L2

Question 1

is it physiologically possible for your heart to miss a beat? if so how missing how any beats leads to what issues

Answer 1

1-2 = no problem

5-10 = unconscious

5 min = clinical help is needed as you could have damage to the heart

10 min = no turning back

Question 2

what is the cardiac cycle/what does it consist of

Answer 2

it is the complete set of contraction and relaxation of the heart

it consists of diastole (ventricles relaxing) and systole (contraction of the ventricles)

the full cycle includes mechanical events (pressure and flow changes), electrical events (ECG) and valvular events (heart sounds)

Question 3

what is diastole

Answer 3

relaxation

Question 4

contraction of the ventricles is known as

Answer 4

systole

Question 5

what happens in the early stages of diastole (diastole 1)

Answer 5

isovolumetric relaxation

diastole is when contraction is finished and starts with all the valves shut therefore there is no blood flow and no blood entering the ventricle

blood is flowing into the artra therefore the pressure is rising. when the pressure in the atra is greater than than in the ventricles the AV valves open passively and ventricular filling begins

Question 6

what is end systolic volume (ESV)

Answer 6

the minimal ventricular volume. this is when there is the least amount of blood in the heart

Question 7

what happens in the later phase of diastole (diolstle 2 )

Answer 7

ventricular filling

The pressure gradient is diving the blood into the ventricles because the ventricle is still relaxing. The start of ventricular filling is very fast (about 90% of the total volume of blood).

late diastole is when the P wave happens as this is when the atria contracts. It only causes about 5mmHg therefore it is only responsible for 10% of blood ejected. this is called arterial top up

Question 8

what is the end diastolic volume (EDV)

Answer 8

this is the amount of blood in a ventral at the end of diastole

at rest this is about 130mL

Question 9

what happens at the start of systole (systole 1)

Answer 9

isovolumetric contraction

the ventricles depolarise causing the QRS complex to be seen in an ECG

the ventricles then contract the the pressure gradient reverces causing the AV valves to close

as all the valves are again closed the pressure in the ventricles increases because of the isovolumetric contraction

Question 10

what happens in the later part of systole (systole 2 )

Answer 10

ventricular ejection

when the pressure in the ventricles exceeds that in the arteries the SL valves open causing arterial blood volume and pressure to increase

if you were looking at the left ventricles you would say that the left ventricular pressure (LVP) and the aortic pressure (AP) rise in parallel

this causes rapid ejection of blood from the heart

Question 11

how much of the hearts blood volume is ejected in the first 1/3 of ventricular ejection

Answer 11

2/3rds of the total volume of blood ejected

Question 12

what happens in the late part of ventricular ejection (still systole 2)

Answer 12

LVP and AP fall to a slow ejection rate as the heart has contracted as much as it can. the ventricle then repolarises which is shown as the T wave

the ventricular pressure falls below the arterial pressure causing the SL valves to close and the ecycle starts again

Question 13

what is end systolic volume

Answer 13

the volume of blood left in the ventricle at the end of systole

at rest this is about 60mL

Question 14

greater pressure in the atrum than the ventricle leads to the opening of the AV valve BECAUSE at rest, the majority of the ventricular filling happens before the atria contract

Answer 14

both statements are true but they are not causal

Question 15

how long does each phase of the cardiac cycle last

Answer 15

diastole 1 = 0.05 sec
diastole 2 = 0.6 sec
systole 1 = 0.05 sce
systole 2 = 0.3 sec

all together the cardiac cycle is about 1 sce at rest

Question 16

what is the name of the diagram which displays al of the information for the cardiac cycle

Answer 16

wiggers diagram

Question 17

describe ventricular volume during diastole

Answer 17

V is constant during isovolumetric relaxation

early rapid ventricular filling followed by late slow ventricular filling

top up after atrial contraction

ventricle is at its max volume at EDV (130mL)

