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Medicine Term 2 > Respiratory Pathophysiology > Flashcards

Respiratory Pathophysiology Flashcards

1
Q

what are the functions of the repsiratory system

A
  • gas exchange
  • regulate pH in body
  • protect from infection
  • communication via speech
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2
Q

what is the pH of the body (ECF)

A

7.4

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3
Q

what are the 2 types of respiration

A

internal (gylcolysis etc) and external (movement of gases between air and body’s cells)

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4
Q

2 types of circulation

A

pulmonary - between heart and lungs

systemic - goes to all areas of body

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5
Q

what is the net volume of gas exchanged in lungs

A

250ml/min O2 : 200ml/min CO2

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6
Q

what is the respiration rate at rest

A

12-18 breaths/min

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7
Q

What is the upper respiratory tract composed of?

A

nose, pharynx (throat), larynx (voice box)

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8
Q

What is the lower respiratory tract composed of?

A

trachea, bronchus and lungs

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9
Q

what is contained in the thoracic cavity

A

heart and lungs

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10
Q

What separates the thoracic cavity from the abdominal cavity?

A

diaphragm

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11
Q

how many lobes are there in each lung and how is lobe separated

A

right - 3 lobes, horizontal fissure between superior and middle. oblique fissure between middle and inferior

left - 2 lobes, oblique fissure

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12
Q

what is the pleural cavity

A

space between lungs and chest wall

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13
Q

What keeps the trachea from collapsing?

A

C-shaped cartilaginous rings, semi-rigid

“patency” open airway

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14
Q

how is the right primary bronchi different to the left

A

it is wider and more vertical form

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15
Q

what is the conducting zone

A

trachea, bronchi, bronchioles, no gas exchange takes place

‘dead space’

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16
Q

how can resistance to air flow be altered

A

by activity of bronchial smooth muscle

  • contract - smaller - inc resistacne
  • relax - inc diameter - dec resistance
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17
Q

what are alveoli

A

air sacs in the lungs

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18
Q

what do the elastic fibres around alveoli do

A

for passive tissue recoil (go back)

used in expiration to push air out

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19
Q

what are type 1 cells in alveoli

A

main cell for wall of alveoli, v thin, gas exchange occurs

capillary always adjacent to them

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20
Q

what are type 2 cells in alveoli

A

secrete surfactant, no gas exchange

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21
Q

what is the capacity of the lungs

A

6L

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22
Q

What is tidal volume?

A

volume of air inhaled in a single breath - 500ml

and then exhaled

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23
Q

what is the air left in the lungs after expiration called

A

functional residual capacity

made up of expiratory reserve volume + residual volume

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24
Q

What is inspiratory reserve volume?

A

Amount of air that can be forcefully inhaled after a normal tidal volume inhalation

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25
Q

What is expiratory reserve volume?

A

Amount of air that can be forcefully exhaled after a normal tidal volume exhalation

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26
Q

What is vital capacity?

A

max vol of air you can breathe out

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27
Q

what is residual volume

A

air remaining in lungs after maximum expiration

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28
Q

what is the purpose of residual volume in lungs

A

prevents alveoli from collapsing and easier to inflate in next inspiration

allow gas exchange between breaths

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29
Q

what is dead space

A

passageways that transport air but are not available for gaseous exchange

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30
Q

what is the volume of dead space in conducting airways

A

150ml

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31
Q

What is the pleural cavity?

A

around each lung
fluid filled
surrounded my membrane
between lungs and rib cage

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32
Q

what are the 2 types of pleural membrane

A

visceral (inner) and parietal

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33
Q

What is the visceral pleura?

A

covers the outer surface of the lungs and goes into the fissures

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34
Q

what is the parietal pleura

A

lines the thoracic cavity

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35
Q

what is in the pleural cavity and its purpose

A

intra pleural fluid

allow membrane to stick together and glide across each other

creates cohesive force, chest wanting to expand//alveoli elastic wanting to recoil

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36
Q

what is boyles law

A

how the pressure exerted by gas is inversely proportional to volume.

inc volume = dec pressure

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37
Q

what are the muscles for inspiration

A 
diaphragm, 
external intercostals 
(scalenes + stermocleidomastoids)

diaphragm contracts and volume inc

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38
Q

what are the muscles for expiration

A

internal intercostals

abdominal muscles

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39
Q

What do the external intercostals do?

A

the raise the ribcage upwards and outwards to increase volume

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40
Q

what are the 3 types of pressure in the thoracic cavity

A

1) intra thoracic (alveolar) pressure - inside lungs (neg/pos)
2) intra pleural pressure - in pleural cavity (neg)
3) transpulmonary pressure - dif between alveolar and intrapleural pressure (pos)

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41
Q

what is pressure measured in

A

mmHg

kPa

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42
Q

What is the purpose of surfactant

A

detergent like fluid

reduces surface tension and prevents alveoli from collapsing

air/water interface

it reduces attraction between H2O molecules, inc lung compliance

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43
Q

What is compliance?

