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Module 103: Theme 3: Physiology of the cardiovascular system. Principles of pathology, diagnosis and treatment of cardiovascular disease > Blood pressure > Flashcards

Blood pressure Flashcards

1
Q

What are the units of blood pressure?

A 
mm Hg (mm of mercury) 
Kilopascals (kPa)
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2
Q

Describe series

A

2 paths in a row. Flow in both paths is the same.

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3
Q

In series which path has the higher pressure?

A

The first path has higher pressure than the second since energy is lost as blood experiences friction and resistance

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4
Q

Describe parallel

A

Branching paths where flow is split between 2 paths.

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5
Q

In parallel which path has the higher pressure?

A

Both paths have equal pressure provided the resistance is the same in both paths

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6
Q

Define portal system

A

2 Capillary beds lie in series

Capillary bed reassembles to a blood vessel that then splits again into another capillary bed

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7
Q

What is the function of a portal system

A

Allows transport of chemicals from one tissue to another without being diluted by mixing with blood at the heart

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8
Q

What is the advantage of a portal system?

A

High concentration of nutrients from 1st capillary bed is delivered to the 2nd capillary bed

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9
Q

List the 3 ways blood pressure is controlled

A

Blood volume
Cardiac output
Peripheral resistance

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10
Q

Give the formula for mean arterial pressure

A

P mean = P diastolic + (P systolic - P diastolic)
——————————–
3

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11
Q

What is mean arterial pressure?

A

Diastolic pressure plus a third of pulse pressure

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12
Q

What is pulse pressure?

A

The difference between diastolic and systolic pressure

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13
Q

Define stroke volume

A

Volume of blood pumped out if a ventricle during one beat of the heart

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14
Q

What is the heart rate reciprocal?

A

RR interval

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15
Q

What is heart rate measured in?

A

Beats per minute

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16
Q

Define cardiac output

A

The volume of blood pumped out of a ventricle in one minute

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17
Q

Give the formula for cardiac output

A

CO = SV X HR

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18
Q

Give the stroke volume of an average sized male

A

70 ml

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19
Q

What is the human heart rate of an average sized adult?

A

70 bpm

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20
Q

Give the figure for the RR interval

A

0.86 seconds

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21
Q

Give a value for cardiac output of an average sized adult

A

4.9 L/min

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22
Q

What is the RR interval?

A

The interval between successive R peaks on an ECG in the QRS complex

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23
Q

What percentage of total blood volume does atrial systole add to fill the ventricles?

A

20-25%

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24
Q

Define end diastolic volume

A

Volume of blood in the ventricle at the end of diastole

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25
Q

What is end diastolic volume associated with?

A

Pre load

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26
Q

Define end systolic volume

A

The volume of blood remaining in a ventricle at the end of diastole

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27
Q

Define ejection fraction

A

The percentage of ventricular volume pumped out during a heart beat

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28
Q

Give the value for average end diastolic volume

A

120ml

29
Q

Give the value for average systolic volume

A

50ml

30
Q

Give the average ejection fraction value

A

58%

31
Q

What does an ejection fraction of 40% indicate?

A

The patient has heart failure

32
Q

What does vasoconstriction cause?

A

Smaller radius
Higher resistance
Lower flow rate

33
Q

Give the formula for conductance

A

conductance (g) = 1
—————-
Resistance

34
Q

Name 4 causes of vasoconstriction and vasodilatation

A

Central regulation
Local regulation of pressure
Immune
Haemostasis

35
Q

Give the name for the opposite of haemostasis

A

Haemorrhage

36
Q

Define haemostasis

A

The stopping of bleeding

37
Q

Define splanchnic circulation

A

The circulation of the gastrointestinal tract originating at the coeliac trunk, the inferior mesenteric artery and the superior mesenteric artery. In the splanchnic circulation, venous blood coming from the intestines rebranches into the hepatic portal system (going to the liver) rather than going directly back to the heart.

38
Q

What happens to blood pressure and heart rate during exercise?

A

Systolic BP increases
Diastolic BP decreases
Heart rate increases

39
Q

What occurs to the blood vessels during exercise?

A

Peripheral vasodilation at the muscles and skin

Vasoconstriction of the splanchnic circulation

40
Q

What happens to blood pressure and heart rate upon standing?

