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A Level PE > Cardiovascular System > Flashcards

Cardiovascular System Flashcards

1
Q

what are the three layers of the heart wall?

A
  1. EPIDCARDIUM
    outer protective layer
  2. MYOCARDIUM
    muscular middle
    layer
    can undergo cardiac
    hypertrophy
  3. ENDOCARDIUM
    thin inner layer
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2
Q

the cardiovascular system is composed of three main parts…

A
  1. the heart
  2. the blood vessels
  3. the blood
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3
Q

the main functions of the cardiovascular system (3)

A
  1. transport of nutrients and removal of waste products
  2. blood cell production
  3. thermoregulation
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4
Q

why is the heart known as a double pump system? (3)

A
  • because it has two circuits that are constantly at work

-the pulmonary circuit carries deoxygenated blood to the lungs and oxygenated blood back to the heart
- the systemic circuit carries oxygenated blood to the body tissues and deoxygenated blood back to the heart

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5
Q

the conduction system (4)

A

SINOATRIAL NODE
- the heart’s natural pacemaker
- sends an electrical signal that tells the heart to beat.
- this signal starts in the upper right part of the heart and allows the atria to fill with blood

ATRIOVENTRICULAR NODE
- after the signal from the SA node causes the atria to contract, the AV node slows the signal down slightly before sending it to the ventricles
- this delay allows the atria to empty fully before the ventricles contract

BUNDLE OF HIS
- the electrical signal travels from the AV node to the bundle of His, which splits into two branches. one for each ventricle.

PURKINJE FIBRES
- spread the electrical signal throughout the ventricles
- this causes them to contract and pump blood out of the heart

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6
Q

how does the SA node generate its own electrical signals? (2)

A
  • it receives messages from the PNS and the SNS to adjust the heart rate, either by increasing it or decreasing it.
  • the cells within the SA node are classed as ‘self-excitable’
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7
Q

define heart rate

A

the number of times at which the heart beats per minute

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8
Q

define bradycardia

A

a decrease in resting heart rate to below 60 BPM

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9
Q

define stroke volume

A

the volume of blood pumped out of the left ventricle per beat

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10
Q

what is the average stroke volume at rest?

A

70 ML

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11
Q

how is stroke volume determined? (3)

A
  1. venous return
    - if the venous return increases, stroke volume will also increase
  2. elasticity of the cardiac fibres
    - the degree of the stretch during the diastole phase
    - the greater the degree of stretch = greater force of contraction = greater SV
  3. contractility of the cardiac tissues
    - the greater the contraction of cardiac tissues = greater force of contraction = greater SV
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12
Q

define ejection fraction

A

the percentage of blood pumped out of the left ventricle, per beat

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13
Q

define venous return

A

the volume of blood returning to the heart via the veins

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14
Q

list the five mechanisms of venous return

A
  • pocket valves
  • skeletal muscle pump
  • respiratory pump
  • smooth muscle
  • gravity
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15
Q

pocket valves (3)

A
  • located in the veins
  • prevent the backflow of blood
  • helps blood move in one direction (towards the heart)
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16
Q

skeletal muscle pump (3)

A
  • during upright posture
  • skeletal muscles compress underlying veins and contract them
  • this increases blood flow back to the heart
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17
Q

respiratory pump (4)

A
  • during inspiration, the diaphragm moves down
  • this expands the thoracic cavity; decreases intra-thoracic pressure; expands the lungs
  • change in pressure is transmitted across the walls of the heart
  • this lowers right atrial pressure, facilitating venous return
18
Q

smooth muscle (2)

A
  • smooth muscle undergoes vasodilation and vasoconstriction
  • through this widening and narrowing of the internal diameter, stroke volume can be increased
19
Q

gravity (3)

A
  • blood from the upper body is aided in its return by gravity
  • when stood up, the blood naturally flows to the lower extremities
  • therefore, blood in the lower body has to work against gravity to return to the heart
20
Q

define cardiac output

A

the volume of blood pumped out of the left ventricle, per minute

21
Q

what is the average cardiac output at rest?

A

5 L

22
Q

what is the equation for cardiac output?

