Biology

Human Excretion and Kidney Physiology

1,215 Questions

Human excretion and kidney physiology questions test your understanding of the excretory system, including the role of renal tubules and glomerular filtration. You will also find topics on urine formation, body water absorption, and excretory products. This section is vital for medical and general science exam preparation.

Glomerular filtrationRenal tubule absorptionExcretory productsRole of sodium ionsHuman excretory system

Human Excretion and Kidney Physiology Questions

Multiple choice

Kidney tubules are lined by

  1. squamous epithelium

  2. Cuboidal epithelium

  3. Columnar epithelium

  4. Simple squamous epithelium

  5. Ciliated epithelium
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Cuboidal epithelium is composed of cube shaped cells that provide mechanical support to the various organs such as kidney tubules, ducts of salivary glands, etc. The nuclei of these cells are usually located at the centre.

Multiple choice

Which among the following statements does not characterises the renal development in humans?

  1. There are three kidney structures which are formed at different times during development.

  2. The final adult kidney forms from the pronephros.

  3. The ureteric bud forms the draining system.

  4. Capillaries invaginate the tubules to form glomeruli.

  5. The final adult kidney rises up the body during development.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

It is the metanephros which goes on to become the adult kidney.

Multiple choice

Which of the following statements concerning renal blood flow are true?

  1. The efferent arterioles deliver blood to the glomerulus.

  2. Vasa recta receive their blood supply from the efferent arterioles.

  3. Vasoconstriction of the afferent arterioles increases glomerular filtration.

  4. Vasoconstriction of the efferent arterioles decreases glomerular filtration.

  5. Vasoconstriction reduces the resistance to flow in a blood vessel.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

For nephrons which are in the outer cortex and do not have vasa recta or long loops of Henle, the efferent arterioles supply the peritubular capillaries. Flow occurs when the pressure at one end of a tube is made greater than that at the other end.

Multiple choice

Which of the following statements are true concerning developmental anomalies of the renal system?

  1. Failure of the ureteric bud to develop causes hypospadias.

  2. Horseshoe kidneys occur when the pronephros fails to regress.

  3. Adult kidneys can only have one renal artery each.

  4. Early splitting of the ureteric bud can result in one kidney having two ureters.

  5. The ureteric bud forms the glans penis.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The ureteric bud forms the collecting system and if it splits before it enters the kidney, the result, which is not uncommon, is that the kidney will have two ureters.

Multiple choice

Paracetamol causes acute and chronic renal tubules failure in humans. From the following statements, select the false statement concerning the renal tubules in kidneys.

  1. The major changes in tubular fluid composition are made in the proximal tubules.

  2. The proximal tubules substantially increases the concentration of urine.

  3. Part of the loop of henle is permeable to water.

  4. The vasa recta are blood vessels.

  5. The walls of the tubules are made up of epithelial cells.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The osmolality of filtered fluid entering the proximal tubule from the glomerulus is essentially that of plasma from which it is produced. Reabsorption in the proximal tubule is iso-osmotic, which means that the osmolality of the tubular fluid does not change because solutes and water are removed together in the same ratio at which they are present in the tubules. For this reason, the concentration of urine (i.e. its osmolality) in the proximal tubule is not altered.

Multiple choice

After medical examination doctor confirmed that Mr. Bansal is suffering from chronic renal disease. In patients with chronic renal disease, which of the following statements does not take place?

  1. Erythropoietin levels are usually lowered.

  2. Anemia is a common problem.

  3. Erythropoietin can be given to treat the anemia.

  4. Erythropoietin is usually given as oral tablets.

  5. Iron deficiency can occur.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

As erythropoietin is a protein, it cannot be given orally as it would be digested in the gut. It is usually given subcutaneously or less commonly, intravenously.

Multiple choice

Which of the following statements concerning the water balance function of kidney is true?

  1. The key hormone regulating water reabsorption is secreted from the posterior pituitary gland.

  2. Aquaporin is the main hormone regulating water reabsorption.

  3. The vasa recta is the same structure as the loop of Henle.

  4. There are osmoreceptors in the pituitary gland.

  5. There is no limit to how much the body can concentrate urine.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The main hormone regulating water reabsorption is anti-diuretic hormone (ADH or vasopressin). There are indeed osmoreceptors in the hypothalamus, which detect an increase in plasma osmolality. In response to input from these receptors and other stimuli, cells in the posterior pituitary gland release ADH.

Multiple choice

The kidneys excrete about 15% of the filtered potassium load of 10 mEq/kg per day. Which among the following statements concerning potassium is true?

  1. Potassium is the major extracellular ion.

  2. Within cells, the concentration of potassium is lower than that of sodium.

  3. Potassium excretion is regulated by altering potassium secretion.

  4. The 3Na+/2K+ ATPase pumps potassium out of the cells.

  5. Selected cells have potassium channels.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Potassium is freely filtered and then most of the filtered potassium is reabsorbed. Potassium excretion is then controlled by the secretion of potassium by the principal cells in the collecting ducts.

Multiple choice

Which of the following statements concerning sodium ions in the nephron is correct?

  1. The concentration of sodium ions is generally higher inside the cells than outside the cells.

  2. Sodium is not filtered in the glomerulus.

  3. Most sodium is reabsorbed in the distal tubule.

  4. There is no active transport of sodium.

  5. The diuretic drug furosemide blocks the NaK2Cl channel in the loop of henle.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

If drugs are given which inhibit sodium reabsorption, then there is more sodium in the tubules and this means that more water stays in the tubules with it because of the osmotic effect of the sodium. Such drugs are known as diuretics because they increase the amount of water excretion. Diuretics such as furosemide (frusemide) inhibit sodium reabsorption in the loop of henle, drugs such as the thiazides oppose sodium reabsorption in the distal tubule and drugs such as amiloride oppose sodium reabsorption in the collecting ducts.

Multiple choice

Which of the following statements is/are incorrect regarding the excretory function of the body?

  1. Carbon dioxide can pass across cell membranes.

  2. Proteins can act as buffers.

  3. The lungs excrete carbon dioxide.

  4. The kidney absorbs all the bicarbonate ions.

  5. There are no buffers in urine.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

There are buffers in the urine, including sodium phosphate. In addition, hydrogen ions can be excreted in the form of ammonium ions (NH4+) in the urine. The buffers are necessary because urine cannot be made very acidic because below a certain pH, the hydrogen ion gradient across the tubule wall cannot be maintained.

Multiple choice

Which of the following statements concerning the excretion of acid by the nephrons are true?

  1. Acid can be excreted as NH3 ions.

  2. Acid excretion mainly occurs in the early nephron.

  3. In the distal nephron, secreted hydrogen ions mainly contribute to bicarbonate reabsorption.

  4. Sodium phosphate is a urinary buffer.

  5. Urine is usually alkaline.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sodium phosphate can exist as Na2HPO4 or NaH2PO4 and the two form a buffer pair. The form NaHPO4 is a weak base which can accept a hydrogen ion to become NaH2PO4. Similarly NaH2PO4 is a weak acid which can donate a hydrogen ion to become Na2HPO4.