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The Heart

The Heart. Location and Structures. Structure cross section. location. Within the thoracic cavity Between the lungs In Mediastinal cavity (mediastinum) The base of the Heart is posterior to the sternum Cone shape; approximately the size of your fist

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The Heart

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  1. The Heart Locationand Structures

  2. Structure cross section

  3. location • Within the thoracic cavity • Between the lungs • In Mediastinal cavity (mediastinum) • The base of the Heart is posterior to the sternum • Cone shape; approximately the size of your fist • Apex of the Heart is superior to the diaphragm, just left of the midline

  4. Pericardial membrane encloses the heart • 3 layers • Fibrous outer layer, is a sac that encloses the heart. Called the fibrous pericardium. (fibrous connective tissue) • Serous membrane with 2 layers that line the fibrous pericardium • Parietal pericardium • Visceral pericardium (epicardium) between these membranes is a serous fluid that prevents rub/friction as the heart beats.

  5. All 4 chambers of the heart are made of myocardium All 4 chambers are lined with endocardium (squamous epithelium, including the valves and the inside of the vessels entering and leaving the heart. Cardiac muscle (smooth muscle action with striated appearance)

  6. Important to note that this is very smooth muscle and it is designed to prevent any aggregation of blood that might initiate clotting. Any rough surface inside the heart or vessels is considered abnormal; and contributes to or is secondary to disease of the heart and vessels. (CAD)

  7. Two upper chambers Left and right atria (plural) atrium (singular) Separated by the interatrial septum Two lower chambers Left and right ventricles Thicker wall separated by the interventricular septum 4 heart chambers

  8. Valves: 4 valves function inside the heart: location and function is stated below • 1. Tricuspid valve: located between the rt. atrium and the rt. ventricle; it opens to allow blood to flow from the rt. atrium into the rt. Ventricle and closes to prevent backflow of blood when the ventricle contract. • 2. Pulmonary (semilunar) valve: located at the junction of the rt. Ventricle and the entrance to the rt. pulmonary artery

  9. Valves continues • 3. Mitral valve: between the left atrium and the left ventricle, allows blood to flow into the left ventricle and prevents backflow of blood when the lft ventricle contracts. • 4. Aortic (semilunar) valve: at the junction of the left atrium and the lft ventricle, prevents backflow when the left ventricle contracts.

  10. Right Atrium Receives blood returning from the upper and lower body via the superior and inferior vena cava (largest veins in the body) The blood returning is deoxygenated blood. During atrial contraction this blood is pumped through the R. atrioventricular valve aka The tricuspid valve (having 3 flaps or cusps). The purpose of valves is to prevent backflow of blood. **leaking valves are a pathological condition contributing to disease processes. Two Atria

  11. Blood enters the R. ventricle from the R. atrium, passing through the tricuspid valve (R. AV valve) From here the blood still w/o oxygen is pumped into the pulmonary artery to the lungs ** the pulmonary artery is the only artery that carries deoxygenated blood. When the R. ventricle contracts the tricuspid valve closes. With contraction the blood goes through the pulmonary valve. Some time called the semilunar valve. It closes when the ventricle relaxes and prevents backflow. Now the blood is in the lungs picking up oxygen. Right Ventricle

  12. From the 4 Pulmonary veins *** only vein in the body to carry oxygenated blood The blood returns into the Left atrium and then flows through the Left atrioventricular valve aka MITRAL VALVE, OR BICUSPID VALVE Into the Left Ventricle. This ventricle has a much thicker myocardial wall. Major pump of the heart and it functions to push all blood out to the body, leaving through the aortic semilunar valve First to the AORTA –largest artery, and immediately the first oxygenated blood branches off to……TBA…………… ** as the pressure of contraction opens the aortic valve the mitral valve closes Blood returning from the lungs

  13. FYI • All valves within the heart are attached to the heart wall with tendons called chordae tendineae and muscles known as papillary muscles. • The heart is actually 2 pumps that contract simultaneously: the atria contract together and then the ventricles contract together

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