Blood Vessels and the Lymphatic System Practice Questions

54 multiple-choice questions on Blood vessels and the lymphatic system for paramedic and EMT students, from Chapter 8 (Anatomy and Physiology). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

54 practice questions

1. Arteries carry blood:

   1. A. Toward the heart
   2. B. Away from the heart
   3. C. From capillaries to venules
   4. D. Under low pressure to the heart
   Show answer

   Answer: B. Away from the heart

   Arteries carry blood away from the heart and veins carry it back. Most, but not all, arteries carry oxygenated blood. Blood flows from capillaries into venules, and veins return it to the heart under low pressure; arteries carry it outward under high pressure.

2. The smooth muscle layer of a blood vessel wall is the:

   1. A. Tunica media
   2. B. Tunica adventitia
   3. C. Tunica intima
   4. D. Endothelium
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   Answer: A. Tunica media

   The layers are the intima (inner lining), the media (smooth muscle), and the adventitia (outer layer).

3. Which vessels are the major site of systemic vascular resistance?

   1. A. Arterioles
   2. B. Capillaries
   3. C. Veins
   4. D. Venules
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   Answer: A. Arterioles

   Arterioles constrict and dilate to control resistance and direct blood flow.

4. Exchange of oxygen and nutrients with the tissues occurs in the:

   1. A. Arteries
   2. B. Capillaries
   3. C. Arterioles
   4. D. Veins
   Show answer

   Answer: B. Capillaries

   Capillary walls are one cell thick, so gases and nutrients can pass through.

5. Veins contain valves that:

   1. A. Increase venous pressure
   2. B. Pump blood toward the heart
   3. C. Prevent blood backflow
   4. D. Regulate venous diameter
   Show answer

   Answer: C. Prevent blood backflow

   Veins are low-pressure vessels, so valves and muscle contraction keep blood moving toward the heart. Valves do not pump; the surrounding skeletal muscle squeezes the veins, and the valves keep the flow one-way. Vein diameter is set by smooth muscle in the vessel wall.

6. Deoxygenated blood from the body returns to the right atrium through the:

   1. A. Coronary arteries
   2. B. Venae cavae
   3. C. Pulmonary artery
   4. D. Pulmonary veins
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   Answer: B. Venae cavae

   The superior vena cava drains the upper body and the inferior vena cava drains the lower body.

7. Blood pressure is equal to:

   1. A. Cardiac output x SVR
   2. B. Preload + afterload
   3. C. Stroke volume / SVR
   4. D. Heart rate x stroke volume
   Show answer

   Answer: A. Cardiac output x SVR

   SVR is systemic vascular resistance. The body keeps BP up by raising heart rate or constricting vessels, which is compensated shock.

8. The lymphatic system:

   1. A. Absorbs dietary glucose from the gut
   2. B. Pumps blood back to the heart
   3. C. Returns fluid, fights infection
   4. D. Produces most plasma proteins
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   Answer: C. Returns fluid, fights infection

   It returns excess interstitial fluid to the bloodstream. Lymph drains into the venous system through the thoracic duct. Lymph nodes filter pathogens. Intestinal lymphatics absorb dietary fat, while glucose enters the portal blood. Most plasma proteins, such as albumin, are made by the liver.

9. After a splenectomy, a patient has a lifelong higher risk of:

   1. A. Overwhelming infection with encapsulated bacteria
   2. B. Severe anemia from loss of red cell production
   3. C. Uncontrolled bleeding from loss of platelets
   4. D. Chronic jaundice from a faster breakdown of old red cells
   Show answer

   Answer: A. Overwhelming infection with encapsulated bacteria

   The spleen filters blood, removes old red cells, and clears encapsulated bacteria such as pneumococcus. Without it, patients can develop rapidly fatal sepsis, so a fever in an asplenic patient is an emergency. Red cells are made in the marrow. Platelet counts often rise after splenectomy. Losing the spleen slows rather than speeds the removal of old red cells, so it does not cause jaundice.

