Textbook questions

Question 1

List the 5 major functions of the blood

Answer 1

transport dissolved gases, nutrients, hormones, metabolic wastes

regulate pH and ion composition of interstitial fluids

restrict fluid losses at injury sites

defend against toxins and pathogens

stabilize body temperature

Question 2

Identify 3 types of formed elements in the blood

Answer 2

RBC, WBC, platelets

Question 3

List the 3 major types of plasma proteins

Answer 3

albumins, globulins, fibrinogen

Question 4

What would be the effects of a decrease in amount of plasma proteins

Answer 4

decrease would lead to lower plasma osmotic pressure, reduced ability to fight infections, decreased transport and binding of some ions, hormones, and other molecules

Question 4

Describe the structure of hemoglobin.

Answer 4

Protein made of 4 globular subunits, each bound to a heme molecule which gives RBC ability to transport oxygen in the blood

Question 5

How would a person’s hematocrit change after a significant blood loss?

Answer 5

after significant blood loss, hematocrit would decrease

Question 6

What effect would obstruction to the renal arteries have on a person’s hematocrit?

Answer 6

The hematocrit would increase, because reduced blood flow to the kidneys triggers the release of erythropoietin, which stimulates an increase in erythropoiesis (red blood cell formation).

Question 7

How would liver disease affect the level of bilirubin in the blood?

Answer 7

Bilirubin would accumulate in the blood, producing jaundice, because diseases that damage the liver, such as hepatitis or cirrhosis, impair the liver’s ability to excrete bilirubin in the bile.

Question 8

What is the function of surface antigens on RBCs?

Answer 8

Surface antigens on RBCs are glycoproteins in the plasma membrane; they determine blood type.

Question 9

Which blood type can be safely transfused into a person with type O blood?

Answer 9

Only type O blood can be safely transfused into a person whose blood type is O.

Question 10

Why can’t a person with type A blood safely receive blood from a person with type B blood?

Answer 10

If a person with type A blood receives a transfusion of type B blood, which contains anti-A antibodies, the red blood cells will agglutinate (clump), potentially blocking blood flow to various organs and tissues.

Question 11

Identify the five types of white blood cells.

Answer 11

The five types of white blood cells are neutrophils, eosinophils, basophils, monocytes, and lymphocytes.

Question 12

Which type of white blood cell would you find in the greatest numbers in an infected cut?

Answer 12

An infected cut would contain a large number of neutrophils, because these phagocytic white blood cells are the first to arrive at the site of an injury.

Question 13

Which type of cell would you find in elevated numbers in a person who is producing large amounts of circulating antibodies to combat a virus?

Answer 13

The blood of a person fighting a viral infection would contain elevated numbers of lymphocytes, because B cells (B lymphocytes) produce circulating antibodies.

Question 14

How do basophils respond to an injury?

Answer 14

Basophils respond to an injury by releasing a variety of chemicals, including histamine and heparin. Histamine dilates blood vessels and heparin prevents blood clotting. Basophils also release other chemicals that attract eosinophils and other basophils to the injured area.

Question 15

Define thrombocytopoiesis.

Answer 15

Thrombocytopoiesis is the term for platelet production.

Question 16

List the three primary functions of platelets.

Answer 16

Platelets release chemicals important to the clotting process, they form a temporary patch in the walls of damaged blood vessels, and they reduce the size of a break in a vessel wall.

Question 17

A decreased number of megakaryocytes would interfere with what body process?

Answer 17

A decreased number of megakaryocytes would interfere with the blood’s ability to clot properly, because fewer megakaryocytes would produce fewer platelets.

Question 18

How could a fat-free diet affect blood clotting?

Answer 18

Vitamin K is necessary for blood clotting, and fats are required for vitamin K absorption. So, if a person did not eat foods containing fat, this would lead to a vitamin K deficiency, which would, in turn, result in a decreased production of several clotting factors—most notably, prothrombin. As a result, clotting time would increase.

Question 19

Unless chemically treated, whole blood will coagulate in a test tube. This clotting process begins when Factor XII becomes activated. Which clotting pathway is involved in this process?

Answer 19

The activation of Factor XII initiates the intrinsic pathway.

Question 20

The formed elements of the blood include (a) plasma, fibrin, and serum, (b) albumins, globulins, and fibrinogen, (c) WBCs, RBCs, and platelets, (d) all of these.

Answer 20

c

Question 21

In the blood of an average adult, the total number of RBCs is about ______, and the hemoglobin concentration is about _______. (a) 10 trillion, 0.15 g/dL, (b) 30 billion, 3 g/dL, (c) 5 trillion, 200 g/dL, (d) 25 trillion, 15 g/dL.

Answer 21

d

Question 22

Plasma contributes approximately ______ percent of the volume of whole blood, and water accounts for ______ percent of the plasma volume. (a) 55, 92, (b) 25, 55, (c) 92, 55, (d) 35, 72.

Answer 22

a

Question 23

Whole blood (a) is acidic, (b) is less cohesive than water, (c) is more resistant to flow than water, (d) has a temperature of about 35°C, (e) has different physical characteristics in veins and arteries.

Answer 23

c

Question 24

The bright red color of blood is due to (a) oxyhemoglobin, (b) deoxyhemoglobin, (c) ferritin, (d) carbaminohemoglobin, (e) transferrin.

Answer 24

a

Question 25

The following is a list of the phases involved in the process of hemostasis.

(1) coagulation

(2) fibrinolysis

(3) vascular spasm

(4) retraction

(5) platelet phase

The correct sequence of these phases is (a) 5, 1, 4, 2, 3, (b) 3, 5, 1, 4, 2, (c) 2, 3, 5, 1, 4, (d) 3, 5, 4, 1, 2, (e) 4, 3, 5, 2, 1.

Answer 25

b

Question 26

Stem cells responsible for lymphocytopoiesis are located in (a) the thymus and spleen, (b) the lymph nodes, (c) the red bone marrow, (d) all of these structures.

Answer 26

d

Question 27

_____ and ______ are also known as clotting factors I and II. (a) Tissue factor, calcium ions, (b) Fibrinogen, prothrombin, (c) Prothrombin, proconvertin, (d) Tissue factor, pro-accelerin.

Answer 27

b

Question 28

What five major functions are performed by blood?

Answer 28

Blood (1) transports dissolved gases, nutrients, hormones, and metabolic wastes; (2) regulates pH and electrolyte composition of interstitial fluids throughout the body; (3) restricts fluid losses through damaged vessels or at other injury sites; (4) defends against toxins and pathogens; and (5) stabilizes body temperature.

Question 29

Name the three major types of plasma proteins and identify their functions,

Answer 29

Major types of plasma proteins are (1) albumins, which maintain the osmotic pressure of plasma and are important in the transport of fatty acids; (2) globulins, which (a) bind small ions, hormones, or compounds that might otherwise be filtered out of the blood at the kidneys or have very low solubility in water (transport globulins), or (b) attack foreign proteins and pathogens (immunoglobulins); and (3) fibrinogen, which functions in blood clotting.

Question 30

Which type of antibodies does plasma contain for each of the following blood types? (a) type A, (b) type B, (c) type AB, (d) type O.

Answer 30

(a) anti-B antibodies; (b) anti-A antibodies; (c) neither anti-A nor anti-B antibodies; (d) both anti-A and anti-B antibodies

Question 31

What four characteristics of WBCs are important to their response to tissue invasion or injury?

