Long term control of blood pressure

Question 1

Control mechanisms of osmotic gradient in the kidneys (2)

Answer 1

1. Determined by sodium ion transport

2. Permeability of the collecting duct to water

Question 2

Permeability of the collecting duct to water regulatory hormones

Answer 2

1. Renin-angiotensin-aldosterone system
2. Antidiuretic hormone (Vasopressin)
3. Atrial natriuretic peptide

Question 3

Plasma volume sensing receptors

Answer 3

Cardiopulmonary baroreceptors

Question 4

Triggers of renin production and secretion from juxtaglomerular cells (3)

Answer 4

Low MAP

• Sympathetic innervation
• Decreased afferent arteriole distension (renal baroreflex)
• Decreased Na+/Cl- delivery through tubule detected by macula densa

Question 5

Renin function

Answer 5

Converts angiotensinogen (from the liver) to angiotensin I

Question 6

Angiotensin converting enzyme

Answer 6

Converts angiotensin I to angiotensin II

Question 7

Angiotensin II functions (3)

Answer 7

• Stimulates aldosterone release from adrenal cortex
• Stimulates ADH release from pituitary gland
• Vasoconstrictor (increases TPR)

Question 8

Aldosterone mechanism of action

Answer 8

1. Increases Na+ reabsorption in loop of Henle
2. Water reabsorption increases (reduced diuresis)
3. Plasma volume increases

Question 9

Triggers of ADH/Vasopressin production (in hypothalamus) and secretion from the posterior pituitary (3)

Answer 9

Low MAP

• Cardiopulmonary baroreceptors detect low plasma volume
• Increased ISF osmolarity sensed by osmoreceptors in hypothalamus
• Circulating angiotensin II

Question 10

ADH/Vasopressin functions (2)

Answer 10

• Increases collecting duct water permeability (reduces diuresis)
• Vasoconstriction

Question 11

Triggers of atrial (and brain) natriuretic peptide production and secretion by myocardial cells (1)

Answer 11

• Increased distension in atria/ventricles

Question 12

ANP/BNP functions (3)

Answer 12

• Increases natriuresis (Na excretion) and diuresis
• Inhibits renin release
• Acts on medullary CV centres to reduce MAP (e.g. reduced sympathetic)