Topic 14-The Heart-Hanna Levi



The Heart


Function: Pumps blood to the lungs for oxygenation and pumps oxygenated blood to the rest of the body.

external image heart_anatomy.gif
Anatomy
  • Size: The heart weighs between 200 and 425 grams (7 to 10 ounces) and is a little bigger then the size of your fist
  • Layers
    • Pericardium: The outermost layer that helps keep the heart in place and prevents it from overfilling with blood.
    • Myocardium: The muscular wall of the heart. The orientation of the heart muscles helps squeeze blood through the heart in the proper directions.
    • Endocardium: The innermost layer that lines the surface of the valves and chambers.

  • Chambers
    • Atria:
      • Right Atrium: Receives blood from the systemic circulation.
      • Left Atrium: Receives blood from the pulmonary circulation.
    • VentriclesRight Ventricle: Pumps blood to the lungs.
      • Left Ventricle: Pumps blood to the rest of the body.

  • Valves: Control the direction of blood flow.
    • Tricuspid: Allows for blood to flow from the right atrium to the right ventricle.
    • Pulmonary: Allows for blood to flow from the right ventricle into the pulmonary arteries.
    • Bicuspid (mitral): Allows for blood to flow from the left atrium to the left ventricle.
    • Aortic: Allows for blood to flow from the left ventricle into the aorta.

  • Coronary Circulation: The major blood vessels lie on the surface of the heart. They originate at the base of the aorta from openings called ostia. ------------ -----------------------------------------------------------------------------------------------------------------------------------Major Arteries:
    • Left main coronary artery divides into:
      • Left Anterior Descending (LAD)
      • Circumflex
    • Right coronary artery

  • Conduction System: Controls the heart rate using electrical impulses from the pacemaker located in the right atrium.


Blood flow through the heart
external image heart_showing_blood_flow.gif

  • Flow through the right side of the heart (oxygen poor)
    1. Vena Cavae: Returns deoxygenated blood from systemic circulatory system
    2. Right Atrium
    3. Tricuspid Valve
    4. Right Ventricle
    5. Pulmonary Valve
    6. Pulmonary Artery: Deoxygenated blood to the lungs

  • Flow through the left side of the heart (oxygen rich)
    1. Pulmonary Veins: Returns oxygenated blood from the pulmonary system
    2. Left Atrium
    3. Bicuspid (Mitral) Valve
    4. Left Ventricle
    5. Aortic Valve
    6. Aorta: Oxygenated blood to the body


Examples of medical problems involving the heart
  • Atherosclerosis (coronary artery disease) resulting in blockage of the coronary arteries
    • Causes/Risk Factors
      • Geneticsatherosclerosis.jpg
      • Age
      • Obesity
      • Smoking
      • Hypertension (High blood pressure)
      • Hyperlipidemia (Elevated cholesterol)
      • Diabetes (Elevated blood sugar)
    • Mechanism
      • Plaque build up
      • Thrombosis (clot)
    • ComplicationsAngina (chest pain)Myocardial infarction (heart attack)
      • Arrhythmia (abnormal heart rhythm) including sudden death from ventricular fibrillation

  • Valvular disease (Stiffening or leakage of the valves)
    • Causes
      • Congenital (born with it)
      • Infection
      • Hypertension
    • Complications
      • Congestive Heart Failure (weakening of the heart muscle resulting in fluid build up in the lungs and body)
      • Infection
      • Arrhythmia

  • Cardiomyopathy (abnormality of the heart muscle)
    • Causes
      • Genetics
      • Hypertension
      • Obesity
      • Viral Infection
    • Complications:
      • Heart Failure
      • Arrhythmia