The+Heart+WG

(1) In which direction does the heart tilt? The heart is tilted to the left

(2) What is the approximate size of the heart? The appropriate size of the heart is the size the size of your both hands clasped together.

(3) Describe the mycoardium. It consists largely of cardiac muscle tissue. It is serviced by the coronary artery and cardiac vein and not by the blood it pumps.

(4) Why do you think a heart attack is sometimes called a mycocardial infarction p. 97? It is called that because when a portion of the heart muscle dies due to a lack of oxygen.

(5) Describe the pericardium. It surrounds the heart, and it is a thick, membrananous sac that supports and protects the heart.

(6) Describe the septum. The spectrum is a wall that separates the heart into a right side and left side.

(7) Where are the atria? Describe their walls. The Atria is the two upper chambers, their walls are thin, and each one has a wrinkled, protruding appendage called an auricle.

(8) Where are the ventricles? Describe their walls. Ventricles are the two lower chambers. There is a right ventricle, and a left one.

(9) Where are the atroventricular valves? They are valves that lie between the atria and the ventricles. Describe their shape (number of flaps) and various names.it is like a clear hospital glove.

(10) What are the chordae tendinae? They support the atrioventricular valve. The chordae are attached to muscular projections of the ventricle walls, called papillary muscles.

(11) Where are the semilunar valves? Why do they have that name? They are flaps shaped like half-moons that lie between the ventricles and their attached vessels.

(12) List the path of blood through the heart. First the blood goes to the superior vena and the inferior vena cava, which carries oxygen-poor blood, and then it enters the right atrium. The right atrium sends blood through an atrioventricular valve to the right ventricle. Then the right ventricle sends blood through the pulmonary semilunar valve into the pulmonary trunk. The pulmonary trunk, which carries oxygen-poor blood, divides into two pulmonary arteries, which go to the lungs. Four pulmonary veins, which carry oxygen-rich blood, enter the left atrium. The left atrium sends blood through an atrioventricular valve to the left ventricle. Finally 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 blood goes to the lungs when it leaves the right side of the body.

(14) Where does blood go when it leaves the left side of the heart? The blood goes to the rest of the body when it leaves the left side of the heart.

(15) Which side of the heart is stronger? Why? The left side is stronger because, blood pressure is greatest in the aorta, and the aorta is on the left side of the heart.

(16) Why is the heart a double pump? It is a double pump because it not only pumps blood out, but it pumps blood in also.

(17) Define systole. Systole is the “working phase”, and refers to the contraction of the chambers.

(18) Define diastole: diastole is called the “resting phase”, and it refers to relaxation of the chambers.

(19) How many times does the heart normally contract in a minute? The heart normally beats about 70 times per minute.

(20) What causes the "Lub" and "dup" of the heart sounds? “Lub” is the sound that occurs when increasing pressure of blood inside a ventricle, forces the cusps of the AV valve to slam shut. The “Dub” sound occurs when the ventricles relax, and the blood in the arteries pushes back, causing the semilunar valves to close.

(21) What is the sinoatrial node? What does it do? Why is called the pacemaker? It’s located in the upper dorsal wall of the right atrium. It initiates the heartbeat and sends out an excitation impulse every 0.85 seconds. Its called the pacemaker because it usually keeps the heartbeat regular

(22) What is the atrioventricular bundle? Why is the delay important between the SA node and AV bundle?

(23) What does in ECG measure?it records the electrical changes that occur in myocardium during a cardia cycle.

(24) What triggers the P wave? The SA node triggers the P wave.

(25) What triggers the QRS wave? The complex signals that the ventricles are about to contract.