The Renal System

Question 1

What are the main functions of the kidneys?

Answer 1

1. Elimination, regulation, secretion
2. Formation and secretion of urine and excretion of waste products.
3. Production and secretion of erythropoitetin.
4. Production and secretion of renin.
5. Converse of Vitamin D to active form.

Question 2

In the kidneys where does blood supply come from?

Answer 2

The aorta via the renal artery and return to vena cava via renal vein.

Question 3

Explain the structure of the kidneys.

Answer 3

• Concave side has an opening called hilum.
• Renal artery, renal vein, nerve supply and lymphatics leave via hilum.
• Medulla divided into 12 pyramids containing bundles of tubules.
• Tubules appear as lines - medullary rays.
• Each pyramid with overlying cortex forms a renal lobe.
• Tip of pyramids empty into renal pelvis.
• Urine is carried from renal pelvis to urinary bladder via urethra.

Question 4

What is the nephron?

Answer 4

The functional unit of the kidney.

Question 5

Explain the steps of urine formation.

Answer 5

• 1st phase = glomerular filtration which occurs in the tuft of capillaries in the bowman’s capsule.
• Blood flowing through the glomerulus is filtered with dissolved materials forced into bowman’s capsule. Large proteins remain in the blood stream.
• 2nd phase = reabsorption which occurs in the proximal renal tubule and loop of henle.
• 3rd phase = tubule secretion which occurs in distal renal tubule.
• The water content of urine is dependant on the reabsorption of water.

Question 6

What does the juxtaglomerular apparatus do?

Answer 6

Regulates the function of each nephron and secretion of renin.

Question 7

What are the 3 phases of passive transport?

Answer 7

1. Filtration - fluid passes through a filter.
2. Diffusion - molecules pass from a high concentration to a lower concentration.
3. Osmosis - movement of fluid with a low concentration to a higher concentration through a semi-permeable membrane.

Question 8

What are the 3 phases of active transport?

Answer 8

1. Filtration
2. Reabsorption
3. Secretion

Question 9

1. What does erythroprotein?
2. What does renin do?
3. Where are they both produced?

Answer 9

1. Stimulates red blood cells production in the bone marrow.
2. Regulates blood pressure.
3. Produced by the kidneys.

Question 10

What does renin stimulate?

Answer 10

Production of angiotensin i which is then converted in the lungs to angiotensin ii which causes vasoconstriction.

Question 11

Explain blood pressure maintenence.

What is the role of aldosterone?

Answer 11

A drop in blood pressure is detected by juxtaglomerular. Renin is released and reacts with angiotensin and converts it to angiotensin i. This travels to the lungs for the conversion to angiotensin ii.

Aldosterone increases reabsorption of sodium from nephron.

Question 12

What are the key changes to the renal system during pregnancy?

Answer 12

• Kidneys enlarge and increase in length due to increased blood flow.
• Glomerular size increases.
• Dilation of the renal calyces, renal pelvis and uterers.
• Vasodilation of the afferent and efferent glomerular capillaries.
• Decrease in renal vascular resistance brought by the relaxing effects of progesterone.
• Trigone elevation occurs with increased vascular tortuousity.

Question 13

By how much does blood volume increase during pregnancy?

Answer 13

30-50%

Question 14

What are the normal limits for systolic and diastolic blood pressure?

Answer 14

Systolic 90-140mmHg

diastolic 60-90mmHg

Question 15

Define trigone of urinary bladder.

Answer 15

A smooth triangular region of the internal urinary bladder formed by the 2 urethral orifices and the internal urethral orifice.