Answer 31

WBCs exhibit (1) emigration (diapedesis), squeezing between adjacent endothelial cells in the capillary wall; (2) amoeboid movement, a gliding movement that transports the cell; (3) positive chemotaxis, the attraction to specific chemical stimuli, and (4) phagocytosis (engulfing particles for neutrophils, eosinophils, and monocytes).

Question 32

Which three substances influence the rate of platelet formation?

Answer 32

The rate of platelet formation is influenced by (1) thrombopoietin or thrombocytestimulating factor, (2) interleukin-6, and (3) multi-CSF.

Question 33

Name the three types of lymphocytes and identify their functions,

Answer 33

The primary lymphocytes are (1) T cells, which are responsible for cellmediated immunity; (2) B cells, which are responsible for humoral immunity; and (3) NK cells, which are responsible for immune surveillance.

Question 34

What is the difference between prothrombin and thrombin?

Answer 34

Prothrombin is an inactive precursor that is converted to thrombin during coagulation. Thrombin is an enzyme that causes the clotting of blood by converting fibrinogen to fibrin.

Question 35

What four conditions cause the release of erythropoietin?

Answer 35

Erythropoietin is released (1) during anemia, (2) when blood flow to the kidneys declines, (3) when the oxygen content of air in the lungs declines, and (4) when the respiratory surfaces of the lungs are damaged.

Question 36

What contribution from the intrinsic and the extrinsic pathways is necessary for the common pathway to begin?

Answer 36

Initiation of the common pathway requires the activation of Factor X by the extrinsic and/or intrinsic pathways

Question 37

Dehydration would (a) cause an increase in the hematocrit, (b) cause a decrease in the hematocrit, (c) have no effect on the hematocrit, (d) cause an increase in plasma volume.

Answer 37

a

Question 38

Erythropoietin directly stimulates RBC formation by (a) increasing rates of mitotic divisions in erythroblasts, (b) speeding up the maturation of red blood cells, (c) accelerating the rate of hemoglobin synthesis, (d) all of these.

Answer 38

d

Question 39

Urine is yellow due to the presence of (a) hemoglobin, (b) biliverdin, (c) stercobilins, (d) bilirubin, (e) urobilins.

Answer 39

e

Question 40

A difference between the A, B, and O blood types and the Rh factor is (a) Rh agglutinogens are not found on the surface of red blood cells, (b) Rh agglutinogens do not produce a cross-reaction, (c) individuals who are Rh− do not carry agglutinins to Rh factor unless they have been previously sensitized, (d) Rh agglutinogens are found free in the plasma, (e) Rh agglutinogens are found bound to plasma proteins.

Answer 40

c

Question 41

What factors determine whether myeloid stem cells develop into RBCs or WBCs?

Answer 41

The hormone multi-CSF stimulates myeloid stem cells to become progenitor cells. Under the influence of the hormone erythropoietin, progenitor cells develop into proerythroblasts and eventually into RBCs. Under the influence of the hormone GM-CSF, progenitor cells develop into blast cells. The hormone G-CSF induces blast cells to become myeloblasts and eventually granulocytes, whereas the hormone M-CSF induces blast cells to become monoblasts and eventually monocytes.

Question 42

How do elements of blood defend against toxins and pathogens in the body?

Answer 42

White blood cells defend against toxins and pathogens. Neutrophils, eosinophils, and monocytes engulf and digest bacteria, protozoa, fungi, viruses, and cellular debris. Lymphocytes are specialized to attack and destroy specific foreign cells, proteins, and cancerous cells, directly or through the production of antibodies.

Question 43

What is the role of blood in the stabilization and maintenance of body temperature?

Answer 43

Blood stabilizes and maintains body temperature by absorbing and redistributing the heat produced by active skeletal muscles.

Question 44

What can be the consequences of having too little or too much iron in the body?

Answer 44

Too much iron can cause problems due to excessive buildup in secondary storage sites, such as the liver and the heart. Too little iron can result in irondeficiency anemia.

Question 45

Why is aspirin sometimes prescribed for the prevention of vascular problems?

Answer 45

Aspirin helps prevent vascular problems by inhibiting clotting. It inhibits platelet enzymes involved in the production of thromboxane A2 and prostaglandins, thereby inhibiting clotting. It also prolongs bleeding time.

Question 46

Damage to the semilunar valve of the right ventricle would affect blood flow into which vessel?

Answer 46

Damage to the semilunar valve of the right ventricle, or pulmonary valve, would affect blood flow to the pulmonary trunk.

Question 47

What prevents the AV valves from swinging into the atria?

Answer 47

Contraction of the papillary muscles (just before the rest of the ventricular myocardium contracts) pulls on the chordae tendineae, which prevent the AV valves from opening back into the atria.

Question 48

Why is the left ventricle more muscular than the right ventricle?

Answer 48

The left ventricle is more muscular than the right ventricle because the left ventricle must generate enough force to propel blood throughout the body, except the lungs, whereas the right ventricle must generate only enough force to propel blood a few centimeters to the lungs.

Question 49

Define autorhythmicity.

Answer 49

Autorhythmicity is the ability of cardiac muscle tissue to contract without neural or hormonal stimulation.

Question 50

Which structure of the heart is known as the cardiac pacemaker?

Answer 50

The sinoatrial (SA) node is known as the cardiac pacemaker or the natural pacemaker.

Question 51

If the cells of the SA node did not function, how would the heart rhythm change and the heart rate be affected?

Answer 51

If the cells of the SA node did not function, the AV node would act as the pacemaker and set the heart rhythm. The heart would still continue to beat, but at a slower rate.

Question 52

Why is it important for impulses from the atria to be delayed at the AV node before they pass into the ventricles?

Answer 52

If the impulses from the atria were not delayed at the AV node, they would be conducted through the ventricles so quickly by the bundle branches and Purkinje cells that the ventricles would begin contracting immediately, before the atria had finished their contraction. As a result, the ventricles would not be as full of blood as they could be, and the pumping of the heart would not be as efficient, especially during physical activity.

Question 53

Give the technical terms for heart contraction and heart relaxation.

Answer 53

The technical term for heart contraction is systole, and the term for heart relaxation is diastole.

Question 54

List the phases of the cardiac cycle.

Answer 54

The phases of the cardiac cycle are atrial systole, atrial diastole, ventricular systole, and ventricular diastole.

Question 55

Is the heart always pumping blood when pressure in the left ventricle is rising? Explain.

Answer 55

No. When pressure in the left ventricle first rises, the heart is contracting but no blood is leaving the heart. During this initial phase of contraction, both the AV valves and the semilunar valves are closed. The increase in pressure is the result of increased tension as the cardiac muscle contracts. When the blood pressure in the ventricle exceeds the blood pressure in the aorta, the aortic semilunar valves are forced open, and blood is rapidly ejected from the ventricle.

Question 56

What could cause an increase in the size of the QRS complex in an electrocardiogram

Answer 56

An increase in the size of the QRS complex indicates a larger-than-normal amount of electrical activity during ventricular depolarization. One possible cause is an enlarged heart. Because more cardiac muscle is depolarizing, the magnitude of the electrical event would be greater.

Question 57

Define cardiac output.

Answer 57

Cardiac output is the amount of blood pumped by the left ventricle in 1 minute.

Question 58

Caffeine has effects on cardiac conducting cells and contractile cells that are similar to those of NE. What effect would drinking large amounts of caffeinated drinks have on the heart?

