioventricular valve
D) ventricle

Question 15

Blood is pumped from the heart to the lungs by the

A) left atrium.
B) right atrium.
C) left ventricle.
D) right ventricle.

Question 16

Although birds and mammals descended from different ancestors, they both have a four-chambered heart. This is the result of

A) the simplification of the cardiovascular system.
B) the necessity for rapid movement of blood.
C) convergent evolution.
D) genetic aberrations that resulted from mistakes in somatic cell division.

Question 17

In mammals, blood returning from the head will pass through the ________ just before entering the right atrium.

A) left atrium
B) superior vena cava
C) inferior vena cava
D) aorta

Question 18

During ventricular systole, the semilunar valves ________ and the AV valves ________.

A) open; open
B) close; open
C) open; close
D) close; close

Question 19

Oxygen-poor blood is carried from the heart of a mammal to the lungs via the

A) pulmonary arteries.
B) pulmonary veins.
C) superior vena cava.
D) inferior vena cava.

Question 20

The location of the heart's pacemaker is a specialized region of cardiac muscle called the

A) atrioventricular node.
B) sinoatrial node.
C) right atrium.
D) left ventricle.

Question 21

Which of the following is the cause of more than half of all deaths in the United States?

A) cardiovascular disease
B) flu
C) cancer
D) diabetes

Question 22

Which of the following can contribute to high blood pressure?

A) regular exercise
B) eating a heart-healthy diet
C) smoking
D) maintaining proper weight

Question 23

Cells make up about what percentage of total blood volume?

A) 10%
B) 25%
C) 45%
D) 80%

Question 24

Which kind of vessel has the lowest blood velocity?

A) artery
B) capillary
C) venule
D) vein

Question 25

Myocardial infarction, also called a heart attack,

A) is caused by excessive blood pressure in the heart.
B) actually causes no permanent damage to the heart.
C) is unrelated to cigarette smoking.
D) is the damage or death of cardiac muscle tissue.

Question 26

In which of the following human blood vessels is the blood pressure lowest?

A) arteries in the head
B) arterioles in the legs
C) capillaries in the feet
D) veins in the head

Question 27

As blood moves away from the heart toward the tissues, the relative size of blood vessels ________, the blood pressure ________, and the velocity of blood flow ________.

A) decreases; decreases; decreases
B) decreases; increases; increases
C) decreases; decreases; increases
D) increases; decreases; decreases

Question 28

Which of the following factors contributes to the flow of blood in veins?

A) skeletal muscle contractions
B) the number of red blood cells in venous blood
C) the diameter of capillaries
D) blood pressure generated by the heart

Question 29

Blood flow through capillaries is controlled by

A) one-way valves.
B) precapillary sphincters only.
C) smooth muscle in the walls of arterioles only.
D) precapillary sphincters and smooth muscle in the walls of arterioles.

Question 30

Arteries are distinguished from veins based on all of the following features except the

A) direction of blood flow relative to the heart.
B) structure of their walls.
C) amount of oxygen present in the blood.
D) blood pressure pushing against the walls of the vessels.

Question 31

The diameter of a capillary is about the same as that of a(n)

A) nerve.
B) red blood cell.
C) arteriole.
D) venule.

Question 32

One way that substances move between blood and interstitial fluid is by

A) alternatively breaking and regenerating membranes of cells lining capillaries.
B) osmosis.
C) pressure-driven flow through clefts between the epithelial cells of the capillary wall.
D) active transport utilizing ATP.

Question 33

Which blood vessels have the thinnest walls?

A) arterioles
B) veins
C) venules
D) capillaries

Question 34

The liquid part of blood is called

A) water.
B) plasma.
C) serum.
D) interstitial fluid.

Question 35

Which of the following statements regarding blood pressure is false?

