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PE ALEVEL > Cardiovascular system > Flashcards

Cardiovascular system Flashcards

1
Q

what side of the heart is bigger and why?

A

left- has to pump blood around the entire body

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2
Q

The heart is myogenic, what does this mean?

A

it contracts by itself without any nerve impulses telling it to do so

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3
Q

what does Sally Always Aims Balls Past Vicky stand for?

A

SA node –> Atrial systole –> AV node –> Bundle of HIS –> Purkinje fibres –> Ventricular systole –>

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4
Q

what detects a stimulus?

A

receptors

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5
Q

what are the three receptors?

A

chemoreceptors, baroreceptors, proprioceptors

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6
Q

what do chemoreceptors detect and cause?

A

increase in CO2 levels = increased HR
decrease in CO2 levels = decrease in HR

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7
Q

what do baroreceptors detect and cause?

A

increase in blood pressure = decrease in HR
decrease in blood pressure = increase in HR

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8
Q

what do proprioceptors detect and cause?

A

increase in body/muscle movement = increase in HR
decrease in body/muscle movement = decrease in HR

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9
Q

what is the sympathetic nervous system?

A

nervous system which sends electrical impulses to the heart to increase HR

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10
Q

what is the parasympathetic nervous system?

A

nervous system which sends electrical impulses to the heart to decrease HR

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11
Q

what is the cardiac control centre (CCC), and where is it found?

A

controls HR- in medulla oblongata

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12
Q

explain the pathway of impulses from a stimuli being detected to the heart.

A

A receptor (chemo,baro,proprio) detects a change (CO2 levels, BP, movement) –> this stimulates the CCC which triggers the para/sympathetic nervous system to send impulses to the SA node –> AV node –> Bundle of HIS –> Purkinje fibres === HR increase or decreases

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13
Q

what is involved in the hormonal control mechanism?

A

adrenaline- a stress hormone that is released by sympathetic nerves and cardiac nerves during exercise = increased HR

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14
Q

what causes adrenaline to be released?

A

anticipatory rise occurs prior to event which maintains HR and causes adrenaline to be released to the SA node == increased filling at the SA node

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15
Q

what is the role of the AV node?

A

receives impulses from the SA node, delays transmission of impulse – allowing ventricular filling and atria to fully contract– sends impulse down septum–> Bundle of HIS–>Purkinje fibres

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16
Q

what is the impact of adrenaline?

A

stimulates the SA node, causing an increase in speed + force of contraction

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17
Q

what is stroke volume?

A

the volume of blood pumped out of the heart ventricles each contraction

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18
Q

what is the average resting SV?

A

70ml

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19
Q

what is SV dependent on?

A

venous return and elasticity of cardiac fibres

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20
Q

what is cardiac output?

A

the volume of blood pumped out of the heart ventricles per minute

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21
Q

what is the equation to work out cardiac output?

A

cardiac output= stroke volume x heart rate

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22
Q

what is venous return?

A

the volume of blood returning to the heart via the veins

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23
Q

what increases when venous return increases?

A

stroke volume

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24
Q

explain Starlings Law.

A

increased venous return causes greater diastolic filling of the heart –> cardiac muscles strengthened = greater force of contraction –> increased ejection fraction

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25
Q

define the elasticity of cardiac fibres.

A

how much the cardiac tissues stretch during diastole

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26
Q

what is the impact/benefit of the elasticity of cardiac fibres?

A

the more cardiac fibres can stretch, the greater the force of contraction = more blood pumped out the heart + increases ejection fraction

27
Q

what is ejection fraction?

A

the percentage of blood pumped out by the left ventricle per beat (average=60%)

28
Q

define diastole

A

when the heart relaxes to fill with blood

29
Q

define systole.

A

when the heart contracts to empty blood

30
Q

what happens to venous return during exercise?

A

it increases == stroke volume increases and more blood pumped out = Starlings law

skeletal and respiratory pump work together to allow venous return to work efficiently - muscles constantly contracting and breathing elevated

31
Q

what are the 6 mechanisms to aid venous return?

A

skeletal muscle pump, respiratory pump, pocket valves, thin layer of smooth muscle walls, gravity, suction pump action of the heart

32
Q

how does the skeletal muscle pump aid venous return?

A

the change in shape of muscles when they contract + relax presses on the veins causing a pumping effect– squeezing blood flow towards the heart

33
Q

how does the respiratory pump aid venous return?

A

when breathing in + out muscles cause pressure changes in the thoracic and abdominal cavities == compressing on the veins and assisting blood flow/return to the heart

34
Q

how do the pocket valves aid venous return?

