Long Term Control of BP Flashcards
What are the functions of the kidney?
Excretion of waste products.
Maintainance of ion balance.
Regulation of pH, osmolarity, and PV.
How does the kidney regulate PV?
Control of Na+ transport (size of osmotic gradient) and permeability of the collecting duct (if water follows the osmotic gradient).
Allows control of water retention and loss.
How does the permeability of the collecting duct affect PV?
Permeable - water reabsorption, little urine, conserves PV.
Impermeable - little reabsorption, diuresis, reduced PV.
Where is renin produced, and what is production a sign of?
In the juxtaglomerular (granule cells) of the kidney.
A sign of low MAP.
What triggers renin production?
Sympathetic nerves to the juxtaglomerular apparatus.
Decreased distension of afferent arterioles and decreased delivery of Na+/Cl- through the tubule (low MAP).
What are the steps of the RAAS?
Renin converts inactive angiotensinogen into angiotensin I, which is converted by angiotensin converting enzyme to angiotensin II.
How does angiotensin II affect aldosterone?
Stimulates aldosterone release from the adrenal cortex (increases Na+ reabsorption in the loop of Henle, decreases diuresis, increases PV).
How does angiotensin II affect ADH?
Increases ADH release from the pituitary (increases water permeability of the collecting duct, decreases diuresis, increases PV and thirst).
How does angiotensin affect blood vessels?
Vasoconstriction - increases TPR.
Where is ADH synthesised and released?
Synthesised in the hypothalamus.
Released from the posterior pituitary.
What triggers ADH release?
A decrease in blood volume (sensed by the arterial baroreflex).
An increase in ISF osmolarity.
Circulating angiotensin II.
What are the functions of ADH?
Indicates low PV and MAP.
Increases collecting duct permeability.
Diuresis decreases, PV increases.
Vasoconstriction - increases MAP.
What are ANP and BNP?
Produced and released from myocardial cells in the atria and ventricles (respectively).
Increases distension.
What are the functions of ANP and BNP?
Indicates high MAP.
Causes natriuresis.
Inhibits renin release.
Acts as medullary CV centres to reduce MAP.
What are examples of drugs that reduce hypertension?
CCBs - arteriolar and venous dilation, depresses cardiac conduction and contraction.
B-adrenoreceptor antagonists - blocks SNS effects that increase HR and BP.
Thiazide diuretics - inhibits NaCl reabsorption, causes natriuresis, reduces PV.
ACEIs and angiotensin II antagonists - prevents angiotensin II production, causes arteriolar dilation (lowers TPR) and venodilation (lowers preload).
