177 Chapter 14 Answers: Cardiovascular System

14.2 Introduction to the Cardiovascular System: Review Questions and Answers

1. Describe the heart and how it functions. The heart is a muscular organ in the chest that consists mainly of cardiac muscle and pumps blood through blood vessels by repeated, rhythmic contractions. The heart has four chambers through which blood flows and valves that keep blood flowing in just one direction. Contractions of the heart are controlled by specialized cardiac muscle cells that send out electrical impulses.
2. Compare and contrast the pulmonary and systemic circulations. The pulmonary circulation includes just the heart, the lungs, and the blood vessels that connect them. It carries blood between the heart and lungs, where blood is oxygenated. The systemic circulation includes the heart and blood vessels that serve the rest of the body. It carries blood between the heart and all the cells of the body, where it delivers oxygen and other substances to the cells and picks up their wastes.
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4. What is blood? What are its chief constituents? Blood is a fluid connective tissue that circulates throughout the body in blood vessels. It consists of a liquid part, called plasma, which contains many dissolved substances; and cells, including erythrocytes, leukocytes and thrombocytes.
5. Name three different types of substances transported by the cardiovascular system. Answers will vary. Sample answer: Oxygen, nutrients, and wastes.
6. Explain why the heart and lungs need blood from the systemic circulation. Answers may vary. Sample answer: The heart and lungs need blood from the systemic circulation because it carries substances such as oxygen and nutrients that are needed for these organs to carry out their functions.
7. Do blood vessels carrying deoxygenated blood from the body back to the heart get increasingly larger or smaller? Larger.

14.3 Heart: Review Questions and Answers

1. What is the heart, where is located, and what is its function? The heart is a muscular organ behind the sternum and slightly to the left of the centre of the chest. Its function is to pump blood through the blood vessels of the cardiovascular system.
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3. Describe the coronary circulation. The coronary circulation consists of blood vessels that carry blood to and from the heart muscle cells. There are two coronary arteries that supply the two sides of the heart with oxygenated blood. Cardiac veins drain deoxygenated blood back into the heart.
4. Summarize how blood flows into, through, and out of the heart. Deoxygenated blood flows into the right atrium through veins from the upper and lower body (superior and inferior vena cava, respectively), and oxygenated blood flows into the left atrium through four pulmonary veins from the lungs. Each atrium pumps the blood to the ventricle below it. From the right ventricle, deoxygenated blood is pumped to the lungs through the two pulmonary arteries. From the left ventricle, oxygenated blood is pumped to the rest of the body through the aorta.
5. Explain what controls the beating of the heart. The normal, rhythmic beating of the heart (sinus rhythm) is controlled by the heart’s pacemaker cells in the sinoatrial node. Electrical signals from pacemaker cells travel to the atria and cause them to contract. Then the signals travel to the atrioventricular node and from there to the ventricles, causing them to contract. Electrical stimulation from the autonomic nervous system and hormones from the endocrine system can also influence heartbeat.
6. What are the two types of cardiac muscle cells in the myocardium? What are the differences between these two types of cells? Cardiomyocytes and pacemaker cells. Cardiomyocytes make up 99% of the cardiac muscle cells in the myocardium and are the cells that contract to cause the heart to beat. Pacemaker cells make up only 1% of the cardiac muscle cells in the myocardium and conduct electrical impulses that cause the cardiomyocytes to contract rhythmically.
7. Explain why the blood from the cardiac veins empties into the right atrium of the heart. Focus on function (rather than anatomy) in your answer. Answers may vary. Sample answer: The cardiac veins carry deoxygenated blood that was utilized by the heart muscle. It empties into the right atrium so that it can then travel to the right ventricle and out to the lungs, where it can become oxygenated again.