A) Normal blood pressure for adult humans is usually at or below 120/80.
B) Hypertension is defined as persistent systolic pressure above 120 and/or diastolic above 80.
C) High blood pressure can lead to an enlarged and weakened heart, increased risk of heart attack, stroke, and kidney failure.
D) The higher number in a blood pressure reading measures the force of a heart contraction.

Question 36

Whether there is a net flow of fluid into or out of a capillary at a given point along its length depends upon

A) whether the fluid contains nutrients or wastes.
B) whether or not the fluid contains oxygen.
C) the balance between blood pressure and osmotic pressure.
D) the needs of the tissue.

Question 37

At any given time, what percentage of the body's capillaries have blood flowing through them?

A) 5-10%
B) 20-25%
C) 40-50%
D) 85-90%

Question 38

What type of blood vessel is solely responsible for exchange between the blood and the interstitial fluid?

A) artery
B) arteriole
C) capillary
D) venule

Question 39

In humans, which blood vessels have valves?

A) arteries in the neck
B) arterioles
C) capillaries
D) veins

Question 40

The main function of the AV node is to

A) initiate the heartbeat.
B) set the rhythm of the heartbeat.
C) relay the signal for the heart to contract from the right ventricle to the right atrium.
D) relay a signal for the ventricles to contract.

Question 41

During exercise, your heart rate can increase dramatically in order to meet the metabolic demands of your tissues. If your heart rate increased to 144 beats per minute, approximately how long would diastole last in a single cardiac cycle?

A) 0.2 second
B) 0.6 second
C) 0.8 second
D) 1.6 seconds

Question 42

Which of the following molecules is least likely to be able to pass through a capillary wall?

A) an enzyme
B) a sodium ion
C) glucose
D) oxygen

Question 43

Bone marrow stem cells are sometimes used to treat certain blood cell diseases, such as

A) leukemia.
B) anemia.
C) cardiovascular disease.
D) hemophilia.

Question 44

Stem cells found in the red marrow inside bones

A) phagocytize bacterial cells.
B) are primarily important in blood clotting.
C) are responsible for an immune response.
D) can differentiate into all blood cells and platelets.

Question 45

Hematocrit is the percentage of red blood cells in the blood. In adult humans, hematocrit is roughly 40-45%, but it can be much higher or lower in other animals. Consider the Weddell seal, a mammal that can dive and hold its breath underwater for upwards of 80 minutes. What is the hematocrit level of a Weddell seal, and why?

A) It is likely lower than that of an adult human because the seal needs access to less oxygen when diving.
B) It is likely lower than that of an adult human because the seal needs access to more oxygen when diving.
C) It is likely higher than that of an adult human because the seal needs access to less oxygen when diving.
D) It is likely higher than that of an adult human because the seal needs access to more oxygen when diving.

Question 46

During exercise, your cardiac output can increase dramatically in order to meet the metabolic demands of your tissues. If your heart rate increased to 150 beats per minute and the volume of blood pumped per beat is 75 mL, what is your cardiac output?

A) 5 L/min
B) 11.25 L/min
C) 11,250 L/min
D) 50,000 L/min

Question 47

Imagine that blood did not contain any dissolved proteins. What would likely happen when this abnormal blood flows through a capillary bed?

A) Nearly all of the fluid in the blood would move out of the capillaries.
B) None of the fluid in the blood would move out of the capillaries.
C) Some of the proteins in the interstitial fluid would flow into the capillaries.
D) The blood would flow normally through the capillaries.

Question 48

You conduct a study with mice to determine whether giving them air with a higher-than-normal oxygen level results in their having a higher-than-normal oxygen content in their blood. What vessel should you draw blood from if you want to measure the highest potential level of oxygen content in the blood?

A) superior vena cava
B) pulmonary vein
C) pulmonary artery
D) inferior vena cava

Question 49

An adult human's red blood cells are formed in the

A) spleen.
B) liver.
C) bone marrow.
D) thyroid gland.

Question 50

How long do human red blood cells circulate in the blood before they wear out and have to be replaced?

