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BRS > Microcirculation, BP, Cardiorespiratory mechanisms and ventillation > Flashcards

Microcirculation, BP, Cardiorespiratory mechanisms and ventillation Flashcards

1
Q

Function of microcirculation?

A

Metabolic exchange at tissue site.

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2
Q

How do you calculate flow rate?

A

Pressure gradient / resistance.

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3
Q

What are the 3 factors that affect resistance in a vessel?

A

Vessel length, Vessel radius and blood viscosity.

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4
Q

What does an increase in vessel length do to resistance?

A

Increases resistance.

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5
Q

What does an increase in vessel radius do to resistance?

A

Decreases resistance.

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6
Q

What does an increase in blood viscosity do to resistance?

A

Increases resistance.

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7
Q

Why does an increase is blood pressure increase flow rate?

A

Increase in pressure gradient.

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8
Q

Why does arterial vasoconstriction decrease blood flow?

A

Decrease in radius of vessel increases resistance to blood flow.

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9
Q

Arterioles main function?

A

Major resistance vessel. Regulate blood flow by altering resistance by altering radius of blood vessel.

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10
Q

How are arterioles adapted?

A

Extensive smooth muscle in their walls and display a partial state of contraction at rest allowing them to vasoconstrict and vasodilate (vascular tone).

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11
Q

Arterioles detect an increase in O2 usage and vasodilate. What is this an example of?

A

Active hyperaemia.

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12
Q

What can result in active hyperaemia?

A

Local metabolites sensed by arterioles. Increase in O2 usage.

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13
Q

During exercise your small intestine arterioles experience unnecessary stretch. What occurs next and what is this called?

A

Myogenic vasoconctriction. Myogenic autoregulation.

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14
Q

What can cause myogenic autoregulation?

A

Change in blood temperature and stretch due to an increase in blood pressure.

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15
Q

What helps regulated systemic arterial blood pressure?

A

Cardiovascular control centre in medulla via sympathetic nervous system and endocrine hormones.

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16
Q

What is the blood pressure equation?

A

Blood pressure = cardiac output x total peripheral resistance

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17
Q

Using the blood pressure equation explain how the cardiovascular control centre can restore low blood pressure?

A

Increase total peripheral resistance by increasing vasoconstriction in certain areas such as the gut.

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18
Q

Vasoconstriction hormones?

A

AVP, Angiotensin II and adrenaline/NA.

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19
Q

In relation to capillaries what do more metabolically active tissues have?

A

Denser capillary networks.

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20
Q

Types of capillary structures?

A

Continuous, fenestrated and discontinuous.

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21
Q

What can diffuse out of continuous capillary gap junctions?

A

Small molecules like oxygen and water.

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22
Q

What is the difference between the different types of capillary structures?

A

Size of gap junctions. Size of gap junctions increases from continuous to fenestrated to discontinuous.

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23
Q

What is bulk flow?

A

A volume of protein-free plasma filters out of the capillary, mixes with the surrounding interstitial fluid (IF) and is reabsorbed.

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24
Q

Term used to describe movement of fluid from capillary into interstitial fluid is known as?

A

Ultrafiltration.

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25
Q

Term used to describe movement of fluid from interstitial fluid into capillary?

A

Reabsorption.

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26
Q

How does the lymphatic system prevent the blood pressure from dropping due to hydrostatic force being greater than colloidal osmotic pressure?

A

Reabsorption of fluid into blood.

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27
Q

Where does reabsorption of fluid into blood occur?

A

Thoracic duct into left subclavian veins

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28
Q

What moves lymph around the body?

A

Skeletal muscles and respiratory movement.

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29
Q

Lymph vessel structure

A

Blind-ended, single-layered and contain large permeable water-filled one-way channels.

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30
Q

What are the pulsatile circulatory sounds heard upon auscultation of the brachial artery?

A

Korotkoff sounds.

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31
Q

The first soft tapping sound when doing an auscultation of the brachial artery represents what?

A

Systolic blood pressure

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32
Q

The last soft tapping sound when doing an auscultation of the brachial artery represent what?

A

Diastolic blood pressure.

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33
Q

What do the terms Hyperpnoea / Hypopnoea mean?

A

Increased depth of breathing / Decreased depth of breathing.

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34
Q

What does the term apnoea mean?

A

Cessation of breathing (no air movement)

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35
Q

What does the term orthopnoea mean?

A

Positional difficulty in breathing (when lying down)

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36
Q

What is tidal volume?

A

Volume of air exchanged during each normal breath.

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37
Q

What is inspiratory reserve volume?

A

Maximal volume of air that can be forcibly inspired after tidal inspiration.

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38
Q

How to calculate inspiratory capacity?

A

Inspiratory reserve volume + Tidal volume.

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39
Q

What is residual volume?

A

Volume of air the remains in lungs after forced expiration.

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40
Q

How to calculate total lung capcity?

A

Residual volume + expiratory reserve volume + tidal volume + inspiratory reserve volume

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41
Q

How to calculate vital capacity?

A

Total lung capacity - residual volume

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42
Q

What is functional residual volume?

A

Total amount of air present in lungs after tidal expiration.

