32 Anatomy & Physiology Foundations Practice Questions & Answers

1. 1. A phlebotomy student asks why the pulmonary artery is classified as an artery when the blood inside it is low in oxygen. What is the correct explanation?

   • A.Vessel names follow the direction of flow, so a vessel carrying blood away from the heart is an artery✓ Answer
   • B.Vessel names follow oxygen content, so the pulmonary artery is a rare exception to a firm rule
   • C.Vessel names follow wall thickness, so a thick-walled vessel is an artery whatever it carries
   • D.Vessel names follow internal pressure, so a low-pressure vessel leaving the heart counts as a vein under that naming rule

   Arteries and veins are defined by the direction of flow relative to the heart, not by oxygen content: an artery carries blood away from the heart. The pulmonary arteries carry oxygen-poor blood to the lungs and the pulmonary veins return oxygen-rich blood to the left atrium, which is the classic exception candidates miss.

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2. 2. Blood has just been ejected from the right ventricle. Which sequence traces its route until it reaches the left atrium?

   • A.Pulmonary valve, then pulmonary arteries, then the lungs, then pulmonary veins, then left atrium✓ Answer
   • B.Aortic valve, then the aorta, then systemic capillaries, then superior vena cava, then left atrium
   • C.Mitral valve, then pulmonary arteries, then the lungs, then superior vena cava, then left atrium
   • D.Tricuspid valve, then pulmonary veins, then the lungs, then pulmonary arteries, then left atrium

   Blood leaving the right ventricle passes the pulmonary semilunar valve into the pulmonary arteries, is oxygenated in the lungs, and returns through the pulmonary veins to the left atrium. The tricuspid valve sits before the right ventricle and the mitral valve after the left atrium, so neither can appear on this segment of the circuit.

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3. 3. A patient asks why the left side of the heart is described as the stronger side. Which explanation is accurate?

   • A.The left ventricle receives blood already under high pressure, so its wall thickens over time
   • B.The left ventricle fills with a much larger volume of blood on each beat than the right does
   • C.The left ventricle wall is thicker because it drives blood through the short pulmonary circuit with each beat
   • D.The left ventricle wall is thicker because it must push blood through the whole systemic circuit✓ Answer

   Both ventricles eject about the same stroke volume, but the left ventricle must overcome the high resistance of the systemic circuit while the right ventricle pumps only into the low-pressure pulmonary circuit. Greater workload, not greater volume, is what builds the thicker left ventricular myocardium.

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4. 4. During palpation an artery feels firm and round while a nearby vein flattens under the fingertip. Which structural difference explains this?

   • A.The artery has a thick tunica adventitia, while the vein has almost no outer connective layer
   • B.The artery contains one-way valves that brace it, while the vein has no valves to support it
   • C.The artery has a thick muscular tunica media, while the thin media of a vein lets it collapse✓ Answer
   • D.The artery has a double endothelial lining, while a single lining cannot hold the vein open

   The tunica media, made of smooth muscle and elastic tissue, is the thickest layer in arteries and keeps the lumen round and firm against high pressure. Veins have a thin media and a relatively thick adventitia, so they collapse easily, and the one-way valves formed by folds of the tunica intima are found in veins rather than arteries.

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5. 5. Where in the circulatory system does the actual exchange of oxygen, nutrients, and wastes between blood and tissue take place?

   • A.In the large veins, where low pressure lets fluid and gases move freely through the wall
   • B.In the arterioles, whose muscular walls open pores that release oxygen into the tissue
   • C.In the capillaries, whose wall is a single endothelial cell thick and permits free diffusion✓ Answer
   • D.In the venules, where slowing blood flow lets wastes pass back across the vessel wall

   Capillaries are the only vessels thin enough for exchange: their wall is a single layer of endothelium (tunica intima alone), so gases, nutrients, and wastes diffuse across it between blood and interstitial fluid. Arterioles, venules, and veins are conduits whose walls are too thick for that exchange.

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6. 6. A differential count is reported on a healthy adult. Which white cell type should appear in the greatest proportion, and which in the smallest?

   • A.Monocytes are the most numerous, and eosinophils are the fewest in a normal adult
   • B.Eosinophils are the most numerous, and lymphocytes are the fewest in a normal adult
   • C.Lymphocytes are the most numerous, and monocytes are the fewest in a normal adult
   • D.Neutrophils are the most numerous, and basophils are the fewest in a normal adult✓ Answer

   In a normal adult differential the neutrophils dominate at roughly half to seventy percent because they are the front-line phagocytes against bacteria, while basophils, which release histamine and heparin, make up one percent or less. Lymphocytes are second in number and monocytes are the largest cells, not the most abundant.

