Cardiovascular System

• Atria

  • Consists of two upper chambers in the heart.
  • The right atrium receives deoxygenated blood from the body.
  • The left atrium receives oxygenated blood from the lungs.
• Ventricles

  • Two lower chambers of the heart
  • The right ventricle pumps deoxygenated blood to the lungs.
  • The left ventricle pumps oxygenated blood to the body.
• Septum

  • Wall of muscle separating the left and right side of the heart.
  • Prevents mixing of oxygenated and deoxygenated blood.
• Vena Cava


  Large vein bringing deoxygenated blood from the body to the right atrium.
• Pulmonary Vein


  • Brings oxygenated blood from the lungs to the left atrium.
• Pulmonary Artery


  • Carries deoxygenated blood from the right ventricle to the lungs.
• Aorta

  • The largest artery, carries oxygenated blood from the left ventricle to the body.
• Myogenic Muscle

  • The heart muscle can contract without needing nerve signals, making it myogenic.
• Sinoatrial Node (SAN)


  • "Pacemaker" of the heart located in the right atrium.
  • Sets the heart’s rhythm by generating electrical impulses.
• Atrioventricular Node (AVN)


  • Relays electrical signals from the SAN to the ventricles, ensuring a delay so atria contract first.
• Purkinje Fibres and Bundle of His


  • Specialized fibers that transmit electrical signals from the AVN through the ventricles, causing them to contract.
• Cardiac Output (CO): The amount of blood the heart pumps per minute.


  Formula: Cardiac Output = Stroke Volume × Heart Rate

  • Stroke Volume (SV): Blood pumped out of the ventricle in one beat
  • Heart Rate (HR): Number of beats per minute.
• Arteries

  • Elastic walls: Allow arteries to expand and recoil to maintain high pressure.
  • Small lumen: Maintains high pressure for blood flow.
  • Thick muscle layer: Provides strength and adjusts the diameter to regulate flow.
  • High pressure: Pushes blood quickly to tissues.
• Veins


  • Large lumen: Reduces resistance to blood flow.
  • Valves: Prevent backflow of blood, especially against gravity.
  • Thin walls: Low blood pressure means less need for thick layers.
• Capillaries


  • Link arteries and veins: Connect arterioles to venules.
  • One cell thick: Facilitates efficient diffusion of oxygen, nutrients, and waste.
  • Site of diffusion: Exchange of gases, nutrients, and waste between blood and tissues.
• Cardiac Cycle


  • Atrial Systole: Atria contract, pushing blood into the ventricles.
  • Ventricular Systole: Ventricles contract, sending blood to the lungs and body.
  • Cardiac Diastole: Heart chambers relax, blood fills atria from veins.
• Opening and Closing of Heart Valves


  • Valves ensure blood flows in one direction.
  • Open and close in response to pressure changes during the cardiac cycle.
• • Arrhythmias:

  • Tachycardia: Fast heart rate.
  • Bradycardia: Slow heart rate.
  • Ventricular Fibrillation: Erratic electrical activity in ventricles.
• Factors Increasing Risk of Cardiovascular Disease (CVD)


  • Uncontrollable: Genetics, age, gender.
  • Controllable: Diet, high blood pressure, smoking, inactivity, caffeine.
• • Antihypertensives:

  • Benefits: Reduce blood pressure.
  • Risks: Dizziness, fainting.
• Statins:


  • Benefits: Lower cholesterol.
  • Risks: Muscle pain, liver damage.
• Transplantation and Immunosuppressants:


  • Benefits: Replaces diseased heart.
  • Risks: Increased infection risk due to immunosuppressants.
• Ventilation and Gas Exchange


  Lung Structure:

  • Trachea, bronchi, bronchioles: Airway passages.
  • Alveoli: Sites of gas exchange.
  • Capillary Network: Surrounds alveoli to facilitate gas exchange.
  • Pleural Membranes: Reduce friction during breathing.
• Mechanics of Ventilation:


  • Inspiration:
  • Diaphragm contracts and flattens, intercostal muscles lift ribs.
  • Thorax volume increases, pressure decreases, air flows in.
  • Expiration:
  • Diaphragm relaxes, intercostal muscles lower ribs.
  • Thorax volume decreases, pressure increases, air flows out.
• Principles of Gas Exchange:


  • Efficient Exchange: Large alveolar surface area, one-cell-thick walls, proximity to capillaries, moisture, diffusion gradients.
• Spirometer and Lung Volumes


  • Tidal Volume (TV): Air inhaled/exhaled in a normal breath.
  • Inspiratory Reserve Volume (IRV): Extra air inhaled beyond normal.
  • Residual Volume (RV): Air left in lungs after maximum exhalation.
  • Vital Capacity (VC): Maximum volume of air exhaled after maximum inhalation.
  • Total Lung Capacity (TLC): Total volume of air lungs can hold.
• Urinary System Structure and Function

  Kidney Functions:

  • Excretion: Removes urea, toxins, excess salts, and water.
  • Osmoregulation: Maintains water and electrolyte balance.
• Nephron Structure:


  • Glomerulus: Filters blood via ultrafiltration.
  • Bowman’s Capsule: Collects filtrate.
  • Proximal Convoluted Tubule: Reabsorbs glucose and ions.
  • Loop of Henle: Concentrates urine by reabsorbing water.
  • Collecting Duct: Adjusts water reabsorption, controlled by ADH.
• Treatments:

  • Dialysis: Removes waste via a machine.
  • Transplant: Replaces a damaged kidney but requires immunosuppressants.