14.4 Blood Vessels: Review Questions and Answers

1. What are blood vessels? Name the three major types of blood vessels. Blood vessels are long, hollow, tube-like structures that carry blood throughout the body. The three major types of blood vessels are arteries, veins, and capillaries.
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3. Compare and contrast how blood moves through arteries and veins. Blood moves through arteries due to pressure from the beating of the heart. Blood moves through veins by the squeezing action of surrounding skeletal muscles. Valves in veins also help move blood by preventing it from flowing backward.
4. What are capillaries, and what is their function? Capillaries are the smallest blood vessels, which connect arterioles and venules. They form capillary beds that function to exchange substances between the blood and surrounding tissues.
5. Does the blood in most veins have any oxygen at all? Explain your answer. Yes. The blood in most veins has hemoglobin that is 75% saturated with oxygen. This is relatively unsaturated compared to the blood in arteries (which is 95–100% saturated), but there is still some oxygen.
6. Explain why it is important that the walls of capillaries are very thin. The walls of capillaries must be very thin because their main function is to exchange substances between the blood and surrounding tissues, including oxygen, water, nutrients, and wastes. The thin walls of capillaries allow these substances to flow easily across them.

14.5 Blood: Review Questions and Answers

1. What is blood? Why is blood considered a connective tissue? Blood is a fluid connective tissue that circulates throughout the body in the cardiovascular system. Blood is considered to be a connective tissue because it forms in bones.
2. Identify four physiological roles of blood in the body. Answers may vary. Sample answer: Four roles of blood in the body are supplying tissues with oxygen and nutrients, removing metabolic wastes produced by cells, helping to defend the body from pathogens and other threats, and transporting hormones and other substances.
3. Describe plasma and its components. Plasma is the straw yellow liquid component of blood that makes up about 55 per cent of blood by volume. It consists of water and many dissolved substances. It also contains blood cells.
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14.6 Cardiovascular Disease: Review Questions and Answers

1. What is cardiovascular disease? How much mortality do cardiovascular diseases cause? Cardiovascular disease is a class of diseases that involve the cardiovascular system. Worldwide, cardiovascular diseases are the leading cause of mortality, causing about a third of all deaths annually.
2. List risk factors for cardiovascular disease. Risk factors for cardiovascular disease include advanced age, male sex, smoking, obesity, diabetes, high blood cholesterol, and lack of exercise.
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4. What is coronary artery disease? Identify two specific coronary artery diseases. Coronary artery disease is a group of diseases that result from atherosclerosis of coronary arteries. Two specific coronary artery diseases are angina and myocardial infarction (heart attack). In angina, cardiac cells receive inadequate oxygen, which causes chest pain. In a heart attack, cardiac cells die because blood flow to part of the heart is blocked. In addition to causing chest pain, a heart attack may cause death or lead to heart arrhythmias, heart failure, or cardiac arrest.
5. Explain how a stroke occurs, and how it affects the patient. A stroke occurs when blocked or broken arteries in the brain result in the death of brain cells. This may occur when an artery is blocked by a clot or plaque or when an artery ruptures and bleeds in the brain. In both cases, part of the brain is damaged and functions such as speech and controlled movements may be impaired in the patient, either temporarily or permanently.
6. Describe the cause of peripheral artery disease. Peripheral artery disease occurs when atherosclerosis narrows peripheral arteries, usually in the legs, often causing pain when walking.
7. What are the similarities between angina and ischemic stroke? Answers may vary. Sample answer: Angina and ischemic stroke both result in reduced or blocked blood flow to the body’s tissues, which causes them to not receive adequate oxygen.
8. How can kidney disease be caused by problems in the cardiovascular system? Answers may vary. Sample answer: Kidney disease can be caused by problems in the cardiovascular system such as atherosclerosis, because it can result in reduced blood flow to the kidneys.
9. Name three components of the plaque that can build up in arteries. Answers will vary. Sample answer: Cholesterol, white blood cells, and smooth muscle cells.