Answer 58

Caffeine acts directly on the conducting system and contractile cells of the heart, increasing the rate at which they depolarize. Drinking large amounts of caffeinated drinks would increase the heart rate.

Question 59

Why is it a potential problem if the heart beats too rapidly?

Answer 59

The heart pumps in proportion to the amount of blood that enters. A heart that beats too rapidly does not have sufficient time to fill completely between beats. Thus, when the heart beats too fast, very little blood leaves the ventricles and enters the circulation, so tissues suffer damage from inadequate blood supply.

Question 60

What effect would stimulating the acetylcholine receptors of the heart have on cardiac output?

Answer 60

Stimulating the acetylcholine receptors of the heart would slow the heart rate (parasympathetic neurons release acetylcholine). Since cardiac output is the product of stroke volume and heart rate, a reduction in heart rate will lower the cardiac output (assuming that the stroke volume remains the same or doesn’t increase).

Question 61

What effect would an increase in venous return have on the stroke volume?

Answer 61

The venous return fills the heart with blood, stretching the heart muscle. According to the Frank–Starling principle, the more the heart muscle is stretched, the more forcefully it will contract (to a point). The more forceful the contraction, the more blood the heart will eject with each beat (stroke volume). Therefore, increased venous return would increase the stroke volume (if all other factors are constant).

Question 62

Joe’s end-systolic volume is 40 mL, and his end-diastolic volume is 125 mL. What is Joe’s stroke volume?

Answer 62

SV = EDV − ESV, so SV = 125 mL − 40 mL = 85 mL

Question 63

Oxygen-rich blood is delivered to the heart muscle by the (a) aorta, (b) aortic sinuses, (c) great cardiac vein, (d) coronary arteries.

Answer 63

d

Question 64

The conducting system of the heart consists of all of the following structures except the (a) sinoatrial node, (b) atrioventricular node, (c) fossa ovalis, (d) atrioventricular bundle

Answer 64

c

Question 65

The serous membrane covering the outer surface of the heart is the (a) parietal layer of the serous pericardium, (b) endocardium, (c) myocardium, (d) visceral layer of the serous pericardium.

Answer 65

d

Question 66

The simple squamous epithelium covering the heart valves is the (a) epicardium, (b) endocardium, (c) myocardium, (d) endothelium.

Answer 66

d

Question 67

The heart is surrounded by the (a) pleural cavity, (b) peritoneal cavity, (c) abdominopelvic cavity, (d) mediastinum, (e) abdominal cavity.

Answer 67

d

Question 68

The cardiac skeleton of the heart has which two of the following functions? (a) It physically isolates the muscle fibers of the atria from those of the ventricles. (b) It maintains the normal shape of the heart. (c) It helps distribute the forces of cardiac contraction. (d) It allows more rapid contraction of the ventricles. (e) It strengthens and helps prevent overexpansion of the heart.

Answer 68

a and b

Question 69

Cardiac output is equal to the (a) difference between the end-diastolic volume and the end-systolic volume, (b) product of heart rate and stroke volume, (c) difference between the stroke volume at rest and the stroke volume during exercise, (d) stroke volume less the end-systolic volume, (e) product of heart rate and blood pressure.

Answer 69

b

Question 70

The first heart sound that you hear when listening to your heart accompanies the closing of (a) only the bicuspid valve, (b) both the semilunar valves, (c) only the tricuspid valve, (d) both the atrioventricular valves.

Answer 70

d

Question 71

Examples of positively inotropic factors are (a) beta-blocking drugs, (b) drugs mimicking epinephrine, (c) calcium-channel blockers, (d) low doses of dopamine.

Answer 71

b

Question 72

What role do the chordae tendineae and papillary muscles play in the normal function of the AV valves?

Answer 72

During ventricular contraction, tension in the papillary muscles pulls against the chordae tendineae, which keep the cusps of the AV valve from swinging into the atrium. This action prevents the backflow, or regurgitation, of blood into the atrium as the ventricle contracts.

Question 73

Describe the three distinct layers that make up the heart wall.

Answer 73

(1) The epicardium is the visceral layer of the serous pericardium, which covers the outer surface of the heart. (2) The myocardium is the muscular wall of the heart, which forms both atria and ventricles. It contains cardiac muscle tissue and associated connective tissues, blood vessels, and nerves. (3) The endocardium is made up of a simple squamous epithelium and an areolar layer that covers the inner surfaces of the heart, including the valves.

Question 74

What are the valves in the heart, and what is the function of each?

Answer 74

The tricuspid valve (right atrioventricular valve) and the mitral valve (left atrioventricular valve) prevent the backflow of blood from the ventricles into the atria. The pulmonary and aortic semilunar valves prevent the backflow of blood from the pulmonary trunk and aorta into the right and left ventricles.

Question 75

Where are the Purkinje fibers located, and what is their function?

Answer 75

The Purkinje fibers radiate from the apex toward the base of the heart. They conduct action potentials very rapidly to all the ventricular cardiac contractile cells in order to start ventricular contraction.

Question 76

What is the cardiac cycle? What phases and events are necessary to complete a cardiac cycle?

Answer 76

The cardiac cycle comprises the events in a complete heartbeat, including a contraction–relaxation period for both atria and ventricles. The cycle begins with atrial systole as the atria contract and push blood into the relaxed ventricles. As the atria relax (atrial diastole), the ventricles contract (ventricular systole), forcing blood through the semilunar valves into the pulmonary trunk and aorta. The ventricles then relax (ventricular diastole). For the rest of the cardiac cycle, both the atria and ventricles are in diastole; passive filling occurs.

Question 77

What three factors regulate stroke volume to ensure that the left and right ventricles pump equal volumes of blood?

Answer 77

The factors that regulate stroke volume are (1) preload, the stretch on the heart before it contracts; (2) contractility, the force of contraction of individual ventricular contractile cells; and (3) afterload, the pressure that must be exceeded before blood can be ejected from the ventricles.

Question 78

The cells of the conducting system differ from the contractile cells of the heart in that (a) conducting cells are larger and contain more myofibrils, (b) contractile cells exhibit pacemaker potentials, (c) contractile cells do not normally exhibit autorhythmicity, (d) both a and b are correct.

Answer 78

c

Question 79

In an adult who is standing at rest, which of the following is larger? (a) the end-systolic volume, (b) the end-diastolic volume.

Answer 79

b

Question 80

If the papillary muscles fail to contract, (a) the ventricles will not pump blood, (b) the atria will not pump blood, (c) the semilunar valves will not open, (d) the AV valves will not close properly, (e) none of these happen.

Answer 80

d

Question 81

Cardiac output cannot increase indefinitely because (a) the available filling time becomes shorter as the heart rate increases, (b) the cardiovascular centers adjust the heart rate, (c) the rate of spontaneous depolarization decreases, (d) the ion concentrations of pacemaker plasma membranes decrease.

Answer 81

a

Question 82

Can a myocardial infarction be diagnosed through blood tests? Explain.

Answer 82

Yes, there are blood tests that can help diagnose a myocardial infarction. Damaged myocardial cells release enzymes into the circulation, and these elevated enzymes can be measured in blood tests. These enzymes include cardiac troponin T, cardiac troponin I, and a special form of creatinine phosphokinase, CK-MB.

Question 83

How is a constant blood supply to the heart muscle ensured?

