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Biology Circulatory System > The Cardiac Cycle > Flashcards

The Cardiac Cycle Flashcards

1
Q

What is blood clotting?

A

A series of steps that take place which results in a blood clot

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2
Q

Describe the process of blood clotting

A
  1. The damaged cells release the enzyme thromboplastin
  2. Thromboplastin converts the plasma protein prothrombin into the enzyme thrombin
  3. Thrombin converts the soluble plasma protein fibrinogen into the insoluble protein fibrin
  4. Fibrin forms a mesh of fibres and traps platelets and red and white blood cells
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3
Q

Which special type of substances/ions are also required for blood clotting?

A

Vitamin K and calcium ions

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4
Q

What are the 3 stages of the cardiac cycle?

A

Atrial systole
Ventricular systole
Ventricular diastole

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5
Q

What do the atria and ventricles do in the atrial systole?

A

Atria contract

Ventricles relax

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6
Q

What do the atria and ventricles do in the ventricular systole?

A

Atria relax

Ventricles contract

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7
Q

What do the atria and ventricles do in the ventricular diastole?

A

Both ventricles and atria relax

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8
Q

How long does the atrial systole last?

A

0.1 s

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9
Q

How long does the ventricular systole last?

A

0.3 s

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10
Q

How long does the atrial diastole last?

A

0.7 s

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11
Q

How long does the ventricular diastole last?

A

0.4 s

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12
Q

Describe the process of atrial systole

A

The atrial walls contract

Blood flows through the atro-ventricular valves into the ventricles because of the high pressure in the atria

The semi lunar valves are closed so blood can’t go into the pulmonary artery and aorta

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13
Q

Describe the process of ventricular systole

A

The ventricular walls contract

Blood flows through the semi lunar valves into the aorta and pulmonary artery due to the high pressure in the ventricles

The atrioventricular valves shut to prevent backflow of blood into the atria

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14
Q

Describe the process of ventricular diastole

A

The ventricles (and atria) relax

The pressure in the ventricles droop

The semi-lunar valves prevent blood going back into the ventricles

The atrioventricular valves are open and blood flow from the atria into the ventricles

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15
Q

How do you calculate heart rate?

A

60 / length of heart beat

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16
Q

Why is there a bump in the ‘atrial pressure curve’ at the start?

A

This is when the atria contract

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17
Q

When do the atrioventricular valves open and how can you see this in a ‘atrial pressure curve’? In which stage of the cardiac cycle does this happen?

A

When the pressure in the atria starts to get greater than in the ventricles

This happens in the atrial systole

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18
Q

When do the atrioventricular valves close and how can you see this in a ‘atrial pressure curve’?

A

When the pressure in the atria starts to get lower than in the ventricles

This happens in the ventricular diastole

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19
Q

Why does the ‘ventricular pressure’ increases slightly in the atrial systole?

A

Because blood is flowing into the ventricles

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20
Q

When does the ‘ventricular pressure’ increase a lot?

A

During ventricular systole

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21
Q

When does the ‘ventricular pressure’ drop?

A

During ventricular diastole

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22
Q

Why does the ‘ventricular pressure’ increase slightly during ventricular diastole?

A

Because as blood flows into the atria, some blood also flows into the ventricles

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23
Q

When do the semi lunar valves open and how can you see this in a ‘ventricular pressure curve’? During which stage does this happen?

A

When the pressure in the ventricles is greater than in the arteries

This happens in the ventricular systole

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24
Q

When do the semi lunar valves close and how can you see this in a ‘ventricular pressure curve’? During which stage does this happen?

A

When the pressure in the ventricles is smaller than in the arteries (to prevent backflow of blood into the ventricles)

This happens in the ventricular diastole

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25
Q

When does the ventricular volume increase to its maximum?

A

As the atria contract and forcing blood into the ventricles (during atrial systole)

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26
Q

When does ventricular volume decrease?

A

During ventricular systole as blood is being forced out

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27
Q

Why does the ventricular volume increase when the heart is in diastole?

A

Blood flows through the atria and ventricles

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28
Q

When is the first heart sound or ‘lub’ heard?

At which stage does this happen?

A

When the atrioventricular valves close

This is the beginning of the ventricular systole

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29
Q

When is the second heart sound or ‘dub’ heard?

At which stage does this happen?

A

When the semilunar valves close

This is the beginning of ventricular diastole

30
Q

Why is the heart. muscle myogenic?

A

It can beat by itself

31
Q

What is the SAN (sinoatrial node)?

