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A-Level PE > cardiac cycle/dynamics and the conduction system > Flashcards

cardiac cycle/dynamics and the conduction system Flashcards

1
Q

what is stoke volume(SV)

A

The volume of blood ejected from the left ventricle per beat (ml)

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2
Q

what is heart rate(HR)

A

The number of times the heart beats per minute (bpm)

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3
Q

what is the average HR

A

72

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3
Q

what is cardiac output (Q)

A

The volume of blood ejected (pumped) from the heart per minute (l/min)

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4
Q

What is bradycardia

A

when your HR is under 60 bpm

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5
Q

how do you calculate max HR

A

220-age

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6
Q

what cause anticipatory rise

A

adrenaline

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7
Q

what happens to HR during exercise

A

HR rises proportionately to exercise intensity
At submaximal levels HR will plateau when a steady state is reached and O2 demand is met.

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8
Q

what happens to HR post exercise

A

nitial rapid drop in HR due to less oxygen demand
Then gradual drop to repay oxygen debt

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9
Q

what is the resting SV

A

72ML

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10
Q

if you are an elite performer how does SV change

A

it decreases

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11
Q

what is starlings law

A

More blood to heart, leads to greater end diastolic volume
Greater stretch of atria walls lead to more forceful contraction

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12
Q

what happens to stroke volume at maximal exercise

A

it decreases slightly due to reduced time to fill heart

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13
Q

what is sub maximal exercise

A

exercise working between 40-60% of max HR

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14
Q

what are the 2 reasons stroke volume increases

A

increased venous return
starlings law

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15
Q

how to calculate stroke volume

A

SV=EDV-ESV

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16
Q

What is Ejection Fraction

A

An ejection fraction of 60 % means that 60 % of the total amount of blood in the left ventricle is pushed out with each heartbeat.

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17
Q

what SV percentage is right and what is too high

A

right=50-70%
too high=75%

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18
Q

how to calculate cardiac output(Q)

A

HR x SV = Q

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19
Q

what is the average Q at rest

A

5L

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20
Q

What happens to Q during exercise

A

Cardiac output increases in line with exercise intensity
Plateaus during maximal exercise, due to inefficient diastolic filling time

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21
Q

what happens to Q after exercise

A

In recovery there is a rapid decrease followed by a slower decrease to resting levels

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22
Q

what is diastole

A

Diastole is the phase of the cardiac cycle that sees the heart relax and fill with blood.

23
Q

what is systole

A

The Systole phase is when the atria contracts, forcing blood into the ventricles

24
Q

how long in total does systole and diastole take

A

0.8s

25
Q

what happens in diastole

A

Oxygenated blood enters LA from pulmonary veins
Rising pressure is Atria against AV valves forces blood into ventricles passively
- right = tricuspid valve
- left = bicuspid valve
Volume of blood after filling stage is called END DIASTOLIC VOLUME (EDV)

26
Q

how long is diastole

A

0.4s

27
Q

how long is atrial systole

A

0.1s

28
Q

what happens in atrial systole

A

the atria contracts, forcing blood into the ventricles.

29
Q

how long is ventricular systole

A

0.3s

30
Q

what happens on the left side of ventricular systole

A

-The ventricles contract, increasing pressure closing the AV valves to prevent backflow into the atria
-Increased blood pressure through ventricular contraction forces blood out of both ventricles (STROKE VOLUME)
-Left ventricle forces blood through aortic valve into aorta (to body)
-the valves remain shut and the aortic valves shut to prevent back flow

31
Q

what happens on the right side of ventricular systole

A

-The ventricles contract, increasing pressure closing the AV valves to prevent backflow into the atria
-Increased blood pressure through ventricular contraction forces blood out of both ventricles (STROKE VOLUME)
-right ventricle forces blood through pulmonary valve into pulmonary artery (to lungs)
-the valves remain shut and the pulmonary valve close to prevent back flow

32
Q

what does myogenic mean

A

this means it generates its own impulse.

33
Q

what does cardiac impulse mean

A

The electrical impulse responsible for stimulating the heart

34
Q

what is the route of the conduction system

A

1.The Sino-atrial Node (SA node) located in the right atrium wall, emits an impulse and fires it through the atria walls, causing an impulse.
2.The impulse spreads to the adjacent interconnecting fibres of the left atrium
3.It moves to the specialised cells called atria-ventricular nodes (AV nodes)
4.AV Node acts as a distributor and passes the action potential (impulse) to the Bundle of His
5. It moves down the bundle of his to the apex of the heart
6.The impulse then spreads up the Purkinje Fibres (in the ventricle walls), causing excitation and ventricular systole (contraction)

35
Q

what is depolarisation

A

At every beat, the heart is depolarized to trigger its contraction

36
Q

What is the stroke volume of an untrained person at rest

A

60-90ml per beat

37
Q

What is the stroke volume of an trained person at rest

A

90-110ml per beat

38
Q

What is the stroke volume of an untrained person during sub-maximal exercise

A

120-140ml per beat

39
Q

What is the stroke volume of an trained person during sub-maximal exercise

A

160-200ml per beat

40
Q

what is venous return

A

the term used for the volume of blood that returns to the RIGHT side of the heart via the venules and veins.

41
Q

why is venous return needed

A

to assist the distribution of blood round the body

42
Q

what happens to Q and SV when venous decrease

A

they decrease

43
Q

what happens to Q and SV when venous increases

A

they increase

44
Q

How does an increase in Venous Return affect ventricular contraction?

A

Increase in blood to right atrium
So, it stretches the (right atrium) chamber
This increase the SA node firing rate
…. So, HR increases

45
Q

what happens to venous return at rest

A

VR is sufficient to maintain SV and Q to meet demand for O2

46
Q

what happens to venous return during exercise

A

Blood pressure (BP) in the veins is too low to maintain VR, so SV and Q decrease

47
Q

what are the 5 mechanisms aiding venous return

A

Pocket Valves
Muscle Pump
Respiratory Pump
Smooth Muscle
Gravity

48
Q

what do pocket valves do

A

Pocket Valves prevent backflow of blood and direct it towards the heart.

49
Q

what do muscle pumps do

A

Veins are situated between skeletal muscles.

When the muscles contract, this helps to push or squeeze blood back to the heart.

50
Q

what do respiratory pumps do

A

During exercise, breathing becomes deeper and faster.

This causes pressure changes in the thorax and abdomen, squeezing large veins and thus blood back to the heart.

51
Q

what do smooth muscles do

A

Contraction and relaxation of smooth muscle in the middle layer of the vein walls helps push the blood towards the heart.

52
Q

what does gravity do

A

Blood from the upper body is aided by gravity

53
Q

what is blood pooling

A

VR requires a force to push the blood back towards the heart

If there isn’t enough pressure, the blood will sit in the pocket valves of the veins.

54
Q

what are the impacts of vr on performance

A

more oxygen to working muscles
less fatigue
quick recovery

A-Level PE (6 decks)

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