10. The tunica intima is:

    1. A. The outer connective tissue layer
    2. B. The inner endothelial lining
    3. C. The smooth muscle layer
    4. D. The elastic middle layer
    Show answer

    Answer: B. The inner endothelial lining

    Damage to it initiates atherosclerosis and clotting.

11. The tunica adventitia is:

    1. A. The outer fibrous layer
    2. B. The smooth muscle layer
    3. C. The inner endothelial lining
    4. D. The layer that forms valves
    Show answer

    Answer: A. The outer fibrous layer

    It is tough connective tissue. It anchors the vessel to surrounding tissue.

12. Arteries have thicker walls than veins because they:

    1. A. Are longer than veins
    2. B. Face higher pressure
    3. C. Carry more total blood
    4. D. Contain more valves
    Show answer

    Answer: B. Face higher pressure

    Arteries carry blood under high pressure from the ventricles, so they need thick, elastic, muscular walls. Veins are thin-walled capacitance vessels that hold more of the total blood volume, they have the valves that arteries lack, and arteries are not longer than the veins that run alongside them.

13. The largest artery in the body is the:

    1. A. Femoral artery
    2. B. Pulmonary artery
    3. C. Carotid artery
    4. D. Aorta
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    Answer: D. Aorta

    It arises from the left ventricle.

14. Arterioles are described as resistance vessels because they:

    1. A. Return blood to the heart
    2. B. Exchange gases with tissues
    3. C. Store most of the body's blood volume
    4. D. Change diameter to control flow
    Show answer

    Answer: D. Change diameter to control flow

    Arterioles have smooth muscle walls richly innervated by the sympathetic system, and changes in their diameter control blood flow to tissues and systemic vascular resistance (and so pressure). Veins return blood to the heart and store most of the blood volume, and gas exchange with tissues happens in the capillaries.

15. Capillary walls consist of:

    1. A. A single endothelial cell layer
    2. B. Smooth muscle and elastic fibers
    3. C. Thick connective tissue
    4. D. Three distinct tissue layers
    Show answer

    Answer: A. A single endothelial cell layer

    This thinness permits diffusion.

16. Precapillary sphincters function to:

    1. A. Regulate flow into capillary beds
    2. B. Prevent backflow into arterioles
    3. C. Pump blood through the capillaries
    4. D. Exchange gases with tissues
    Show answer

    Answer: A. Regulate flow into capillary beds

    They shunt blood to active tissues.

17. Venules function to:

    1. A. Regulate arterial pressure
    2. B. Collect blood from capillaries
    3. C. Deliver oxygenated blood to tissues
    4. D. Exchange nutrients with cells
    Show answer

    Answer: B. Collect blood from capillaries

    They begin the venous return.

18. Veins are called capacitance vessels because they:

    1. A. Have thick muscular walls
    2. B. Carry blood at high pressure
    3. C. Lack one-way valves
    4. D. Hold most blood volume
    Show answer

    Answer: D. Hold most blood volume

    Roughly two-thirds of the blood volume sits in the thin-walled, distensible venous system, which is why veins are called capacitance vessels. Veins have thin rather than thick muscular walls, carry blood at low pressure, and limb veins do contain one-way valves.

19. Venous return is assisted by:

    1. A. Valves, muscle pump, breathing
    2. B. A faster heart rate alone
    3. C. Arterial pressure pushing through
    4. D. Gravity in all body positions
    Show answer

    Answer: A. Valves, muscle pump, breathing

    Prolonged standing reduces it.

20. Blood pressure is highest in the:

    1. A. Venae cavae
    2. B. Aorta
    3. C. Capillary beds
    4. D. Large veins
    Show answer

    Answer: B. Aorta

    The aorta and large arteries carry the highest pressure. It falls progressively through the circulation.

21. Mean arterial pressure is important because it:

    1. A. Equals the systolic pressure
    2. B. Reflects only peak systolic pressure
    3. C. Measures the pulse pressure directly
    4. D. Reflects average perfusion pressure
    Show answer

    Answer: D. Reflects average perfusion pressure

    It is roughly diastolic plus one-third of pulse pressure.