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43
Q

How to calculate functional residual volume?

A

Expiratory reserve volume + residual volume

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44
Q

What is minute ventilation?

A

Amount of air moving in and out of lungs per minute.

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45
Q

How do you calculate alveolar ventilation?

A

[Tidal volume - dead space] x breathing frequency

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46
Q

What is dead space?

A

Part of lungs where there is no gas exchange.

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47
Q

What affects total lung capacity?

A

Height, sex, pulmonary disease.

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48
Q

What is conducting zone in the lungs?

A

Provides passageways for air to travel into and out of lungs.

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49
Q

Why is conducting zone regarded as anatomical dead space?

A

No gas exchange takes place in the conducting zone.

50
Q

What is the respiratory zone in the lungs?

A

Areas with alveoli that have a blood supply.

51
Q

Which area of the lungs is equivalent to alveolar ventilation?

A

Respiratory zone.

52
Q

Why is non-perfused parenchyma regarded as alveolar dead space?

A

Non perfused parenchyma contain alveoli with no blood supply and so no gas exchange can take place here.

53
Q

How is physiological dead space calculated?

A

Anatomical dead space (conducting zone) + alveolar dead space (non perfused parenchyma)

54
Q

At functional residual capacity what are the lungs forces like?

A

The lung-chest forces are in equilibrium. Chest recoil = lung recoil.

55
Q

What membrane surround the lungs?

A

Visceral pleural membrane.

56
Q

What membrane covers the inner surface of the chest wall?

A

Parietal pleural membrane.

57
Q

What is the function of the pleural fluid in the pleural cavity?

A

Reduces friction between the membranes when you breath.

58
Q

Why is normal breathing regarded as negative pressure breathing?

A

Pressure of alveolar reduced bellow pressure of atmosphere.

59
Q

What is positive pressure breathing?

A

Pressure of atmosphere increased above alveolar pressure.

60
Q

Examples of positive pressure breathing?

A

Mechanical ventilation, CPR, High pressure chamber.

61
Q

What occurs in inspiration?

A

Diaphragm moves down and intercostal muscles move rib cage up and out.

62
Q

What is dalton’s law?

A

Pressure of gas mixture is equal to sum of partial pressure of gases in the mixture.

63
Q

What is fick’s law?

A

Diffusion is directly proportional to concentration gradient, exchange surface area and diffusion capacity of gas and inversely proportional to thickness of exchange surface.

64
Q

What is henry’s law?

A

Solubility of gas is directly proportional to partial pressure of that gas in equilibrium with that liquid.

65
Q

What is boyle’s law?

A

At constant temperature, volume of gas is inversely proportional to pressure of that gas.

66
Q

What is charles law?

A

At constant pressure, volume of gas is proportional to temperature of that gas.

67
Q

Modification of inspired air in airways?

A

Air is warmed, humidified, slowed (air lower in lungs is barely moving) and mixed.

68
Q

Why is haemoglobin essential to life?

A

Dissolved oxygen is not enough to sustain life.

69
Q

Why does HbO2 saturation need to be interpreted with haemoglobin?

A

Someone who has lost lots of blood can still have a HbO2 of 100%.

70
Q

What are factors that increase Hb oxygen affinity?

A

A decrease in temperature, alkalosis, hypocapnia (low blood C02 levels) and low 2,3-DPG levels in blood.

71
Q

What does 2,3 DPG do? What kind of protein does this make haemoglobin?

A

Release oxygen from haemoglobin. Haemoglobin is an allosteric protein.

72
Q

What are the factors that decrease Hb oxygen affinity?

A

An increase in temperature, acidosis, hypercapnia (high blood C02 levels) and high 2,3-DPG levels in blood.

73
Q

How does haemoglobin and haemoglobin oxygen saturation change in a normal person, anaemic patient and a patient with polycthaemia?

A

Haemoglobin oxygen saturation will be the same but haemoglobin would be different. Low Hb in anaemic and high Hb in polycthaemia patient.

74
Q

What does carbon monoxide do to blood O2 and HbO2 saturation?

A

Low blood O2 as its harder to release oxygen from carbon monoxide bound haemoglobin. Reduced HbO2 saturation as haemoglobin binds to carbon monoxide instead of oxygen.

75
Q

What protein has a greater affinity to oxygen than HbA or HbA2?

A

Fetal haemoglobin.

76
Q

Purpose of fetal haemoglobin having a greater affinity to oxygen that HbA?

A

To extract oxygen from mothers blood in placenta.

77
Q

What protein has a greater affinity to oxygen than fetal haemoglobin?

A

Myoglobin.

78
Q

Purpose of myoglobin having a greater affinity for oxygen that HbA?

A

To extract oxygen from circulating blood and store it.

79
Q

What is the HbO2 of blood arriving to alveoli like?

A

Still fairly high at around 75%.

80
Q

Why may the blood leaving the lungs not have 100% HbO2?

A

Due to bronchial circulation drainage of deoxygenated blood into pulmonary vein

81
Q

What are the 3 ways in which CO2 is transported in the blood?

