Cardiovascular System

Image Source: sciencenotes.org

  1. Introduction


    • The cardiovascular system (also called the circulatory system) consists of the heart, blood vessels, and blood.
    • Its primary function is to transport oxygen, nutrients, hormones, and waste products throughout the body.
    • It also helps maintain body temperature, pH balance, and fluid homeostasis.

  2. Components of the Cardiovascular System

    A. Heart

    • A muscular organ that pumps blood.
    • Located in the mediastinum of the thoracic cavity, behind the sternum.
    • Size roughly that of a fist.
    • Divided into four chambers:
    • Right atrium
    • Right ventricle
    • Left atrium
    • Left ventricle

    B. Blood Vessels

    • Arteries: carry blood away from the heart (usually oxygen-rich).

    • Veins: carry blood to the heart (usually oxygen-poor).
    • Capillaries: small vessels where exchange of gases and nutrients occurs.

    C. Blood


    • Fluid that carries cells, nutrients, gases, and wastes.
    • Composed of:
    • Red Blood Cells (RBCs)
    • White Blood Cells (WBCs)
    • Platelets
    • Plasma (fluid portion)

  3. Anatomy of the Heart  

     

    Image Source: wikipedia

    External Features

    • Apex: pointed end, directed downward to left.
    • Base: broad upper part.
    • Covered by a double membrane called pericardium (fibrous & serous layers).

    Internal Features

    • Chambers: Right & Left atria (upper), Right & Left ventricles (lower).

    • Valves:
    • Atrioventricular valves (AV): Tricuspid (right), Mitral/Bicuspid (left).
    • Semilunar valves: Pulmonary (right ventricle to pulmonary artery), Aortic (left ventricle to aorta).
    • Septum: Divides heart into right and left sides.

  4. Blood Flow Through the Heart (Circulation Pathway)

    • Deoxygenated blood enters the right atrium from the superior/inferior vena cava.

    • Passes through the tricuspid valve to the right ventricle.
    • Pumped through the pulmonary valve into pulmonary artery → lungs (gas exchange).
    • Oxygenated blood returns via pulmonary veins to the left atrium.
    • Passes through the mitral valve to the left ventricle.
    • Left ventricle pumps oxygen-rich blood through the aortic valve into the aorta → systemic circulation.

  5. Types of Circulation

    A. Pulmonary Circulation

    • Heart to lungs and back.
    • Purpose: oxygenate blood and remove carbon dioxide.

    B. Systemic Circulation

    • Heart to the rest of the body and back.

    • Delivers oxygen/nutrients; removes waste products.

    C. Coronary Circulation

    • Supplies blood to the heart muscle itself.

    • Coronary arteries and veins.

  6. Blood Vessels Structure & Function

    A. Arteries

    • Thick muscular walls.
    • Carry oxygenated blood (except pulmonary artery).
    • High pressure vessels.

    B. Veins

    • Thinner walls, valves to prevent backflow.

    • Carry deoxygenated blood (except pulmonary veins).
    • Low pressure vessels.

    C. Capillaries

    • Single layer of endothelial cells.

    • Site of nutrient and gas exchange.

  7. Cardiac Cycle & Heart Sounds

    Cardiac Cycle

    • Consists of systole (contraction) and diastole (relaxation).

    • Atria contract → ventricles fill.
    • Ventricles contract → blood ejected.
    Heart Sounds
    • “Lub” = closure of AV valves (start of systole).
    • “Dub” = closure of semilunar valves (start of diastole).

  8. Electrical Conduction System of Heart

    Controls heartbeat.

    • Key component

    • SA Node (pacemaker)

    • AV Node

    • Bundle of His

    • Purkinje fibers

    • Generates impulses that cause heart contractions.

  9. Blood Components and Their Functions

    A. Red Blood Cells (Erythrocytes)

    • Transport oxygen via hemoglobin.
    B. White Blood Cells (Leukocytes)
    • Immune defense.
    C. Platelets (Thrombocytes)
    • Blood clotting.
    D. Plasma
    • Transport medium for nutrients, hormones, waste.

  10. Common Cardiovascular Disorders

    • Hypertension (high blood pressure).

    • Coronary artery disease (blockage of coronary arteries).
    • Heart failure (inability to pump sufficient blood).
    • Arrhythmias (abnormal heartbeat).
    • Myocardial infarction (heart attack).
    • Peripheral artery disease (narrowing of arteries).
    • Varicose veins (enlarged veins).

  11. Nursing Considerations

    • Monitor vital signs (pulse, BP, respiratory rate).

    • Promote cardiovascular health (diet, exercise, smoking cessation).
    • Recognize signs of cardiac distress (chest pain, shortness of breath).
    • Administer cardiac medications (beta blockers, diuretics, anticoagulants).
    • Postoperative care for cardiac surgeries.
    • Educate patients about disease prevention and medication adherence.

 

Scroll to Top