A

It is known as the pacemaker

32
Q

What does AVN stand for?

A

Atrioventricular node

33
Q

What does RA stand for?

A

Right atrium

34
Q

What does LA stand for?

A

Left atrium

35
Q

What does RV stand for?

A

Right ventricle

36
Q

What does LV stand for?

A

Left ventricle

37
Q

What sets the heart rate?

A

How often the SAN sends out an electrical signal

38
Q

Describe the sequence of events that occur during a heartbeat involving the SAN and AVN

A
  1. The SAN sends out electrical impulses causing the atria to contract
  2. The electrical impulses are picked up by the AVN
  3. After a short delay these impulses are passed on the bundle of His
  4. The bundle of His takes the excitation wave to the base of the ventricles
  5. The excitation wave passes through the wall to the base of the ventricles causing them to contract
39
Q

What is the bundle of His and where is it located?

A

Specialised conducting fibres

They are in the wall (septum) between the left and right ventricles

40
Q

What is septum?

A

Wall

41
Q

Why is the short delay when the electrical impulse are passed on the bundle of His by the AVN so important?

A

It gives the blood time to flow from the atria into the ventricles and therefore allows the atria to finish contracting before the ventricles contract

42
Q

What is another name for the bundle of His?

A

Purkinje fibres

43
Q

Why does the excitation wave pass through the wall to the base of the ventricles to make them contract?

A

To make sure that the ventricles contract from the base upwards forcing the blood up and out of the ventricles into the arteries

44
Q

What are the three things you can get information on from an electrocardiograph (ECG)?

A

How fast your heart is beating

Whether the rhythm of your heartbeat is steady or irregular

The strength and timing of electrical signals as they pass through each part of your heart

45
Q

What are the characteristics in an ECG?

A

The P wave
QRS complex
T wave

46
Q

What does the P wave in an ECG represent?

A

The contraction (depolarisation) of the atria

47
Q

What does the QRS complex in an ECG represent?

A

The contraction (depolarisation) of the ventricles

48
Q

What does the T wave in an ECG represent?

A

Relaxation (repolarisation) of the ventricles

49
Q

When does the heart muscle depolarise?

A

When it contracts

50
Q

When does the heart muscle repolarise?

A

When it relaxes (regains charge)

51
Q

How many electrodes are placed on the chest when an ECG is recorded?

A

12

52
Q

What is tachycardia?

A

A heart rate which is too fast

53
Q

What is tachycardia caused by?

A 
Exercise
Anxiety, pain, fear
Hypotension
Over-active thyroid
Drug effects (stimulants such as caffeine)
54
Q

What is hypotension?

A

Low blood pressure

55
Q

What heart rate is considered tachycardia?

A

Above 120 bpm

56
Q

What is brachycardia?

A

A heart rate which is too slow

57
Q

What heart rate is considered brachycardia?

A

Below 60 bpm

58
Q

What is hypothermia?

A

High blood pressure

59
Q

What is brachycardia caused by?

A 
Drug effects (such as beta blockers)
Hypothermia
Under-active thyroid
Myocardial infarction
Electrolyte disorders
60
Q

What is myocardial infarction?

A

A heart attack where the supply of blood to the heart is suddenly blocked by (usually) a blood clot

61
Q

What do beta blockers do?

A

Block adrenaline

62
Q

What is an electrolyte disorder?

A

An electrolyte disorder occurs when the levels of electrolytes in your body are either too high or too low

63
Q

What are electrolytes?

A

Electrolytes are chemicals that conduct electricity when dissolved in water.

They regulate nerve and muscle function, hydrate the body, balance blood acidity and pressure, and help rebuild damaged tissue.

The electrolytes in human bodies include:

sodium
potassium
calcium
bicarbonate
magnesium
chloride
phosphate
64
Q

Do fit, athletic individuals have a high or low heart rate?

A

Slow (brachycardia)

65
Q

What is fibrillation?

A

Irregular heart beat

66
Q

What causes fibrillation?

A

When the atria and ventricles lose their rhythm and stop contracting properly

67
Q

What are the consequences of fibrillation?

A

Chest pain
Fainting
Lack of pulse
Death

68
Q

What is cardiac output?

A

The volume of blood pumped out by the left ventricle in one minute

69
Q

What is the stroke volume?

A

Stroke volumeVolume of blood pumped out by the left ventricle

70
Q

How do you calculate cardiac output?

A

Stroke volume x heart rate

Biology Circulatory System (6 decks)

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