Human physiology worksheet with answers

Which hormone, released by the pineal gland in darkness, helps regulate the sleep–wake cycle?

1. AAdrenaline
2. BOxytocin
3. CCortisol
4. DMelatonin

Which blood vessels have valves that prevent blood flowing backwards?

1. AArterioles
2. BVeins
3. CArteries
4. DCapillaries

Which organ makes most plasma proteins, such as albumin?

1. AKidney
2. BBone marrow
3. CLiver
4. DSpleen

Why do myelinated axons conduct action potentials faster than unmyelinated ones?

1. AMyelin makes the axon thinner
2. BThe impulse jumps between nodes of Ranvier
3. CMyelin contains more sodium channels
4. DMyelin releases neurotransmitter along the axon

What is the main effect of aldosterone on the kidney?

1. ASodium reabsorption and potassium secretion in the distal nephron
2. BWater reabsorption by inserting aquaporins only
3. CIncreased filtration in the glomerulus
4. DGlucose reabsorption in the proximal tubule

During which phase of the cardiac cycle are all four heart valves closed while ventricular pressure rises?

1. AAtrial systole
2. BRapid ejection
3. CIsovolumetric contraction
4. DRapid filling

Which substance's clearance is used as the gold standard to measure glomerular filtration rate?

1. ACreatinine
2. BUrea
3. CGlucose
4. DInulin

In the renin–angiotensin–aldosterone system, where is angiotensin I mainly converted to angiotensin II?

1. AIn the lungs
2. BIn the kidneys' juxtaglomerular cells
3. CIn the liver
4. DIn the adrenal cortex