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7. 7. Which statement correctly describes platelets and the part they play when a vessel wall is injured?

   • A.They are the largest formed element and engulf bacteria at the site of the injured vessel
   • B.They are fragments of megakaryocytes and clump together to form the first plug at the injury✓ Answer
   • C.They are whole cells with a nucleus and release the fibrin that seals the injured vessel
   • D.They are immature red cells and carry oxygen to the tissue around the injured vessel

   Platelets are not whole cells but cytoplasmic fragments shed from megakaryocytes in the bone marrow, and they are the smallest formed element. They adhere to the damaged vessel wall and aggregate into the temporary platelet plug of primary hemostasis, before the fibrin clot is built.

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8. 8. Place the phases of hemostasis in the order the body carries them out after a small vessel is cut.

   • A.Vasoconstriction, then the platelet plug, then the fibrin clot, then breakdown of the clot✓ Answer
   • B.Platelet plug, then vasoconstriction, then breakdown of the clot, then the fibrin clot
   • C.Fibrin clot, then vasoconstriction, then the platelet plug, then breakdown of the clot
   • D.Vasoconstriction, then the fibrin clot, then breakdown of the clot, then the platelet plug

   Hemostasis runs in four fixed steps: the vessel constricts to slow flow, platelets adhere and aggregate into a temporary plug, the coagulation cascade converts fibrinogen to fibrin and stabilizes that plug, and finally fibrinolysis dissolves the clot as the vessel heals. Each step depends on the one before it.

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9. 9. Which pathway of coagulation does each test evaluate: the prothrombin time with INR, and the activated partial thromboplastin time?

   • A.The PT evaluates the intrinsic pathway, and the aPTT evaluates the extrinsic pathway
   • B.The PT evaluates platelet function, and the aPTT the firmness of the fibrin clot formed
   • C.The PT evaluates the extrinsic and common pathways, and the aPTT the intrinsic pathway✓ Answer
   • D.The PT evaluates fibrinolysis, and the aPTT evaluates the common pathway on its own

   The prothrombin time with INR measures the extrinsic pathway (tissue factor and factor VII) as it feeds the common pathway, which is why it monitors warfarin. The aPTT measures the intrinsic pathway (factors XII, XI, IX, and VIII) into the common pathway and is the test used to follow heparin.

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10. 10. Calcium is designated factor IV of the coagulation system. What role does it play, and what happens when a chelating agent binds it in a specimen?

    • A.It carries the clotting factors in plasma, so binding it releases them and speeds the cascade
    • B.It is required at several steps of the cascade, so binding it stops the specimen from clotting✓ Answer
    • C.It is the substance converted into fibrin, so binding it makes the clot form even faster
    • D.It dissolves clots once healing begins, so binding it leaves the specimen clotted and unusable

    Calcium (factor IV) is an obligatory cofactor at several points in both the intrinsic and extrinsic pathways and in the common pathway. Chelating agents work by binding that calcium so the cascade cannot proceed, which is exactly how an anticoagulated specimen is kept liquid.

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11. 11. A patient with type AB blood and a patient with type O blood are compared. Which statement about their red cells and their plasma is correct?

    • A.Type O is the universal red cell donor, and type AB is the universal plasma donor✓ Answer
    • B.Type O carries both A and B antigens, and type AB carries both A and B antibodies
    • C.Type AB plasma holds anti-A and anti-B, and type O plasma holds neither antibody
    • D.Type AB is the universal red cell donor, and type O is the universal plasma donor

    Type O red cells carry neither the A nor the B antigen, so they can be given to any ABO recipient, which makes O the universal red cell donor. The roles reverse for plasma: AB plasma contains no anti-A or anti-B antibody, so it is the universal plasma donor while AB red cells can go only to AB recipients.

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12. 12. An Rh-negative patient has never been transfused and has never been pregnant. What should be true of her plasma with respect to anti-D antibody?

    • A.Anti-D is absent, because it forms only after exposure to D-positive red cells✓ Answer
    • B.Anti-D is present but too weak to matter until a first transfusion is given later
    • C.Anti-D is present from birth, in the same way anti-A and anti-B occur in ABO groups
    • D.Anti-D is absent, because Rh-negative people are unable to make that antibody at all

    Unlike the ABO antibodies, anti-D does not occur naturally: an Rh-negative person makes it only after immune exposure to D-positive red cells through transfusion or pregnancy. That is why Rh status matters for transfusion compatibility and for hemolytic disease of the newborn.

