heart

The Heart pp.88-91 DeMarcus Waggoner Many questions, but your answers can be brief except for number 12.

(1) In which direction does the heart tilt? left (2) What is the approximate size of the heart? The heart is the size of the fist. (3) Describe the mycoardium. The major portion of the heart, which consist largely of cardiac muscle tissue. (4) Why do you think a heart attack is sometimes called a mycocardial infarction p. 97? Because a portion of the heart muscle dies due to a lack of oxygen. (5) Describe the pericardium. A thick, membranous sac that secretes a small quantity of lubricating liquid. (6) Describe the septum. A wall that seperates the heart into a rigt side and left side. (7) Where are the atria? Describe their walls. The atria surround two valvues. The right atrium sends blood through an atrioventricular valve (the tricuspid valve) to the right ventrical. (8) Where are the ventricles? Describe their walls. The ventricalsin the lower chamber of the heart, and there are two ventricles a left and a right ventrical. The walls are made of choarade, which are attached to the muscular projections of the ventricular walls. They support the valves and prevent them from inverting when the heart contracts. (9) Where are the atroventricular valves? Describe their shape (number of flaps) and various names. The two valves that lie between the atria ad the ventricles are called the atrioventricular valves. The valve on the right side is tricuspid because it has three flaps. The ones on the left are called bicuspid because they have twoflaps (10) What are the chordae tendinae? They are strong fibrous strings that support the atroventricular valves. (11) Where are the semilunar valves? Why do they have that name? Their flaps resemble half moons, between the ventricles and their attatched vessels. The pulmonary semilunar valve lies between the right cventricle and the pulmonary trunk. The aortic semilunar valve lies between the left ventricle and the aorta. (12) List the path of blood through the heart. The superior vena cava and the inferior vena cava, which carry O2-poor blood, enter the right atrium. The right atrium sends blood through an atrioventricular valve (the tricuspid valve) to the right ventricle. The right ventricle sends blood through the pulmonary semilunar valve into the pulmonary trunk. The pulmonary trunk divides into two pulmonary arteries, which go to the lungs. Four pulmonary veins, which carry O2-rich blood, enter the left atrium The left atrium sends blood through an atrioventricular valve (the bicuspid, or mital, valve) to the left ventricle The left ventricle sends blood through the aortic semilunar valve into the aorta to the body proper. (13) Where does blood go when it leaves the right side of the heart? The right side send it to the lungs. (14) Where does blood go when it leaves the left side of the heart? The blood goes to the rest of the body after leaving the left side of the heart. (15) Which side of the heart is stronger? Why? The lift side is stronger because it sends blood throughout the entire body. (16) Why is the heart a double pump? Because it has to send blood to the lungs and the rest of the body. (17) Define systole. The working phase, refers to the contraction of the chambers. (18) Define diastole The resting phase, refers to relaxation of the chambers. (19) How many times does the heart normally contract in a minute? 70 (20) What causes the "lub" and "dup" of the heart sounds? Lub comes from the vibrations occurring when the atrioventricular valves close due to ventricular contraction. The dub comes from the semilunar valves closing due to the back pressure of blood in the arteries. (21) What is the sinoatrial node? What does it do? Why is called the pacemaker? The SA node