Urinary Physiology

Question 1

What is the function of the kidneys?

Answer 1

Regulation of ECF volume and therefore BP
Regulation of osmolarity
Maintenance of ion balance
Homeostatic balance of pH
Excretion of waste
Production of hormones - erythropoietin, renin

Question 2

What are the main functions in the glomerular apparatus?

Answer 2

Filtration - glomerular capillaries (hydrostatic forces exceeds oncotic pressure)
Reabsorption - peritubular capillaries (oncotic pressure exceeds hydrostatic forces)
Secretion - peritubular capillaries into the lumen
Excretion

Question 3

Afferent arteriole

Answer 3

Short and wide
Little resistance to flow
Increased resistance means decreased GFR

Question 4

Efferent arteriole

Answer 4

Long and narrow
High post-capillary resistance
Increased resistance means increased GFR

Question 5

Filtration barriers

Answer 5

Glomerular capillary endothelium
Basal lamina (basement membrane)
Epithelium of Bowman's capsule (podocytes)

Question 6

What happens in the descending loop of henle?

Answer 6

Fluid is becoming more concentrated as water is moving out into the interstitium

Question 7

What happens in the ascending loop of henle?

Answer 7

NaCl is being removed into the interstitium, the fluid is becoming less concentrated

Question 8

Collecting duct

Answer 8

Water regulation - controlled by ADH
No ADH = watery pee
High ADH = concentrated pee

Question 9

What produces renin?

Answer 9

Juxtaglomerular cells

Question 10

What part of the nephron does aldosterone act?

Answer 10

Distal tubule, bit of the collecting duct

Question 11

Respiratory acidosis lab values

Answer 11

Rest opposite to pH
pH - low
PCO2 - increased (primary)
HCO3 - increased (compensatory)

Question 12

What are the causes of respiratory acidosis?

Answer 12

Acute - drugs which depress medullary respiratory centres (opiates, barbiturates), obstruction of major airways
Chronic - lung disease (bronchitis, emphysema, asthma)

Question 13

Respiratory alkalosis lab values

Answer 13

Rest opposite to pH
pH - high
PCO2 - decreased (primary)
HCO3 - decreased (compensatory)

Question 14

What are the causes of respiratory alkalosis?

Answer 14

Acute - voluntary hyperventilation, aspirin, first ascent to altitude
Chronic - long-term residence at altitude

Question 15

Metabolic acidosis lab values

Answer 15

All decreased
pH - low
HCO3 - decreased (primary)
PCO2 - decreased (compensatory)

Question 16

What are the causes of metabolic acidosis?

Answer 16

Increased H production - eg DKA, lactic acidosis
Renal failure - failure to excrete normal dietary H
Loss of bicarb - eg diarrhoea

Question 17

Metabolic alkalosis

Answer 17

All increased
pH - high
HCO3 - increased (primary)
PCO2 - increased (compensatory)

Question 18

What are the causes of metabolic alkalosis?

Answer 18

Vomiting - increased H ion loss
Aldosterone excess - increased renal H loss
Excessive administration of HCO3 (if renal function is impaired)
Massive blood transfusion - 8 units