Answer 83

The coronary arteries provide a constant blood supply to the heart muscle. The interconnections between the arteries, called arterial anastomoses, ensure constant blood supply to all parts of the myocardium, despite pressure fluctuations in the left and right coronary arteries as the heart beats.

Question 84

What is cardiac reserve? What effect does exercise have on it?

Answer 84

Cardiac reserve is the difference between resting and maximal cardiac outputs. Exercise increases cardiac output significantly.

Question 85

What factors influence cardiac output?

Answer 85

Stroke volume and heart rate influence cardiac output.

Question 86

What effect does sympathetic stimulation have on the heart? What effect does parasympathetic stimulation have on the heart?

Answer 86

Sympathetic activation increases the heart rate and the force of contractions; parasympathetic stimulation decreases the heart rate and the force of contractions.

Question 87

Why are compounds such as propranolol, metoprolol, atenolol, and labetalol useful in treating hypertension?

Answer 87

These drugs lower blood pressure as they block beta receptors, alpha receptors, or both, and prevent sympathetic stimulation of the heart.

Question 88

Vern is suffering from cardiac arrhythmias and is brought into the emergency room of a hospital. In the emergency room he begins to exhibit tachycardia and as a result loses consciousness. Explain why Vern lost consciousness.

Answer 88

During tachycardia (an abnormally fast heart rate), there is less time between contractions for the heart to fill with blood again. Thus, over time the heart fills with less and less blood, and pumps less blood out. As the stroke volume decreases, the cardiac output decreases. When cardiac output decreases to the point where not enough blood reaches the brain, loss of consciousness occurs.

Question 89

Harvey has a heart murmur in his left ventricle that produces a loud “gurgling” sound at the beginning of systole. Which valve is probably faulty?

Answer 89

Harvey probably has a regurgitating mitral valve, or left atrioventricular (AV) valve. When an AV valve fails to close properly, blood flowing back into the atrium produces a murmur. A murmur at the beginning of systole implicates the AV valve because this is the period when the valve has just closed and the blood in the ventricle is under increasing pressure; thus the likelihood of backflow is the greatest. A sound heard at the end of systole or the beginning of diastole would implicate a regurgitating semilunar valve—in this case, the aortic valve.

Question 90

The following measurements were made on two individuals (the values recorded remained stable for 1 hour): Person 1: heart rate, 75 bpm; stroke volume, 60 mL Person 2: heart rate, 90 bpm; stroke volume, 95 mL Which person has the greater venous return? Which person has the longer ventricular filling time?

Answer 90

Using CO = HR × SV, person 1 has a cardiac output of 4500 mL, and person 2 has a cardiac output of 8550 mL. According to the Frank–Starling principle, in a normal heart the cardiac output is directly proportional to the venous return. Thus, person 2 has the greater venous return. Ventricular filling decreases with increased heart rate; person 1 has the lower heart rate and therefore the longer ventricular filling time.

Question 91

Karen is taking the medication verapamil, a drug that blocks the calcium channels in cardiac muscle cells. What effect should this medication have on Karen’s stroke volume?

Answer 91

By blocking calcium channels, verapamil will decrease the force of cardiac contraction, which directly lowers Karen’s stroke volume.

Question 92

Identify the layers of the epidermis.

Answer 92

The layers of the epidermis are the stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.

Question 93

Dandruff is caused by excessive shedding of cells from the outer layer of skin on the scalp. So dandruff is composed of cells from which epidermal layer?

Answer 93

Dandruff consists of cells from the stratum corneum.

Question 94

A splinter that penetrates to the third layer of the epidermis of the palm is lodged in which layer?

Answer 94

This splinter is lodged in the stratum granulosum.

Question 95

Why does taking a bath cause wrinkly fingertips and toes?

Answer 95

Wrinkles in the tips of the fingers (and toes) are due to the constriction of blood vessels in the underlying skin, which causes the skin to shrink. This effect is controlled by the autonomic nervous system, a division of the nervous system that acts outside our awareness.

Question 96

Some criminals sand the tips of their fingers so as not to leave recognizable fingerprints. Would this practice permanently remove fingerprints? Why or why not?

Answer 96

Sanding the tips of the fingers will not permanently remove fingerprints. The ridges of the fingerprints are formed in layers of the skin that are constantly regenerated, so these ridges will eventually reappear. The pattern of the ridges is determined by the arrangement of tissue in the dermis, which is not affected by sanding.

Question 97

Name the sources of epidermal growth factor in the body.

Answer 97

Salivary glands and duodenal glands (glands of the duodenum) produce epidermal growth factor (EGF).

Question 98

Identify some roles of epidermal growth factor related to the epidermis.

Answer 98

Epidermal growth factor (EGF) promotes the divisions of basal cells in the stratum basale and stratum spinosum, accelerates the production of keratin in differentiating keratinocytes, stimulates epidermal development and epidermal repair after injury, and stimulates synthetic activity and secretion by epithelial glands.

Question 99

Describe the location of the dermis.

Answer 99

The dermis (a connective tissue layer) is located between the epidermis and the subcutaneous layer (hypodermis).

Question 100

Where are the capillaries and sensory nerve fibers that supply the epidermis located?

Answer 100

The capillaries and sensory nerve fibers that supply the epidermis are located in the papillary layer of the dermis.

Question 101

What accounts for the ability of the dermis to undergo repeated stretching?

Answer 101

The presence of elastic fibers and the flexibility and resilience of skin turgor allow the dermis to undergo repeated cycles of stretching and recoiling (returning to its original shape).

Question 102

List the two terms for the tissue that connects the dermis to underlying tissues.

Answer 102

The tissue that connects the dermis to underlying tissues is the subcutaneous layer or hypodermis.

Question 103

Describe the subcutaneous layer.

Answer 103

The subcutaneous layer is a layer of loose connective tissue (areolar tissue) and adipose tissue below (deep to) the dermis. The subcutaneous layer is not considered a part of the integument, but it is important in stabilizing the position of the skin in relation to underlying tissues.

Question 104

Identify several functions of subcutaneous fat.

Answer 104

Subcutaneous fat provides insulation to help reduce heat loss, serves as an energy reserve, and acts as a shock absorber for the body.

Question 105

Name the two major pigments in the epidermis.

Answer 105

The two major pigments in the epidermis are melanin, which ranges in color from red-yellow (pheomelanin) to brown-black (eumelanin), and carotene, an orange-yellow pigment.

Question 106

Why does exposure to sunlight darken skin?

Answer 106

When exposed to the ultraviolet (UV) radiation in sunlight, melanocytes in the epidermis and dermis synthesize the pigment melanin, darkening the skin.

Question 107

Why does the skin of a fair-skinned person appear red during exercise in hot weather?

Answer 107

When skin gets warm, arriving oxygenated blood is diverted to the superficial dermis for the purpose of eliminating heat. The oxygenated blood gives a reddish coloration to the skin.

Question 108

Explain the relationship between sunlight exposure and vitamin D3 synthesis.

Answer 108

In the presence of ultraviolet radiation in sunlight, epidermal cells in the stratum spinosum and stratum basale convert a cholesterol-related steroid compound into cholecalciferol, or vitamin D3.

Question 109

In some cultures, women must be covered completely, except for their eyes, when they go out in public. Explain why these women may develop bone problems later in life.

Answer 109

Cholecalciferol (vitamin D3) is needed to form strong bones and teeth. When the body surface is covered, UV light cannot penetrate to the stratum basale in the skin to begin vitamin D3 production, resulting in fragile bones.

