Pathophysiology of Cardiovascular System

Pathophysiology of the Cardiovascular System

• Hypertension is a primary risk factor for cardiovascular disease and mortality in industrialized nations.
• Complications of hypertension include hypertensive urgencies/emergencies and diabetic hypertension.
• Types of circulations: Pulmonary, Systemic, and Coronary.

Heart Circulations

• Pulmonary Circuit: Carries deoxygenated blood from the heart to the lungs.
• Systemic Circuit: Transports oxygenated blood from the heart to the rest of the body.
• Coronary Circuit: Supplies blood to the heart muscle itself.

Types of Cells in the Heart

• Cardiac Electrical Cells (Pacemaker Cells): Generate and conduct electrical impulses; include SA and AV nodes.
• Cardiac Muscle Cells (Myocardial Cells): Responsible for contraction; contractile properties.

Cardiac Cycle and Function

• Cardiac Output (CO): Volume of blood ejected from the ventricle to the body per minute.
• Preload: The amount of blood in the ventricle before contraction; influenced by venous return.
• Afterload: Resistance the heart faces when pumping blood.
• Heart Rate (HR): Number of heartbeats per minute.
• Stroke Volume (SV): Blood volume pumped from the left ventricle per beat.

Cardiac Feedback Loops

• Physical Exam Symptoms: Headaches, dizziness, blurred vision, palpitations, chest pain, and difficulty breathing.
• Laboratory tests for cardiac evaluation include ECG and exercise tolerance tests.

Complications of Hypertension

• Classified into hypertensive urgency (non-organ damage) and hypertensive emergency (organ damage).
• Diabetic Hypertension: Common in individuals with diabetes; results from blood vessel damage.
• Gestational Hypertension: Develops post-20 weeks of pregnancy; can evolve into preeclampsia, impacting organ systems.

Autonomic Regulation of Heart Function

• Medulla: Controls heart function via sympathetic and parasympathetic nervous systems.
• Baroreceptors sense arterial pressure changes; chemoreceptors detect changes in blood gases.

Chemical Factors Influencing Heart Function

• Hormones: Adrenaline increases cardiac contractility and conduction speed.
• Electrolytes: Calcium and potassium levels influence heart cell firing rates and contraction strength.

The Vascular System

• Comprises arterial and venous systems, facilitating blood flow throughout the body.
• Arterial System: Moves blood away from the heart.
• Venous System: Returns blood from capillary beds to the heart.

Blood Pressure Regulation

• Formula: Blood Pressure (BP) = Cardiac Output (CO) × Total Peripheral Resistance (TPR).
• Factors affecting blood pressure include cardiac pump efficiency, blood volume, and arterial wall elasticity.

Types and Stages of Hypertension

• Primary Hypertension: Often caused by renin-angiotensin-aldosterone system abnormalities and high sodium intake.
• Secondary Hypertension: Related to underlying conditions like thyroid dysfunction, diabetes, and certain medications.

Renin-Angiotensin System (RAS)

• Regulates blood pressure and fluid balance; crucial for maintaining circulatory homeostasis.

Diagnosis and Management of Hypertension

• Diagnosis requires multiple BP readings and consideration of medical history and family history.
• Management strategies include lifestyle modifications (diet, exercise, smoking cessation) and medications (ACE inhibitors, diuretics).

Case Study: Mary Jones

• Symptoms: Occasional headaches, fatigue, and elevated blood pressure (150/90 mmHg).
• History: Smoker, family history of hypertension; exhibits signs of stage 1 hypertension based on BP readings.

This quiz covers the pathophysiology of the cardiovascular system, including the heart's electrical cells, muscle cells, and circulatory paths. Learn about the pulmonary, systemic, and coronary circuits and how they function. Get ready to test your knowledge!