22. Pulse pressure narrows in early shock because:

    1. A. Heart rate slows
    2. B. Diastolic pressure falls
    3. C. Diastolic rises as SV falls
    4. D. Systolic pressure rises sharply
    Show answer

    Answer: C. Diastolic rises as SV falls

    Vasoconstriction raises diastolic pressure while stroke volume (SV) falls. It is an early, often overlooked sign.

23. A septic shock patient has warm, flushed skin and a low diastolic pressure. Which change is most responsible?

    1. A. Venous constriction raising preload and venous return
    2. B. Widespread arteriolar dilation lowering vascular resistance
    3. C. Closure of capillaries in the skin from vasoconstriction
    4. D. Thickening of the arterial walls from chronic disease
    Show answer

    Answer: B. Widespread arteriolar dilation lowering vascular resistance

    Arterioles are the main resistance vessels. In distributive (septic) shock, inflammatory mediators dilate them, so SVR and diastolic pressure fall and the skin is often warm early. Venous constriction and skin capillary closure would cause cool, pale skin. Arterial thickening is a chronic change.

24. Systemic vascular resistance falls in which type of shock?

    1. A. Hypovolemic
    2. B. Cardiogenic
    3. C. Distributive
    4. D. Obstructive
    Show answer

    Answer: C. Distributive

    Distributive shock includes septic, neurogenic, and anaphylactic shock. The skin may be warm early in these states.

25. The vasomotor center that controls vessel tone is located in the:

    1. A. Cerebellum
    2. B. Spinal cord
    3. C. Hypothalamus
    4. D. Medulla
    Show answer

    Answer: D. Medulla

    It responds to baroreceptor input.

26. Baroreceptors are located in the:

    1. A. Renal cortex and medulla
    2. B. Hypothalamus and pituitary gland
    3. C. Carotid sinus and aortic arch
    4. D. Pulmonary veins and alveoli
    Show answer

    Answer: C. Carotid sinus and aortic arch

    They sense pressure changes and adjust output and tone.

27. Chemoreceptors that influence circulation respond to:

    1. A. Body temperature
    2. B. Arterial blood pressure
    3. C. O2, CO2, and pH
    4. D. Blood volume only
    Show answer

    Answer: C. O2, CO2, and pH

    They affect both breathing and vascular tone.

28. The carotid arteries supply the:

    1. A. Heart muscle
    2. B. Arms and shoulders
    3. C. Head and brain
    4. D. Lungs and bronchi
    Show answer

    Answer: C. Head and brain

    The vertebral arteries also supply the brain. The heart muscle is supplied by the coronary arteries, and the bronchi by bronchial arteries arising from the aorta.

29. The brachial artery is used for blood pressure measurement because it:

    1. A. Is superficial in the upper arm
    2. B. Has the strongest pulse
    3. C. Reflects central aortic pressure
    4. D. Is the largest peripheral artery
    Show answer

    Answer: A. Is superficial in the upper arm

    The brachial artery runs superficially along the medial upper arm, so a cuff can compress it against the humerus and a stethoscope can hear it at the antecubital fossa. Its pulse is not the strongest, it is not the largest peripheral artery (the femoral is larger), and a peripheral cuff reading differs from central aortic pressure. It is also the infant pulse check site.

30. The radial pulse is located:

    1. A. Along the side of the neck
    2. B. In the antecubital fossa
    3. C. On the thumb side of the wrist
    4. D. On the little-finger side of the wrist
    Show answer

    Answer: C. On the thumb side of the wrist

    It is the most commonly used pulse point.

31. The femoral pulse is located in the:

    1. A. Antecubital fossa
    2. B. Popliteal fossa
    3. C. Groin
    4. D. Medial ankle
    Show answer

    Answer: C. Groin

    It is checked when peripheral pulses are absent.

32. The dorsalis pedis pulse is found:

    1. A. Behind the medial malleolus
    2. B. Behind the knee
    3. C. On the top of the foot
    4. D. In the groin
    Show answer

    Answer: C. On the top of the foot

    The posterior tibial pulse is behind the medial malleolus.

