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Flashcards in Hypertension - Howlett 1 Deck (23)
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1

Primary hypertension

High blood pressure
Very common
Causes mostly unknown (obesity, inactivity, smoking, stress)
Asymptomatic until damage to heart, brain, retina etc

2

Risk factors of hypertension

Age, family history, obesity, inactivity, smoking, stress

3

Blood pressure control mechanisms

SNS (fast controlling)
Renin-angiotensin system (RAS): longer term control
Affect cardiac output and peripheral resistance

4

Renin-angiotensin system

Renin/Angiotensin increase Na retention, which increases plasma volume
This increases arterial pressure

5

Agents to treat hypertension

1. Diuretics
2. Drugs that affect the SNS
3. Vasodilators
4. Drugs that affect the RAS

6

Diuretics

Act on cells in the renal tubule to promote diuresis and naturiesis
Include: Loop, Thiazide and Potassium sparing diuretics
Deplete Na stores in body causing vascular smooth muscle to become less stiff
Initial drop in BP due to lower blood volume and reduced CO
Eventually CO returns to normal but peripheral resistance is lower

7

Loop diuretics

Inhibit Cl/K cotransporter in loop of henle

8

Thiazide diuretics

Inhibit Na channel and increase Na and water in the lumen of the distal tubule
Mainly used in hypertension

9

Potassium sparing diuretics

Inhibit K/Na exchanger in the collecting duct
Must be used with other diuretics because they cause too much K is being lost as exchanger is trying to absorb Na
Mainly used in hypertension

10

Drugs affecting the SNS

Act at specific sites in the SNS and classified based on site

11

Centrally acting drugs (SNS)

Clonidine, methyldopa
Decrease SNS outflow centrally, act at the BP control centre in the brain to reduce BP
Can cause sedation
Methyldopa is bad for pregnancy

12

Beta-blockers

Propranolol, metoprolol
Short term: decrease HR and reduce force of contraction which reduced CO and decreases BP
Long term: decrease renin release - lower angiotensin II and aldosterone

13

Alpha1-blockers

Prazosin
block alpha1 receptors on vascular smooth muscle cells
Blocks the effects of the SNS on blood vessels
Causes vasodilation and reduces BP
Can cause orthostatic hypertension

14

Vasodilators

Ca channel blockers

15

Ca channel blockers

Nifedipine, diltiazen and verapamil
Block influx of CA and contraction in vascular smooth muscle

16

Nifedipine

Act on blood vessels only
Ca channel blockers

17

Diltiazem

+ verapamil
Act on heart and blood vessels
Treat angina and arrhythmias

18

Verapamil

+diltiazen
Act on heart and blood vessels
Treat angina and arrhythmias

19

OTHER direct vasodilators

Hyrdalazine, sodium nitroprusside, minoxidil

20

Drugs that affect RAS

ACE inhibitors
Angiotensin II receptor blockers

21

ACE inhibitors

Captopril
Inhibit formation of angiotensin II from angiotensin I by inhibiting ACE
Do not take during pregnancy

22

Angiotensin II receptor blockers of RAS

Losartan
Block receptors for angiotensin II, causing vasodilation and decrease in BP
Block of receptors on adrenal gland causes decrease of aldosterone release which leads to decrease in Na and water retention

23

Polypharmacy

Multiple agents needed to control BP