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Module 103: The Heart, Lungs and Blood > Theme 3: Lecture 2 - Blood pressure > Flashcards

Theme 3: Lecture 2 - Blood pressure Flashcards

1
Q

Units of BP

A

mmHg (or kPa)

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2
Q

What is a portal system

A

2 capillary beds in series (When a capillary bed reassembles to a blood vessel that splits again into another capillary bed)

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3
Q

What does a capillary system allow

A

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

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4
Q

Give an example of a portal system

A

Hepatic portal system

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5
Q

An increase in what things will cause an increase in BP

A
  • Peripheral resistance
  • Cardiac output
  • Blood volume
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6
Q

Why is there not one measurement of BP

A

The arterial pressure changes due to systole and diastole

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7
Q

Equation for mean arterial pressure

A

P mean = P diastole + (P systole - P diastole)/3

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8
Q

Stroke volume

A

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

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9
Q

Heart rate

A

measured in beats per minute. Its reciprocal is the RR interval, which is 60 ÷ HR.

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10
Q

RR interval

A

Time elapsed between 2 heart beats (reciprocal of heart rate)

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11
Q

Cardiac output

A

Volume of blood pumped out of a ventricle per minute

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12
Q

Cardiac output equation

A

CO = HR x SV

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13
Q

Normal stroke volume

A

70mL

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14
Q

Normal heart rate

A

70 bpm

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15
Q

Normal RR interval

A

0.86 s

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16
Q

Normal cardiac output

A

4.9 L/min

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17
Q

End diastolic volume

A

Volume of blood in a ventricle at the end of filling (diastole). EDV is associated with “pre-load”, how stretched the muscle is.

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18
Q

End systolic volume

A

Volume of blood remaining in a ventricle at the end of contraction (systole). So: SV = EDV – ESV

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19
Q

Ejection fraction

A

Percentage of filled ventricular volume pumped out during a heart beat: SV / EDV

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20
Q

How much does atrial systole add to total fill of ventricles

A

20-25%

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21
Q

Normal end diastolic volume

A

120mL

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22
Q

Normal end systolic volume

A

50mL

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23
Q

Normal ejection fraction

A

58% (50-70%)

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24
Q

Vasomotor

A

actions on a blood vessel that alter its diameter

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25
Q

What does vasoconstriction lead to

A

a smaller radius which leads to a higher resistance which leads to a lower flow rate

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26
Q

What causes dilation on constriction of individual blood vessels

A
  • Central regulation (CNS, autonomic, endocrine)
  • Local regulation of pressure
  • Immune
  • Haemostasis
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27
Q

What happens to blood vessels during exercise

A
  • Peripheral vasodilation (skin/muscle)

- Vasoconstriction of splanchnic circulation

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28
Q

What happens to blood pressure and heart rate in exercise

A
  • Increased systolic BP
  • Decreased diastolic BP
  • Increased heart rate
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29
Q

What happens initially when you stand

A

-Initially a drop in BP then compensatory recovery (ie increase back to normal)

30
Q

What happens to the blood vessels and heart rate during standing

A
  • peripheral vasoconstriction (arterial + venous)

- increased HR

31
Q

What happens to blood pressure and heart rate after standing up

A
  • no change in systolic BP
  • increased in diastolic BP
  • increased heart rate
32
Q

How is blood pressure controlled systemically

A
  • Local (Endothelial, Nitric Oxide (NO))
  • Neurological – the autonomic system
  • Humoral – renal / pituitary / adrenal
33
Q

What does nitric oxide do

A

causes smooth muscle relaxation leading to vasodilatation

34
Q

What is nitric oxide released by

A

endothelial cells

35
Q

What are the local blood flow conditions that would cause vasodilatation

A
  • increased hydrostatic pressure

- increased shear force

36
Q

What is shear force protective for

A

it’s atherogenic (protective against atherosclerosis)

37
Q

What is shear force increased by

A

laminar flow (smooth, opposite to turbulent flow)

38
Q

What does increased sympathetic stimulation cause in relation to BP and cardiac output

A
  • Constricts blood vessels
  • increase in peripheral resistance
  • increase in pressure
  • increase in heart rate
  • increase in cardiac output
39
Q

