Long Term Control of Blood pressure- Physiology

Question 1

What is primarily responsible for the long term control of blood pressure?

Answer 1

hormones which act upon the kidneys

Question 2

List the 5 functions of the kidney

Answer 2

• Excretion of waste products
• Maintenance of ion balance
• Regulation of pH
• Regulation of osmolarity
• Regulation of plasma volume

Question 3

Where is renin produced?

Answer 3

the juxtaglomerular cells (granule cells) of the kidney

Question 4

Which three things trigger renin production?

Answer 4

signs of low mean arterial pressure, including;

a) Activation of sympathetic nerves to the juxtaglomerular apparatus
b) Decreased distension of afferent arterioles supplying the kidney (the “renal baroreflex”)
c) Decreased delivery of Na+/Cl- to the macular densa through the tubule

Question 5

What is the function of renin?

Answer 5

Converts inactive angiotensinogen (the inactive precursor in the blood) to angiotensin which is in turn converted by angiotensin converting enzyme to angiotensin II (the active hormone)

Question 6

What does angiotensin II stimulate?

Answer 6

Angiotensin II stimulates the release of aldosterone (a steroid hormone) from the adrenal cortex

Question 7

What are three main effects of angiotensin II?

Answer 7

1. Increases Na+ reabsorption in the loop of Henle. This then reduces diuresis and increases plasma volume
2. Increases the release of ADH from the pituitary. This increases water permeability of the collecting duct and therefore reduces diuresis, increases plasma volume and increases sense of thirst
3. It is a vasoconstrictor. Therefore, increases TPR

Question 8

Where is antidiuretic hormone made and where is it released from?

Answer 8

is synthesised in the hypothalamus & released from the posterior pituitary

Question 9

what stimulates the release of ADH?

Answer 9

• A decrease in blood volume (as sensed by cardiopulmonary baroreceptors and relayed via medullary cardiovascular centres)
• An increase in the osmolarity of interstitial fluid (as sensed by osmoreceptors in the hypothalamus)
• The presence of circulating angiotensin II (triggered by the renin-angiotensin-aldosterone system)

Question 10

What are the two main effects of ADH?

Answer 10

• ADH increases the permeability of the collecting duct to H2O which reduces diuresis and increases plasma volume
• ADH causes vasoconstriction (hence its alternative name, vasopressin), therefore increasing mean arterial pressure

Question 11

Where is Atrial natriuretic peptide produced and released from?

Answer 11

Atrial natriuretic peptide is produced in, and released from myocardial cells in the atria

Question 12

Where is brain natriuretic peptide produced and released from?

Answer 12

brain natriuretic peptide is produced in, and released from myocardial cells the ventricles (despite the name!)

Question 13

What is the release of atrial natriuretic peptide and brain natriuretic peptide stimulated by?

Answer 13

increased distension of the atria & ventricles (a sign of increased mean arterial pressure)

Question 14

What are the three main effects of atrial natriuretic peptide and brain natriuretic peptide?

Answer 14

1. Increase the excretion of Na+ (natriuresis)
2. Inhibit the release of renin
3. Act on medullary cardiovascular centres in the brain to reduce mean arterial pressure