ACE inhibitors and Angiotensin receptor blockers Flashcards
(30 cards)
When is the RAAS activated ?
When blood pressure/volume falls, in response to salt/water loss and reduced glomerular filtration
What senses the drop in blood volume?
Central veins (will be less stretched)
What senses the fall in bp?
Baroreceptors in carotid arteries and aortic arch as they will be less stimulated
What will the decrease in baroreceptor stimulation do to sympathetic NS?
Increase sympathetic nerve activity
What receptors can noradrenaline work on?
B1 receptors
What can the macula dense cells detect?
A fall in tubular sodium and they will send a signal to the granular cells to secrete Renin
What do pressure-sensitive granular cells do when responding to localised fall in Renin arterial pressure?
Secrete renin
Where are G-protein coupled angiotensin II receptors located?
Proximal convoluted tubule
What will angiotensin II attached to G-protein coupled angiotensin II receptors do?
Cause an early stimulus of increased sodium reabsorption from the tubular lumen
What is the larger, indirect action of angiotensin II?
Angiotensin II acts on angiotensin receptors expressed in the adrenal cortex to stimulate aldosterone secretion
Where will aldosterone move to?
Back in the blood to the kidney and will act on receptors in the DCT to promote a larger increase in sodium reabsorption
How is further stimulation of Renin secretion stopped?
Negative feedback
What type of receptor does aldosterone (mineralocorticoid) work on ?
Intracellular / nuclear receptor
What will the mechanism of action of aldosterone do to the capacity of the DCT
It will increase the capacity for the reabsorption of sodium
(There is also a net loss of K+ and H2O)
Free water balance is coupled to ________ balance to maintain __________ _________
Sodium
Osmotic pressure
Where is cellular osmolarity detected ?
Specialised Receptors in the hypothalamus
When specialised receptors in the hypothalamus detect an increase in osmolarity, what do they do?
Send a message to posterior pituitary to secrete vasopressin
What is vasopressin ?
Antidiuretic hormone which travels to the kidney in the blood to exert an action on vasopressin V2 receptors located in the collecting duct .
They are G-protein coupled receptors and are designed to increase the permeability of the collecting duct so that the water can more easily follow sodium by osmosis
What does cAMP secrete ?
Protein kinase A activation
What do the aquaporins now on the membrane do?
Make the membrane more permeable and water can pass more readily from the lumen back into the interstitial and the blood.
What aquaporins are on the side of the lumen and the interstitial side?
Lumen - AQP 2
Interstitium - AQP 3, AQP 4
How can Ang II increase glomerular filtration pressure ?
Constrict renal efferent arteriole which reduces filtration area
What can you tell me about the number of Ang II receptors on the efferent arteriole?
They are more abundant than on the affetent arterioles and they mediate vasoconstriction
AT1 receptor has a higher agonist potency to which angiotensin?
Ang II > Ang III ( active metabolite with one less amino acid)
Note AT2 have similar potency to both