33. The hepatic portal system carries blood from the:

    1. A. GI organs to the liver
    2. B. Kidneys to the vena cava
    3. C. Liver to the small intestine
    4. D. Lungs to the left atrium
    Show answer

    Answer: A. GI organs to the liver

    Blood passes through the liver before returning to general circulation. The liver processes absorbed nutrients first.

34. The pulmonary circulation carries blood:

    1. A. From the left ventricle to the lungs
    2. B. Aorta to the bronchial tree
    3. C. Right heart to lungs to left heart
    4. D. From the body to the right atrium
    Show answer

    Answer: C. Right heart to lungs to left heart

    It runs from the right ventricle to the lungs and back to the left atrium. It is a low-pressure circuit.

35. Systemic circulation begins at the:

    1. A. Right ventricle
    2. B. Left ventricle
    3. C. Left atrium
    4. D. Pulmonary artery
    Show answer

    Answer: B. Left ventricle

    It ends at the right atrium.

36. An aneurysm is:

    1. A. A clot inside the vessel
    2. B. A fully blocked vessel
    3. C. A ballooned weak vessel wall
    4. D. A sudden spasm of the vessel wall
    Show answer

    Answer: C. A ballooned weak vessel wall

    Rupture is catastrophic.

37. Atherosclerosis reduces perfusion by:

    1. A. Narrowing the vessel lumen
    2. B. Dilating and weakening vessels
    3. C. Thinning the vessel lining
    4. D. Increasing wall elasticity
    Show answer

    Answer: A. Narrowing the vessel lumen

    It also stiffens the vessel wall. Plaque also serves as a site for clot formation.

38. Blood flow through a vessel is most affected by changes in:

    1. A. Vessel radius
    2. B. Blood temperature
    3. C. Vessel length
    4. D. Blood oxygen content
    Show answer

    Answer: A. Vessel radius

    Flow changes dramatically with small changes in diameter. This is why catheter size matters so much for fluid rates.

39. Capillary exchange occurs by:

    1. A. Phagocytosis by endothelium
    2. B. Diffusion, filtration, osmosis
    3. C. Pumping by capillary smooth muscle
    4. D. Active transport alone
    Show answer

    Answer: B. Diffusion, filtration, osmosis

    Hydrostatic and oncotic pressures govern fluid movement.

40. The lymphatic system returns interstitial fluid to circulation through the:

    1. A. Ducts into the subclavian veins
    2. B. Thoracic duct into the aorta
    3. C. Cisterna into the renal veins
    4. D. Portal vein into the liver sinusoids
    Show answer

    Answer: A. Ducts into the subclavian veins

    The thoracic duct and right lymphatic duct drain into the subclavian veins. About 3 L is returned daily.

41. Lymph nodes function to:

    1. A. Produce red and white blood cells
    2. B. Store fat absorbed from the gut
    3. C. Secrete hormones into lymph
    4. D. Filter lymph and trap pathogens
    Show answer

    Answer: D. Filter lymph and trap pathogens

    They house immune cells that fight infection. They swell during infection.

42. Lymph flow is propelled primarily by:

    1. A. A dedicated lymphatic heart
    2. B. Muscle action and valves
    3. C. Arterial pressure transmitted
    4. D. Gravity in the upright position
    Show answer

    Answer: B. Muscle action and valves

    Skeletal muscle contraction, respiratory movement, and one-way valves move lymph. There is no lymphatic heart.

43. Lymphedema results from:

    1. A. Excess lymph production
    2. B. Heart failure alone
    3. C. Blocked or removed lymphatics
    4. D. Low plasma protein from malnutrition
    Show answer

    Answer: C. Blocked or removed lymphatics

    Obstruction or removal of lymph vessels or nodes causes tissue swelling. It commonly follows lymph node surgery.

44. The lymphatic system also absorbs:

    1. A. Dietary glucose
    2. B. Water and sodium
    3. C. Dietary fats
    4. D. Amino acids
    Show answer

    Answer: C. Dietary fats

    Lacteals in the villi perform this function.

