Hypertension Flashcards
Hypertension
• Hypertension – high blood pressure
– Maybe transient or persistent
– Primary (essential) or secondary
• Hypertension is defined as chronically elevated blood pressure with a systolic pressure of 140mmHg or above or a diastolic pressure of 90mmHg or above (WHO)
• If other risk factors are present then a BP of 135/85 is classed as hypertension
Regulation of Blood Pressure
• Blood pressure is regulated by numerous
mechanisms including:
– The renin angiotensin aldosterone system
– Natriuretic Peptide (ANP & BNP) Release
– Aldosterone release
– other mechanisms include
antidiuretic hormone (ADH) and regulation of
blood volume
Renin Angiotensin Aldosterone –
Renal Control of Blood Pressure
• Renin is released in response to low blood
pressure
* the plasma protein angiotensinogen
is converted to Angiotensin I by renin then to Angiotensin II by the Angiotensin converting enzyme (ACE)
Impact of Aldosterone Release
Increased sodium reabsorption means increased water reabsorption (osmosis)
Increased water reabsorption means increased blood volume
Increased blood volume means increased blood pressure
Impact of Atrial Natriuretic Peptide
(ANP) Release
ANP helps reduce blood pressure
The decrease in renin release also inhibits ADH and aldosterone release
A decrease in ADH and aldosterone will
reduce water reabsorption and sodium retention leading to decreased blood volume and decreased blood pressure
Decreased angiotensin also causes
vasodilation and decreased blood
pressure
B- and C-type natriuretic peptides
also have very important actions
*BNP has most influence on ventricles
Regulation of Sodium and Water Balance
and the Maintenance of Blood Pressure
Mechanisms do not work
alone (increase interconnected)
The renin angiotensin system, the release of ADH and neural regulation via the sympathetic nervous system all help maintain blood pressure homeostasis
Primary or Essential Hypertension
• 90% of cases of hypertension • no underlying cause identified • cannot be cured but can be controlled • Likely to be a mix of hereditary and environmental (life style) factors: – Heredity (runs in families) – Diet, high salt intake, saturated fat and cholesterol and deficiency of K+, Ca2+ and Mg2+ – Obesity – Age, post 40+ years – Diabetes mellitus – Stress – Smoking, nicotine is a vasoconstrictor – Excessive alcohol intake • Control: – Diet: restriction of salt, fat cholesterol intake – Losing weight – Stop smoking – Reduce alcohol intake – Manage stress Unfortunately can’t change the genes you inherit and your age. Can manage your environment/lifestyle. • Control: anti-hypertensive drugs
Secondary Hypertension
• 10% of cases of hypertension
• Cause is identifiable
– renal failure/obstruction of renal arteries
– pregnancy
– Hyperthyroidism
• Also sleep apnoea, oestrogen and glucocorticoid administration, anti-inflammatory agents, other drug treatments (eg. Cyclosporin, sympathomimetics).
• Rarer causes of severe or resistant hypertension (esp. in younger individuals) are aortic coarctation, phaeochromocytoma, Cushing’s syndrome &Conn’s syndrome. (from NZ Primary Care Handbook).
• Correction is by resolving the cause and if
treated the blood pressure will return to normal
Effects of Hypertension on the Body
- stroke
- blood vessel damage
- heart attack or heart failure
- kidney failure
Hypertension promotes atherosclerosis
Hypertension causes:
• Damage to the endothelium of the blood vessels
• Thickening of the arterial wall and decreased lumen
• A decreased lumen will increase peripheral
resistance
• An increased peripheral resistance will increase fat deposits decreasing the lumen further.
Hypertension effects the heart
- thickening the walls of the ventricles
Hypertension Prevention and Control
Exercise and healthy weight
Lifestyle changes and/or medication may reduce high BP to healthy levels.
- diuretics, beta-blockers, potassium replacements, calcium channel blockers & ACE inhibitors.