Question 110

Describe a typical strand of hair.

Answer 110

A typical hair is a keratinous strand produced by epithelial cells of the hair follicle.

Question 111

What happens when the arrector pili muscle contracts?

Answer 111

The contraction of the arrector pili muscle pulls the hair follicle erect. The result is known as “goose bumps.”

Question 112

Once a burn on the forearm that destroys the epidermis and extensive areas of the deep dermis heals, will hair grow again in the affected area?

Answer 112

Even though hair is a derivative of the epidermis, the hair follicles are in the dermis. Where the epidermis and deep dermis are destroyed, new hair will not grow.

Question 113

Identify two types of exocrine glands found in the skin.

Answer 113

Two types of exocrine glands found in the skin are sebaceous (oil) glands and sweat glands.

Question 114

What are the functions of sebaceous secretions?

Answer 114

The functions of sebaceous secretions (called sebum) are to lubricate and protect the keratin of the hair shaft, lubricate and condition the surrounding skin, and inhibit the growth of bacteria.

Question 115

Deodorants are used to mask the effects of secretions from which type of skin gland?

Answer 115

Deodorants are used to mask the odor of apocrine sweat gland secretions, which contain several kinds of organic compounds. Some of these compounds have an odor, and others produce an odor when metabolized by skin bacteria.

Question 116

Which type of skin gland is most affected by the hormonal changes that occur during puberty?

Answer 116

Apocrine sweat glands enlarge and increase secretory activity in response to the increase in sex hormones that occurs at puberty.

Question 117

What substance makes fingernails hard?

Answer 117

Keratin is the substance that makes fingernails hard.

Question 118

What term is used to describe the thickened stratum corneum underlying the free edge of a nail?

Answer 118

The area of thickened stratum corneum under the free edge of a nail is called the hyponychium

Question 119

Where does nail growth occur?

Answer 119

Nail growth occurs at the nail root, an epidermal fold that is not visible from the surface.

Question 120

What term describes the combination of fibrin clots, fibroblasts, and the extensive network of capillaries in healing tissue?

Answer 120

The combination of fibrin clots, fibroblasts, and the extensive network of capillaries in tissue that is healing is called granulation tissue.

Question 121

Why can skin regenerate effectively even after considerable damage?

Answer 121

Skin can regenerate effectively even after considerable damage because stem cells persist in both the epithelial and connective tissue components of skin. When injury occurs, cells of the stratum basale replace epithelial cells, and mesenchymal cells replace cells lost from the dermis.

Question 122

Older people do not tolerate the summer heat as well as they did when they were young, and they are more prone to heat-related illnesses. What accounts for these changes?

Answer 122

As a person ages, the blood supply to the dermis decreases and eccrine sweat glands become less active. These changes make it more difficult for older individuals to cool themselves in hot weather.

Question 123

Why does hair turn white or gray with age?

Answer 123

With advancing age, melanocyte activity decreases, leading to gray or white hair.

Question 124

The two major components of the integumentary system are (a) the cutaneous membrane and the accessory structures, (b) the epidermis and the subcutaneous layer, (c) the hair and the nails, (d) the dermis and the subcutaneous layer.

Answer 124

a

Question 125

Beginning at the basement membrane and traveling toward the free surface, the epidermis includes the following strata: (a) corneum, lucidum, granulosum, spinosum, basale, (b) granulosum, lucidum, spinosum, basale, corneum, (c) basale, spinosum, granulosum, lucidum, corneum, (d) lucidum, granulosum, spinosum, basale, corneum.

Answer 125

c

Question 126

A glassy layer present only in thick skin is the (a) stratum corneum, (b) stratum lucidum, (c) stratum granulosum, (d) stratum spinosum, (e) stratum basale.

Answer 126

b

Question 127

Exposure of the skin to ultraviolet (UV) radiation (a) can result in increased numbers of melanocytes forming in the skin, (b) can result in decreased melanin production in melanocytes, (c) can cause destruction of vitamin D3, (d) can result in damage to the DNA of cells in the stratum basale, (e) has no effect on the skin cells.

Answer 127

d

Question 128

Which layer of the dermis is involved in dermatitis? (a) the subcutaneous layer, (b) the superficial fascia, (c) the reticular layer, (d) the papillary layer.

Answer 128

d

Question 129

The lamellar corpuscles in the reticular layer of the dermis are specialized in sensing (a) pain, (b) deep pressure and vibration, (c) temperature, (d) light touch.

Answer 129

b

Question 130

The accessory structures of the integument include the (a) blood vessels, glands, muscles, and nerves, (b) tactile discs, lamellar corpuscles, and tactile corpuscles, (c) hair, skin, and nails, (d) hair follicles, nails, sebaceous glands, and sweat glands.

Answer 130

d

Question 131

Each of the following is a part of the hair follicle, except the (a) glassy membrane, (b) external root sheath, (c) internal root sheath, (d) eponychium.

Answer 131

d

Question 132

The two types of exocrine glands in the skin are (a) eccrine and sweat glands, (b) sebaceous and sweat glands, (c) apocrine and sweat glands, (d) sebaceous and eccrine glands.

Answer 132

b

Question 133

Sebaceous follicles are large sebaceous glands found on all the following body parts except the (a) face, (b) external genitalia, (c) arms, (d) nipples.

Answer 133

c

Question 134

An important example of a specialized gland in the skin is the (a) mammary gland, (b) mucous gland, (c) apocrine sweat gland, (d) eccrine sweat gland.

Answer 134

a

Question 135

The cells that create scar tissue during the repair of an injury are (a) mast cells, (b) macrophages, (c) fibroblasts, (d) melanocytes.

Answer 135

c

Question 136

Muscle weakness and a reduction in bone strength in the elderly result from decreased (a) vitamin D3 production, (b) melanin production, (c) sebum production, (d) dermal blood supply.

Answer 136

a

Question 137

In which layer(s) of the epidermis does cell division occur?

Answer 137

Epidermal cell division occurs in the stratum basale.

Question 138

What is the function of the arrector pili muscles?

Answer 138

These smooth muscles cause hairs to stand erect when stimulated.

Question 139

What widespread effects does epidermal growth factor (EGF) have on the integument?

Answer 139

Epidermal growth factor promotes the divisions of basal cells in the stratum basale and stratum spinosum, accelerates the production of keratin in differentiating epidermal cells, stimulates both epidermal development and epidermal repair after injury, and stimulates secretory product synthesis and secretion by epithelial glands.

Question 140

What two major layers constitute the dermis, and what components are in each layer?

Answer 140

The dermis is made up of (1) the papillary layer, which consists of areolar connective tissue and contains capillaries and sensory nerve fibers and receptors, and (2) the reticular layer, which consists of dense irregular connective tissue and bundles of collagen fibers. Both layers contain networks of blood vessels, lymphatic vessels, and nerve fibers.

Question 141

List the four phases in the regeneration of the skin after an injury.

Answer 141

Regeneration of injured skin involves (1) bleeding and inflammation (inflammation phase), (2) scab and granulation tissue formation (migration phase), (3) loss of granulation and undermining of the scab (proliferation phase), and (4) scarring (scarring phase).

Question 142

How is thin skin different from thick skin?

Answer 142

Thin skin contains four layers of keratinocytes, whereas thick skin contains five layers.

