Module 23 Urinary System

Question 1

What are the functions of the urinary system?

Answer 1

Regulation of ions in the plasma (Na+, Ca+2, K+, Cl-, Mg+2)
Regulation of blood volume and blood pressure
Regulation of plasma osmolarity (water conservation)
Regulation of blood pH (via H+ and HCO3-)
Removal of waste (metabolic waste like urea, foreign substances)
Produce EPO (hormone), renin, vitamin D3 and glucose via gluconeogenesis

Question 2

What are the two purposes of the kidneys?

Answer 2

1. Filter blood plasma especially ion concentration of (Na+, Ca +2, K+, Cl-, Mg+2)
2. Regulate osmolarity (water content) of the blood

Question 3

What is the flow of urine?

Answer 3

Exits out of the kidneys via the ureter, then is stored in the bladder, and then exits via the urethra.

Question 4

What is the flow of blood into and out of the kidney?

Answer 4

1. Blood comes from the renal arteries and enters the kidneys in arterioles to the renal cortex.
2. Enters the glomerulus which is capillary #1
3. Exits glomerulus and enters the peritubular capillaries (capillary # 2)
4. Enters the vasa recta which is now going back through the renal medulla
5. Leaves via the renal vein eventually.

Question 5

Draw a nephron

Answer 5

Include
1. Bowman’s capsule
2. Proximal Tubule
3. Loop of Henle with Descending and Ascending labeled
4. Distal Tubule
5. Collecting Duct

Question 6

Practice question

Write an equation for the volume of urine produced (i.e. the amount of excretion), using the amount of filtration (F), reabsorption (R) and secretion (S).

A) Urine volume = F + R + S

B) Urine volume = F – R – S

C) Urine volume = F + R – S

D) Urine volume = F – R + S

Answer 6

D

Question 7

Filtration

Answer 7

Small polar molecules move out of the glomerulus into the bowman’s capsule. They pass through three layers.
1. Endothelial cells
2. Basement membrane
3. Podocytes

Question 8

Reabsorption of glucose occurs where?

Answer 8

in the proximal tubule

Question 9

Reabsorption of Na+ occurs where?

Answer 9

everywhere including the collecting duct, in the proximal and distal tubules; except the loop of henle.
Primarily in the distal tubule by aldosterone.

Question 10

Reabsorption of water occurs where?

Answer 10

Everywhere including the collecting duct and it’s regulated by aldosterone.