Unit 2 KA6 - structure and function of the heart

Question 1

at each contraction of the heart, the …….. …………. pumps the ………. volume of blood through the …………. ………….. as the ………. …………… pumps through the …………

Answer 1

right ventricle, same, pulmonary artery, left ventricle

Question 2

what is heart rate?

Answer 2

the no. of heartbeats that occurs per minute

Question 3

what is stroke volume?

Answer 3

the volume of blood expelled by each ventricle on contraction

Question 4

the ………… the contraction, the greater the SV

Answer 4

stronger

Question 5

what is cardiac output and how is it calculated?

Answer 5

the volume of blood pumped out of each ventricle per minute

HR x SV

Question 6

what is the cardiac cycle?

Answer 6

the pattern of contraction (systole) and relaxation (diastole) shown by the heart during one heartbeat

Question 7

what does AV valve stand for and what is their function?

Answer 7

atrioventricular valves prevent the backflow of blood from ventricles to atria

Question 8

function of the semilunar valves?

Answer 8

to prevent the backflow of blood at the entrance of the pulmonary and aorta arteries
these valves open during ventricular contraction allowing blood into the arteries and close when arterial pressure exceeds ventricular pressure

Question 9

describe atrial and ventricular diastole

Answer 9

the blood returning from the vena cava and pulmonary veins going into the atria flows into the ventricles

• AV valves open
• SL valves closed

Question 10

describe atrial systole

Answer 10

atrial systole transfers the remainder of the blood in the atria to go through the AV valves to the ventricles

• atria are in systole
• ventricles are in diastole
• AV valves open
• SL valves closed

Question 11

describe ventricular systole

Answer 11

ventricular systole closes the AV valves and pumps the blood out through the SL valves to the aorta and pulmonary artery

• AV valves closed
• SL valves open

Question 12

in …………., the ………….pressure in the arteries …………the SL valves
the opening and closing of the …….. and ……… valves are responsible for the heart sounds heard with a ………….

Answer 12

diastole, higher, closes, AV, SL, stethoscope

Question 13

what is the function of the SAN and what does it stand for?

Answer 13

sinoatrial node/pacemaker, located in the wall of the right atrium, sets the rate at which the heart contracts

Question 14

describe the first stage in the cardiac conducting system

Answer 14

the timing of the cardiac muscle cell contraction is controlled by impulses from the SAN spreading through the atria causing atrial systole

Question 15

describe the second stage in the cardiac conducting system

Answer 15

the impulses then travel to the atrioventricular node (AVN) which is located in the centre of the heart

Question 16

describe the third stage in the cardiac conducting system

Answer 16

the impulses from the AVN travel down fibres in the central wall of the heart and then up through the walls of the ventricles, causing ventricular systole

Question 17

the timing of cardiac cells ………… is controlled by the ………. from the …………….. (SAN) spreading through the…………….. - these …………. generate …………….. that can be detected by an ……………………. (ECG)

Answer 17

contracting, impulses, sinoatrial node, ventricles, impulses, currents, electrocardiogram

Question 18

describe and name the 3 distinct waves which indicate a normal ECG pattern

Answer 18

1 - P wave: electrical impulses spread over the atria from the SAN
2 - QRS wave complex: the electrical impulses passing through the ventricles
3 - T wave: the electrical recovery of the ventricles near the end of the ventricular systole