14.7 Case Study Conclusion and Chapter Summary: Review Questions and Answers

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2. Alex goes to the doctor and learns that his blood pressure is 135/90 mm Hg. Answer the following questions about his blood pressure:
   1. Is this a normal blood pressure? Why or why not? No, this is not a normal blood pressure because higher than 120/80 mm Hg.
   2. Which number refers to the systolic pressure? Which number refers to the diastolic pressure? 135 is the systolic pressure; 90 is the diastolic pressure
   3. Describe what the atria and ventricles of Alex’s heart are doing when the pressure is at 135 mm Hg. 135 mm Hg is the systolic pressure, when the atria relax and fill with blood and the ventricles contract to push blood out of the heart.
   4. Alex’s doctor would like him to lower his blood pressure. Why do you think he would like Alex to do this, and what are some ways in which he may be able to lower his blood pressure? Answers may vary. Sample answer: High blood pressure, or hypertension, can lead to several cardiovascular diseases. Since Alex’s blood pressure is high, his doctor would like him to lower it to avoid these serious health risks. Some ways Alex may be able to reduce his blood pressure are: lowering the salt in his diet, adopting a healthier diet, or using medications.
3. What are three functions of the cardiovascular system? Answers will vary. Sample answer: Three functions of the cardiovascular system are to: transport oxygen and nutrients to cells in the body; remove waste products; and defend the body against infection.
4. Which are the chambers of the heart that receive blood? The right and left atria. Which are the chambers of the heart that pump blood? The right and left ventricles.
5. Valves prevent blood from flowing backward in the cardiovascular system. Why do you think this is important? Answers may vary. Sample answer: The cardiovascular system needs to carry oxygen and nutrients to the body’s cells and then remove carbon dioxide and other wastes from those cells. It depends on a one-way flow of blood from the heart, to the body’s cells, and then back again for this to work. Therefore, preventing backwards flow is important because if it were to occur, deoxygenated blood would remain near the body’s cells instead of moving forward to get oxygenated again.
6. Compare the coronary arteries, pulmonary arteries, and arteries elsewhere in the body in terms of their target tissues (i.e. where they bring blood to) and whether they are carrying oxygenated or deoxygenated blood. The coronary arteries bring oxygenated blood to the heart. The pulmonary arteries bring deoxygenated blood to the lungs. Arteries elsewhere in the body carry oxygenated blood away from the heart to tissues throughout the body.
7. Due to a reduction in the amount of oxygen that gets to the cells of the body, anemia causes weakness and fatigue. Explain how oxygen is transported to the cells of the body, and which blood cells are affected in anemia. Oxygen binds to the protein hemoglobin, which is in red blood cells. Erythrocytes transport the oxygen to the cells of the body. It is the erythrocytes that are affected in anemia.
8. What are the two conditions that are precursors to virtually all cases of cardiovascular disease? Hypertension (high blood pressure) and atherosclerosis.
9. What are the main differences between the coronary circulation, pulmonary circulation, and systemic circulation? The coronary circulation carries blood to and from the muscle cells of the heart so that these cells can receive necessary substances and have their wastes removed. The pulmonary circulation carries blood between the heart and lungs so that deoxygenated blood can become oxygenated. The systemic circulation brings oxygenated blood from the heart out to the cells of the body and returns deoxygenated blood back to the heart.
10. Define sinus rhythm. The sinus rhythm refers to the normal rhythmic beating of the heart.
11. Generally speaking, which is a more serious and immediately life-threatening condition: heart failure or cardiac arrest? Explain your answer. Cardiac arrest is generally more serious and immediately life-threatening than heart failure because it occurs when the heart no longer pumps blood or pumps blood so poorly that vital organs can no longer function. This is a medical emergency requiring immediate intervention. Heart failure, on the other hand, occurs when the pumping action of the heart is impaired so that tissues get some oxygen, but not enough. This is a chronic condition that tends to get worse over time, although it can be managed with medications.