Blood Pressure Regulation and Hypertension

Study Notes

Blood pressure is regulated by the interaction of stroke volume (SV) and peripheral resistance (PR)
Sympathetic nervous system (SNS) and renin-angiotensin-aldosterone system (RAAS) play a crucial role in blood pressure regulation

Normal blood pressure is 120/80 mmHg
Hypertension is defined as a systemic arterial pressure exceeding 140/90 mmHg
General narrowing of arterioles is the direct cause of hypertension
Main risk factors for hypertension include obesity, excessive salt consumption, stressful conditions, sedentary lifestyle, and age

Primary hypertension (~90% of cases) is multifactorial, with genetic predisposition and environmental factors contributing to its development
Secondary hypertension (~10% of cases) can be caused by other organ changes, such as kidney disease, hormone overproduction, or atherosclerosis

Treatment of co-morbidities and prevention of target organ damage
Administration of low-dose, long-acting preparations is recommended
Combined treatment is most often used, with options including fixed combination pills or individualized therapy

Reducing stroke volume:
- Diuretics (reduce circulating blood volume)
- Beta-blocking sympatholytics (reduce heart rate and heart muscle function)
Expanding the vascular system:
- Sympatholytics (central nervous system effect or alpha-sympatholytics)
- Drugs that inhibit the RAAS system (beta-blockers, direct renin inhibitors, ACE inhibitors, angiotensin II receptor blockers)
Arteriolar vasodilators:
- Directly acting on vessel walls, promoting NO formation and vasodilation
Ca-channel inhibitors (blockers):
- Reducing intracellular calcium in smooth muscle cells, reducing contraction

Reduce extracellular volume, leading to decreased blood volume and preload, and ultimately decreased SV
After 6-8 weeks, SV recovers, but PR decreases, maintaining the effect
Types of diuretics:
- Thiazides (e.g., hydrochlorothiazide, indapamide)
- Loop diuretics (e.g., furosemide)
- Potassium-sparing diuretics (e.g., eplerenone, aldosterone antagonists)