Mediastinum & Heart - Cardiac Cycle & Conduction System

Question 1

conduction system of the heart is innervated by the ____ but isn’t necessary to create a heart beat

Answer 1

ANS

Question 2

first electrical stimulus within the heart arises from the

drives the entire heart rate (sets the pace)

Answer 2

sinoatrial (SA) node

Question 3

lies in the right atrium, lateral to the SVC enters within the upper portion of the crista terminalis

Answer 3

SA node

Question 4

each time the SA node ____ it causes a heart beat

Answer 4

depolarizes

Question 5

after the electricle impusle leaves the SA node it travels to the

Answer 5

atrioventricular (AV) node

Question 6

function of the AV node

Answer 6

1. delays electricle activity before allowing it to pass into ventricles
2. allows proper systole

Question 7

from the AV node the electricle impulses travel down the ____ ____ via the ____ ____ ____

Answer 7

from the AV node the electricle impulses travel down the interventricular spetum via the bundle of His

Question 8

the bundle of his divides into right & left bundle branches and spread along sides of each ____ along the ____ ____

Answer 8

ventricle

interventricular septum

Question 9

once bundle of his branches reach the apex of the heart, they divide into ____ ____ which travel up the outside walls of the ____

Answer 9

purkinje fibers

ventricles

Question 10

what happens when the right and left atria contract together?

Answer 10

ejecting blood into the ventricles throught the tricuspid and bicuspid valves

Question 11

what happens when the right and left ventricles contract together?

Answer 11

ejecting blood out the heart through the semilunar valves (pulmonary & aortic valves)

Question 12

when the heart is contracting is said to be in

Answer 12

systole

Question 13

when the heart is relaxing and filling is said to be in

Answer 13

diastole

Question 14

what makes the ventricles have a more forceful ejection of blood through the aorta?

Answer 14

ventricular wall thickness of the left ventricle

Question 15

what are the 4 phases of the cardiac cycle?

Answer 15

1. atrial systole
2. ventricular diastole
3. ventricular systole
4. atrial diastole

Question 16

heart at complete relaxation the pressure is very ____

Answer 16

low

Question 17

blood flow (return) from the lungs (pulmonary arteries) and system blood flow (SVC and IVC) is passive into the ____

Answer 17

atria (atrial diastole)

Question 18

produces increased pressure into the ventricles with increased pressure into the aorta until the pressures are almost equal

Answer 18

ventricular systole

Question 19

during the last part of systole the pressures start to ____

Answer 19

decrease

Question 20

because the pressure starts to decrease during the last part of systole the back flow of blood in the aorta …

Answer 20

the aortic semilunar valve closes preventing blood flow back into the ventricle then blood under low pressure enters the coronary arteries

Question 21

elastic properties of the aorta cause a recoil that

Answer 21

ejects the “backflow” blood systemically, back toward the coronary arteries

Question 22

semilunar valves - closed

atrioventricular valves - open

Answer 22

valves in diastole

Question 23

atrioventricular valves - closed

semilunar valves - open

Answer 23

valves in systole