HEART-Cardiovascular system

HEART-Cardiovascular system

1. Position of heart in the body: behind the sternum (breastbone) and slightly to the left, in the medial cavity of the thorax, the MEDIASTINUM

2. Cover of the heart-PERICARDIUM: is a DOUBLE layered SEROUS MEMBRANE

   • pericardium's functions:
     • 1. Protects heart r.g infections cannot enter heart
       • 2. Anchors/hold heart in position
         • 3. prevent overfilling of heart with blood
           • 4. fluid in the pericardial cavity provides friction-free environment for contraction
   • The membrane has 2 layers:
     • 1. parietal
     • 2. inner visceral layer
     • In-between is fluid

3. Main function of heart is to pump blood around the body

4. 2 main circulations in the heart:

   • 1. Pulmonary circuit: blood is pumped from heart to lungs, and from lungs to heart
     • 1. needs lower pressure to pump blood to lungs, thus less muscles, hence is thinner than 2
   • 2. Systemic circuit: blood is pumped from heart to body, and from body to heart
     • 2. needs higher pressure to pump blood everywhere in the body, hence it needs more muscles, thus it is thicker

5. Structure of heart

   • 1. sides of heart (2)
     • Left ventricle
       • pumps to body (systemic c.), needs higher pressure, more muscles, thicker
     • Right ventricle
       • pumps blood to lungs (pulmonary), less pressure, less muscles, thinner
     • separated by INTERVENTRICULAR SEPTUM
   • 2. layers of the heart wall (3)
     • a.) Epicardium (= inner visceral pericardium)
       • Function: supports blood vessels and nerves
       • b.) Myocardium
         • made of CARDIAC muscle
         • c.) Endocardium
           • made of simple squamous epithelium, covers all inner surfaces, is continuous with blood vessels that present a smooth surface for blood flow
   • 3. chambers of heart (4)
     • Left atrium (thefilling chamber)
     • Right atrium (the filling chamber)
     • Left ventricle (pump)
     • Right ventricle (pump)
   • 4. Valves of the heart (4)
     • A.) Atrioventricular valves (between atria and ventricles) These are anchored by papillary muscles and chordae tendinae)
       • 1. Bicuspid valve (prevents backflow from LV to LA)
       • 2. Tricuspid (prevent backflow of blood from LV to LA)
     • B.) Semilunar valves (between ventricles and major arteries)
       • 3. Aortic semilunar valve (prevents backflow from LV to aorta)
       • 4. Pulmonary semilunar valve (prevents backflow from RV to pulmonary artery)
   • 5. Major blood vessels
     • 1. Aorta
     • 2. Left pulmonary artery
     • 3. L pulmonary vein
     • 4. Right pulmonary veins
     • 5. R pulmonary artery
     • 6. Inferoir vena cava
     • 7. Superior vena cave