Endocrine and neuronal regulation of blood pressure Flashcards
What are the two ways in which blood pressure is controlled?
Short term regulation
Long term regulation
What controls short term regulation of blood pressure ?
Autonomic nervous system
Baroreflex
What controls long term regulation of blood pressure?
Kidney
What is an example of something that triggers short term control of blood pressure ?
Postural hypotension - decrease in blood pressure due to gravity to head/neck
What is an example of something that triggers long term control of blood pressure?
Increase uptake of salt/ water fue to consumption of salty food
How does the baroreflex control blood pressure?
Baroreceptors detect changes in arterial pressure
Signal is sent to the medulla of the brainstem
Vagus nerve adjusts heart rate
Sympathetic nerves adjust cardiac contractility and peripheral resistance
How does the vagus nerve adjust heart rate?
Decrease in vagal activity leads to an increase in heart rate
How do the sympathetic nerves adjust cardiac contractility and peripheral resistance?
Causes vasoconstriction of peripheral blood vessels
How do the kidneys regulate long term control of blood pressure?
Hormones act on the kidney to regulate long term control of blood pressure
How do the hormones released that act on the kidney affect long term control of blood pressure?
Affect sodium and water reabsorption
What are the three hormones that act on the kidney that regulate long-term control of blood pressure?
Atrial natriuretic peptide
Renin-angiotensin system
ADH
What organ synthesises ANP?
The heart
What is the goal of ANP?
To decrease blood volume
How does ANP control blood pressure?
ANP binds to receptors on the DCT and collecting ducts
Interacts with NCC (sodium-chlorine cotransporter) and ENaC (epithelial sodium channel)
ANP also inhibits renin secretion - inhibits the renin-aldosterone system
What is the effect of ANP on the renin-angiotensin system?
Inhibits the renin-angiotensin system
Inhibits renin secretion
What part of the heart secretes ANP?
Cardiac atrial myocytes synthesise and store ANP
What do ventricles produce?
BNP
Brain natriuretic peptide
First isolated in the brain
Structure of ANP
28 aa peptide
17 aa ring in the middle of the molecule
What is the main goal of the renin-angiotensin system?
Increase blood pressure
What is the sensor of the renin-angiotensin system?
The juxtaglomerular apparatus
What does the juxtaglomerular apparatus control?
Blood pressure
Concentration of solutes in the plasma
What is the juxtaglomerular apparatus made of?
Glomerulus
Macula densa cells
Granular renin producing cells
Afferent and efferent arterioles
Which cells produce renin?
Granular renin producing cells
What are granular renin producing cells sensitive to?
Perfusion pressure - when P is low in afferent arteriole, it stimulates renin secretion
NaCl deliver to macula densa cells - when decreased, renin secretion is enhanced
What happens when delivery of NaCl to macula densa cells is decreased?
Renin secretion is enhanced
Describe the steps of renin-angiotensin system
- Angiotensinogen is released from the liver
- Renin is released from the kidneys, converts Angiotensinogen -> Angiotensin I
- Angiotensin I is inactive
- ACE releasedfrom the lungs and converts Angiotensin I -> II
What are the effects of Angiotensin II?
Can affect smooth muscle receptors
Causes release of Aldosterone from the adrenal gland
When in high concentration, can activate the release of ADH
What does Angiotensin II release when in high concentration?
ADH
What is ADH?
A small peptide
What is another name for ADH?
Vasopressin
What are the two receptors for ADH?
V1
V2
Where is the receptor V1 found?
In the vasculature
What happens when ADH binds to V1?
G-protein coupled receptor
Increases IP3+ and Ca2+ levels
Causes vasoconstriction and release of von Willebrand factor/ factor VIII from endothelial cells
What happens when ADH binds to V2?
G-protein coupled receptor
Increases cAMP levels
Causes insertion of aquaporin-2 channels into the luminal membrane of principal cells
Which cells of the collecting duct does ADH affects?
Principal cells
What types of receptors are V1 and V2?
G-protein coupled receptors
What is normal plasma osmolarity?
280 - 330 mosm/L
What releases ADH?
Posterior pituitary
Which nucleus of the posterior pituitary releases ADH?
Suprachiasmatic nucleus
What happens to the kidneys upon prolonged hypertension?
Kidney injury develops
Leads to hypertensive nephropathy
Damage to the capillaries leads to fibrosis
What consequences does kindey injury have on blood volume regulation?
Kidney injury impairs blood volume regulation
What causes benign arterial hypertension?
Excess sodium in the blood leads to activation of Angiotensin
Pathogenesis of benign arterial hypertension
Activation of angiotensin causes accumulation of hyaline in the wall of arterioles
Narrowing lumina and thickening walls leads to ischaemia
Tubular atrophy, interstitial fibrosis , glomerular alterations and periglomerular fibrosis
In advanced stages = renal failure
What structural changes does benign arterial hypertension cause?
Tubular atrophy
Interstitial fibrosis
Glomerular alterations
Periglomerular fibrosis
