Hypertension Flashcards
Determinants of blood flow
Change in blood pressure
Resistance
Vascular Tone
Clinical hypertension
Defined as a rise in arterial pressure sufficient to raise the incidence of strokes, myocardial infarction, heart failure and renal failure
Essential (primary hypertension)
Generally described as a blood pressure that is associated with significant cardiovascular risk
Secondary hypertension
Associated with other conditions such as renal disease, hyperthyroidism, pregnancy, use of drugs
“Normal” blood pressure
Depends on age, gender, ethnicity
Influenced by weight, food consumption, genes, stress etc
Baroreceptors
Mechanoreceptors
Sensitive to pressure or stretch
Increases in arterial pressure leads re increased stretch on the baroreceptors
This causes increased firing rate in the afferent nerves
The opposite happens when there is a decrease in pressure
When to treat hypertension
With low risk patients: BP 140/90 mmHg
Changes to lifestyle can control hypertension
Non-pharmacological interventions
Diet (control salt intake), exercise, smoking, alcohol, life-style
Pharmacological interventions lower BP by:
Reducing TPR: Reduce vasoconstriction via relaxation of vascular smooth muscle
a- adrenoreceptors leads to vasoconstriction
angiotensin II leads to vasoconstriction
Calcium channel blockers leads to vasodilation
Reducing CO: reduce blood volume, reduce cardiac force (and rate)
Diuretics leads to reduce blood volume
ẞ1 and ß2 adrenoreceptors antagonists leads to reduce cardiac force (and rate)
a1 adrenoreceptors
Receptors lie close to site of release and are mainly responsible for neuronally-mediated vasoconstriction
a2 adrenoreceptors
Receptors lie elsewhere on the muscle fibres and are activated by hormonally released (circulating) catecholamines
a adrenoreceptors ANTAGONISTS
Reduce a-mediated vasoconstriction, hence also reduce TPR
Phentolamine
Non-selective (a1 and a2) adrenoreceptor antagonist