45. The tonsils and adenoids are:

    1. A. Endocrine glands of the throat
    2. B. Lymphatic tissue in the pharynx
    3. C. Salivary glands of the throat
    4. D. Cartilage supporting the pharynx
    Show answer

    Answer: B. Lymphatic tissue in the pharynx

    They guard the entrance to the airway and digestive tract. They trap inhaled and ingested organisms.

46. The spleen is part of which systems?

    1. A. Endocrine and urinary
    2. B. Digestive and endocrine
    3. C. Digestive and urinary
    4. D. Lymphatic and circulatory
    Show answer

    Answer: D. Lymphatic and circulatory

    It filters blood and supports immunity.

47. Capillary refill assesses:

    1. A. Blood pressure directly
    2. B. Oxygen saturation
    3. C. Cardiac rhythm
    4. D. Peripheral perfusion
    Show answer

    Answer: D. Peripheral perfusion

    It is more reliable in children than adults.

48. Blood is shunted away from the skin and gut during shock in order to:

    1. A. Conserve core body heat
    2. B. Preserve brain and heart flow
    3. C. Keep the kidneys fully perfused
    4. D. Lower the workload of the heart
    Show answer

    Answer: B. Preserve brain and heart flow

    The lungs are also prioritized. This is why the skin becomes cool and pale. Renal flow is also reduced during shock, which is why urine output falls, and vasoconstriction raises rather than lowers the heart's workload.

49. Orthostatic changes occur when:

    1. A. Blood pressure rises on standing
    2. B. Heart rate falls on standing
    3. C. Blood pools in the legs on standing
    4. D. Circulation improves on standing
    Show answer

    Answer: C. Blood pools in the legs on standing

    Reduced venous return causes a rise in heart rate or a fall in blood pressure. They suggest volume depletion.

50. Which vessel carries oxygen-poor blood away from the heart?

    1. A. Pulmonary artery
    2. B. Carotid artery
    3. C. Aorta
    4. D. Femoral artery
    Show answer

    Answer: A. Pulmonary artery

    It is the exception to the usual rule.

51. Blood in which vessel has the highest oxygen content?

    1. A. Pulmonary artery
    2. B. Superior vena cava
    3. C. Pulmonary vein
    4. D. Coronary sinus
    Show answer

    Answer: C. Pulmonary vein

    Pulmonary veins carry freshly oxygenated blood from the lungs to the left atrium. The pulmonary artery carries deoxygenated blood to the lungs, even though it is an artery. The venae cavae return deoxygenated blood from the body, and the coronary sinus drains heart muscle, which extracts a large share of the oxygen.

52. Varicose veins result from:

    1. A. Incompetent venous valves
    2. B. Arterial narrowing in the legs
    3. C. High arterial pressure
    4. D. Excess clotting in the veins
    Show answer

    Answer: A. Incompetent venous valves

    Prolonged standing contributes.

53. A deep vein thrombosis commonly forms in the:

    1. A. Deep veins of the legs
    2. B. Pulmonary arteries
    3. C. Superficial veins of the arms
    4. D. Superficial veins of the legs
    Show answer

    Answer: A. Deep veins of the legs

    The pelvic veins are another common site. Immobility is a major risk factor. Clots reach the pulmonary arteries as emboli after forming in the deep veins. Clots in superficial leg veins cause superficial thrombophlebitis, which is not a DVT.

54. Six hours after a tibia fracture, the patient has pain out of proportion to the injury and severe pain when you stretch his toes, but a palpable pedal pulse. What is most likely happening?

    1. A. Rising compartment pressure is compressing capillaries
    2. B. An artery in the leg is fully occluded by a clot
    3. C. The venous valves in the leg are failing to close
    4. D. Fat from the marrow is embolizing to the lungs
    Show answer

    Answer: A. Rising compartment pressure is compressing capillaries

    In compartment syndrome, pressure in a closed fascial space rises above capillary perfusion pressure, so muscle and nerves become ischemic. The early signs are pain out of proportion and pain on passive stretch. Pulses are usually present until very late, so a palpable pulse does not rule it out. Fat embolism causes respiratory and neurologic signs.