Heart+JO

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? The Apex (pointed end) is tilted toward the left

(2) What is the approximate size of the heart? Approx. size is about the size of your hand wrapping around your fist

(3) Describe the myocardium. Is the major part of the heart and consist of mainly cardiac muscle tissue

(4) Why do you think a heart attack is sometimes called a myocardial infarction p. 97? Because a heart attack is due to a portion of the muscle dying, due to lack of oxygen, and the myocardium is the muscle.

(5) Describe the pericardium. Thick membranous sac, supports and protects heart

(6) Describe the septum. Separates heart into the left and right sides.

(7) Where are the atria? Describe their walls. There are two upper, thin walled, atria, the right and left. Known as atrium when singular.

(8) Where are the ventricles? Describe their walls. They are located bellow the atria and have thicker walls, also have a right and left.

(9) Where are the atrioventricular valves? Describe their shape (number of flaps) and various names. The atrioventricular valves are located between the atria and ventricles. The Av valve on the right has three flaps or cusps, also known as a tricuspid, the one on the left a bicuspid. They are half moon shaped and bishop’s hat shaped.

(10) What are the chordae tendineae? Strong fibrous strings supporting av valves.

(11) Where are the semi-lunar valves? Why do they have that name? They have the name because they are shaped similar to partial moons and are located between ventricles.

(12) List the path of blood through the heart. First to superior vena cava, then inferior vena cava, carrying poor blood to right atrium, then through an AV valve to right ventricle. Following that it is sent to pulmonary trunk, it’s then divided into two pulmonary arteries, which go to lungs. Four pulmonary veins carry rich blood into left atrium, then its sent to left ventricle via the bicuspid AV valve, and from there its sent to the aorta to the body.

(13) Where does blood go when it leaves the right side of the heart? It heads to the lungs.

(14) Where does blood go when it leaves the left side of the heart? It heads to the body.

(15) Which side of the heart is stronger? Why? The left is stronger because it is sending to a great/ further away part of the body, while the right is sending strictly to the conveniently located lungs.

(16) Why is the heart a double pump? One to get the blood oxygenated and the other to send it to the body.

(17) Define systole. The part of the heart beat that contracts and pushes blood into the chambers and then to the arteries.

(18) Define diastole when the muscle relax and allow blood to fill the chambers

(19) How many times does the heart normally contract in a minute? Contracts about .85 seconds

(20) What causes the "lub" and "dup" of the heart sounds? The “lub” is the increase of blood pressure, causes av to slam shut. The “dup” is the ventricle relaxing, semi-lunar valves close.

(21) What is the sinoatrial node? What does it do? Why is called the pacemaker? Located in the upper dorsal wall of atrium, it initiates heartbeat and automatically sends out the .84 sec reaction contraction. It is called the pace maker because it keeps the heart regular.

(22) What is the atrioventricular bundle? Why is the delay important between the SA node and AV bundle? Allow for electrical current to flow from cell to cell.

(23) What does in ECG measure? “Electrocardiodiagram” records electrical changes that occur in myocardium during cardiac cycle.

(24) What triggers the P wave? The SA “sinoatrial” triggers the P wave which is an electrical change.

(25) What triggers the QRS wave? The p wave then signals the QRS wave to contract the ventricles.