long term control of blood pressure Flashcards
is long term control of blood pressure mediated by arterial baroreflex?
no
where does the long term control of blood pressure revolve around?
around the control of plasma volume by the kidneys
what three hormone systems does long term control of blood pressure?
Renin-angiotensin-aldosterone system Antidiuretic factor (ADH, vasopressin) Atrial natriuretic peptide
whats the function of the kidney?
Excretion of waste products Maintenance of ion balance Regulation of pH Regulation of osmolarity Regulation of plasma volume
what regulates plasma volume?
kidney
does renal counter current system create a high or low osmolarity outside the collecting duct?
high
what determines how big the osmotic gradient is?
control of Na transport
what does control over the permeability of the collecting duct to water determine?
determines if water follows that osmotic gradient or not
can you control how much water is lost in the urine and how much is retained?
yes
what effect will making the collecting duct very permeable to water do?
result in lots of water reabsorption, little urine, and conserve plasma volume
what effect will making the collecting duct very impermeable to water?
result in little reabsorption, lots of urine (= diuresis), and a reduction in plasma volume
will a permeable collecting duct result in small or large volume of hyper or hypo osmotic urine?
small volume of hyper osmotic urine
will a impermeable collecting duct result in small or large volume of hyper or hypo osmotic urine?
large volume of hypo osmotic
where is renin produced?
From the juxtaglomerular (= granule cells) of the kidney
what triggers renin production?
Activation of sympathetic nerves to the juxtaglomerular apparatus
Decreased distension of afferent arterioles (the “renal baroreflex”)
Decreased delivery of Na+/Cl- through the tubule
what are all signs of low MAP
Activation of sympathetic nerves to the juxtaglomerular apparatus
Decreased distension of afferent arterioles (the “renal baroreflex”)
Decreased delivery of Na+/Cl- through the tubule
what does renin do?
Converts inactive angiotensinogen to angiotensin I
Which is in turn converted by angiotensin converting enzyme to angiotensin II
what does angiotensin II do?
Stimulates release of aldosterone from the adrenal cortex
Increases release of ADH from the pituitary
Is a vasoconstrictor
whats the effect of Stimulates release of aldosterone from the adrenal cortex
Increases Na+ reabsorption in the loop of Henle
Therefore reduces diuresis and increases plasma volume
whats the effect of Increased release of ADH from the pituitary
Increases water permeability of the collecting duct
Therefore reduces diuresis and increases plasma volume
And increases sense of thirst
whats the effect of vasoconstriction on TPR
increases
can you say that Renin-angiotensin-aldosterone system is a negative feedback system?
yes
Multiple mechanism detect any decrease in MAP
Stimulates release of renin
This evokes multiple mechanisms which increase MAP
where is antidiuretic produced?
Synthesised in the hypothalamus
Released from the posterior pituitary
what triggers ADH release?
A decrease in blood volume
An increase in osmolarity of interstitial fluid
Circulating angiotensin II
what does ADH do?
Increases the permeability of the collecting duct to H2O, therefore reduces diuresis and increases plasma volume Causes vasoconstriction (hence its alternative name, vasopressin), therefore increasing MAP
can you say that ADH is a negative feedback system?
yes
Multiple mechanism detect any decrease in MAP
Stimulates release of ADH
This evokes multiple mechanisms which increase MAP
where is atrial natriuretic peptide produced?
Produced in, and released from myocardial cells in the atria
what triggers ANP release?
Increased distension of the atrium
what does ANP do?
Increases excretion of Na+ (natriuresis)
Inhibits the release of renin
Acts on medullary CV centres to reduce MAP
can you say that ANP is a negative feedback system?
yes