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13. 13. A phlebotomy student is learning the antecubital veins by name and position. Which description places the three principal veins correctly on the arm?

    • A.The basilic runs along the lateral thumb side, the cephalic along the medial little-finger side, and the median cubital above both.
    • B.The cephalic runs along the lateral thumb side, the basilic along the medial little-finger side, and the median cubital between them.✓ Answer
    • C.The median cubital runs along the lateral thumb side, the cephalic turns medially at the wrist, and the basilic crosses the forearm.
    • D.The cephalic and the basilic both run along the medial side, and the median cubital lies lateral to each of them near the elbow.

    In anatomical position the palms face forward, so the cephalic vein ascends the lateral (thumb) side of the arm and the basilic ascends the medial (little-finger) side. The median cubital connects the two across the antecubital fossa, which is why it lies most centrally of the three.

    Ref QB-75Y3FZSource: CLSI GP41, Collection of Diagnostic Venous Blood Specimens — vein selection in the antecubital fossaReport a problem with this question

14. 14. Why does the anatomy lying under the basilic vein make it the least desirable antecubital vein to puncture?

    • A.The ulnar artery and the ulnar nerve lie just beneath it, so the vein rolls away from the needle far more than the others.
    • B.A large lymphatic trunk lies just beneath it, so a puncture there draws tissue fluid into the tube and dilutes the specimen.
    • C.The brachial artery and the median nerve lie just beneath it, so a deep or misdirected needle can reach either structure.✓ Answer
    • D.The radial artery and the radial nerve lie just beneath it, so the vein itself sits much deeper than the other two veins.

    The basilic vein lies on the medial side of the antecubital fossa directly over the brachial artery, the median nerve and the medial antebrachial cutaneous nerve. Because those structures sit immediately deep to it, an accidental arterial puncture or nerve injury is far more likely there than at the other antecubital veins.

    Ref QB-NMEKPXSource: CLSI GP41, Collection of Diagnostic Venous Blood Specimens — order of preference for antecubital veinsReport a problem with this question

15. 15. On anatomical grounds, what makes the median cubital vein the first choice in the antecubital fossa?

    • A.It is large and well anchored by surrounding tissue, and it sits farthest from the artery and nerve of the region.✓ Answer
    • B.It is the deepest vein of the region, so the surrounding muscle holds it still while the needle is advanced.
    • C.It is the only antecubital vein with valves, so blood is held in place and the tube fills more completely.
    • D.It lies directly over the brachial artery, so arterial pressure keeps it full and easy to find by palpation.

    The median cubital is typically the largest and most superficial of the antecubital veins and is held firmly by the surrounding connective tissue, so it does not roll under the needle. It also lies at a distance from the brachial artery and median nerve, which is what makes it both the safest and the least painful choice.

    Ref QB-65MR9YSource: CLSI GP41, Collection of Diagnostic Venous Blood Specimens — vein selection priorityReport a problem with this question

16. 16. A vein wall is described from the lumen outward. Which account of the three layers is correct?

    • A.The intima is a fibrous connective tissue coat, the media is the endothelial lining, and the adventitia is smooth muscle.
    • B.The intima is a layer of smooth muscle, the media is the connective tissue coat, and the adventitia lines the open lumen.
    • C.The intima is elastic cartilage, the media is the endothelial lining, and the adventitia is fat and lymphatic tissue.
    • D.The intima is the endothelial lining, the media is muscle and elastic tissue, and the adventitia is connective tissue.✓ Answer

    The innermost tunica intima is a smooth endothelium that lets blood flow without clotting; the tunica media is smooth muscle with elastic fibers that changes vessel diameter; and the tunica adventitia is connective tissue that anchors the vessel to surrounding structures. A needle entering a vein crosses these three layers in that order before reaching the lumen.

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17. 17. How does the relative thickness of the wall layers compare between an artery and a vein?

    • A.The intima is the thickest layer of an artery, while the media is the thickest layer of a vein.
    • B.The media is the thickest layer of an artery, while the adventitia is the thickest layer of a vein.✓ Answer
    • C.The adventitia is the thickest layer of an artery, while the intima is the thickest layer of a vein.
    • D.The media is the thickest layer of both vessels, and a vein simply has a narrower lumen than an artery.