A) 1 to 2 weeks
B) 1 month
C) 3 to 4 months
D) 10 to 12 months

Question 51

Which of the following cells are phagocytes?

A) monocytes and neutrophils
B) basophils and eosinophils
C) eosinophils and lymphocytes
D) lymphocytes and basophils

Question 52

Which of the following statements about blood clotting is true?

A) The first response to an injury is dilation of the damaged blood vessels.
B) During the clotting response, platelets rapidly congregate in the interstitial fluid.
C) Fibrin is enzymatically converted to fibrinogen.
D) Threads of fibrin form a fibrin clot.

Question 53

A man has been standing in one place without moving for a long time. You walk by and notice that his ankles are swollen. What is a likely explanation for this observation?

A) Since the man has not flexed his leg muscles, blood has not moved upward through the veins so it stays pooled at his ankles.
B) The man's blood pressure has likely increased because of inactivity, and thus the blood has pooled at his ankles.
C) Since the man hasn't flexed his leg muscles, blood has not moved upward through the arteries so it stays pooled at his ankles.
D) The man's heart rate has likely increased because of inactivity, and thus the blood has pooled at his ankles.

Question 54

What is the most common cause of anemia?

A) vitamin deficiency
B) low blood pressure
C) iron deficiency
D) inefficient hemoglobin production

Question 55

Plasma proteins are involved in all of the following activities except

A) fighting infection.
B) maintaining osmotic balance.
C) carrying oxygen.
D) blood clotting.

Question 56

Which of the following can increase red blood cell concentration in a unit of blood?

A) training at low altitudes
B) reducing blood levels of EPO
C) blood doping
D) hydration

Question 57

Blood clots are formed by platelets and the plasma protein

A) thrombus.
B) fibrin.
C) erythropoietin.
D) fibrinogen.

Question 58

Sometimes when a person in a movie is stabbed or cut, blood forcefully sprays out of the wound. This is realistic only if the severed vessel is under a high degree of pressure. Which of the following vessels, if severed, would result in the most forceful spray of blood?

A) pulmonary artery
B) inferior vena cava
C) capillaries in the body
D) aorta

Question 59

Which of the following statements about red blood cells is true?

A) The main function of red blood cells is to carry nutrients.
B) Red blood cells are shaped like biconcave disks.
C) Each red blood cell contains about 1 million molecules of hemoglobin.
D) Red blood cells in adult humans have nuclei.

Question 60

To view the path of blood flow through the heart and body, scientists and physicians perform an angiogram by injecting a dye into the blood and monitoring its movement. Imagine that this dye was injected into the pulmonary vein. Which of the following is the correct order of structures that the dye will flow through immediately after the pulmonary vein?

A) lungs, pulmonary artery, left atrium, left ventricle
B) left atrium, left ventricle, aorta, body arteries
C) right atrium, right ventricle, aorta, body arteries
D) lungs, pulmonary artery, right atrium, right ventricle

Question 61

Excessive accumulation of fluid in tissues outside of the blood vessels is called edema. Which of the following scenarios could result in edema?

A) an increase in the concentration of proteins in the blood
B) a decrease in the volume of blood in the cardiovascular system
C) an alteration of capillary walls so that they are less leaky
D) an increase in the pressure of blood flowing through capillaries

Question 62

A red blood cell is in an artery in the right leg. How many capillary beds will it pass through before it returns to the left atrium of the heart?

A) none
B) one
C) two
D) three

Question 63

Which part of this figure depicts an arteriole?

A) A
B) B
C) C
D) D

Question 64

In which part of this figure would blood have the highest oxygen content?