Question 143

In clinical practice, drugs can be delivered by diffusion across the skin. This delivery method is called transdermal administration. Why are fat-soluble drugs more suitable for transdermal administration than drugs that are water soluble?

Answer 143

The integument is the first barrier to substances entering the body. This method of delivering drugs requires the substance to move across the epidermal plasma membranes. The lipid bilayer of the plasma membranes creates a barrier that prevents water from rapidly entering or leaving the cells. Fatsoluble (lipophilic) substances, such as oil containing a dissolved drug, can easily pass through this barrier to underlying connective tissue and enter the circulation. Water-soluble drugs are lipophobic and thus do not readily penetrate the integument.

Question 144

In evaluating burns, it is important to determine the depth of the burn correctly. How would you differentiate among a first-degree burn, a second-degree burn, and a third-degree burn?

Answer 144

In a first degree burn, only the surface of the epidermis is damaged. The skin reddens and can be painful. In a second-degree burn, the entire epidermis and some of the dermis are damaged. Hair follicles and glands are usually not affected, but blistering, pain, and swelling occur. Third-degree burns destroy the epidermis and dermis, extending into the subcutaneous layer. Despite swelling, these burns are less painful than second-degree burns, because sensory nerves are destroyed.

Question 145

Why is it important for a surgeon to choose—when possible—an incision pattern according to the skin’s tension lines?

Answer 145

Incisions along tension lines—which represent the orientation of dermal collagen and elastin fibers—are more likely to remain closed, and thus heal more quickly, than incisions that cut across tension lines.

Question 146

The fibrous protein that is responsible for the strength and water resistance of the skin surface is (a) collagen, (b) eleidin, (c) keratin, (d) elastin, (e) keratohyalin.

Answer 146

c

Question 147

The darker a person’s skin color, (a) the more melanocytes she has in her skin, (b) the more layers she has in her epidermis, (c) the more melanin her melanocytes produce, (d) the more superficial her blood vessels.

Answer 147

c

Question 148

In order for bacteria on the skin to cause an infection in the skin, they must accomplish all of the following, except (a) survive the bactericidal components of sebum, (b) avoid being flushed from the surface of the skin by sweat, (c) penetrate the stratum corneum, (d) penetrate to the level of the capillaries, (e) escape the dendritic cells.

Answer 148

d

Question 149

In an elderly person, blood supply to the dermis is reduced and sweat glands are less active. This combination of factors would most affect (a) the ability to thermoregulate, (b) the ability to heal injured skin, (c) the ease with which the skin is injured, (d) the physical characteristics of the skin, (e) the ability to grow hair.

Answer 149

a

Question 150

Lisa is unhappy about the presence of white patches on several parts of her body. These patches do not cause pain or discomfort, but Lisa considers them disfiguring. Identify Lisa’s condition, and explain what has caused it.

Answer 150

Lisa has vitiligo. The white patches on her skin are the result of the loss of melanocytes in those areas. This condition develops when the body’s immune defenses malfunction and antibodies attack normal melanocytes.

Question 151

Exposure to optimum amounts of sunlight is necessary for proper bone maintenance and growth in children. (a) What does sunlight do to promote bone maintenance and growth? (b) If a child lives in an area where exposure to sunlight is rare because of pollution or overcast skies, what can be done to minimize impaired maintenance and growth of bone?

Answer 151

(a) Ultraviolet radiation in sunlight converts a cholesterol-related steroid compound into vitamin D3, or cholecalciferol. This compound is then converted to the hormone calcitriol, which is essential for absorbing the calcium and phosphate ions by the small intestine that is necessary for normal bone maintenance and growth. (b) The child can drink more milk. Milk is routinely fortified with cholecalciferol, normally identified as “vitamin D,” which is easily absorbed by the intestines.

Question 152

One of the factors to which lie detectors respond is an increase in electrical skin conductance due to the presence of moisture. Explain the physiological basis for the use of this indicator.

Answer 152

Sweating from eccrine sweat glands is precisely regulated, and one influencing factor is emotional state. Presumably, a person who is lying is nervous and sweats profusely; the lie detector machine detects a change in electrical skin conductance caused by this sweating.

Question 153

Many people change the natural appearance of their hair, either by coloring it or by altering the degree of curl in it. Which layers of the hair do you suppose are affected by the chemicals added during these procedures? Why are the effects of the procedures not permanent?

Answer 153

The chemicals in hair dyes break the protective covering of the cortex, allowing the dyes to stain the medulla of the shaft. Dying is not permanent because the cortex remains damaged, allowing shampoo and UV rays from the sun to enter the medulla and affect the color. Also, the living portion of the hair remains unaffected, so that when the shaft is replaced the color will be lost.

Question 154

List the five general classes of blood vessels.

Answer 154

The five general classes of blood vessels are arteries, arterioles, capillaries, venules, and veins.

Question 155

Which type of vessel is characterized by thin walls with very little smooth muscle tissue in the tunica media?

Answer 155

Blood vessels with thin walls and very little smooth muscle tissue in the tunica media are veins. Arteries and arterioles have a large amount of smooth muscle tissue in a thick, well-developed tunica media.

Question 156

Why are valves located in veins but not in arteries?

Answer 156

In the arterial system, pressures are high enough to keep the blood moving forward. In the venous system, blood pressure is too low to keep the blood moving on toward the heart. Valves in veins prevent blood from flowing back toward the capillaries whenever the venous pressure drops.

Question 157

Where in the body would you find fenestrated capillaries?

Answer 157

Fenestrated capillaries are located where fluids and small solutes move freely into and out of the blood, including endocrine glands, the choroid plexus of the brain, absorptive areas of the intestine, and filtration areas of the kidneys.

Question 158

Identify the factors that contribute to total peripheral resistance.

Answer 158

The factors that contribute to total peripheral resistance are vascular resistance, vessel length, vessel luminal diameter, blood viscosity, and turbulence.

Question 159

In a healthy person, where is blood pressure greater: at the aorta or at the inferior vena cava? Explain.

Answer 159

In a healthy person, blood pressure is greater at the aorta than at the inferior vena cava. Blood, like other fluids, moves along a pressure gradient from areas of high pressure to areas of low pressure. If the pressure were higher in the inferior vena cava than in the aorta, the blood would flow backward.

Question 160

While standing in the hot sun, Lailah begins to feel lightheaded and faints. Explain what happened.

Answer 160

While Lailah was standing for a period of time, blood pooled in her lower limbs, which decreased venous return to her heart. In turn, cardiac output decreased, so less blood reached her brain, causing light-headedness and fainting. A hot day adds to this effect, because the loss of body water through sweating reduces blood volume.

Question 161

Mike’s blood pressure is 125/70. What is his mean arterial pressure (MAP)?

Answer 161

Mike’s mean arterial pressure (MAP) is approximately 88.3 mm Hg; 70 + (125 − 70)/3 = 70 + 18.3 = 88.3.

Question 162

Describe the actions of vasodilators and local vasodilators.

Answer 162

Vasodilators promote the dilation of precapillary sphincters. Local vasodilators, such as decreased O2 level or increased CO2 level, act on tissues to accelerate blood flow.

Question 163

How would applying slight pressure to the common carotid artery affect your heart rate?

Answer 163

Pressure on the common carotid artery would decrease blood pressure at the baroreceptors in the carotid sinus. This decrease would lower the frequency of action potentials along the glossopharyngeal nerve (IX) to the medulla oblongata, and more sympathetic impulses would be sent to the heart. The net result would be an increase in the heart rate.

