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Chapter 14: Cardiovascular System: The HEART

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PERICARDIUM
- this is the membrane that surrounds and protects the heart.
- it confines the heart to its position in the mediastinum.
- it consists of 2 principle portions:
*Fibrous Pericardium
*Serous Pericardium
Pericardium: FIBROUS PERICARDIUM
- this is the superficial layer of pericardium, which is a tough inelastic, dense irregular connective tissue.
- prevents overstretching of the heart, provides protection, and anchors the heart in the mediastinum.
Pericardium: SEROUS PERICARDIUM
- this is a loose fitting membrane that encloses the heart.
- this is the the thinner more delicate membrane of the pericardium that forms a double layer around the heart:
*Parietal Layer - outer layer
*Visceral Layer - inner layer
Layers of Heart Wall
- the wall of the heart consists of 3 layers:
*Epicardium - external layer, made up of mesothelium and connective tissue
*Myocardium - middle layer, is responsible for the pumping action of the heart and is composed of cardiac muscle tissue w/ intercalated discs.
*Endocardium - inner layer, is connective tissue covered w/ endothelium.
Chambers Of The Heart
- the heart is a dual pump that contains four chambers, two upper/receiving chambers called ATRIA, and two lower/pumping chambers called VENTRICLES.
- Atria receive blood from blood vessels called veins.
- ventricles eject blood from the heart into blood vessels called arteries.
Chambers of Heart: RIGHT ATRIUM
- this is a receiving chamber of the heart.
- it receives blood from 3 veins:
--the Superior Vena Cava
--Inferior Vena Cava
--Coronary Sinus
- blood passes from the this chamber into the right ventricle through the Tricuspid Valve
Chambers of Heart: RIGHT VENTRICLE
- this chamber of the heart forms the anterior surface of the heart.
- contains both Trabiculae Carneae & Chordae Tendinae
- this chamber passes blood through the Pulmonary Valve into the pulmonary trunk.
Chambers of Heart: LEFT ATRIUM
- this chamber forms most of the base of the heart.
- this chamber receives blood from 4 pulmonary veins, which are divided into right and left sides.
- blood passes from this chamber into the left ventricle through the Bicuspid Valve.
Chambers of Heart: LEFT VENTRICLE
- this chamber is the thickest part of the heart, and forms the apex of the heart.
-contains trabeculae carnae & chordae tendinae
- blood passes from this chamber through the Aortic Valve into the Ascending Aorta, which is the largest artery of the body.
Heart Valves: ATRIOVENTRICULAR VALVES
- these are the valves that are located b/w an atrium and a ventricle, which include the:
*Tricuspid valve
*Bicuspid valve
-blood moves from the atria into the ventricles through these valves, when atrial pressure is higher than ventricular pressure.
Heart Valves: SEMILUNAR VALVES
- these valves are made up of 3 crescent moon shaped cusps.
- these valves allow ejection of blood from the heart into arteries, and prevent backflow of blood into the ventricles.
- these valves open when pressure in the ventricles, exceeds the pressure in the arteries.
- valves included are:
*Aortic Valve
*Pulmonary Valve
Blood Circulation: SYSTEMATIC CIRCULATION
- in this type of blood circulation, the left side of the heart receives oxygenated blood from the lungs.
- left ventricle ejects blood into aorta, which branches into smaller arteries that carry blood to all organs of the body (except for alveoli) of the lungs.
- in the tissues blood unloads O2 and picks up CO2.
Blood Circulation: PULMONARY CIRCULATION
- the right side of the heart is the pump for this type of circulation.
- it receives all dark red deoxygenated blood.
- blood ejected from right ventricle flows into the pulmonary trunk, which branches into pulmonary arteries that carry blood to the lungs.
- in Pulmonary Capillaries, blood unloads CO2 (exhales) and picks up O2; the oxygenated blood then flows into pulmonary veins and back to the left atrium.