A

they open to allow blood to flow through the veins and close to prevent the backflow of blood due to low BP in the veins – so blood flows in one direction towards the heart

35
Q

what is enough to maintain venous return during rest?

A

valves and smooth muscles walls

36
Q

why do we need to maintain a high venous return after exercise?

A

to maintain the mechanisms through an active cool down – preventing blood pooling

37
Q

what is increased venous return caused by?

A

increase in pressure in veins nearby, decrease in right atrial pressure, decrease in venous resistance

38
Q

how does oxygen travel in the blood to the muscles

A

it binds to haemoglobin

39
Q

what percentage of O2 binds to haemoglobin?

A

97%

40
Q

what happens to O2 at the muscles?

A

oxygen dissociates from haemoglobin as there is a lower partial pressure of o2 in the muscles compared to the blood

41
Q

what is oxyhaemoglobin dissociation?

A

the movement of oxygen from oxyhaemoglobin to the muscles

42
Q

what does myoglobin do?

A

it stores O2 in the muscles for when the mitochondria needs it

43
Q

what is Bohr shift?

A

the movement of the S-shaped oxygen-dissociation curve to the right

44
Q

why does Bohr shift occur?

A

due to:
-an increase in CO2
-a decrease in pH
-an increase in body temperature .

this makes O2 dissociate more easily from haemoglobin in the blood so O2 diffuses into the muscles

45
Q

how does Bohr shift affect haemoglobins affinity for O2?

A

it reduces it - so muscles receive more O2 during exercise

46
Q

what does affinity mean?

A

how easily a substance combines with another

47
Q

what centre is blood flow controlled by?

A

vasomotor centre - in the medulla oblongata (in the brain)

48
Q

how is blood flow directed during exercise?

A

–receptors stimulate vasomotor centre
–this redistributes blood flow through vasodilation + vasoconstriction

49
Q

what is vasodilation?

A

the widening of blood vessels to increase the flow of blood into the capillaries

50
Q

what is vasoconstriction?

A

the narrowing of blood vessels to reduce blood flow to the capillaries

51
Q

where does vasodilation and vasoconstriction occur during exercise?

A

vasodilation= in the arterioles supplying the muscles with blood== increasing blood flow and O2

vasoconstriction=in the arterioles supplying the organs with blood, decreasing blood flow and O2

52
Q

what else causes blood to be redirected?

A

stimulation of the sympathetic nerves, in the walls of the blood vessels

53
Q

what does an increase in sympathetic stimulation cause?

A

vasoconstriction, so blood flow reduces
-meaning blood can be redistributed to muscles during exercise

54
Q

what does a decrease in sympathetic stimulation cause?

A

vasodilation, so blood flow increases

55
Q

what are pre-capillary sphincters?

A

tiny rings at the opening of capillaries

56
Q

what do pre-capillary sphincters do?

A

-aid blood redistribution
-contract=to restrict blood flow
-relax=to increase blood flow

57
Q

what do pre-capillary sphincters do during exercise?

A

-they relax at working muscles to increase blood flow + O2

58
Q

why is blood redistribution important?

A

-it increase supply of O2 to working muscles
-it removes waste products from the muscles
-it ensures more blood moves to the surface of the skin during exercise to regulate body temperature + remove heat
-it directs more O2 to the heart as it requires more O2 during exercise

59
Q

what is the arterio-venous difference (A-VO2 diff)?

A

the difference between oxygen content of the arterial blood arriving at the muscles + the venous blood leaving the muscles

60
Q

what level is the AVO2 diff at during rest + exercise?

A

at rest: low
during exercise: high

61
Q

how does training impact AVO2 diff?

A

it increases it– as trained athletes can use a greater amount of O2 from the blood

62
Q

why is there an increase in AVO2 diff at the start of exercise?

A

more O2 is extracted by the working muscles/ stored in myoglobin
- venous blood has less O2 to return to the heart

63
Q

what is cardiovascular drift?

A

an increasein HR due to a decrease in stroke volume/ejection fraction
- occurs after 10 minutes of steady exercise in a warm environment

64
Q

why does cardiovascular drift occur?

A
  • due to a reduction of fluid in the blood plasma as there is an increase in sweating making the blood more viscous
    –> so venous return decreases =reduces atrial filling and stroke volume
    –HR increases to try to maintain cardiac output to cool the body down – through vasodilation
    -starlings law

PE ALEVEL (27 decks)

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