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THE HEART

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I. Location

  • A. In the thoracic cavity between lungs, 2/3 left of midsagittal
  • B. Function- pump blood to body and lungs

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II. Pericardial sac (pericardium)

  • A. parietal pericardium
    • 1. External (outer) layer-bag
  • B. epicardium aka: visceral pericardium
    • 1. On heart wall
  • C. pericardial cavity and pericardial fluid
    • 1. Reduce friction

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III. The heart wall

  • A. epicardium (visceral pericardium)-dense connective tissue
    • 1. Penetrated by fat

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  • B. myocardium- cardiac muscle

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  • C. endocardium- simple squamous epithelium (inner lining)

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Cardiac Muscle Cells

  • 1. Have striations (stripes) like skeletal muscle cells, but are smaller
  • 2. One nucleus
  • 3. Intercalated discs
    • Hold the cells together
    • Help make stronger contractions
    • Action potentials can travel quickly from one cell to another

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The Pulmonary circuit goes to the lungs.

The Systemic Circuit goes to the the rest of the body.

Be sure this gets into your notes

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IV. Heart chambers

  • A. 4 chambers
    • 1. Atrium (left and right atria)
      • a. receive blood and pump it to the ventricles
      • b. divided by the septum
      • c. fossa ovalis (foramen ovale)
    • 2. Ventricles (left and right)
      • a. 2 muscular pumps
      • b. divided by the interventricular septum

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V. Heart Valves

  • A. Two atrioventricular valves (AV valves)
    • 1. Tricuspid valve- between right atrium and ventricle
    • Prevents blood from reentering the right atrium
    • 2. Bicuspid (mitral) valve- between left atrium and ventricle
    • Prevents blood from reentering the left atrium
      • a. chordae tendineae and papillary muscles stop valves from going too far

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B. Two semilunar valves

  • 3. Pulmonary semilunar valve- between the pulmonary artery and right ventricle
    • Prevents blood from reentering the right ventricle
  • 4. Aortic semilunar valve- between aorta and left ventricle
    • Prevents blood from reentering the left ventricle

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Coronary Circulation

  • 1. The left and right coronary arteries take oxygenated blood from the aorta
  • Supplies blood to the muscle tissue of the heart

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