    An artery must withstand the pressure of each ventricular ejection, so its muscular and elastic tunica media is the dominant layer. A vein carries blood at low pressure and needs support rather than recoil, so its connective tissue adventitia is the thickest layer and its lumen is comparatively wide.

    Ref QB-559E4XSource: Tortora & Derrickson, Principles of Anatomy and Physiology — comparison of arteries and veinsReport a problem with this question

18. 18. Why do veins contain one-way valves while arteries do not?

    • A.Arterial pressure is low, so arteries rely on the heart valves while each vein segment closes off on its own.
    • B.Venous blood is deoxygenated, so valves are needed to keep it from mixing with arterial blood in the tissues.
    • C.Vein walls are muscular, so valves keep their own contractions from driving blood back into the capillary beds.
    • D.Venous pressure is low, so valves keep blood from falling backward between pushes from the skeletal muscles.✓ Answer

    Blood returning to the heart in the veins is under low pressure and often has to move against gravity, so it depends on the skeletal muscle pump squeezing the vessels. Valves hold the column of blood in place between those squeezes; arteries carry blood under high pressure driven directly by the heart and need no such devices.

    Ref QB-UMJKQ6Source: Tortora & Derrickson, Principles of Anatomy and Physiology — venous return and the skeletal muscle pumpReport a problem with this question

19. 19. How does the wall of a capillary differ in structure from the wall of an artery or a vein?

    • A.It has the same three layers, but every one of them is thinner and more elastic than in the larger vessels.
    • B.It is a single layer of endothelial cells, with no muscular layer and no outer connective tissue coat.✓ Answer
    • C.It is a double layer of smooth muscle with an endothelial lining, but it has no outer connective tissue coat.
    • D.It is a coat of connective tissue alone, since exchange takes place through the pores in that fibrous wall.

    A capillary wall is reduced to the tunica intima alone — one layer of endothelial cells on a basement membrane. That single-cell thickness is exactly what permits gases, nutrients and wastes to diffuse between blood and tissue, which thicker arterial or venous walls could not allow.

    Ref QB-C5RRA7Source: Tortora & Derrickson, Principles of Anatomy and Physiology — capillary structure and exchangeReport a problem with this question

20. 20. Whole blood is described in terms of its two main fractions. Which statement expresses their relationship correctly?

    • A.The formed elements take up somewhat more than half the volume, and plasma accounts for the rest.
    • B.Plasma and the formed elements take up equal volumes, with the buffy coat counted inside the plasma.
    • C.Plasma takes up somewhat more than half the volume, and the formed elements account for the rest.✓ Answer
    • D.Plasma takes up nearly the whole volume, and the formed elements amount to only a trace of the sample.

    Plasma, the liquid portion, occupies a little more than half the volume of whole blood, and the formed elements — red cells, white cells and platelets — make up the remainder. The relationship matters because the packed cell layer seen after centrifugation is always the smaller of the two fractions in a healthy sample.

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21. 21. Which component is present in plasma but missing from serum, and what accounts for its absence?

    • A.Albumin and the globulins, because they are pulled into the cell layer while the specimen clots.
    • B.Fibrinogen and the other clotting factors, because an anticoagulant destroyed them before spinning.
    • C.Potassium and the other electrolytes, because they remain with the red cells once a clot has formed.
    • D.Fibrinogen and the other clotting factors, because they were used up while the specimen clotted.✓ Answer

    Serum is what remains of the liquid portion after blood has been allowed to clot: the fibrinogen has been converted to fibrin and the clotting factors have been consumed in building that clot. Plasma comes from blood in which clotting was prevented, so it still contains fibrinogen and the full set of factors.

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22. 22. A provider explains a hematocrit result to a patient. What does the hematocrit express?

    • A.The share of a whole blood sample's volume that is taken up by packed red cells.✓ Answer
    • B.The amount of hemoglobin carried inside one average circulating red blood cell.
    • C.The number of red cells counted within a measured volume of the whole sample.
    • D.The share of the sample's volume taken up by white cells and platelets together.

    Hematocrit is a volume fraction, not a count: it reports what proportion of a whole blood sample the red cell mass occupies once the cells are packed down. That is why it moves with the patient's fluid status, rising when a patient is dehydrated and falling when plasma volume expands.

    Ref QB-UPGRQ6Source: Tortora & Derrickson, Principles of Anatomy and Physiology — the blood: hematocritReport a problem with this question

23. 23. Which description of the mature red blood cell shows how its structure suits its work?

