Long Term Control of Blood Pressure

Question 1

Long term control of blood pressure revolves around

Answer 1

Control of plasma volume by the kidney

Question 2

3 hormone systems involved

Answer 2

Renin-angiotensin-aldosterone system
Antidiuretic factor (ADH, vasopressin)
Atrial natriuretic peptide

Question 3

Functions of the kidney

Answer 3

Excretion of waste products
Regulation of plasma volume
Maintenance of ion balance
Regulation of pH and osmolality

Question 4

Function of loop of Henle

Answer 4

Pump sodium ions out to create a concentration (osmotic) gradient which controls how much water is absorbed into the blood

Question 5

Function of renal counter-current system

Answer 5

Creates a very high osmolality outside the collecting duct

Question 6

What determines if water follows the osmotic gradient at kidneys or not

Answer 6

The permeability of the collecting duct to water

Question 7

Where is renin produced

Answer 7

Juxtaglomerular (granule cells) of the kidney

Question 8

Triggers for renin production (=signs of low MAP)

Answer 8

Activation of sympathetic nerves to the juxtaglomerular apparatus
Decrease distension (dilation) of afferent arterioles (renal baroreflex)
Decreased delivery of sodium/chlorine ions through the tubule

Question 9

Function of renin

Answer 9

Converts active angiotensinogen to angiotensin I - then converted by angiotensin converting enzyme to angiotensin II

Question 10

Functions of angiotensin II

Answer 10

Stimulates release of aldosterone from the adrenal cortex
Increases release of ADH from pituitary
Is a vasoconstrictor

Question 11

Effect of aldosterone release by angiotensin II

Answer 11

Increases sodium ion reabsorption in the loop of Henle which reduces diuresis and increases plasma volume

Question 12

Effect of increasing ADH release by angiotensin II

Answer 12

Increase water permeability of collecting duct which reduced diuresis and increases plasma volume, and increases sense of thirst

Question 13

Effect of vasoconstriction by angiotensin II

Answer 13

Increases TPR

Question 14

Where is ADH synthesised

Answer 14

Hypothalamus

Question 15

Where is ADH released from

Answer 15

Posterior pituitary

Question 16

What triggers ADH release (=signs of low plasma volume and/or MAP)

Answer 16

Decrease in blood volume
Increase in osmolality of ISF
Circulating angiotensin II

Question 17

Function of ADH

Answer 17

Increases permeability of collecting duct to water which reduced diuresis and increases plasma volume
Causes vasoconstriction which increases TPR so MAP

Question 18

Negative feedback system entails

Answer 18

Multiple mechanisms detect any decrease in MAP
Stimulates release of hormone
Evokes multiple mechanisms which increase MAP

Question 19

Where is atrial natriuretic peptide (ANP) produced and released

Answer 19

Myocardial cells in atria

Question 20

Trigger of ANP release (=signs of increased MAP)

Answer 20

Increased distension of the atrium

Question 21

Diuresis

Answer 21

Increased production of urine

Question 22

Functions of ANP

Answer 22

Increases excretion of sodium ions
Inhibits release of renin
Acts on medullary CV centres to reduce MAP

Question 23

Effects of sustained residence in space (or bed rest)

Answer 23

Fools cardiopulmonary baroreceptors into thinking that there is a high plasma volume resulting in triggering a reduction in plasma volume

Question 24

What percentage of hypertension is classed as secondary (due to a known cause)

Answer 24

5-10%

Question 25

Drugs treatments for hypertension

Answer 25

Calcium ion channel antagonists
Beta adrenoceptor antagonist
Thiazide diuretics
Angiotensin converting enzyme inhibitors
Angiotensin II antagonist