4.2 Circulatory System

Introduction

  • Vital network transporting nutrients, oxygen, hormones, and removing waste.
  • Composed of heart, blood vessels, and blood.

Internal Structure of the Heart

  • Muscular organ, acts as a pump.
  • Four Chambers: Two atria (receive blood), two ventricles (pump blood).
  • Valves: Prevent backflow (tricuspid, pulmonary, mitral, aortic).
  • Septum: Separates right and left sides.
  • Pacemaker (SA node): Controls heart rate.

Blood Vessels

  • Arteries: Thick-walled, carry oxygenated blood away from heart (except pulmonary artery).
    • Aorta: Largest artery.
    • Coronary Artery: Supplies heart muscle.
  • Veins: Carry deoxygenated blood back to heart (except pulmonary veins).
    • Vena Cava: Largest vein.
    • Coronary Vein: Drains heart muscle.
  • Capillaries: Tiny vessels connecting arteries and veins; site of exchange.

Circulation of Blood

  • Double Circulation: Blood travels twice through the heart for each complete body circuit.
    • Pulmonary Circulation: Heart → Lungs (oxygenation) → Heart.
    • Systemic Circulation: Heart → Body (oxygen delivery) → Heart.

Blood

  • Fluid consisting of red and white blood cells, plasma, and platelets.
  • Carries oxygen, nutrients, and waste products.

Blood Groups

  • A, B, AB, and O: Determined by antigens on red blood cell surface.
  • Universal Donor: Blood group O.
  • Universal Acceptor: Blood group AB.
  • Palpitations: Rapid, strong, or irregular heartbeat.
  • Cardiac Arrest: Sudden loss of heart function, breathing, consciousness.
  • Hypertension: High blood pressure.
  • Atherosclerosis: Hardening of arteries due to plaque buildup.
  • Heart Attack: Blood flow to heart blocked (often by clot).
  • Stroke: Blood flow to brain interrupted.
  • Heart Failure: Heart can't pump effectively.
  • Arrhythmia: Irregular heartbeat.

Lymphatic System

  • Network of tissues and organs.
  • Rids body of toxins, waste, unwanted materials.
  • Part of circulatory and immune systems.