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PE - Year 12 > 1.1 The Cardiovascular System > Flashcards

1.1 The Cardiovascular System Flashcards

1
Q

What is the cardiovascular system?

A

The body’s transport system which includes the heart and the blood vessels

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2
Q

How is the heart divided?

A

Divided into 2 parts by a muscular wall called the septum.

Each part contains 2 chambers - an atrium and a ventricle.

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3
Q

Which chamber is smaller and why?

A

Atria are smaller as all they do is push the blood down into the ventricles. This doesn’t require much force so they have thinner muscular walls.

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4
Q

Which chamber is bigger and why?

A

Ventricles have much thicker muscular walls as they need to contract with greater force in order to push blood out of the heart.

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5
Q

Which side of the heart is larger and why?

A

Left side is larger as it needs to pump blood all around the body, whereas right side pumps deoxygenated blood to the lungs which is closer.

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6
Q

What are the blood vessels of the heart?

A

Vena cava
Pulmonary vein
Pulmonary artery
Aorta

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7
Q

What is the role of the vena cava?

A

Brings deoxygenated blood back to the right atrium.

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8
Q

What is the role of pulmonary vein?

A

Delivers oxygenated blood to the left atrium.

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9
Q

What is the role of the pulmonary artery?

A

Delivers deoxygenated blood to the lungs.

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10
Q

What is the role of the aorta?

A

Delivers oxygenated blood to the rest of the body.

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11
Q

What are the main valves in the heart?

A
  1. Tricuspid valve
  2. Bicuspid valve
  3. Semi-lunar valve
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12
Q

Where are the valves located?

A 
Tricuspid = between right atrium and right ventricle
Bicuspid = between left atrium and left ventricle 
Semi-lunar = between left and right ventricles, pulmonary artery and aorta
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13
Q

What is the role of valves?

A

Regulate blood flow by ensuring it only flows in one direction. The open to allow blood to pass through, then close to prevent back flow.

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14
Q

Define cardiac conduction system

A

Group of specialised cells located in the wall of the heart which send electrical impulses to the cardiac muscle, causing it to contract.

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15
Q

How is the heart muscle described?

A

Myogenic - capacity to generate its own impulses

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16
Q

How does an electrical impulse travel?

A
  1. SAN
  2. Impulse spreads through the aria walls causing them to contract and force blood into the ventricles.
  3. Passes through AVN
  4. Ventricular systole begins
  5. Passes down through bundle of His
  6. Passes through purkinji fibres causing the ventricles to contract
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17
Q

Summarise the cardiac conduction system (SAABPV)

A 
SAN
Atrial systole
AVN
Bundle of His
Purkinje fibres
Ventricular systole
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18
Q

What are 2 neural control mechanisms?

A

Sympathetic system - part of the autonomic nervous system that speeds up HR

Parasympathetic system - part of the autonomic nervous system that decreases HR

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19
Q

What 2 parts make up the nervous system?

A

Central nervous system (CNS), and the peripheral nervous system

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20
Q

What makes up the CNS?

A

Brain and spinal chord

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21
Q

What makes up the peripheral nervous system?

A

Nerve cells

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22
Q

How are the CNS and peripheral NS controlled?

A

Co-ordinated by the cardiac control centre located in the medulla oblongata.

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23
Q

Define medulla oblongata

A

The most important part of the brain as it regulates processes that keep us alive such as breathing and HR

24
Q

What stimulates the cardiac control centre?

A

Chemoreceptors, baroreceptors, proprioceptors

25
Q

Define chemoreceptors

A

Found in the carotid arteries and aortic arch and they sense chemical changes.

26
Q

Define baroreceptors

A

Contain nerve endings that respond to stretching of the atrial wall caused by changes in blood pressure. They establish a set point for BP.

27
Q

Define proprioceptors

A

Sensory nerve endings in the muscles, tendons and joints that detect changes in muscle movement.

