Test 4 - Cardiovascular System: The Heart The function of...

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Cardiovascular System: The Heart The function of the heart is to produce pressure changes that drive blood through vasculature. 1. Location and Size -heart is located in a cavity called the mediastinum -it is located between the two lungs, the thoracic vertebrae, and the sternum -about the size of a fist 2. Very Basic Gross Anatomy a. Four Chambers 1. Atria (two) -receiving chambers i. Right Atrium -receives blood from body from superior/inferior vena cava and coronary sinus -pumps blood into right ventricle ii. Left Atrium -receives oxygenated blood from the lungs from the pulmonary vein 2. Ventricles (two) -dispersing chambers -larger than the atria i. Right Ventricle -receive blood from right atria -pumps blood to lungs via pulmonary artery ii. Left Ventricle -receives blood from left ventricle -pumps blood to rest of body -walls of the left ventricle are thicker than the right because it has to create a greater force to pump blood to the body b. Great Vessels 1. Superior and Inferior Vena Cava -veins carrying blood to the heart and the right atrium 2. Aorta -artery carrying blood away from the heart to the rest of the body 3. Pulmonary Trunk -made up of left and right pulmonary arteries that carry blood to lungs 3. Pericardium -covers heart -made of two layers: a. Visceral -lies directly on heart b. Parietal -lines heart cavity 4. Histology of the heart wall a. Epicardium (visceral pericardium)
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-outer layer of the heart wall -dense irregular connective tissue b. Myocardium -middle layer -the heart itself -comprised of cardiac muscle -wraps around the heart -myocardial layer is thicker around the left ventricle because the left ventricle has to produce the most force to carry out systemic circulation c. Endocardium -inner layer of the heart wall -continuous with the endothelium of blood vessels -composed of thin and slick squamous cells i. Bacterial Endocardius -pathology that occurs when bacteria from the esophagus gets into the endocardium and causes inflammation -this can severely damage the heart wall -normally occurs in dogs Gross Internal Anatomy 1. Heart Valves a. Atrioventricular Valves (AV) -located between atrium and ventricle on each side of heart -prevent backflow of blood from ventricles to atri i. Tricuspid Valve -AV valve between the right atrium and right ventricle -has 3 flaps or cusps ii. Bicuspid Valve -AV valve between the left atrium and left ventricle -has 2 flaps or cusps i. Chordae Tendineae -collagen cords that anchor AV cusps to ventricular wall -the cords (heart strings) hold the cusps downward allowing blood to flow in one direction ii. Papillary Muscles -finger-like projections of the cardiac muscle wall that serve as a point of attachment for chordae tendineae -pull downward during ventricular contraction b. Semilunar Valves (SL) -located between the ventricles and the body -prevent backflow into ventricles -form three crescent moon shaped flaps -not anchored by tendons but they contain cusps that close during ventricular relaxation to prevent backflow i. Pulmonary Semilunar Valve -between right ventricle and pulmonary artery
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ii. Aortic Semilunar Valve
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Test 4 - Cardiovascular System: The Heart The function of...

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