the heart

• Heart


  • 4 chambers divided by a muscular wall called the septum
  • Left and right atria
  • Left and right ventricles
• Blood flow through the heart

  1. Blood flows from atria to ventricles

  2. Ventricles contract to pump blood out of the heart into arteries
• Valves


  One-way valves that prevent backflow of blood
• Coronary arteries


  Deliver blood supply to the heart muscle (myocardium)
• Monitoring heart activity


  1. Heart sounds using stethoscope

  2. ECG to monitor electrical activity

  3. Pulse rate to measure heart rate
• Physical activity


  Increases heart rate to meet increased demand for oxygen and glucose
• Heart valves


  • 2 atrioventricular valves between atria and ventricles
  • 2 semilunar valves at entrances to major arteries
• Atrioventricular valves


  Close when ventricles contract to prevent backflow
• Semilunar valves


  Open when ventricles contract to allow blood flow, close when ventricles relax to prevent backflow
• Ventricle walls


  • Thicker and stronger than atria to generate higher pressure
  • Left ventricle wall thicker than right to pump blood to all organs
• Septum


  Divides the two sides of the heart to prevent mixing of oxygenated and deoxygenated blood
• Coronary heart disease is caused by blockages in the coronary arteries that restrict blood flow to the myocardium
• Risk factors for coronary heart disease

  • Lifestyle factors (diet, stress, smoking, lack of exercise)
  • Non-modifiable factors (age, sex, genetics)
• Excessive calorie intake and certain nutrient consumption can cause inflammation and plaque buildup in arteries
• Smoking increases risk of death from coronary heart disease
• Lack of exercise weakens the heart muscle and reduces its efficiency
• Coronary heart disease risk increases with age and is more common in men than women
• Stress increases blood pressure, a significant risk factor for heart disease