Heart Anatomy

  

Photo of Nathan taken by Dr. Haus

The Heart

The heart is the organ that pumps the blood throughout the entire body.  The heart plus all the blood vessels of the body is called the cardiovascular system.  The cardiovascular system ensures that nutrients are brought to and all waste materials are brought away from the cells of the body.

The cardiovascular system is essentially a simple plumbing system.  There are a large amount of pipes of various sizes (blood vessels) and one pump (the heart) that keeps the water (blood) moving.  Understanding the anatomy of the heart is critical to understanding how the heart functions and what is occurring in a sick heart.

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Heart Anatomy

The heart consists of three types of structures:  blood vessels, heart chambers, and heart valves.  Each component of the heart allows the heart to achieve its function of moving blood throughout the body.

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Blood Vessels

The major blood vessels of the heart are the cranial (superior) vena cava, the caudal (inferior) vena cava, the pulmonary artery, the pulmonary vein, and the aorta.  The terms cranial and caudal vena cava are the term for these vessels in quadruped species (species that walk on four legs).  The terms superior and inferior are used in bipedal species such as humans who walk on two legs.

The cranial (superior) vena cava, caudal (inferior) vena cava, and pulmonary artery all carry deoxygenated blood which is blood that has a LOWER amount of oxygen in it.  This blood needs to be delivered to the lungs where carbon dioxide is removed from the blood while oxygen is placed into the blood.  This is done through the process of breathing.  

Remember, an artery moves blood AWAY from the heart regardless of whether the vessel contains a high or low amount of oxygen in it.

The pulmonary vein and aorta carry oxygenated blood which is blood that has a HIGHER amount of oxygen in it.  Oxygenated blood needs to be delivered to the cells of the body to bring them oxygen.  This is done through the heart beating and the blood moving within the vascular system.

Remember, a vein carries blood TOWARDS the heart regardless of whether the vessel contains a high or low amount of oxygen in it.

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Heart Chambers

There are four (4) heart chambers in mammals, birds, and crocodilians.  These heart chambers collect blood while the heart is relaxing and then push the blood in a forwards direction when the heart is beating.  The four (4) heart chambers are the right atrium, the left atrium, the right ventricle, and the left ventricle.

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Heart Valves

Lastly, the four-chambered heart contains four (4) heart valves.  The heart valves prevent the blood from flowing in a backwards direction.  Remember, the blood must move in the forwards direction or else the blood will not be able to flow throughout the body.  When blood moves backwards in a disease state, the body will become sick as there will not be enough oxygen getting to the cells of the body.

The four (4) heart valves are the tricuspid (right atrioventricular) valve, the bicuspid (mitral or left atrioventricular valve), the pulmonary valve, and the aortic valve.

Key:

1.  Cranial (superior) vena cava

2.  Caudal (inferior) vena cava

3.  Tricuspid (right atrioventricular) valve

4.  Pulmonary valve

5.  Pulmonary artery

6.  Pulmonary veins

7.  Bicuspid/mitral (left atrioventricular) valve

8.  Aortic valve

9.  Aorta

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