Renal system

Question 1

Name three roles of the kidneys

Answer 1

1. Regulation of water content in the blood
2. Removal of metabolic waste products and foreign chemicals in urine
3. Essential endocrine secretion such as renin

Question 2

Which system regulates
Na+

Answer 2

Renin-Angiotensin system activated by low Na+, low blood pressure and low blood volume

Question 3

Which SYSTEMS regulate K+

Answer 3

1. Aldosterone - increases number of K+ channels
2. Dietary K+
3. Electrochemical gradients
4. Acid-base disturbance - alkalosis causes hypokalemia (K+ moves out of blood into cells)

Question 4

What factors does reabsorbtion of ions/molecules depend on

Answer 4

• Tight junctions- they are less permeable in distal then proximal
• Carriers, channels and pumps

Question 5

Main function of glomerulus

Answer 5

Filters around 20% of blood plasma initially

Question 6

Main function of the collecting duct

Answer 6

• ADH secreted by pituatry gland
• ADH binds to vasopresin II receptors
• cAMP causes aquoporins translocation which increase water and urea permeability

Question 6

Main function of the PCT

Answer 6

• Where most glucose, amino acids, Na+, Cl-, HCO3- are reabsorbed back into blood
• Via facilitated diffusion
• leaky tight junctions allow water and K+ to be reabsorbed
• Bicaarbonate moves into ISF by HCO3-/Cl- exchange

Question 6

Main function of loop of Henle

Answer 6

• Ascendling limb is impermeable to water so it stays in, Na moves out = lowering WP of medulla
• Descending limb water moves out and Na moves in.
• Overall water is reasborbed in the DL

Question 6

Main function of the distal tubule

Answer 6

• Absorbtion and secretion in this region regulated
• Enzymes such as renin and hormones such as aldosterone

Question 7

Main two ways acid/base is regulated

Answer 7

• Buffering [H+] - by proteins, phosphates and bicarbonate
• Elimiation of acid products by renal and respiratory systems

Question 8

What illnesses can acidosis cause?

Answer 8

• Damage to respiratory centre in the brain stem
  could also be drug-induced
• Disorders of respiratory muscles
  polio, multiple sclerosis
• Disorders of gas exchange
  chronic obstructive pulmonary disease (COPD), pneumonia and emphysema cause ↓ exchange of CO2 between blood and alveoli

Question 9

What causes alkalosis

Answer 9

• Gain of HCO3-
  Some antacid drugs
  Diuretic drugs (enhance HCO3- reabsorption)
• Loss of acid (H+ )
  Vomiting
  Excess Aldosterone - increases H+ secretion in distal tubules
  Diuretic drugs (enhance H+ secretion)

Question 10

How to compensate for acid-base disorders if they are renal or respiratory

Answer 10

When the primary disorder is metabolic, compensation is respiratory. When the primary disorder is respiratory, compensation is renal.

Question 11

What role does the sympathetic system play on kidneys

Answer 11

• Constriction of afferent arterioles to reduce GFR (decreases Na+ and water excretion)
• Increases renin release/angiotensin II formation to increases Na+ and water reabsorption