A) A
B) B
C) C
D) D

Question 65

After reading the paragraphs below, answer the questions that follow.
To evaluate cardiac function, scientists and physicians measure both the pressure and the volume inside the heart. When both pressure and volume data are plotted on the same graph, the resulting graph is called a pressure-volume loop. To create a pressure-volume loop, a catheter (a thin tube) is inserted into the vessels of the heart, and measurements of both left ventricular pressure and left ventricular volume are taken. The data are plotted on a graph, and cardiac function can then be evaluated from the distribution of the data and the shape of the loop.
The following figure shows a typical left ventricle pressure-volume loop for a healthy young adult. The cardiac cycle proceeds counterclockwise. Each complete turn around the loop (for example, starting at point A and ending back at point A) represents one complete cardiac cycle.

What part of the diagram represents ventricular diastole?

A) point B
B) point C
C) the line between points A and B
D) the line between points C and D

Question 66

Which part of this figure depicts a pulmonary artery?

A) A
B) B
C) C
D) D

Question 67

After reading the paragraphs below, answer the questions that follow.
To evaluate cardiac function, scientists and physicians measure both the pressure and the volume inside the heart. When both pressure and volume data are plotted on the same graph, the resulting graph is called a pressure-volume loop. To create a pressure-volume loop, a catheter (a thin tube) is inserted into the vessels of the heart, and measurements of both left ventricular pressure and left ventricular volume are taken. The data are plotted on a graph, and cardiac function can then be evaluated from the distribution of the data and the shape of the loop.
The following figure shows a typical left ventricle pressure-volume loop for a healthy young adult. The cardiac cycle proceeds counterclockwise. Each complete turn around the loop (for example, starting at point A and ending back at point A) represents one complete cardiac cycle.

How much blood is ejected from the left ventricle during one contraction?

A) 35 mL
B) 65 mL
C) 70 mL
D) 135 mL

Question 68

You are taking someone's blood pressure and are listening to sounds of blood flow just under the blood pressure cuff. If this person is hypertensive and has a blood pressure of 140/90, what would be the blood pressure associated with the first sound you hear?

A) above 140 mm Hg
B) between 90 and 140 mm Hg
C) below 90 mm Hg
D) between 70 and 120 mm Hg

Question 69

After reading the paragraphs below, answer the questions that follow.
Electrocardiographs (ECGs or EKGs) provide data about the electrical activity of the heart. By placing a series of "leads" on a person's chest, the electrical activity of the heart can be recorded and analyzed in order to detect irregular heartbeats (arrhythmias) and other conditions. The figure below shows a normal EKG tracing for one cardiac cycle.
The P region represents electrical activity spreading through the atria. The QRS region represents electrical activity spreading through the ventricles. The T region represents electrical activity in the ventricles returning to rest.
What is happening in the heart during the QRS region?

A) The atria are filling with blood.
B) The ventricles are filling with blood.
C) The atria are contracting.
D) The ventricles are contracting.

Question 70

After reading the paragraphs below, answer the questions that follow.
To evaluate cardiac function, scientists and physicians measure both the pressure and the volume inside the heart. When both pressure and volume data are plotted on the same graph, the resulting graph is called a pressure-volume loop. To create a pressure-volume loop, a catheter (a thin tube) is inserted into the vessels of the heart, and measurements of both left ventricular pressure and left ventricular volume are taken. The data are plotted on a graph, and cardiac function can then be evaluated from the distribution of the data and the shape of the loop.
The following figure shows a typical left ventricle pressure-volume loop for a healthy young adult. The cardiac cycle proceeds counterclockwise. Each complete turn around the loop (for example, starting at point A and ending back at point A) represents one complete cardiac cycle.

Aortic stenosis is a disease in which the aortic valve (the semilunar valve between the left ventricle and the aorta) narrows, resulting in increased left ventricular pressure and reduced ejection volume (the amount of blood that the left ventricle ejects). What would the pressure-volume graph for a patient with aortic stenosis look like compared to the graph shown above for a healthy young adult?