    • A.It is a round cell with a large nucleus that directs hemoglobin production while it circulates.
    • B.It is a flat disc with several nuclei, which lets it divide in the bloodstream and replace worn-out cells.
    • C.It is a biconcave disc without a nucleus, giving surface area for gas exchange and room for hemoglobin.✓ Answer
    • D.It is a fragment of a larger cell that lets it pass through capillary walls into the tissue spaces.

    The mature erythrocyte loses its nucleus and organelles, which frees the whole interior for hemoglobin, and its biconcave shape maximizes surface area relative to volume so oxygen diffuses in and out quickly. The same flexible shape lets the cell bend through capillaries narrower than itself.

    Ref QB-B7BK56Source: Tortora & Derrickson, Principles of Anatomy and Physiology — erythrocyte structure and functionReport a problem with this question

24. 24. What does hemoglobin do, and which part of the molecule makes that possible?

    • A.It carries oxygen, and the calcium held in the globin chain is what binds each oxygen molecule.
    • B.It clots the blood, and the iron in each heme group is what links the fibrin strands together.
    • C.It carries glucose, and the protein portion is what holds the sugar during transport in plasma.
    • D.It carries oxygen, and the iron atom in each heme group is what binds each oxygen molecule.✓ Answer

    Hemoglobin is a protein made of globin chains, each holding a heme group with an iron atom at its center, and it is that iron that reversibly binds oxygen in the lungs and releases it in the tissues. Because binding is reversible, the same molecule can load and unload oxygen on every circuit.

    Ref QB-VPU3W7Source: Tortora & Derrickson, Principles of Anatomy and Physiology — hemoglobin and oxygen transportReport a problem with this question

25. 25. White cells fall into granulocyte and agranulocyte lines. Which statement matches each line to its work?

    • A.Granulocytes such as eosinophils build the clot, while agranulocytes such as monocytes carry antibodies in plasma.
    • B.Granulocytes such as lymphocytes provide specific immunity, while agranulocytes such as neutrophils engulf bacteria.
    • C.Granulocytes such as monocytes carry oxygen to tissue, while agranulocytes such as basophils release histamine.
    • D.Granulocytes such as neutrophils engulf bacteria, while agranulocytes such as lymphocytes provide specific immunity.✓ Answer

    Granulocytes — neutrophils, eosinophils and basophils — carry visible cytoplasmic granules and act mainly through phagocytosis and the release of chemical mediators in the immediate, non-specific response. Agranulocytes — lymphocytes and monocytes — lack those prominent granules; lymphocytes mount antibody and cell-mediated responses aimed at particular organisms, and monocytes mature into macrophages.

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26. 26. In a healthy adult, where are the red cells, white cells and platelets of the circulating blood produced?

    • A.In the red bone marrow, which releases the finished cells into the circulating blood.✓ Answer
    • B.In the spleen, which releases the finished cells and later filters the aging ones out.
    • C.In the lymph nodes, which release the finished cells into the lymph and then the blood.
    • D.In the liver, which releases the finished cells along with the plasma proteins it makes.

    Hematopoiesis in the adult takes place in red bone marrow, where a common stem cell gives rise to erythrocytes, the several leukocyte lines and the megakaryocytes that shed platelets. The liver and spleen perform that job only during fetal life, and afterwards the spleen mainly removes aging red cells rather than producing them.

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27. 27. The intrinsic and extrinsic pathways of coagulation converge. Where do they meet, and what follows?

    • A.At factor VII; the common pathway then makes plasmin, which breaks fibrin into soluble fragments.
    • B.At factor X; the common pathway then makes thrombin, which converts fibrinogen into fibrin.✓ Answer
    • C.At fibrinogen; the common pathway then makes tissue factor, which draws platelets to the injury.
    • D.At factor XII; the common pathway then makes antithrombin, which stabilizes the plug already formed.

    Both pathways end by activating factor X, which is the start of the common pathway. Activated factor X converts prothrombin to thrombin, and thrombin then converts soluble fibrinogen into the insoluble fibrin strands that turn the loose platelet plug into a stable clot.

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28. 28. Once the injured vessel wall has healed, what does fibrinolysis accomplish?

    • A.Thrombin breaks down the fibrin mesh, so the trapped platelets return to the circulation.
    • B.Plasmin lays fresh fibrin over the clot, so the healed wall is reinforced against injury.
    • C.Plasmin breaks down the fibrin mesh, so the clot dissolves and the vessel lumen reopens.✓ Answer
    • D.Calcium draws the fibrin strands tight, so the clot shrinks away and is then reabsorbed.

