Cardiovascular System- The Heart Anatomy Chap. 21

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Cardiovascular System-The HeartAnatomy Chap. 21
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• The Cardiovascular system is comprised of the
  heart, blood vessels, blood
• The heart acts as a pump, creating pressure
  which causes blood to move through the blood
  vessels of the body, allowing O2 nutrients to
  be distributed to, wastes removed from, body
  tissues

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Heart Anatomy Overview
Play Heart Anatomy video
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Anatomical Features of the Heart

• The heart lies within the mediastinum of the
  thoracic cavity
• Hollow muscular organ with four internal chambers
• (2) atria (lt. atrium rt. atrium)- receive
  blood from veins
• (2) ventricles (lt. ventricle rt. ventricle)-
  pump blood into arteries

• Superior aspect of heart is the base (3rd
  intercostal space/sternal angle), where the blood
  vessels attach Inferior is the apex (5th
  intercostal space), which rests on the relaxed
  diaphragm

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Pericardium

• The heart lies enclosed within pericardial
  membranes
• Fibrous pericardium (pericardial sac) outer
  layer of dense CT that protects anchors
• Serous pericardium double layered membrane with
  pericardial fluid between
• Parietal pericardium lines the pericardial sac
• Visceral pericardium covers the heart also
  known as the epicardium

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Layers of Heart Wall

• Epicardium (a.k.a. visceral pericardium)
• Myocardium
• Endocardium

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Cardiac muscle tissue
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• Because of the characteristics of cardiac muscle
  tissue the arrangement of connective tissue
  (fibrous skeleton) within the heart, the heart
  basically has two functional units
• the myocardium of the atria (upper chambers) act
  as one functional unit
• the myocardium of the ventricles (lower
  chambers) act as the other

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This allows the atria to contract simultaneously
while the ventricles are relaxed then the
ventricles contract simultaneously while the
atria relax
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• External Features
• Auricles
• Coronary sulcus contains the coronary sinus
• Anterior interventricular sulcus contains
  coronary vessels
• Posterior interventricular sulcus contains
  coronary vessels

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• Atrioventricular (AV) valves
• Tricuspid
• Bicuspid

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Semilunar valves
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Anatomy
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Coronary Circulation

• Myocardium receives oxygenated blood from the
  left right Coronary arteries branches off the
  ascending aorta
• left coronary artery ? anterior interventricular
  branch circumflex branch
• right coronary artery ? marginal branch
  posterior interventricular branch

• Deoxygenated blood is drained through Cardiac
  veins (Great, posterior, middle small cardiac
  veins), which all eventually merge and drain into
  the coronary sinus

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Conducting System

• Intrinsic regulating system that generates
  heartbeat
• comprised of functionally specialized
  autorhythmic (conducting) cells which can
  spontaneously generate action potentials
• SA node (pacemaker) ? AV node ? AV bundle (of
  His) ? Bundle branches ? Purkinje fibers

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Movement of blood through heart heart sounds

• The activity of the conduction system results in
  the contraction (systole) relaxation (diastole)
  of the heart chambers
• atria will contract as ventricles remain relaxed
  (atrial systole/ventricular diastole). Blood
  moves from atria to ventricles
• as atria relax, ventricles begin to contract
  (atrial diastole/ventricular systole). The AV
  valves (tricuspid bicuspid/mitral) snap shut to
  prevent backflow of blood into atria. The closing
  of the valves makes a sound Lub
• as blood moves from ventricles to arteries
  (pulmonary trunk aorta), pressure will increase
  in the arteries and decrease in the ventricles.
  Semilunar valves will then shut ? Dupp as
  ventricles relax
• all 4 chambers will be in diastole, and then
  cycle begins again