A) taller and wider
B) taller and narrower
C) shorter and narrower
D) shorter and wide

Question 71

After reading the paragraphs below, answer the questions that follow.
To evaluate cardiac function, scientists and physicians measure both the pressure and the volume inside the heart. When both pressure and volume data are plotted on the same graph, the resulting graph is called a pressure-volume loop. To create a pressure-volume loop, a catheter (a thin tube) is inserted into the vessels of the heart, and measurements of both left ventricular pressure and left ventricular volume are taken. The data are plotted on a graph, and cardiac function can then be evaluated from the distribution of the data and the shape of the loop.
The following figure shows a typical left ventricle pressure-volume loop for a healthy young adult. The cardiac cycle proceeds counterclockwise. Each complete turn around the loop (for example, starting at point A and ending back at point A) represents one complete cardiac cycle.

If the time it takes to go around the loop is 1 second, what is the cardiac output in units of liters per minute?

A) 3.9 L/min
B) 4.2 L/min
C) 7.0 L/min
D) 8.1 L/min

Question 72

After reading the paragraphs below, answer the questions that follow.
To evaluate cardiac function, scientists and physicians measure both the pressure and the volume inside the heart. When both pressure and volume data are plotted on the same graph, the resulting graph is called a pressure-volume loop. To create a pressure-volume loop, a catheter (a thin tube) is inserted into the vessels of the heart, and measurements of both left ventricular pressure and left ventricular volume are taken. The data are plotted on a graph, and cardiac function can then be evaluated from the distribution of the data and the shape of the loop.
The following figure shows a typical left ventricle pressure-volume loop for a healthy young adult. The cardiac cycle proceeds counterclockwise. Each complete turn around the loop (for example, starting at point A and ending back at point A) represents one complete cardiac cycle.

At what point of the diagram is the left ventricle filled with the least amount of blood and at the highest pressure?

A) point A
B) point B
C) point C
D) point D

Question 73

The anterior interventricular artery supplies a portion of the heart wall with oxygenated blood. Suppose that blood is flowing through a healthy region of this artery but then flows through a region that is atherosclerotic. What will happen to blood flow when it reaches the atherosclerotic region?

A) Blood velocity will increase.
B) Blood velocity will decrease.
C) The amount of oxygen in the blood will increase.
D) The amount of oxygen in the blood will decrease.

Question 74

Which of the following describes the stage of the cardiac cycle shown?

A) AV and semilunar valves both open, ventricles contracting
B) AV valves open, semilunar valves closed, ventricles contracting
C) AV valves closed, semilunar valves open, ventricles contracting
D) AV valves closed, semilunar valves open, ventricles relaxed

Question 75

Ventricular contraction normally begins at the apex (bottom of the heart). What would likely happen if ventricular contraction originated at the intersection of the atria and the ventricles instead?

A) Blood would be pumped through the semilunar valves.
B) Blood would be pumped into the pulmonary artery and aorta.
C) Blood would be pumped back into the atria.
D) Blood would be pumped down to the apex of the heart.

Question 76

After reading the paragraphs below, answer the questions that follow.
Electrocardiographs (ECGs or EKGs) provide data about the electrical activity of the heart. By placing a series of "leads" on a person's chest, the electrical activity of the heart can be recorded and analyzed in order to detect irregular heartbeats (arrhythmias) and other conditions. The figure below shows a normal EKG tracing for one cardiac cycle.
The P region represents electrical activity spreading through the atria. The QRS region represents electrical activity spreading through the ventricles. The T region represents electrical activity in the ventricles returning to rest.
Suppose a person has a heart rate of 60 beats/min and that the start of the P region until the end of the T region represents one cardiac cycle. If the x axis in the EKG is time, approximately how much time passes between the start of the P region and the end of the T region?

