Question

1. Consider the urinary system
(a) What are the three basic renal processes leading to urine formation?
(b) Consider the net filtration pressure (NFP) according to the following information,
Glomerular blood hydrostatic pressure (GBHP): 90 mmHg
Capsular hydrostatic pressure (CHP): 35 mmHg
Blood colloid osmotic pressure (BCOP): 40 mmHg
Mean arterial pressure (MAP): 93 mmHg
(i) Calculate the net filtration pressure (NFP). Show your calculations.
(ii) Suppose a tumor is pressing on and obstructing the left ureter. What affect might
this have on CHP and thus on NFP in the left kidney? Would the right kidney
also be affected?
(c) Name the hormone that regulates plasma osmolarity. Briefly explain how the hormone
works in regulating plasma osmolarity and urine formation when the body has an
increase in plasma osmolarity.

Answer 1

1. A. There are three main processes involved in   urine formation: glomerular filtration, reabsorption, and secretion. These processes ensure that only waste and excess water are removed from the body.

In glomerular filtration ,blood flows through the glomerulus, blood pressure pushes water and solutes from the capillaries into the capsule through a filtration membrane.

Filtration membrane, allows water and small solutes to pass but blocks blood cells and large proteins. Those components remain in the bloodstream. The filtrate flows from the glomerular capsule further into the nephron.

The needed substances and some water are reabsorbed through the tube wall into adjacent capillaries. This reabsorption of vital nutrients from the filtrate is the second process in urine creation.

Waste ions and hydrogen ions secreted from the blood complete the formation of urine

B.

a) Net filtration pressure (NFP) = glomerular blood hydrostatic pressure(GBHP) – [capsular hydrostatic pressure (CHP) + blood colloid osmotic pressure (BCOP).

Here GBHP is 90 mmhg

CHP is 35 mmHg

BCOP is 40mmhg

NFP = 90-(35+40)

=90-75

=15

b) obstruction of the left ureter would increase CHP and thus decrease NFP of the left kidney.

The urine would back up behind the obstruction, eventually reaching the small tubes of the kidney and it's collecting area( renal pelvis), causing the kidney to become distended and increasing the pressure on its internal structures eventually leading to failure of that kidney.

Obstruction in the left ureter have no effect on right kidney.

C)antidiuretic hormonesecretion is regulating the plasma osmolarity, or the concentration of solutes in blood.