heart

Question 1

where is the atrio-ventricular valve

Answer 1

connecting the atrium and ventricle

Question 2

where is the semi-lunar valve

Answer 2

connecting the ventricle and the aorta/pulmonary artery

Question 3

what is the first ‘lub’ sound of the heart caused by

Answer 3

the atrioventricular valves closing

Question 4

what is the second ‘dub’ sound of the heart

Answer 4

semi-lunar valves closing

Question 5

first stage of the cardiac cycle

Answer 5

• ventricles relax
• atria contract
• volume decreases
• pressure increases
• pushes blood into ventricles through AV valves
• ventricular pressure increases

Question 6

second stage of the cardiac cycle

Answer 6

• atria relax
• ventricles contract
• decreasing volume
• increasing pressure
• pressure is higher in ventricles than atria, causing AV valve to shut
• pressure is higher in ventricles than aorta/pulmonary artery, causing semi-lunar valve to open
• blood is forced out into arteries

Question 7

third stage of the cardiac cycle

Answer 7

• ventricles and atria relax
• higher pressure in arteries than in ventricles causes SL valves to close
• higher pressure in veins than in atria forces blood into atria
• increases pressure in atria
• lower pressure in ventricles than atria so AV valves open and blood flows to ventricles passively

Question 8

why is the left side of the heart thicker

Answer 8

• has to produce sufficient force to move blood to the whole body and overcome resistance of aorta

Question 9

how to calculate cardiac output

Answer 9

heart rate(bpm) x stroke volume(blood volume pumped during each heartbeat cm3)

Question 10

diastole

Answer 10

• heart relaxes
• atria and ventricles fill with blood
• volume and pressure of blood in heart build up

Question 11

systole

Answer 11

• atria contract (atrial systole)
• then ventricles contract (ventricular systole)
• pressure increases dramatically
• blood is forced out the heart
• volume/pressure in heart are low at the end of systole

Question 12

myogenic

Answer 12

• cardiac muscle
• it can contract and relax without receiving signals from nerves

Question 13

rhythm of the heart

Answer 13

• wave of electrical excitation begins at sino-atrial node (right atrium wall)
• causes atria to contract
• layer of non-conductive collagen tissue prevents it spreading directly to ventricles
• waves transferred from SAN to atrioventricular node
• AVN imposes slight delay before stimulating bundle of His (conducting tissue made up of Purkyne fibres) which are in septum
• bundle of His splits into 2 branches conducting wave to the apex
• at the apex, Purkyne fibres spread out through both ventricle walls, causing them to contract (from bottom up)

Question 14

Tachycardia

Answer 14

• when heartbeat is very rapid

Question 15

Bradycardia

Answer 15

when heart beat slows down to below 60 bpm

Question 16

ectopic heartbeat

Answer 16

extra heartbeat out of normal rhythm

Question 17

atrial fibrillation

Answer 17

• rapid electrical impulses generated in atria
• contract very fast