4.2 Hypertension and the Control of Blood Pressure Flashcards
What does RAAS stand for?
Renin-angiotensin-aldosterone system
Where is renin released from?
Granular cells of the juxtaglomerular apparatus
What stimulates renin release?
Reduced NaCl levels
What is the function of renin?
Converts angiotensinogen to angiotensin I
What converts angiotensin I to angiotensin II?
ACE- angiotensin converting enzyme
What is the action of angiotensin II?
Vasoconstriction
Stimulates Na+ reabsorption in the kidney
Increased release of noradrenaline
Stimulates aldosterone
Where does aldosterone act?
Principle cells of collecting duct
What does aldosterone cause?
Increase Na+ reabsorption
Where is aldosterone released from?
Adrenal cortex
What additional action does ACE have?
Breaks down bradykinin to peptide fragments. Bradykinin is a vasodiltor
How does the sympathetic nervous system act to reduce renal blood flow?
Vasoconstricts arterioles
Activates Na-H-exchanger in PCT
Stimulates renin release
What is the function of antidiuretic hormone (ADH)?
Forms concentrated urine by retaining urine
What is ADH release stimulated by?
Increased plasma osmolarity
Severe hypovolaemia
What is the function of ANP?
Promotes Na+ excretion
Where is ANP synthesised and stored?
Atrial myocytes
When os ANP released?
When stretch receptors in the atria are stimulated
What are the effects of ANP?
Vasodilation of arterioles
Increases GFR
Inhibits Na+ reabsorption
How do prostaglandins act on the kidney?
Vasodilate afferent arteriole
How do NSAIDs affect vasodilation of the kidneys?
NSAIDs inhibit prostaglandin synthesis
What affect does dopamine have on the kidney?
Vasodilation of arterioles
What is hypertension?
Sustained high blood pressure
How can hypertension be treated using the urinary system?
Lower blood volume by lowering reabsorption of water and Na+
Name some diuretic drugs used to treat hypertension
ACE inhibitors
Thiazode diuretics
Ca2+ channel blockers
Beta-blockers
