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Pathophysiology Circulatory System

Circulatory System Study Guide

1. Heart Valves

Normal Physiology

  • Ensure unidirectional blood flow through heart chambers.

  • Atrioventricular (AV) valves:

    • Tricuspid: Between right atrium & ventricle.

    • Mitral/Bicuspid: Between left atrium & ventricle.

  • Semilunar valves:

    • Pulmonic valve: Controls flow to pulmonary artery.

    • Aortic valve: Controls flow to aorta.

Pathological Changes & Predisposing Factors (PF)

  • Stiffening or deformity of valves.

  • Causes:

    • Congenital defects.

    • Scar tissue from trauma, ischemia, or inflammation.

Nursing Problems & Assessment Findings

  • Valvular stenosis (narrowing).

  • Valvular regurgitation (incompetence).

2. Pericardium

Normal Physiology

  • Two layers:

    • Tough outer layer resists distention.

    • Serous inner layer forms a cavity with fluid for lubrication.

  • Functions:

    • Protects heart from friction/injury.

    • Prevents overfilling of the heart.

Pathological Changes & PF

  • Pericardial effusion (excess fluid in pericardial cavity).

  • Causes: Trauma, inflammation, cancer, myocardial infarction (MI).

Nursing Problems & Example Disorders

  • Disorder: Pericardial effusion.

3. Myocardium

Normal Physiology

  • Function: Heart's working muscle; involuntary contractions.

Pathological Changes & PF

  • Cardiomyopathy (disease of heart muscle).

  • Causes: Genetics, infections, ischemia, autoimmune diseases, drugs.

Nursing Problems & Example Disorders

  • Disorder: Cardiomyopathy, Myocardial infarction (MI).

4. Endocardium

Normal Physiology

  • Function: Lines the heart wall.

Pathological Changes & PF

  • Infective endocarditis (bacterial infection leading to vegetative lesions).

  • Causes: Heart defects, prosthetic valves, dental/oral infections, skin lesions.

Nursing Problems & Example Disorders

  • Disorder: Infective endocarditis.

5. Ventricles

Normal Physiology

  • Right ventricle: Pumps blood to lungs.

  • Left ventricle: Pumps blood to the body.

Pathological Changes & PF

  • Heart failure → compensatory mechanisms:

    • ↑ Sympathetic activity.

    • RAAS activation (fluid retention).

    • Myocardial hypertrophy (heart muscle thickening).

  • Causes: MI, cardiomyopathy, hypertension, fluid overload.

Nursing Problems & Example Disorders

  • Right heart failure:

    • Forward effects: Poor oxygenation.

    • Backward effects: Peripheral edema, ascites.

  • Left heart failure:

    • Forward effects: Poor systemic circulation.

    • Backward effects: Pulmonary congestion, dyspnea.

6. Blood Vessels

Structure of Blood Vessels

  • Tunica externa: Connective tissue for support.

  • Tunica media: Smooth muscle for contraction/relaxation.

  • Tunica intima: Endothelial lining for smooth blood flow.

A. Arteries & Arterioles

  • Function: Carry oxygenated blood to tissues.

  • Pathological Changes & PF:

    • Atherosclerosis, embolism, thrombus, trauma.

  • Nursing Problems:

    • Ischemia: Inadequate oxygen supply.

    • Infarction: Tissue death.

  • Example Disorders:

    • Chronic: Peripheral Artery Disease (PAD).

    • Acute: Acute arterial occlusion.

B. Capillaries

  • Function: Site of gas, nutrient, and waste exchange.

  • Pathological Changes & PF:

    • Trauma, ischemia.

C. Venules & Veins

  • Function: Return blood to the heart.

  • Pathological Changes & PF:

    • Chronic venous insufficiency (CVI) – incompetent valves.

    • Deep vein thrombosis (DVT) – clot formation.

Key Nursing Considerations

  • Monitor signs of heart failure: Fluid retention, dyspnea, fatigue.

  • Assess circulation: Capillary refill, pulses, skin temperature.

  • Prevent complications: Early mobilization, anticoagulants for DVT risk.

  • Educate patients: Lifestyle changes for heart health, medication adherence.