CARDIAC CYCLE

Question 1

Describe Diastole; how many distinct phases it has? and its proportion to each beat?

Answer 1

Ventricular relaxation- fills with blood

last 2/3 of each beat

split into 4 distinct phases

Question 2

describe systole

Answer 2

Ventricular contraction- generates pressure then ejects blood out

lasts 1/3 ofeach beat

split into 3 distinct phases

Question 3

what are the stages of the cardiac cycle?

Answer 3

1. Atrial systole- DISATOLE
2. Isovolumetric contraction- SYSTOLE
3. rapid ejection- SYSTOle
4. Slow ejection- SYSTOLE
5. Isovolumetric relaxation- DIASTOLE
6. Rapid paasive filling- DIASTOLE
7. Slow pssive filling- DIASTOLE

Question 4

how can stroke volume and ejection fraction be calculated?

Answer 4

SV- end-diastolic volume minus End-systolic volume

ejection fraction= Stoke volume/End diastolic volume

Question 5

Describe what happens in the 1st stage of cardiac cycle

Answer 5

Atrial systole

• P- wave on ECG shows start of atrial systole
• atria full form passive filling by pressure gradient
• Atria cintract to top up volume of blood already in ventricles
• there could be a 4th abnormal heart sound caused by pulmonary embolism, tricuspid incompetence and congestive heart failure

Question 6

explain the features and what happens in ISOVOLUMETRIC CONTRACTION

Answer 6

• ECG- marked by QRS complex; shows ventricular depolarisation
• AV valves shut (interval between closure of AV valves and opening of semi lunar valves)
• isometric contraction of ventricles as semilunar valves are also shut.
• ist heart sound heard by CLOSURE of AV valves and associated vibrations

Question 7

what are the features and what happens in rapid ejection stage of the cardiac cycle?

Answer 7

• Opening of BOTH semi lunar valves
• pressure in ventricles build up and start to go above aortic and pulmonary artery pressure
• after load overcome;
• ISOTONIC contraction as blood rushes out of ventricles
• NO heart sound for this phase

Question 8

what are the features and event of the 4th stage of the cardiac cycle?

Answer 8

REDUCED EJECTION

• Marks end of systole
• reduced pressure gradient means that semilunar valves BEGIN to close;
• blood flow from ventricles decrease, volume also decreases at a slower rate
• pressure in ventricles start to fall

Question 9

explain the features and events of the 5th stage of the cardiac cycle

Answer 9

ISOVOLUMETRIC RELAXATION

• Both semiluar valves shut
• AV valves are also shut unitl ventricular pressure falls below atrial pressure
• atrial pressure start to rise
• dichrotic notch- aortic wall relaxes; causing reboud pressure against aortic valve
• 2nd heart sound is heard by closure of semi lunar valves

Question 10

describe the events and features of RAPID passive filling (cardiac cycle stage)

Answer 10

• electrical quiescene- flat ECG line
• AV valves open; blood flow into ventricles
• atria doesnt contract
• abnormal 3rd heart sound may be heard of there’s hypertension or mitral incompetence. this signifies turbulent ventricular filling

Question 11

Describe the events and features of the LAST stage of the cardiac cycle

Answer 11

REDUCED PASSIVE FILLING

• this is called diastasis
• ventricular volume fill more slowly
• ventricle fill quite well WITHOUT atrai contraction

Question 12

contrast the volume of blood and patterns of pressure in the right and left ventricles

Answer 12

same volume of blood

same PATTERN of pressure changes

HOWEVER; left ventricle has higher systole pressure of 120mm/Hg. right = 25mm/Hg

Question 13

Draw and label a pressure volume loop. label axis; label signifcant points and cardiac cycle stages

when does pre load occur and after load occur

Answer 13

Pre-load at “a”

after load is just after “b”- rapid ejection occurs due to overcoming after load

Question 14

how does increase in pre-load affect the presure volume loop

Answer 14

higher pre-load means there’s higher stroke volum.

higher left ventricle volume pumped out but pressures stays relatively the same

Question 15

How does increases in After load affect the pressure volume loop

Answer 15

lower stroke volume; have to wotk harder to overcome aortic pressure. hence point B is higher (pressure).

Question 16

apart from pre load and after load? what ELSE affects stroke volume?

explain how and what causes it? How is it measured?

Answer 16

CONTRACTILITY- strength of heart contraction (CAPABILTIY)

increased by sympathetic stimulation

measured by ejection fraction

Question 17

how does contractitlity affect frank sterling relationship?

Answer 17

higher gradient for active force.

Question 18

which is the longest phase in cardiac cycle?

Answer 18

reduced passive filling

Question 19

how does acute blood loss and exercise affect pressure volume loop

Answer 19

acute blood loss- less venous retunr, less stroke volume

exercise- more venous return but higher pressure in aorta to overcome but can oversome it

Question 20

What phase of the cardiac cycle does this image represent

Answer 20

Atrial systole (DIASTOLE)

Question 21

What phase of the cardiac cycle does this image represent

Answer 21

ISOVOLUMETRIC CONTRACTION

Question 22

What phase of the cardiac cycle does this image represent?

Answer 22

RAPID EJECTION

Question 23

What phase of the cardiac cycle does this image represent

Answer 23

Reduced ejection

T- represents repolarisation

Question 24

What phase of the cardiac cycle does this image represent

Answer 24

ISOVOLUMETRIC RELAXATION

Question 25

What phase of the cardiac cycle does this image represents? work it out

Answer 25

RAPID PASSIVE FILLING

Question 26

What phase of the cardiac cycle does this image represent?

Answer 26

Reduced passive filling