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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
define the elasticity of cardiac fibres.
how much the cardiac tissues stretch during diastole
26
what is the impact/benefit of the elasticity of cardiac fibres?
the more cardiac fibres can stretch, the greater the force of contraction = more blood pumped out the heart + increases ejection fraction
27
what is ejection fraction?
the percentage of blood pumped out by the left ventricle per beat (average=60%)
28
define diastole
when the heart relaxes to fill with blood
29
define systole.
when the heart contracts to empty blood
30
what happens to venous return during exercise?
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
what are the 6 mechanisms to aid venous return?
skeletal muscle pump, respiratory pump, pocket valves, thin layer of smooth muscle walls, gravity, suction pump action of the heart
32
how does the skeletal muscle pump aid venous return?
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
how does the respiratory pump aid venous return?
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
how do the pocket valves aid venous return?
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
what is enough to maintain venous return during rest?
valves and smooth muscles walls
36
why do we need to maintain a high venous return after exercise?
to maintain the mechanisms through an active cool down -- preventing blood pooling
37
what is increased venous return caused by?
increase in pressure in veins nearby, decrease in right atrial pressure, decrease in venous resistance
38
how does oxygen travel in the blood to the muscles
it binds to haemoglobin
39
what percentage of O2 binds to haemoglobin?
97%
40
what happens to O2 at the muscles?
oxygen dissociates from haemoglobin as there is a lower partial pressure of o2 in the muscles compared to the blood
41
what is oxyhaemoglobin dissociation?
the movement of oxygen from oxyhaemoglobin to the muscles
42
what does myoglobin do?
it stores O2 in the muscles for when the mitochondria needs it
43
what is Bohr shift?
the movement of the S-shaped oxygen-dissociation curve to the right
44
why does Bohr shift occur?
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
how does Bohr shift affect haemoglobins affinity for O2?
it reduces it - so muscles receive more O2 during exercise
46
what does affinity mean?
how easily a substance combines with another
47
what centre is blood flow controlled by?
vasomotor centre - in the medulla oblongata (in the brain)
48
how is blood flow directed during exercise?
--receptors stimulate vasomotor centre --this redistributes blood flow through vasodilation + vasoconstriction
49
what is vasodilation?
the widening of blood vessels to increase the flow of blood into the capillaries
50
what is vasoconstriction?
the narrowing of blood vessels to reduce blood flow to the capillaries
51
where does vasodilation and vasoconstriction occur during exercise?
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
what else causes blood to be redirected?
stimulation of the sympathetic nerves, in the walls of the blood vessels
53
what does an increase in sympathetic stimulation cause?
vasoconstriction, so blood flow reduces -meaning blood can be redistributed to muscles during exercise
54
what does a decrease in sympathetic stimulation cause?
vasodilation, so blood flow increases
55
what are pre-capillary sphincters?
tiny rings at the opening of capillaries
56
what do pre-capillary sphincters do?
-aid blood redistribution -contract=to restrict blood flow -relax=to increase blood flow
57
what do pre-capillary sphincters do during exercise?
-they relax at working muscles to increase blood flow + O2
58
why is blood redistribution important?
-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
what is the arterio-venous difference (A-VO2 diff)?
the difference between oxygen content of the arterial blood arriving at the muscles + the venous blood leaving the muscles
60
what level is the AVO2 diff at during rest + exercise?
at rest: low during exercise: high
61
how does training impact AVO2 diff?
it increases it-- as trained athletes can use a greater amount of O2 from the blood
62
why is there an increase in AVO2 diff at the start of exercise?
more O2 is extracted by the working muscles/ stored in myoglobin - venous blood has less O2 to return to the heart
63
what is cardiovascular drift?
an increasein HR due to a decrease in stroke volume/ejection fraction - occurs after 10 minutes of steady exercise in a warm environment
64
why does cardiovascular drift occur?
- 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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