A

Systolic BP not changed
Diastolic BP increases
Heart rate increases

41
Q

What happens generally upon standing?

A

Blood pressure drops initially since blood pools in the legs. Then compensatory response occurs to increase blood pressure to normal. Peripheral vasoconstriction occurs in both arteries and veins and heart rate increases

42
Q

List the 3 ways systemic blood pressure is controlled

A

Local- endothelial and nitric oxide
Neurological- The autonomic nervous system
Humoral- renal/pituitary/adrenal

43
Q

Define shear force

A

The force on the endothelium in the direction of the flow of blood

44
Q

Define laminar flow

A

Flow without turbulence or eddies, where the flow of all molecules is directly in the direction of the overall flow of all fluid.

45
Q

How is local vasomotor controlled?

A

Release of vasodilator compounds such as nitric oxide by epithelial cells

46
Q

Stimulation of the sympathetic nervous system does what?

A

Constricts blood vessels leading to an increase in peripheral resistance, blood pressure, heart rate and cardiac output

47
Q

State the function of baroreceptors

A

To detect pressure changes and feedback to the brain

48
Q

Where are baroreceptors located?

A

In the transverse aortic arch and carotid sinuses of left and right internal carotid arteries

49
Q

What do chemoreceptors do?

A

Detect when oxygen levels are low and feedback to the brain

50
Q

Where are the chemoreceptors located?

A

Aortic bodies

Carotid bodies

51
Q

What is the frank-starling mechanism?

A

The stroke volume of the heart increases in response to an increase in the volume of blood filling the heart

52
Q

Define venous return

A

the volume of blood flowing back to the heart through the veins

53
Q

Define preload

A

The initial stretching of cardiac myocytes prior to contraction

54
Q

When does volume overload occur?

A

When preload becomes too large

Eg in hypertension

55
Q

List the factors causing an increase in preload

A
  • Increase in atrial contractility
  • Increase in ventricular compliance
  • Increase in central venous pressure caused by a decrease in venous compliance and an increase in thoracic venous blood pressure
  • Decrease in heart rate
  • Increase in aortic pressure
56
Q

Define afterload

A

The resistance that the chambers of the heart must overcome in order to eject the blood from the heart

57
Q

What does an increase in afterload cause?

A

Pressure overload

58
Q

How can afterload be increased?

A

Increased by back pressure

Increased if exit valves fail to open completely

59
Q

Describe how the thoracic pump works

A

During inspiration the intrathoracic pressure is negative whereas the abdominal pressure is positive. Therefore creates a pressure gradient and pulls blood towards the right atrium

60
Q

Describe how the muscle pump of venous return works

A

Rhythmical contractions of limb movements occurs during normal locomotor activity. Blood is squeezed out of veins and valves maintain direction

61
Q

Describe why pulmonary circulation is special

A 
High capillary density
Endocrine control of blood pressure (ACE)
Acts as a filter 
Low vascular resistance 
Acts as a blood reservoir
62
Q

When do the arterioles in the lungs constrict?

A

When o2 is low and H+ and CO2 is low

63
Q

Poor ventilation causes what?

A

Poor perfusion

64
Q

What is the advantage of arterioles in the lungs constricting when o2 is low?

A

To minimise the amount of blood that is poorly oxygenated

65
Q

Give some interesting points about coronary circulation

A

Cardiac muscle has high demand
Most flow occurs during diastole
Obtains blood almost before aorta

66
Q

What can chronic hypertension lead to?

A 
Aneurysm or stroke
MI
Kidney failure
Heart failure
Cardiac hypertrophy
67
Q

What is orthostatic hypotension?

A

Low BP on standing causing low venous return
Dizziness or syncope
Caused by drugs, old age or hypovolaemia

68
Q

What is hypovolaemia?

A

Where a person doesn’t have enough fluids in system

69
Q

Give the signs and symptoms of cardiogenic shock

A 
Tachycardia
Tachypnoea
Low urine output
Hypotension
Confusion
Syncope
Acidosis

Module 103: Theme 3: Physiology of the cardiovascular system. Principles of pathology, diagnosis and treatment of cardiovascular disease (19 decks)

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