Biology

Human Excretion and Kidney Physiology

1,152 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

Where does the filtration of blood occur in the kidneys?

  1. Vasa recta

  2. Collecting duct

  3. Bowman’s capsule

  4. Tubular part of nephron
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Filtration of blood occurs in the kidneys in a cup shaped part of nephron, which receives the glomerular filtrate is called Bowman’s capsule.  

Multiple choice

The net pressure gradient that causes the fluid to filter out of the glomeruli into the capsule is

  1. 20 mm Hg.

  2. 50 mm Hg.

  3. 75 mm Hg.

  4. 30 mm Hg.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

 The net pressure gradient that causes the fluid to filter out of the glomeruli into the capsule is 20 mm Hg. A glomerular hydrostatic pressure of 70 mm Hg develops in glomerulus. It is opposed by blood osmotic pressure (30 mm Hg) and capsular hydrostatic pressure (20 mm Hg ) inside the Bowman's capsule.

Multiple choice

A person is undergoing prolonged fasting. His urine will be found to contain abnormal quantities of

  1. fats

  2. amino acids.

  3. ketones

  4. glucose.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

  A person is undergoing prolonged fasting. His urine will be found to contain abnormal quantities of ketones. Ketones are metabolic end-products of fatty acid metabolism. In healthy individuals, ketones are formed in the liver and are completely metabolized so that only negligible amounts appear in the urine. However, when carbohydrates are unavailable or unable to be used as an energy source, fat becomes the predominant body fuel instead of carbohydrates and excessive amounts of ketones are formed as a metabolic byproduct. Higher levels of ketones in the urine indicate that the body is using fat as the major source of energy.

Multiple choice

The basis for the current treatment of urea cycle disorders is

  1. replacement of missing enzyme activity by enzyme infusion

  2. kidney transplant

  3. coenzyme replacement

  4. providing alternative pathways for excretion of ammonia
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Urea cycle disorders lead to buildup of ammonia. The mainstay of current treatment is to use substances such as sodium benzoate and sodium phenylacetate to complex with ammonia, forming water soluble compounds that can be excreted in the urine. In some cases, liver transplantation is used successfully as well.

Multiple choice

Which of the following statements is false?

  1. Lungs throw out oxygen and carbon dioxide.

  2. Sweat is excreted by the skin.

  3. Undigested food is thrown out as feces.

  4. Waste products are harmful to our body.

  5. Digestive juices make easy digestion.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Lungs belong to our respiratory system, and are responsible for breathing in and out. We breathe in oxygen, and we breathe out carbon dioxide.

Multiple choice

Regarding the human kidneys, which among the following statements is false?

  1. The renal cortex lies outside the medulla.

  2. The right kidney lies lower than the left kidney.

  3. The renal veins drain directly into the inferior vena cava.

  4. The link between the kidney and the bladder is the urethra.

  5. The renal cortex contains all the glomeruli.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The link between the kidneys and the bladder is the ureter. The urethra drains urine out of the bladder.

Multiple choice

Considering the glomerular filtration, which among the following statements is true?

  1. The main site of glomerular filtration is the loop of Henle.

  2. Bowman's capsule surrounds the perinephric fat.

  3. The filtration barrier contains three layers of cells.

  4. Constriction of the afferent arterioles increases filtration.

  5. Small molecules are more easily filtered than large molecules.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Glomerular filtration of molecules depends on their size and their charge. Small molecules are filtered more because they pass through the filtration barrier more easily than large molecules.

Multiple choice

Which of the following statements concerning sodium and water regulation by kidneys is NOT true?

  1. Body volume is regulated by changing body sodium content and maintaining a normal osmolality.

  2. Body osmolality is usually regulated by changing body water content by keeping body sodium content constant.

  3. Stretch receptors provide information about body volume.

  4. The receptors in the pituitary provide information about osmolality.

  5. Renal sodium excretion is the main influence on body volume.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Body osmolality is sensed in the hypothalamus by osmoreceptors which influence thirst (water intake) and ADH (anti-diuretic hormone or vasopressin) secretion (which influences water output by the kidneys).

Multiple choice

Which of the following statements is true for glomerular filtration?

  1. The main site of glomerular filtration is the loop of Henle.

  2. Bowman's capsule surrounds the perinephric fat.

  3. The filtration barrier accomodates two layers of cells.

  4. Constriction of the afferent arterioles enhances filtration.

  5. Glomerular filtration of molecules is independent of their size and charge.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The filtration barrier is made up of two layers of cells and the basement membrane which lies between them. These two layers of cells in the filtration barrier are the endothelial cells of the glomerular capillaries and the epithelial cells of Bowman's capsule .

Multiple choice

Which of the following statements is correct for acid base regulation in the body?

  1. A rise in the plasma level of bicarbonate ions lowers the pH of plasma.

  2. The pH of a buffer solution is always 7.0.

  3. Carbon dioxide directly raises the pH of body fluids.

  4. Overall human metabolism results in acid production.

  5. Buffers present in kidneys must be strong acids or bases.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Carbon dioxide and bicarbonate ions are effectively a buffer pair.  If carbon dioxide is added to body fluids, the direct effect is the production of carbonic acid and thus a rise in the pH as some of this carbonic acid dissociates to produce free H+ ions.

Multiple choice

Uremia is caused due to

  1. malfunctioning of heart

  2. malfunctioning of liver

  3. malfunctioning of urethra

  4. malfunctioning of kidney

  5. insect bite
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Uremia is caused due to malfunctioning of kidney. It results in high fever and fatigue.