Question 164

What effect would vasoconstriction of the renal artery have on blood pressure and blood volume?

Answer 164

Vasoconstriction of the renal artery would decrease both blood flow and blood pressure at the kidney. In response, the kidney would increase the amount of renin it releases, which in turn would lead to an increase in the level of angiotensin II. The angiotensin II would bring about increased blood pressure and increased blood volume.

Question 165

Why does blood pressure increase during exercise?

Answer 165

Blood pressure increases during exercise because (1) cardiac output increases and (2) resistance in visceral tissues increases.

Question 166

Name the immediate and long-term problems related to the cardiovascular response to hemorrhaging.

Answer 166

The immediate problem during hemorrhaging is maintaining adequate blood pressure and peripheral blood flow; the long-term problem is restoring normal blood volume

Question 167

Explain the role of aldosterone and ADH in long-term restoration of blood volume.

Answer 167

Both aldosterone and ADH promote fluid retention and reabsorption at the kidneys, preventing further reductions in blood volume.

Question 168

Identify the two circuits of the cardiovascular system.

Answer 168

The two circuits of the cardiovascular system are the pulmonary circuit and the systemic circuit.

Question 169

Identify the major patterns of blood vessel organization seen in the pulmonary and systemic circuits of the cardiovascular system.

Answer 169

The major patterns are as follows: (1) The peripheral distributions of arteries and veins on the body’s left and right sides are generally identical, except near the heart, where the largest vessels connect to the atria or ventricles; (2) a single vessel may have several names as it crosses specific anatomical boundaries, making accurate anatomical descriptions possible; and (3) tissues and organs are usually serviced by several arteries and veins.

Question 170

Name the blood vessels that enter and exit the lungs, and whether they contain primarily oxygenated or deoxygenated blood.

Answer 170

The pulmonary arteries enter the lungs carrying deoxygenated blood, and the pulmonary veins leave the lungs carrying oxygenated blood.

Question 171

Trace the path of a drop of blood through the lungs, beginning at the right ventricle and ending at the left atrium.

Answer 171

The path of blood through the lungs is right ventricle → pulmonary trunk → left and right pulmonary arteries → pulmonary arterioles → alveolar capillary network → pulmonary venules → pulmonary veins → left atrium.

Question 172

A blockage of which branch from the aortic arch would interfere with blood flow to the left arm?

Answer 172

A blockage of the left subclavian artery would interfere with blood flow to the left arm.

Question 173

Why would compression of the common carotid arteries cause a person to lose consciousness?

Answer 173

Compression of the common carotid arteries would decrease blood pressure at the carotid sinus and cause a rapid reduction in blood flow to the brain, resulting in a loss of consciousness. An immediate reflexive increase in heart rate and blood pressure would follow.

Question 174

Isabella is in an automobile accident, and her celiac trunk is ruptured. Which organs will be affected most directly by this injury?

Answer 174

Rupture of the celiac trunk would most directly affect the stomach, spleen, liver, and pancreas.

Question 175

Whenever Noah gets angry, a large vein bulges in the lateral region of his neck. Which vein is this?

Answer 175

The vein that is bulging in Noah’s neck is the external jugular vein.

Question 176

A thrombus that blocks the popliteal vein would interfere with blood flow in which other veins?

Answer 176

A blockage of the popliteal vein would interfere with blood flow in the tibial and fibular veins (which form the popliteal vein) and the small saphenous vein (which joins the popliteal vein).

Question 177

Name the three vessels that carry blood to and from the placenta.

Answer 177

Two umbilical arteries supply blood to the placenta, and one umbilical vein returns blood from the placenta. The umbilical vein then drains into the ductus venosus within the fetal liver. (Remember, arteries carry blood away from the heart, and veins carry blood to the heart.)

Question 178

A blood sample taken from an umbilical cord contains high levels of oxygen and nutrients, and low levels of carbon dioxide and waste products. Is this sample from an umbilical artery or the umbilical vein? Explain.

Answer 178

This blood sample was taken from the umbilical vein, which carries oxygenated, nutrient-rich blood from the placenta to the fetus.

Question 179

Name the structures in the fetal circulation that stop functioning at birth. What becomes of these structures?

Answer 179

Structures specific to the fetal circulation include two umbilical arteries, an umbilical vein, the ductus venosus, the foramen ovale, and the ductus arteriosus. In the newborn, the foramen ovale closes and persists as the fossa ovalis, a shallow depression

Question 179

Identify components of the cardiovascular system that are affected by age.

Answer 179

Components of the cardiovascular system affected by age include the blood, heart, and blood vessels.

Question 180

Define thrombus.

Answer 180

A thrombus is a stationary blood clot within the lumen of a blood vessel.

Question 181

Define aneurysm.

Answer 181

An aneurysm is the ballooning out of a weakened arterial wall resulting from sudden pressure increases.

Question 182

Describe what the cardiovascular system provides for all other body systems.

Answer 182

The cardiovascular system provides other body systems with oxygen, hormones, nutrients, and white blood cells in blood, while removing carbon dioxide and metabolic wastes; it also transfers heat to body tissues.

Question 183

What is the relationship between the skeletal system and the cardiovascular system?

Answer 183

The skeletal system provides calcium needed for normal cardiac muscle contraction, and it protects developing blood cells in the red bone marrow. The cardiovascular system provides calcium and phosphate for bone deposition, delivers erythropoietin to red bone marrow, and transports parathyroid hormone and calcitonin to osteoblasts and osteoclasts.

Question 184

The blood vessels that play the most important role in regulating blood pressure and blood flow to a tissue are the (a) arteries, (b) arterioles, (c) veins, (d) venules, (e) capillaries.

Answer 184

b

Question 185

Cardiovascular function is regulated by all of the following except (a) local factors, (b) neural factors, (c) endocrine factors, (d) venous return, (e) conscious control.

Answer 185

e

Question 186

Chemoreceptors that respond to changes in carbon dioxide and oxygen levels in blood are located in the (a) aortic sinuses, (b) aortic bodies, (c) right atrium, (d) brainstem, (e) atrioventricular node.

Answer 186

b

Question 187

The two-way exchange of substances between blood and body cells occurs only through (a) arterioles, (b) capillaries, (c) venules, (d) all of these.

Answer 187

b

Question 188

Large molecules such as peptides and proteins move into and out of the bloodstream by way of (a) continuous capillaries, (b) fenestrated capillaries, (c) thoroughfare channels, (d) venules.

Answer 188

b

Question 189

The local control of blood flow due to the action of precapillary sphincters is (a) vasomotion, (b) autoregulation, (c) selective resistance, (d) turbulence.

Answer 189

b

Question 190

Blood is transported through the venous system by means of (a) skeletal muscle contractions, (b) decreasing blood pressure, (c) the respiratory pump, (d) a and c.

Answer 190

d

Question 191

The most important factor in vascular resistance is (a) the viscosity of the blood, (b) the diameter of the lumen of blood vessels, (c) turbulence due to irregular surfaces of blood vessels, (d) the length of the blood vessels.

Answer 191

b

Question 192

Net hydrostatic pressure forces water ______ a capillary; net osmotic pressure reabsorbs water _______ a capillary. (a) into, out of, (b) out of, into, (c) out of, out of, (d) into, into.

