Quiz2Know

Human body

Vital Organ Functions

Explore how the heart, lungs, kidneys, liver, and brain sustain life through coordinated physiological processes.

This is a free, 10-question multiple-choice quiz. Answer each question to see whether you got it right, with an explanation for every answer. There is no sign-up and no time limit — take it as many times as you like, and scroll down for the full answer key once you are done.

Question 1 of 10

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What functional unit within the kidney filters blood to produce urine?

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Answer key & explanations

Every question in this quiz, with the correct answer marked and an explanation of why it is right. Use it to revise before or after taking the quiz above.

  1. 1.What functional unit within the kidney filters blood to produce urine?

    • AAlveolus
    • BNephron✓ Correct
    • CLobule
    • DSarcomere

    Correct answer: Nephron

    Each kidney contains roughly one million nephrons, which regulate water balance, filter waste products, and maintain electrolyte concentrations.

  2. 2.Which vital organ produces bile to assist with lipid digestion?

    • APancreas
    • BGallbladder
    • CLiver✓ Correct
    • DStomach

    Correct answer: Liver

    The liver synthesizes bile, which emulsifies fats in the small intestine, though bile is concentrated and stored in the gallbladder.

  3. 3.Where does gas exchange between inspired air and capillary blood occur in the lungs?

    • ATrachea
    • BBronchi
    • CBronchioles
    • DAlveoli✓ Correct

    Correct answer: Alveoli

    Alveoli are microscopic air sacs surrounded by capillaries where oxygen diffuses into the blood and carbon dioxide diffuses out.

  4. 4.Which heart chamber pumps oxygen-rich blood into the systemic circulation via the aorta?

    • ALeft ventricle✓ Correct
    • BRight ventricle
    • CLeft atrium
    • DRight atrium

    Correct answer: Left ventricle

    The left ventricle possesses the thickest muscular wall because it must generate enough pressure to circulate oxygenated blood throughout the body.

  5. 5.Which region of the human brain regulates autonomic vital functions like respiration and heart rate?

    • ACerebellum
    • BCerebrum
    • CMedulla oblongata✓ Correct
    • DCorpus callosum

    Correct answer: Medulla oblongata

    Located in the brainstem, the medulla oblongata contains cardiac, vasomotor, and respiratory centers that sustain baseline survival.

  6. 6.What dual function characterizes the pancreas?

    • AThermal regulation and electrolyte storage
    • BEndocrine hormone secretion and exocrine enzyme secretion✓ Correct
    • CBile production and blood filtration
    • DRed blood cell production and fluid excretion

    Correct answer: Endocrine hormone secretion and exocrine enzyme secretion

    The pancreas secretes digestive enzymes into the duodenum (exocrine function) and releases insulin and glucagon directly into the bloodstream (endocrine function).

  7. 7.What primary muscular organ contracts to drive inhalation during normal breathing?

    • AIntercostal muscles
    • BDiaphragm✓ Correct
    • CScalene muscle
    • DPectoralis minor

    Correct answer: Diaphragm

    The diaphragm moves downward when contracting, increasing chest cavity volume and reducing internal air pressure so air rushes into the lungs.

  8. 8.Which organ is responsible for filtering old red blood cells and holding a reserve of platelets?

    • ASpleen✓ Correct
    • BThymus
    • CThyroid
    • DAdrenal gland

    Correct answer: Spleen

    The spleen acts as a lymphoid blood filter, recycling iron from degraded erythrocytes and storing immune cells and platelets.

  9. 9.Which heart valve prevents backflow of blood from the left ventricle into the left atrium?

    • ATricuspid valve
    • BPulmonary valve
    • CAortic valve
    • DMitral valve✓ Correct

    Correct answer: Mitral valve

    The mitral (bicuspid) valve closes during ventricular systole to ensure blood flows forward into the aorta rather than backward into the left atrium.

  10. 10.Which hormone produced by the kidneys stimulates the bone marrow to produce red blood cells?

    • AAldosterone
    • BErythropoietin✓ Correct
    • CRenin
    • DCalcitriol

    Correct answer: Erythropoietin

    When renal tissues detect low oxygen levels in the blood, the kidneys secrete erythropoietin (EPO) to accelerate red blood cell production.

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