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

(1) In which direction does the heart tilt? Its tilted so the apex is pointed to the left (2) What is the approximate size of the heart? The size of when you make a fist and then put the other hand on the fist. (3) Describe the mycoardium. The myocardium consists largely of cardiac muscle tissue. It is serviced by the coronary artery and cardiac vein and not boy the blood it pumps. (4) Why do you think a heart attack is sometimes called a mycocardial infarction p. 97? Because it is when a portion of the heart muscle dies to to ack of oxygen. (5) Describe the pericardium. It is a thick membranous sac tat supports and protects the heart. It secretes lubrication fluid, and the pericardium slides smoothly over the surface as the heart pumps the blood. (6) Describe the septum. The wall called the septum seperates the heart into the right side and a left side (7) Where are the atria? Describe their walls. The atria are two of the hearts four chambers. The two upper thin walled atria are called the left and right atrium each onehas a wrinkled rotruding appendage called an auricle. (8) Where are the ventricles? Describe their walls. The lower to chamvers are called ventricles. They are thick walled (9) Where are the atroventricular valves? Describe their shape (number of flaps) and various names. The valves that lie between the atria and the ventricles are called this. These walves are supported by strong fibrous strings called chardai tendineae. The tricuspid vavlve because it has three flaps. (10) What are the chordae tendinae? They are strings that support the valves (11) Where are the semilunar valves? Why do they have that name? the remaining two halves are half mooned shapes and are this, semilunar valves (12) List the path of blood through the heart. The superiour vena vcava and inferior vena cava enter the right atrium. The right atrium sneds blood through an atrioventricular valve to the right ventricle. The right ventricle sends blood through the pulmonary seminular valve into the pulmonary trunk. It goes into pulmonary arteries then they go the lungs. Four pulmonary veings enter the left atrium. The left atrium sends it through an atrioventricular valve to the left ventricle. This sends it through the aortic semilunar valve ino the aorta to the body proper.

(13) Where does blood go when it leaves the right side of the heart? lungs (14) Where does blood go when it leaves the left side of the heart? Through the body (15) Which side of the heart is stronger? Why? Left side cause it has to go to the entire body (16) Why is the heart a double pump? (17) Define systole. The working phase refers to construction 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? About seventy times per minute (20) What causes the "lub" and "dup" of the heart sounds? Lub occurs when increasing pressure of blood inside a ventrical forces the cusps of the av valve to slam shut. The dup occus when the ventricals relax, and the blood in the arteries pushes back, causing the smilunar valves to close. (21) What is the sinoatrial node? What does it do? Why is called the pacemaker? (22) What is the atrioventricular bundle? Why is the delay important between the SA node and AV bundle? (23) What does in ECG measure? Is a recording of the electrical changes that occur n myocardium during a cadiac cycle. (24) What triggers the P wave? Indicates the atria are about to contract (25) What triggers the QRS wave? Complex signals that the ventricles are about to contract.