A) 0.1 second
B) 1 second
C) 10 seconds
D) 60 seconds

Question 77

Ron and Tiffany are studying circulatory system function. They designed an experiment to test whether the diameter of a tube affects the rate of flow through the tube. In their experiment, they ran water from a large container through five tubes with different diameters for exactly 30 seconds for each tube. They measured the volume of liquid that passed through the tube during the 30-second period, testing each tube three times and pouring the water back into the container after each test. The results of the experiment are shown in the following table.
$\begin{array} { | l | l | l | } \hline& \text { Diameter of } &{ \text { Average Volume } } \\ & \text { Tube } ( \mathrm { cm } ) & \text { Fluid (mL) } \\\hline \text { Tube A } & 0.5 & 210 \\\hline \text { Tube B } & 0.6 & 350 \\\hline \text { Tube C } & 0.7 & 480 \\\hline \text { Tube D } & 0.8 & 600 \\\hline \text { Tube E } & 0.9 & 975 \\\hline\end{array}$

-Ron and Tiffany modified the experiment to see how long it would take to pass 1,000 mL of fluid through each tube. Based on the results shown in the table, which tube would it take the longest for 1,000 mL of fluid to flow through?

A) tube A
B) tube B
C) tube C
D) tube D
E) tube E

Question 78

Ron and Tiffany are studying circulatory system function. They designed an experiment to test whether the diameter of a tube affects the rate of flow through the tube. In their experiment, they ran water from a large container through five tubes with different diameters for exactly 30 seconds for each tube. They measured the volume of liquid that passed through the tube during the 30-second period, testing each tube three times and pouring the water back into the container after each test. The results of the experiment are shown in the following table.
$\begin{array} { | l | l | l | } \hline& \text { Diameter of } &{ \text { Average Volume } } \\ & \text { Tube } ( \mathrm { cm } ) & \text { Fluid (mL) } \\\hline \text { Tube A } & 0.5 & 210 \\\hline \text { Tube B } & 0.6 & 350 \\\hline \text { Tube C } & 0.7 & 480 \\\hline \text { Tube D } & 0.8 & 600 \\\hline \text { Tube E } & 0.9 & 975 \\\hline\end{array}$

-Which statement best summarizes the results of the experiment?

A) The larger the tube diameter, the greater the flow volume.
B) The larger the tube diameter, the smaller the flow volume.
C) The tube diameter shows no clear relationship to flow volume.

Question 79

After reading the paragraphs below, answer the questions that follow.
To evaluate cardiac function, scientists and physicians measure both the pressure and the volume inside the heart. When both pressure and volume data are plotted on the same graph, the resulting graph is called a pressure-volume loop. To create a pressure-volume loop, a catheter (a thin tube) is inserted into the vessels of the heart, and measurements of both left ventricular pressure and left ventricular volume are taken. The data are plotted on a graph, and cardiac function can then be evaluated from the distribution of the data and the shape of the loop.
The following figure shows a typical left ventricle pressure-volume loop for a healthy young adult. The cardiac cycle proceeds counterclockwise. Each complete turn around the loop (for example, starting at point A and ending back at point A) represents one complete cardiac cycle.

At what point on the diagram does the aortic valve (the semilunar valve that separates the left ventricle and the aorta) open?

A) point A
B) point B
C) point C
D) point D

Question 80

Ron and Tiffany are studying circulatory system function. They designed an experiment to test whether the diameter of a tube affects the rate of flow through the tube. In their experiment, they ran water from a large container through five tubes with different diameters for exactly 30 seconds for each tube. They measured the volume of liquid that passed through the tube during the 30-second period, testing each tube three times and pouring the water back into the container after each test. The results of the experiment are shown in the following table.
$\begin{array} { | l | l | l | } \hline& \text { Diameter of } &{ \text { Average Volume } } \\ & \text { Tube } ( \mathrm { cm } ) & \text { Fluid (mL) } \\\hline \text { Tube A } & 0.5 & 210 \\\hline \text { Tube B } & 0.6 & 350 \\\hline \text { Tube C } & 0.7 & 480 \\\hline \text { Tube D } & 0.8 & 600 \\\hline \text { Tube E } & 0.9 & 975 \\\hline\end{array}$

-The results suggest that the smallest flow volume would be found in the ________ of the human body.

A) arteries
B) veins
C) capillaries
D) arterioles