Answer 192

b

Question 193

The three arteries formed by the branching of the celiac trunk are the (a) common hepatic, left gastric, and splenic, (b) left colic, sigmoid, and rectal, (c) middle colic, right colic, and ileocolic, (d) gastroduodenal, cystic, and right gastric.

Answer 193

a

Question 194

The unpaired arteries supplying blood to the visceral organs include (a) the adrenal, renal, and lumbar arteries, (b) the iliac, gonadal, and femoral arteries, (c) the celiac and superior and inferior mesenteric arteries, (d) all of these

Answer 194

c

Question 195

The paired arteries supplying blood to the body wall and other structures outside the abdominopelvic cavity include the (a) left gastric, hepatic, splenic, and phrenic arteries, (b) adrenal, colic, lumbar, and gonadal arteries, (c) iliac, femoral, and lumbar arteries, (d) celiac, left gastric, and superior and inferior mesenteric arteries

Answer 195

c

Question 196

Peripheral distributions of arteries and veins are identical on the left and right sides of the body, except near the (a) gonads, (b) heart, (c) kidneys, (d) lower limbs.

Answer 196

b

Question 197

The vessel that transports venous blood from organs in the peritoneal cavity to the liver is the (a) inferior vena cava, (b) hepatic vein, (c) cystic vein, (d) hepatic portal vein.

Answer 197

d

Question 198

What are the primary forces that cause fluid to move (a) out of a capillary at its arterial end and into the interstitial fluid, (b) into a capillary at its venous end from the interstitial fluid?

Answer 198

(a) Capillary hydrostatic pressure forces fluid out of a capillary at the arterial end. (b) Blood colloid osmotic pressure causes the movement of fluid back into a capillary at its venous end.

Question 199

What cardiovascular changes occur at birth?

Answer 199

When an infant takes its first breath, the lungs expand and pulmonary vessels dilate. The smooth muscles in the ductus arteriosus contract, due to increased venous return from the lungs, isolating the pulmonary and aortic trunks, and blood begins flowing through the pulmonary circuit. As pressure increases in the left atrium, the valvular flap closes the foramen ovale, completing the vascular remodeling.

Question 200

A major difference between the arterial and venous systems is that (a) arteries are usually more superficial than veins, (b) in the limbs there is dual venous drainage, (c) veins are usually less branched compared to arteries, (d) veins exhibit a much more orderly pattern of branching in the limbs, (e) veins are not found in the abdominal cavity.

Answer 200

b

Question 201

Which of the following conditions would have the greatest effect on peripheral resistance? (a) doubling the length of a vessel, (b) doubling the diameter of a vessel, (c) doubling the viscosity of the blood, (d) doubling the turbulence of the blood, (e) doubling the number of white cells in the blood.

Answer 201

b

Question 202

Baroreceptors stimulated by increased blood pressure (a) induce vasoconstriction and cause an increase in cardiac output, (b) induce vasodilation and cause a decrease in cardiac output, (c) do none of these.

Answer 202

b

Question 203

Relate the anatomical differences between arteries and veins to their functions.

Answer 203

Artery walls are generally thicker and contain more smooth muscle and elastic fibers, enabling them to resist and adjust to the pressure generated by the heart. Venous walls are thinner; the pressure in veins is less than that in arteries. Arteries constrict more than veins do when not expanded by blood pressure, due to a greater degree of elastic tissue. Finally, the endothelial lining of an artery has a pleated appearance because it cannot contract and so forms folds. The lining of a vein looks like a typical endothelial layer.

Question 204

How is arterial blood flow to the tissues controlled by the capillaries?

Answer 204

Bands of smooth muscles, called precapillary sphincters, are present at the entrances of the capillaries. Their contraction and relaxation control blood flow to the tissues. Contraction of the sphincters narrows the capillary entrances, reducing or stopping the flow of blood. When the sphincters relax, the entrances dilate, and blood flows into the capillaries. The central passageway in the arteriole system acts as a thoroughfare channel. Blood flow through this channel is controlled by the sphincter effect of the arteriole.

Question 205

How is blood pressure maintained in veins to counter the force of gravity?

Answer 205

Contraction of the surrounding skeletal muscles squeezes venous blood toward the heart. This mechanism, the muscular pump, is assisted by the presence of valves in the veins, which prevent backflow of the blood. The respiratory pump, which results from the increase in internal pressure of the thoracic cavity during exhalation, pushes venous blood into the right atrium.

Question 206

Compare hypertension and hypotension.

Answer 206

Abnormally high blood pressure is termed hypertension, whereas abnormally low blood pressure is called hypotension. Of the two, hypertension is more common. Many cases of hypotension result from aggressive drug treatment for hypertension. Smoking, stress, and obesity are some of the factors that lead to hypertension.

Question 207

Why is blood flow to the brain relatively continuous and constant?

Answer 207

The brain receives arterial blood from four arteries that form anastomoses within the cranium. An interruption of any one vessel will not compromise the blood flow to the brain.

Question 208

Compare the effects of the cardioacceleratory and cardioinhibitory centers on cardiac output and blood pressure.

Answer 208

The cardioacceleratory and vasomotor centers are stimulated when general sympathetic activation occurs. The result is an increase in cardiac output and blood pressure. When the parasympathetic division is activated, the cardioinhibitory center is stimulated, reducing cardiac output.

Question 209

Bob is sitting outside on a warm day and is sweating profusely. Mary wants to practice taking blood pressures, and he agrees to play the patient. Mary finds that Bob’s blood pressure is elevated, even though he is resting and has lost fluid from sweating. (She reasons that fluid loss should lower blood volume and, thus, blood pressure.) Why is Bob’s blood pressure high instead of low?

Answer 209

Fluid loss lowers blood volume, leading to sympathetic stimulation, which elevates blood pressure. So, Bob’s blood pressure is high instead of low.

Question 210

People with allergies commonly take antihistamines with decongestants to relieve their symptoms. The container warns that individuals who are being treated for high blood pressure should not take the medication. Why not?

Answer 210

Antihistamines and decongestants are sympathomimetic drugs; they have the same effects on the body as does stimulation of the sympathetic nervous system. In addition to the desired effects of counteracting the symptoms of the allergy, these medications can produce an increased heart rate, increased stroke volume, and increased peripheral resistance, all of which will contribute to elevating blood pressure. In a person with hypertension (high blood pressure), these drugs would aggravate this condition, with potentially hazardous consequences.

Question 211

Jolene awakens suddenly to the sound of her alarm clock. Realizing that she is late for class, she jumps to her feet, feels light-headed, and falls back on her bed. What probably caused this reaction? Why doesn’t this happen all the time?

Answer 211

When Jolene stood up rapidly, gravity caused her blood volume to move to the lower parts of her body away from the heart, decreasing venous return. The decreased venous return resulted in a decreased end-diastolic volume (EDV), leading to a decreased stroke volume and cardiac output. In turn, blood flow to the brain decreased, so the diminished oxygen supply caused her to be light-headed and feel faint. This reaction doesn’t happen all the time because as soon as the pressure drops due to inferior movement of blood, baroreceptors in the aortic arch and carotid sinuses trigger the baroreceptor reflex. Action potentials are carried to the medulla oblongata, where appropriate responses are integrated. In this case, we would expect an increase in peripheral resistance to compensate for the decreased blood pressure. If this doesn’t compensate enough for the drop, then an increase in heart rate and force of contraction would occur. Normally, these responses occur so quickly that changes in pressure following changes in body position go unnoticed.