28
Q

Memory tool for receptors

A

Chemoreceptors = increase in CO2 = increased HR

Baroreceptors = increase in blood pressure = decreased HR

Proprioceptors = increase in muscle movement = increased HR

29
Q

Define adrenaline

A

Stress hormone that is released by the sympathetic nerves and cardiac nerve during exercise which increases HR

30
Q

Define stroke volume

A

Volume of blood pumped out by the ventricles in each contraction

31
Q

What does stroke volume depend on?

A

Venous return - if this increases, so does SV

Elasticity of cardiac fibres - the more they can stretch, the greater the force of contraction which increases ejection fraction (Starling’s Law)

32
Q

Define ejection fraction

A

% of blood pumped out by left ventricle per beat

33
Q

Define diastole phase

A

When the heart relaxes to fill with blood

34
Q

Memory tool for Starling’s Law

A

Increase venous return = greater diastole = cardiac muscle stretched = more force of contraction = increased ejection fraction

35
Q

Define cardiac output

A

Volume of blood pumped out by the ventricles per minute

36
Q

How do you calculate cardiac output?

A

SV x HR

37
Q

Define cardiac hypertrophy

A

Thickening of the muscular wall of the heart so it becomes thicker and stronger

38
Q

Define bradycardia

A

A decrease in resting heart rate to below 60 bpm

39
Q

What can a lack of exercise lead to?

A

Heart disease
High blood pressure
Increased cholesterol levels

40
Q

What is cardiovascular drift?

A

During steady state exercise heart rate slowly climbs

41
Q

When does cardiovascular drift occur?

A

During prolonged exercise (after 10 mins) in a warm environment.

42
Q

Why does cardiovascular drift occur?

A

When we sweat, a portion of this lost fluid comes from plasma volume. This decreases venous return and stroke volume, so HR increases to compensate and maintain a higher cardiac output.

43
Q

Define blood pressure

A

The force exerted by the blood against the blood vessel wall.

44
Q

What is the difference between systolic and diastolic pressure?

A

Systolic - the pressure in the arteries when the ventricles are contracting.
Diastolic - the pressure in the arteries when the ventricles are relaxing.

45
Q

Define venous return

A

The return of blood to the right side of the heart via the vena cava.

46
Q

Describe Starling’s Law

A

During exercise, venous return increases. This means that if more blood is being pumped back to the heart, then more blood has to be pumped out, so stroke volume increases.

47
Q

What are the venous return mechanisms?

A
  1. Skeletal muscle pump
  2. Respiratory pump
  3. Pocket valves
48
Q

How does the skeletal muscle pump aid venous return?

A

When muscles contract and relax they change shape meaning muscles press on nearby veins. This causes a pumping effect which squeezes the blood towards the heart.

49
Q

How does the respiratory pump aid venous return?

A

When muscles contract and relax during breathing, pressure changes occur in the thoratic (chest) and abdominal cavities. This compresses nearby veins and squeezes blood to the heart.

50
Q

How do pocket valves aid venous return?

A

Prevent back flow

51
Q

What happens to oxygen during exercise?

A

It diffuses into capillaries, 3% dissolves into plasma, and 97% combines with haemoglobin to form oxyhemoglobin

52
Q

How is oxygen stored in the muscles?

A

By myoglobin

53
Q

Define the Bohr shift

A

When an increase in blood CO2 and a decrease in pH results in a reduction of the affinity of haemoglobin for oxygen.

54
Q

What 3 factors are responsible for the oxyhaemoglobin dissociation curve?

A
  1. Increase in blood temp - o2 dissociates more readily.
  2. Partial pressure of co2 increases - oxygen dissociates faster.
  3. pH - decrease in blood acidity causes o2 to dissociate more quickly.
55
Q

Define vascular shunt mechanism

A

The redistribution of cardiac output.

56
Q

Why should athletes not eat less than an hour before competition?

A

A full gut results in blood being directed to the stomach instead of the working muscles.

57
Q

What is the difference between vasoconstriction and vasodilation?

A

Vasoconstriction - narrowing of blood vessels to reduce blood flow into the capillaries.

Vasodilation - widening of the blood vessels to increase blood flow into the capillaries.

PE - Year 12 (12 decks)

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