A

HR (heart rate) x SV (stroke volume)

23
Q

what are the changes in heart rate during exercise? (3)

A
  • heart rate increases
  • how much it increases depends on the intensity of the exercise
  • increase in HR is directly proportional to exercise intensity
24
Q

what are the changes in stroke volume during exercise? (4)

A
  • stroke volume increases as exercise increases
  • only increases until around 40-60% of maximum intensity
  • after this SV begins to drop off slightly
  • this is because the duration of the diastole phase decreases, meaning the heart isn’t pumping out as much blood per contraction.
25
Q

what are the changes in cardiac output during exercise? (3)

A
  • increases
  • because the cardiac muscle (myocardium) can get physically bigger and stronger
  • this means more blood can be pumped out the left ventricle, per beat and therefore per minute
26
Q

describe and explain the heart rate response during maximal exercise (5)

A
  • before exercise starts, there is an anticipatory rise due to the secretion of adrenaline, which stimulates the sinoatrial node to make the heart contract faster and stronger
  • when exercise begins, there is a sharp rise in heart rate due to mainly anaerobic work (because at this time, there isn’t a sufficient amount of oxygen for aerobic work)
  • towards the end of exercise, the heart rises more due to maximal workloads stressing the anaerobic system
  • when exercise ends, there is a rapid decline in heart rate as soon as the exercise stops, because there is a decrease in the demand for oxygen by the working muscles
  • after exercise, there is a slow recovery as the body systems return to resting levels
27
Q

where is the cardiac control centre found?

A

in the medulla oblongata of the brain

28
Q

how many sub-divisions does the cardiac control centre have?

A

TWO
- sympathetic nervous system
- parasympathetic nervous system

29
Q

sympathetic nervous system (2)

A
  • speeds up heart rate via the accelerator nerve
  • releases the hormones epinephrine and norepinephrine
30
Q

parasympathetic nervous system (2)

A
  • slows down heart rate via the vagus nerve
  • releases a hormone called acetylcholine
31
Q

what happens to the SNS and PNS during rest and during exercise? (3)

A
  • at rest, the PNS is in control of heart rate
  • at the beginning of exercise, your body removes the parasympathetic stimulation, which enables the heart rate to gradually increase
  • as exercise increases in intensity, the sympathetic nervous system becomes more dominant and takes control of heart rate
32
Q

list the three ways in which the cardiac control centre regulates heart rate

A
  1. neural control
  2. hormonal control
  3. intrinsic control
33
Q

neural control (3)

A
  • involves receptors detecting changes in the body as a result of increased physical activity
  • they send messages to the CCC, and in turn the ANS sends a message to the SA node
  • this will either be done via the accelerator nerve or the vagus nerve
34
Q

list the four types of receptors that detect change during physical exercise

A

(P C B T)

proprioceptors
chemoreceptors
baroreceptors
thermoreceptors

35
Q

proprioceptors (2)

A
  • pick up movement within the joints and muscles
  • increased intensity = increased amounts of movement

e.g. muscle spindle

36
Q

chemoreceptors (3)

A
  • pick up chemical changes, such as lowered pH in the blood and a decrease in oxygen
  • increase in intensity = increase in CO2 and lactic acid
  • found in : muscle tissue, the aorta, the carotid artery
37
Q

baroreceptors (3)

A
  • pick up changes in blood pressure
  • increase in intensity = increased blood pressure
  • found in: the aorta, the carotid artery
38
Q

thermoreceptors (3)

A
  • pick up changes in body temperature and muscle temperature
  • increase in intensity = increased body temperature
  • found in: the skin, skeletal muscle, and the liver
39
Q

hormonal control (4)

A
  • before and during exercise, adrenaline and noradrenaline is released into the blood stream
  • these hormones act directly on the SA node, stimulating an increase in HR
  • both also aid the redistribution of blood to the muscles through vasodilation and vasoconstriction
  • when intensity begins to drop, the hormone acetylcholine takes over to lower HR
40
Q

intrinsic control (2)

A
  • the heart internally controlling itself
  • two factors to consider:

TEMPERATURE - increased temp of cardiac muscle = sped up nerve impulses = increased HR

STARLING’S LAW - as venous return increases, so does SV

A Level PE (6 decks)

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