CVS 5 Control Of Blood Presure+ Hypertension Flashcards
Normal range of blood pressure
Systolic - 90-120
Diastolic - 60-80
BP in stage 1 hypertension
> 140/90 mmHg
BP in stage 2 hypertension
160/100 mmHg
BP in severe hypertension
> 180 systolic or > 110 diastolic
Difference in the changes of the stages of hypertension
+ 20 systolic: - normal 90-120
- stage 1 140
- stage 2 160
- severe 180
+ 10 diastolic: - normal 60-80
- stage 1 90
- stage 2 100
- severe 110
Causes of primary hypertension
Idiopathic - Unknown
Causes of secondary hypertension
ROPED
- Renal disease e.g. renal artery stenosis
- Obesity
- Pregnancy induced or Pre-eclampsia
- Endocrine e.g. Cushing’s syndrome, hyperaldosteronism
- Drugs e.g. alcohol, steroids, NSAIDS, oestrogen
What organs should be assessed by clinical history + physical exam in relation to hypertension?
Brain
Eyes
Heart
Kidneys
Arteries
What controls short term regulation of blood pressure?
Baroreceptors reflexes
Why can baroreceptors only work in short term regulation of BP?
Threshold for baroreceptor firing resets
So not long term
Where are baroreceptors located?
Carotid sinus
Aortic arch
What are the neurohumoral pathways that control blood pressure?
1- renin-angiotensin-aldosterone-system
2- sympathetic nervous system
3- anti diuretic hormone
4- atrial natriuretic peptide
Where is renin released from?
Granular cells of juxaglomerular apparatus (JGA) in kidney
What is renin release stimulated by?
- decreased NaCl delivery to distal convoluted tubule
- decreased kidney perfusion
- sympathetic stimulation of JGA
What is kidney perfusion detected by?
Baroreceptors in afferent arteriole to kidney
What can a decrease in kidney perfusion be due to?
Renal artery stenosis
Decrease circulating volume
What is the pathway in RAAS?
Angiotensinogen > angiotensin I > angiotensin II
renin. ACE
What is angiotensinogen produced by?
Liver
What type of receptor is angiotensin receptor 1/2?
G protein coupled receptor
Action of angiotensin II
- increases BP
- vasoconstriction of arterioles
- increased Na+ reabsorption at kidney
- stimulates sympathetic NS to release more NA
- acts on hypothalamus to increase thirst + increase ADH release
- aldosterone release from adrenal cortex
Where is aldosterone released from?
Adrenal cortex
Zona glomerulosa
Action of aldosterone on kidney
- increased expression of Na/K ATPase > increased Na reabsorption > H2O follows - H2O reabsorption
- activates apical Na+ and K+ channels
ACE action on bradykinin
Breaks down bradykinin into peptide fragments
Function of bradykinin
Vasodilator
Why do ACE inhibitors cause dry coughs?
Prevent breakdown of bradykinin
Build up bradykinin cause cough