    Fibrinolysis is the fourth and final phase of hemostasis: plasminogen in the clot is converted to the enzyme plasmin, which digests the fibrin mesh once repair of the vessel wall is under way. Without this step the clot would remain in place and obstruct flow through the vessel.

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29. 29. Two anticoagulants work by different mechanisms. Which statement distinguishes a calcium-binding anticoagulant from heparin?

    • A.The calcium binder boosts a natural inhibitor of thrombin, while heparin removes an ion the cascade requires.
    • B.The calcium binder removes an ion the cascade requires, while heparin boosts a natural inhibitor of thrombin.✓ Answer
    • C.The calcium binder dissolves fibrin once it forms, while heparin stops platelets from sticking to the vessel.
    • D.The calcium binder adds extra calcium to the sample, while heparin supplies the tissue factor that starts it.

    Calcium is factor IV and is needed at several steps of the cascade, so a chelating agent prevents clotting simply by binding it out of reach. Heparin does not touch calcium at all: it potentiates antithrombin, the body's own inhibitor of thrombin and factor Xa, which is why the two classes have different effects on the specimen.

    Ref QB-67JW9YSource: CLSI GP41, Collection of Diagnostic Venous Blood Specimens — anticoagulant additives and their mechanismsReport a problem with this question

30. 30. A phlebotomist records a site on the forearm nearer the wrist than the elbow and on the thumb side. Which pair of terms describes it?

    • A.Proximal and medial, since it is nearer the trunk and toward the little-finger side.
    • B.Superior and ventral, since it is above the elbow and on the front of the forearm.
    • C.Distal and medial, since it is farther from the trunk and toward the little-finger side.
    • D.Distal and lateral, since it is farther from the trunk and toward the thumb side.✓ Answer

    Proximal and distal are measured from the point of attachment to the trunk, so a forearm site closer to the wrist is distal to the elbow. Medial and lateral are measured from the body's midline in anatomical position, where the palms face forward, so the thumb side of the arm is the lateral side.

    Ref QB-U2WA3USource: Tortora & Derrickson, Principles of Anatomy and Physiology — anatomical position and directional termsReport a problem with this question

31. 31. The wall of the heart is described from the inside outward. Which sequence of layers is correct?

    • A.Myocardium lining the chambers and valves, then the muscular endocardium, then the outer epicardium.
    • B.Pericardium lining the chambers and valves, then the muscular epicardium, then the outer myocardium.
    • C.Endocardium lining the chambers and valves, then the muscular myocardium, then the outer epicardium.✓ Answer
    • D.Epicardium lining the chambers and valves, then the muscular myocardium, then the outer endocardium.

    The endocardium is a smooth endothelial lining continuous with the lining of the great vessels, so blood inside the chambers and over the valves never touches a rough surface. The myocardium is the contractile muscle that does the pumping, and the epicardium is the outer covering that also forms the inner layer of the pericardial sac.

    Ref QB-CJ3GNUSource: Tortora & Derrickson, Principles of Anatomy and Physiology — layers of the heart wallReport a problem with this question

32. 32. How does the lymphatic system relate to the circulation of the blood?

    • A.It carries oxygenated blood beside the arteries and empties into the capillary beds of the tissue.
    • B.It collects fluid that has leaked into the tissues and returns it to the blood through large veins.✓ Answer
    • C.It filters the plasma proteins out of the blood and passes them to the kidneys to be excreted.
    • D.It stores the spare red cells the body is not using and releases them into the arteries on demand.

    Capillary pressure forces more fluid out of the blood than is reabsorbed, and the lymphatic vessels pick up that excess as lymph, filter it through lymph nodes, and empty it back into large veins near the base of the neck. The lymphatic system therefore maintains blood volume and tissue fluid balance rather than pumping blood itself.

    Ref QB-V29N8VSource: Tortora & Derrickson, Principles of Anatomy and Physiology — the lymphatic system and return of interstitial fluidReport a problem with this question

Concept-focused practice questions based on CLSI GP41 (venous blood collection), the CLSI order of draw, and the OSHA Bloodborne Pathogens Standard (29 CFR 1910.1030). Not affiliated with the NHA, ASCP, or CLSI, and not medical advice. Facility protocols and current CLSI standards take precedence — always follow your employer's procedures. About the CPT exam →