Long Term Control of Blood Pressure Flashcards
What is long term control of blood pressure?
Not so muchcontrolled by arterial baroreflex but more by the kidney
What are the functions of the kidney?
Excretion of waste products
Maintenance of ion balance
Regulation of pH
Regulation of osmolarity
Regulation of plasma volume
What are the three hormone system which regulate the water absorption?
- RAAS (Renign-algiotensin-aldosterone system)
- Antidiuretic hormone
- Atrial Natriuretic Peptide and Brain natriuretic peptide
What is the RAAS system?
It is a feedback system which detects disturbances in plasma volume and mean arterial pressure.
It produces a hormone called renin which is produced in the juxtaglomerular cells in the kidney also known as the granule cells. This produces an appropiate response.
What is the function of renin?
Renin converts inactive angiotensis to angiotensin 1. Which in turn converted by angiotensin converting enzyme to angiotensin 2. Angiotensin 2 is the active hormone
What triggers Renin production?
- Activation of the sympathetic nerves to the juxtaglomerular apparatus
- Decrease distension of afferent arterioles
- Decreased delivery of sodium and chlorine through the tubule
What does Angiotensin II do?
This is a negative feedback system.
- Stimulates the release of aldersterone from the adrenal cortex.
- Increases the release of ADH (anit-diuretic hormone) from the pituatry gland.
- Is a vasoconstrictor
What is the result of the release of alderstorone from adrena cortex as a result of angiotensin II?
Increases absorption of sodium in the loop of Henle. This results in a bigger oscmotic gradient. There is therefore decrease diuresis and increase in plasma volume and then increase in MAP.
What is the results of increase release of antidiuretic hormon from the pituitary gland due to angiotensin II?
This results in the increase of water permeability in the colecting duct and less excreted in the urine. Therefore there is a reduced diuresis and increased plasma volume. Also increase in the sense of thirst.
What is the result of vasoconstriction due to angiotensin II?
It constricts the blood vessels that will increase the total peripheral resistance and increase mean arterial pressure.
What does antidiuretic hormone do?
It is a negative feedback system.
- Increase the permeability of the collecting duct to water therefore reduces diuresis and increase the plasma volume
- Causes vasconstriction, therefore increases MAP
Where is anti-diueretic hormone produced?
It is synthesised in the hypothalamus. It is released from the posterior pituitary into the bloodstream
What triggers the anti-diuretic hormone release?
- It is triggered by the decrease in blood volume. This is sensed by the cardiopulmonary baroreceptors and relayed via medullary cardiovascular centres.
- An increase in osmolarity of interstitial fluid as sensed by the osmoreceptros in the hypothalamus.
- Circulation angiotensisn II which is triggered by the RAAS system.
Where are Atrial Natriuretic peptide and breain natriuretic peptide produced?
It is produced and released from myocardial cells in the atria and the ventricles respectively.
What triggers the release of ANP and BNP?
Increased distension of the atria and ventricles - A sign of increased MAP.
What does ANP and BNP do?
This is again a negative feedback system but is working the opposite way to decrease mean arterial pressure.
- Increase the excretion of sodium:
- Inhibit the release of renin
- Act on medullary CV centres to reduces MAP
All above decrease mean arterial pressure.
