7.1 Alterations in Blood Pressure and Flow

High blood pressure strains the heart and blood vessels, leading to serious health issues. This section explores how hypertension develops, from narrowed arteries to an overactive hormone system, and its impact on the body.

We'll also look at the difference between primary and secondary hypertension, their causes, and diagnosis. Then, we'll dive into low blood pressure, its risks, and how changes in blood flow affect our health.

Hypertension and Blood Pressure Alterations

Pathophysiology of hypertension

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Top images from around the web for Pathophysiology of hypertension

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  Frontiers | Endothelial Dysfunction in Hypertension: Current Concepts and Clinical Implications View original

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• Sustained elevated blood pressure above 130/80 mmHg increases strain on cardiovascular system
• Increased peripheral vascular resistance narrows arterioles impeding blood flow
• Elevated cardiac output forces heart to pump harder and faster
• Overactive renin-angiotensin-aldosterone system (RAAS) promotes sodium retention and vasoconstriction
• Left ventricular hypertrophy thickens heart muscle reducing pumping efficiency
• Arterial stiffening decreases vessel elasticity impairs blood flow
• Endothelial dysfunction impairs vasodilation and promotes inflammation
• Atherosclerosis narrows arteries further restricting blood flow
• Increased risk of heart failure due to prolonged cardiac stress
• Higher incidence of coronary artery disease from damaged vessel walls
• Greater likelihood of stroke from weakened cerebral blood vessels

Primary vs secondary hypertension

• Primary (essential) hypertension has no identifiable underlying cause accounts for 90-95% of cases
• Primary hypertension influenced by genetic predisposition and environmental factors (diet, stress)
• Secondary hypertension caused by identifiable underlying condition accounts for 5-10% of cases
• Secondary hypertension causes include renal artery stenosis narrowing kidney blood supply
• Pheochromocytoma tumor secretes excess catecholamines raising blood pressure
• Primary aldosteronism overproduces aldosterone increasing sodium retention
• Cushing's syndrome excess cortisol production leads to hypertension
• Primary hypertension diagnosed through exclusion of other causes
• Secondary hypertension requires targeted testing based on suspected underlying condition

Blood Flow Alterations and Hypotension

Risk factors for hypotension

• Blood pressure below 90/60 mmHg can lead to inadequate organ perfusion
• Dehydration reduces blood volume decreasing cardiac output
• Blood loss from trauma or internal bleeding rapidly lowers blood pressure
• Severe infection or sepsis causes vasodilation and capillary leakage
• Certain medications (diuretics, beta-blockers) can excessively lower blood pressure
• Endocrine disorders (Addison's disease) disrupt hormonal blood pressure regulation
• Dizziness and fainting result from reduced cerebral blood flow
• Reduced organ perfusion can cause multi-organ dysfunction
• Shock in severe cases leads to life-threatening circulatory failure
• Cognitive impairment in elderly patients due to chronic cerebral hypoperfusion

Altered blood flow mechanisms

• Changes in blood vessel diameter affect blood flow resistance
• Vasoconstriction narrows vessels increasing blood pressure
• Vasodilation widens vessels decreasing blood pressure
• Alterations in blood viscosity affect flow dynamics and resistance
• Obstruction of blood vessels impedes normal circulation
• Thrombosis forms blood clots within vessels
• Embolism occurs when clots or other materials travel and lodge in vessels
• Ischemia results from reduced oxygen supply to tissues risking damage
• Edema develops from fluid accumulation due to increased capillary permeability
• Altered organ function impacts multiple body systems
• Kidneys experience reduced glomerular filtration rate impairing waste removal
• Brain may suffer cognitive impairment or stroke from inadequate blood flow
• Heart can develop myocardial infarction or heart failure from poor perfusion
• Baroreceptor reflex rapidly adjusts heart rate and vessel tone to maintain pressure
• Hormonal responses (antidiuretic hormone, aldosterone) regulate blood volume and pressure