The renal system

First listen to the presentation: The renal system

Structure

1. Describe the position and composition of the kidneys

Answer: The kidneys are a pair of organs situated in the retroperitoneum; they are composed of a cortex and a medulla.

2. What vessels are attached to the kidneys? What fraction of the cardiac output goes to the kidneys?

Answer: renal artery, renal vein, ureters; 25%.

Function

3. What three functions does the kidney undertake and in what order?

Answer: filtration, secretion and reabsorbtion.










4. What are the functional units of the kidneys? Name the regions of this functional unit.

Answer: nephrons; Bowman's capsule, ascending and descending limbs, loop of Henle.

5. Describe the glomerulus.

Answer: the glomerulus is a system of arterial capillaries inside the Bowman's capsule with an afferent vessel and an efferent vessel.








6. Describe what happens at the glomerulus.

Answer: blood enters via the afferent vessel and leaves via the efferent vessel; water and solutes leave the blood and enter the Bowman's capsule; blood cells and blood proteins are retained in the blood.




7. Name four things that are secreted into the nephron.

Answer: hydrogen ions, potassium ions, ammonia, drugs and toxins.









8. Name four things that are reabsorbed into the blood at the nephron.

Answer: water, sodium ions, vitamins, nutrients (eg sugar).

Urinary bladder and micturition

9. Describe the urinary bladder. What is the major difference in males and females?

Answer: reservoir composed of smooth muscle, two ureters enter and the urethra leaves. The female urethra is shorter than the male urethra.

10. Describe normal micturition.

Answer: bladder fills to ~250ml; stretch receptors sense filling; internal sphincter relaxes spontaneously; external sphincter can be relaxed voluntarily.