What do baroreceptors do

A
  • Detect pressure and feed back to the brain

- Activity leads to a decrease in BP

40
Q

Where are baroreceptors located

A
  • transverse aortic arch

- carotid sinuses of the left and right internal carotid arteries

41
Q

What do chemoreceptors do

A

Detect when CO2 levels are low and feed back to the brain

42
Q

Where are chemoreceptors located

A
  • carotid bodies

- aortic bodies

43
Q

How does the heart pump the right amount of blood as the volume of blood entering the heart must equal the volume of blood leaving the heart

A

Due to the Frank Starling mechanism

44
Q

Frank Starling law

A

the stroke volume of the heart increases in response to an increase in the stretching of blood filling the heart (the end diastolic pressure)

45
Q

Venous return

A

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

46
Q

Preload

A

the initial stretching of the cardiac myocytes during diastole (prior to contraction). Depends on venous return

47
Q

Volume overload

A

Results when preload becomes too large

48
Q

5 factors that cause an increase in preload

A
  • decrease in heart rate
  • increase in aortic pressure
  • increase in atrial contractility
  • increase in ventricular compliance
  • increase in central venous pressure
49
Q

2 factors that cause an increase in central venous pressure

A
  • decrease in venous compliance

- increase in thoracic venous blood volume

50
Q

Afterload

A

the resistance that the chambers of the heart must overcome in order to eject blood out of the heart (resistance during systole)

51
Q

What is afterload increased by

A
  • back pressure from aorta or pulmonary arteries

- if the exit valve fails to open completely

52
Q

Pressure overload

A
  • results from elevated afterload

- a pathological state

53
Q

What is the thoracic pump for venous return

A
  • “pulls” the blood (from below) towards the right atrium.
  • during inspiration intrathoracic pressure is negative and abdominal pressure is positive (compression of abdominal organs by diaphragm).
  • Creates a pressure gradient
54
Q

What is the muscle pump in venous return

A
  • Rhythmical contraction of limb muscles as occurs during normal locomotor activity
  • Squeezes blood out of nearby veins
  • Venous valves assure one-way flow toward heart
55
Q

Describe the pulmonary circulation

A
  • High Capillary Density
  • Low Vascular Resistance
  • Acts as Blood Reservoir
  • Acts as Filter
56
Q

What controls the BP of the pulmonary circulation

A

endocrine control via ACE

57
Q

What happens to arterioles if O2 is low in a region of the lung

A

they constrict

58
Q

What happens to arterioles if CO2 or H+ are high in an area of the lung

A

they constrict

59
Q

What does poor ventilation in the lung lead to

A
  • reduced perfusion

- this minimises the amount of blood that is poorly oxygenated

60
Q

Describe the coronary circulation

A
  • Cardiac Muscle has High Demand
  • Most Flow occurs during Diastole (unusual)
  • Obtains blood almost before aorta
61
Q

What is hypertension

A

high blood pressure (esp high diastolic pressure)

62
Q

What may chronic hypertension result in (7 things listed)

A
  • Coronary artery disease
  • MI
  • Aneurysm
  • Stroke
  • Kidney failure
  • Heart failure
  • Cardiac hypertrophy
63
Q

Symptoms of hypertension

A

often asymptomatic

64
Q

What is hypertension caused by

A
  • mismatch in blood volume and circulatory capacity
  • most cases are idiopathic
  • often secondary to kidney disease
65
Q

What is orthostatic hypotension

A

low BP on standing up due to decreased venous return

66
Q

Symptoms of orthostatic hypotension

A
  • dizziness

- syncope

67
Q

hypovolaemia

A

too little blood volume

68
Q

Causes of orthostatic hypotension

A
  • drugs
  • hypovolaemia
  • age
69
Q

What is cardiogenic shock

A

shock due to heart not pumping enough blood to meet body’s demands

70
Q

Signs and symptoms of cardiogenic shock (7 things listed)

A
  • tachycardia
  • tachypnoea
  • low urine output
  • hypotension
  • confusion
  • syncope
  • acidosis
71
Q

Compensatory mechanisms of cardiogenic shock

A
  • tachycardia

- tachypnoea

72
Q

Things seen when the body fails to compensate cardiogenic shock

A
  • low urine output
  • hypotension
  • confusion
  • syncope

Module 103: The Heart, Lungs and Blood (51 decks)

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