A

CO2 in blood. CO2 that reacts with water to produce carbonic acid in the blood. Carbonic acid in haemoglobin.

82
Q

What happens to carbonic acid in haemoglobin?

A

H+ ions bind to haemoglobin chain. Bicarbonate leaves red blood cell in exchange of a chloride ion via the AE1 transporter.

83
Q

Why is the AE1 transporter on red cells important?

A

Allows negative chloride ions to enter the RBC to maintain resting membrane potential.

84
Q

How does pressure of alveoli and volume of lungs change during inspiration?

A

Pressure of alveoli decreases. Volume of lungs increases.

85
Q

How does the pressure of pleural cavity change during inspiration?

A

Decreases.

86
Q

How does the pressure of pleural cavity change during expiration?

A

Increases.

87
Q

Why isn’t total resistance to air flow and airway generation a linear relationship?

A

Increase in number of airways at a certain airway generation offsets decrease in radius of airways.

88
Q

Why does resistance to airflow decrease later in inspiration?

A

Greater lung volume and more dilated airways results in lower resistance.

89
Q

What blood vessels hold most of the blood volume?

A

Veins and venules.

90
Q

Why is the mean arterial pressure equation an approximation?

A

Assumes steady flow (which does not occur due to the intermittent pumping of the heart). Rigid vessels
Right atrial pressure is negligible.

91
Q

Types of blood flow?

A

Laminar flow and turbulent flow.

92
Q

What is laminar blood flow?

A

Velocity of fluid is constant at any one point and flow in layers. Blood flows fastest closest to the centre of lumen; blood cells closest to the wall experience more friction.

93
Q

What is turbulent blood flow?

A

Blood flows in irregular manner and is prone to pooling.

94
Q

What can turbulent blood flow damage?

A

Endothelium of blood vessels.

95
Q

How do you calculate pulse pressure?

A

Systolic blood pressure - diastolic blood pressure.

96
Q

How to calculate MAP using pulse pressure?

A

Diastolic blood pressure + 1/3 (pulse pressure).

97
Q

Why is there negative pressure in pleural cavity at rest?

A

Lungs trying to contract inwards and chest wall trying to contract outwards.

98
Q

Why can small to medium airways collapse but large airways can’t?

A

Large airways contain cartilage rings that prevent airway collapse.

99
Q

What is compliance and how is it calculated?

A

Tendency to distort under pressure. Change in volume / change in pressure.

100
Q

What is elastance and how is it calculated?

A

Tendency to recoil to its original volume. Change in pressure / change in volume.

101
Q

What can result in decreased arterial compliance?

A

Increase in stiffness of arteries as we age.

102
Q

What does an increase in arterial stiffness result in?

A

Increase in systolic blood pressure. Lower diastolic pressure as less diastolic flow.

103
Q

What induces diastolic blood flow after systole?

A

Recoil of elastic arteries.

104
Q

Why does pressure fall slowly in aorta after aortic valve closes?

A

Diastolic flow in the downstream circulation.

105
Q

What facilitates venous return?

A

Contraction of skeletal muscle around veins. Movement of diaphragm and chest.

106
Q

What can incompetent valves in veins cause? Where does this usually happen?

A

Varicose veins. Happens usually in the legs.

107
Q

Prolonged elevation of venous pressure can cause what?

A

Oedema.

108
Q

How does an aneurysm happen?

A

Weak muscle fibres in artery wall. Inward force produced by artery wall doesn’t match the blood pressure and so blood vessel expands until it ruptures.

109
Q

Why is it important that veins are more compliant than arteries?

A

Veins store most of the body’s blood. A small increase in pressure expands the volume of veins a lot.

110
Q

When are veins the most compliant?

A

At low pressures.

111
Q

When standing upright, why does the bottom of the lung have greater ventilation?

A

Smaller and more compliant alveoli at the bottom of the lungs and effects of gravity.

112
Q

When standing upright, why does the bottom of the lung have greater perfusion?

A

Due to gravity which results in higher flow rate.

113
Q

Why does perfusion vary more than ventilation when comparing base and apex of lungs?

A

Blood is more dense than air. Blood experiences effects of gravity more.

114
Q

During exercise what shift is seen in an oxygen dissociation curve?

A

Rightwards shift.

115
Q

A person with polycthaemia what shift would we see in the oxygen dissociation curve compared to a normal person?

A

Shift upwards.

116
Q

A person with anaemia what shift would we see in the oxygen dissociation curve compared to a normal person?

A

Downwards shift.

117
Q

A person with carbon monoxide poisoning what shift would we see in the oxygen dissociation curve compared to a normal person and why?

A

Downwards and left shift.

Decreased capacity so can’t carry as much oxygen. Increased affinity to oxygen, can’t lose oxygen as easily from haemoglobin.

118
Q

How may type 1 diabetes shift the oxygen dissociation curve?

A

Shift to the right due to development of diabetic ketoacidosis.

119
Q

What increases the concentration of dissolved oxygen in the blood?

A

Increase in tidal volume.

120
Q

Why can tachycardia cause myocardial ischaemia?

A

Reduced diastolic filling time of coronary arteries.

BRS (52 decks)

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