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The heart is located in the __1__, where is is surrounded by a tough fibrous membrane called the _2_,. The _3_ ___ is the actual compartment formed by the _2_ that encloses the heart.
1- mediastinum
2- pericardium
3- pericardial sac
Which portion of the heart is the base?
The base of the heart is the broad superior end, where the large vessels attach.
Which portion of the heart is the apex?
About 2/3 of the heart is to the left of the midsagittal plane, with its apex of the heart, or cone-shaped end, pointing downward (to the left), in contact with the diaphragm.
What is the relationship between the heart and the lungs?
Ventilation of the lungs brings oxygen in contact with blood from the heart. The pumping action of the heart then circulates the oxygenated blood through the body and returns deoxygenated blood to the lungs for removal of carbon dioxide.
The vessels that connect the heart and lungs are called ____.
Pulmonary vessels
Structure of the Epicardium (visceral pericardium).
Serous membrane of connective tissue, covered with epithelium and including blood capillaries, lumph capillaries, and nerve fibers.
Function of the Epicardium (visceral pericardium).
Lubricative outer covering.
Structure of the myocardium.
Cardiac muscle tissue, separated by connective tissues and inbluding blood capillaries, lymph capillaries, and nerve fibers.
Function of the myocardium.
Contractile layer to eject blood from heart chambers.
Structure of the endocardium.
Epithelial membrane and connective tissues, including elastic and collagenous fibers, blood vessels, and specialized muscle fibers.
Function of the endocardium.
Strengthened protective inner lining of the chambers and valves.
Which of the three heart layers is the thickest? Why?
The myocardium, especially in the ventricular walls, where forceful contraction is necessary to pump blood throughout the body. Also thicker around the left ventricle.
What are the trabeculae carneae?
Latticelike arrangement of the endocardium. It cosists primarily of dense fibrous connective tissues; it provides a strong, flexible framework for the walls of the lower heart chambers.
What are the 2 upper chambers of the heart, and what divides them?
upper right and upper left atria, separated by the thin, muscular interatrial septum.
What are the 2 lower chambers of the heart, and what divides them?
lower right and lower left ventricles, separated by the thick, muscular interventricular septum.
What valve is located between the right atrium and right ventricle?
Right atrioventricular valve (AV valve), also know as the tricuspid valve.
What is the structure & function of the tricuspid valve?
Composed of 3 cusps that prevent a backflow of blood from the right ventricle into the right atrium during ventricular contraction.
What valve is located between the right ventricle and the pulmonary trunk?
The pulmonary semilunar valve.
What is the structure & function of the pulmonary semilunar valve?
Composed of 3 half-moon shaped flaps that prevent a backflow of blood from the pulmonary trunk into the right ventricle during ventricular relaxation.
What valve is located between the left atrium and the left ventricle?
The left atrioventricular valve (AV valve), also known as the bicuspid or mitral valve.
What valve is located between the left ventricle and the ascending aorta?
The aortic semilunar valve.
What is the structure and function of the aortic semilunar valve?
Composed of 3 half-moon-shaped flaps that prevent backflow of blood from the aorta into the left ventricle during ventricular contraction.
Describe the structure & functions of the papillary muscles & chordae tendineae?
Each cusp of the AV valves is held in position by strong tendinous cords, the chordae tendineae, which are secured to the ventricular wall by cone-shaped papillary muscles. As blood is ejected from the atria, the chordae tendineae are pulled taut, preventing eversion of the valves & backflow of blood from the ventricles into the atria.
What is the pulmonary circuit of blood?
Through the lungs; involves the right ventricle, which pumps deoxygenated blood to the lungs; the pulmonary trunk & pulmonary arteries; a capillary network in the lungs; the pulmonary veins; & the left atrium, which receives oxygenated blood from the lungs.
What is the systemic circuit of blood?
Involves the left ventricle & the remainder of the arteries, capillaries, & veins of the body. The right atrium of the heart receives deoxygenated blood from the systemic circuit.
List the flow of blood through the heart.
1. Right Atrium
2. Right AV (tricuspid) valve
3. Right Ventricle
4. Pulmonary semilunar valve
5. Pulmunary trunk
6. Right & left pulmonary arteries (low O2); to lungs
7. Right and left pulmonary veins (high O2); from lungs
8. Left atrium
9. Left AV (bicuspid/mitral) valve
10. Left ventricle
11. Aortic semilunar valve
12. Aorta
13. Stystemic System (arteries; 02)
14. Superior & inferior vena cava
15. Coronary sinus
Describe briefly the flow of blood through the heart.
Blood fills both atria and beigins to flow into both ventricles. Next, the atria contract, emptying the remaining blood into the ventricles. The ventricles then contract, forcing blood into the ascending aorta & pulmonary trunk.
Correlate the contractions of the heart chambers & the opening & closing of the heart valves & explain what causes the characteristic "lub-dub" sounds.
During atrial contraction, the AV valves are open & the semilunar valves are closed; during ventricular contraction, the reverse is true. The loud "lub", or 1st sound, is produced by the closing of the AV valves. The softer "dub", or 2nd sound, is produced by the closing of the semilunar valves.
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