Urinary 3 - Control of Blood Pressure Flashcards
Which forces are named ‘Starling’s forces’?
1) Hydrostatic pressure
2) Oncotic pressure
Define hydrostatic pressure:
The pressure exerted by a liquid
Define oncotic pressure:
Osmotic pressure exerted by proteins in plasma
What effect does oncotic pressure usually have on water in the body?
It tends to pull water into the circulatory system
What effect does hydrostatic pressure tend to have on water in the body?
Pushes water out of the circulatory system
What effect does the sympathetic NS have on the RAA-system?
Stimulates Renin release and the RAA-system
Name 2 factors which stimulate the RAA-system:
1) Sympathetic NS (beta-1)
2) Decreased [NaCl] in Distal Tubule (Macula Densa)
How does the Macula Densa respond if it detects decreased [NaCl] in the Distal Tubule?
Stimulates Juxtaglomerular cells to release:
- Renin (stimulates RAA-system)
- Prostaglandins (vasodilation of afferent arteriole)
What cells release Renin?
Juxtaglomerular cells in the kidney
What is the function of Renin?
Enzyme causes conversion of Angiotensinogen to Angiotensin I
Where is Angiotensinogen released from?
Liver
What enzyme converts Angiotensin I to Angiotensin II?
ACE = Angiotensin Converting Enzyme
Where is Angiotensin Converting Enzyme released from?
Vascular endothelium
Name the main proteins involved in the RAA-system:
- Renin
- Angiotensinogen
- Angiotensin I
- Angiotensin Converting Enzyme
- Angiotensin II
What effect does Angiotensin II have on aldosterone release?
Increases aldosterone release
What effect does Angiotensin II have on ADH release?
Increases ADH release
What effect does Angiotensin have on the thirst response?
Increases thirst response
What is the overall effect of the RAA-system on blood pressure?
Increases blood pressure
How does Aldosterone increase blood pressure?
Causes increased numbers of ENaC in Collecting Ducts
How does ADH increase blood pressure?
Increases insertion of AQP2 into apical membrane of Collecting duct principle cells.
Name the 2 types of Natriuretic peptides:
1) Atrial Natriuretic Peptide (ANP)
2) Brain Natriuretic Peptide (BNP)
Where are natriuretic peptides synthesised and stored?
Heart (Atrial myocytes)
Name 4 factors which increase the secretion of natriuretic peptides into the circulation:
1) Increased sympathetic NS stimulation to heart
2) Cardiac distension
3) Increased Angiotensin II
4) Increased Endothelin
What is the overall effect of Natriuretic peptides on blood pressure?
Decrease blood pressure
What is the overall effect of increased sympathetic stimulation on blood pressure?
Increased blood pressure
What are the 2 main effects Natriuretic peptides have on the kidneys?
1) Natriuresis (causes diuresis)
2) Decreased Renin release (decreases RAA-system)
How do Natriuretic peptides effect blood vessels?
Cause vaso- and veno-constriction
Name the most sensitive serum biomarker of heart failure:
Brain Natriuretic Peptide (BNP)
How do natriuretic peptides affect GFR?
Increase GFR (vasodilation of afferent arteriole to cause natriuresis and diuresis)
How does heart failure affect ADH release?
Increases release of ADH
Describe the production of Prostaglandins:
Arachidonic Acid is converted to Prostaglandin via Cyclo-oxygenase (COX)
What effect do Prostaglandins have on the GFR?
Increase GFR as vasodilate afferent arterioles
What reaction is catalysed by Cyclo-oxygenase?
Arachidonic Acid to Prostaglandins
Name the potent vasodilator produced by endothelial cells:
Nitric Oxide
Describe the production of Bradykinin:
Kininogen is converted to Bradykinin via Kallikrein
How do ACE inhibitors cause a cough?
ACEi also inhibit the breakdown of Bradykinin, so the pro-inflammatory Bradykinin settles in lung tissue, causing cough.
How do ACE inhibitors affect Bradykinin?
They inhibit the breakdown of Bradykinin into inactive metabollites.
What effect does Dopamine have on renal blood vessels and GFR?
Vasodilation = increased GFR
What effect does Dopamine have on renal reabsorption of NaCl?
Inhibits Na+/H+ exchanger and Na+/K+-ATPase in PCT and TAL
= Decreases NaCl reabsorption
Name some causes of hypertension:
- Conn’s syndrome
- Cushings syndrome
- Phaeochromocytoma
- Renovascular disease
- Renal parenchymal disease
(95% unknown cause)
Name some non-pharmacological treatments of Hypertension:
- Weight loss
- Increase exercise levels
- Decrease salt intake
Name some Pharmacological treatments of Hypertension:
- Thiazides (diuretics)
- ACE inhibitors
- DHP Ca2+ channel blockers
- alpha1 antagonists
- Angiotensin II Receptor Blockers (ARBs)
Define hypertension:
Sustained BP > 140/90 mmHg