Question 18

describe ventricular volume during systole

Answer 18

constant during isometric contraction

rapid fall during early ejection
slow fall during late ejection

volume is at its min at ESV (60mL)

Question 19

describe ventricular pressure during diastole

Answer 19

pressure is at its min at the start of diastole but rises a little during ventricular filling and after atrial contraction (the A wave)

Question 20

describe ventricular pressure during systole

Answer 20

pressure rises dramatically during isometric contraction and reaches its max pressure during the ejection phase

pressure falls during late systole

Question 21

describe arterial pressure during diastole

Answer 21

pressure continues to fall during diastole to its min. it reaches its min arterial pressure at the end of diastole which is known as your diastolic blood pressure

Question 22

describe arterial pressure during systole

Answer 22

the ventricular pressure is larger than the arterial pressure therefore the SL valves open and artery pressure rises to a maximum.

NOTE that the pressure in the ventricle drops faster than in the arterie as the heart is unable to contract any more

this is your systolic pressure

Question 23

what can be seen when the semilunar valves snap shut

Answer 23

the incisura or dicrotic notch

Question 24

at rest what is the average systolic and diastolic pressure

Answer 24

diastolic pressure = 80mmHg

systolic = 120mmHg

Question 25

how could you calculate ejection fraction/what is the ejection fraction

(use average numbers for when at rest)

Answer 25

end diastolic volume = 130mL
end systolic volume = 60mL

therefore stroke volume is 70mL which is about 55-60% of the total volume. this is the ejection fraction

Question 26

what can you tell from the ejection fraction

Answer 26

how healthy the heart is

above 50% is healthy and anything less suggests the heart is failing

this shows the strength of contraction

Question 27

when is the pressure in the ventricle and the arteries the same

Answer 27

at the very start of systole

Question 28

what are the differences between the left and the right side of the heart (in terms of resistance and pressure

Answer 28

pulmonary resistance (right side) is lower than the total peripheral resistance (left side)

the pressure in the right ventricle and the pulmonary artery is lower than the left ventricle and the aortic pressure

this is because the right only has to pump to the lungs whereas the left is around the whole body

Question 29

what are the values for pressure in the right ventricle and pulmonary artery during diastole and systole

Answer 29

ventricle = 0/1 during diastole and 25mmHg during systole

pulmonary artery = 8 during diastole and 25mmHg during systole

Question 30

describe the first heart sound (S1)

Answer 30

happens when the AV valves close (M1 -T1)

the sound is long and slow (lub)

Question 31

describe the second heart sound (S2)

Answer 31

the closure of the semilunar valves (A2 - P2) which produces a short high pitch dub

Question 32

describe the third heart sound (S3)

Answer 32

you hear this because of the passive ventricular filling during early diastole. you are only able to hear this in the young as their heart is able to relax very quickly

Question 33

what is the 4th heart sound (S4)

Answer 33

this is the result of ventricular filling following atrial contraction. you hear this because of reduced ventricular compliance

you only hear the 4th heart sound in diseased hearts as the atria is trying to push more blood into the ventricles but the ventricles won’t stretch anymore

Question 34

what makes up an ECG

Answer 34

PQRST

P wave = atrial depolarisation and contraction

QRS complex = ventricular depolarisation and contraction

T wave = ventricular repolarisation and relaxation

Question 35

at rest how long is diastole and systole

Answer 35

D = 0.66s (2/3 of the cardiac cycle)

S = 0.33s (1/3 of the cardiac cycle)

Question 36

when we exercise our heart rate increases. what effect does this have on the cardiac cycle

Answer 36

at max our heart rate can be 180bpm meaning that the cardiac cycle is about 0.33 sec rather than 1 sec

to achieve this we spend less time in diastole (about 0.13s (1/3)) and more time in systole (0.2s (2/3))

this is because the heart has a set time it needs for contraction but it is able to spend less time relaxing. this is important because we have to maintain SV otherwise there would be no point in speeding up our HR