Circulatory Notes

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Circulatory Notes
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The Anatomy of the Heart

• There are four chambers in the heart - two atria
  and two ventricles.
• The atria are responsible for receiving blood
  from the veins leading to the heart. When they
  contract, they pump blood into the ventricles.
• It is the ventricles that are the real
  workhorses, for they must force the blood away
  from the heart with sufficient power to push the
  blood all the way back to the heart.

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• The muscle in the walls of the ventricles is much
  thicker than the atria. The walls of the heart
  are really several spirally wrapped muscle
  layers. This spiral arrangement results in the
  blood being wrung from the ventricles during
  contraction.
• Between the atria and the ventricles are valves,
  overlapping layers of tissue that allow blood to
  flow only in one direction. Valves are also
  present between the ventricles and the vessels
  leading from it.

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The Blood Vessels

• There are three types of vessels
• 1. Arteries - a muscular blood vessel that
  carries blood away from the heart.
• 2. Veins - a blood vessel that carries blood to
  the heart.
• 3. Capillaries Small blood vessels, the walls
  are so thin that oxygen and glucose can pass
  through them and enter the cells. Waste products,
  such as carbon dioxide, pass back into the
  bloodstream via the capillaries to be carried
  away and expelled from the body.

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Flow of blood

• Blood from the body flows
• to the Superior and Inferior Vena Cava,
• then to the Right Atrium
• through the Tricuspid Valve
• to the Right Ventricle
• through the Pulmonic Valve
• to the Pulmonary Artery
• to the Lungs

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• The blood picks up oxygen in the lungs, and then
  flows from the lungs
• to the Pulmonary Veins
• to the Left Atrium
• through the Mitral valve
• to the Left Ventricle
• through the Aortic Valve
• to the Aorta
• to the body

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Circulatory Problems

• Atherosclerosis is a degenerative disease that
  results in narrowing of the coronary arteries.
• Coronary arteries can become clogged or occluded,
  leading to damage to the heart muscle supplied by
  the artery.
• Valvular regurgitation occurs when the valves
  become so worn that they cannot close completely,
  and blood flows back into the atria or the
  ventricles.
• Valvular regurgitation occurs when the valves
  become so worn that they cannot close completely,
  and blood flows back into the atria or the
  ventricles.

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Stained cross sections through coronary artery
(left) and a coronary artery with lipid deposits
in its walls (right).