Long Term Control Of Blood Pressure Flashcards
Functions of the kidney
Excretion of waste products Maintenance of ion balance Regulation of pH Regulation of osmolarity Regulation of PLASMA VOLUME
Filtrations of blood in kidney
Into lumen in bowman’s capsule glomerulus
Then reabsorption and secretion in peritubular capillaries
Then just reabsorption in loop of Henle
More reabsorption and secretion in distal tubule and collecting duct
Then fluid goes to bladder and blood goes to renal vein
Describe the renal counter current system
Creates a very high osmolarity outside the collecting duct by control of Na transport
Control of the permeability of the collecting duct to water will determine if water follows the gradient or not
So the kidney can control how much water is lost in the urine and how much is retained
Diuresis
Lots of urine, caused by little resorption and a reduction in plasma volume
Three hormones involved in kidney control of plasma volume
Renin-angiotensin-aldosterone system (RAAS)
Anti-diuretic factor (ADH, vasopressin)
Atrial natriuretic peptide
Where is renin produced
From the juxtaglomerular cells of the kidney
What triggers renin production
Activation of sympathetic nerves to the juxtaglomerular apparatus
Decreases distension of afferent arterioles
Decreased delivery of Na/Cl through the tubule (senses in macula densa)
ALL ARE SIGNS OF REDUCED MAP
What does renin do
Converts inactivate angiotensinogen into angiotensin 1 which is then converted by angiotensin converting enzyme into angiotensin 2
What does angiotensin 2 do
Stimulates release of aldosterone from the adrenal cortex which increases Na reabsorption from the loop of Henle and reduces diuresis and increases plasma volume
Increases ADH release from the pituitary which increases water permeability of the collecting duct and increases plasma volume as well as a sense of thirst
It’s also a vasoconstrictor so increases TPR
Where is anti-diuretic hormone (ADH) produced
In the hypothalamus but released from posterior pituitary
What triggers ADH release
A decrease in blood volume (by cardiopulmonary baroreceptors )
An increase in the osmolarity of interstitial fluid (by osmoreceptors in the hypothalamus)
Circulating angiotensin 2 (RAAS)
What does ADH do
Increases permeability of collecting duct to ADH so reduces diuresis
Also causes vasoconstriction so also called vasopressin
Where is atrial natriuretic peptide (ANP) produced
In the myocardial cells of the atria
BNP is in ventricles and brain
What triggers ANP release
Increased distension of the atrium (increased MAP)
What does ANP do
Increases excretion of Na (natriuresis)
Inhibits renin release
Acts on medullary CV centres to reduce MAP