A

change in volume relative to change in pressure

ability of lungs to expand under pressure (stretchability)

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44
Q

what does low and high compliance mean

A

low - small inc in lung volume for large dec in ip pressure (difficulty breathing in)

high - large inc in lung volume for small dec in ip pressure (difficulty breathing out)

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45
Q

what is ventilation

A

movement of air in and out of the lungs

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46
Q

What is pulmonary ventilation?

A

total air movement in/out lungs L/min

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47
Q

what is alveolar ventilation

A

fresh air getting to alveoli and therefore gas exchange L/min

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48
Q

What is Dalton’s Law?

A

The total pressure of a gas mixture is equal to the sum of the pressure that each gas would exert independently

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49
Q

What is atmospheric pressure?

A

760 mmHg

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50
Q

how do you calculate partial pressure

A

percentage of air we breathe x atmospheric pressure

e.g. 21% (O2 in air) x 760 = 160mmHg

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51
Q

how does the air we breathe in become diluted

A

saturated w water vapour

dead space

mix w residual volume

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52
Q

what is the alveolar partial pressure of oxygen and CO2

A

O2 - 100mmHg (13.3kPa)

CO2 - 40mmHg (5.3kPa)
46mmHg (6.2kPa)

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53
Q

what is bronchial circulation

A

bronchial arteries provide oxygenated blood to lung tissue

nutritive

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54
Q

what is pulmonary circulation

A

circulation between heart and lungs

gas exchange

high flow, low pressure system

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55
Q

how does o2 and co2 diffuse in body

A

due to differences in partial pressure

PaO2 - 100mmHg , tissue Pp is 40mmHg

PaCO2 - 40mmHg, tissue pp is 46mmHg

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56
Q

what affects the rate of gas exchange in lungs

A
  • proportional to pp gradient
  • gas solubility
  • surface area
  • thickness of membrane
  • distance
57
Q

what is emphysema

A

alveoli become damaged, reduces surface area and loss of elasticity, low PO2 in pulmonary vein

58
Q

what is fibrosis

A

thickened alveolar membrane (resist expansion), slows gas exchange + loss of compliance = >alveolar ventilation

59
Q

what is pulmonary oedema

A

fluid in the interstitial space between alveoli and capillary - inc distance = rate of gas exchange is slower

60
Q

what is asthma

A

chronic inflammation of the airways, inc airway resistance, dec airway ventilation

PO3 low in alveoli and vein

61
Q

what are obstructive lung diseases

A

obstruction of air flow, on expiration usually

e.g. asthma, COPD

62
Q

what are restrictive lung dieseases

A

restrict lung expansion, on inspiration

e.g. fibrosis, oedema, pneumothorax, infant respiratory distress syndrome

63
Q

what can be used to measure lung function

A

spirometer

static - volume exhaled

dynamic - time taken to exhale a certain vol measured

64
Q

what is FEV1 and FVC and the ratio

A

FEV1 - forced expiratory volume in 1 second

FVC - forced vital capacity, how much air can be expired in total

FEV1/FVC - 80% ratio stays same

65
Q

What is perfusion?

A

blood flow reaching alveoli

66
Q

what is shunt in the lungs

A

alveoli less ventilated which means theres and increase in CO2 and decrease in O2 in blood because its not being replenished, will dilute oxygen content, affect pp gradient for diffusion .

Ventilation < Perfusion

67
Q

what is the control to shunt

A

constrict blood vessels in response to hypoxia

minimise blood sent to poorly ventilated areas

dilate bronchioles to inc ventilation

68
Q

what is alveolar dead space

A

Alveoli that are ventilated but not perfused due to collapse of them

Ventilation > Perfusion

69
Q

what is the control to alveolar dead space

A

pulmonary vasodilation to increase O2 in blood

bronchial constrictions for fall in CO2

70
Q

more ventilation and perfusion at base of lungs than apex

A

base of lungs more blood flow than ventilation as arterial pressure > alveolar pressure - compresses the alveoli

71
Q

How does O2 travel in the blood?

A

bound to haemoglobin protein in rbc, 197ml per L

in solution in plasma 3ml per L

5 L of blood in total

72
Q

How does CO2 travel in the blood?

A

in solution in plasma 77%

7% dissolved in plasma

23% haemoglobin

73
Q

what is the O2 demand of resting tissue

A

250ml/min

74
Q

what is the reservoir of O2

A

1000ml/min

as 200ml x 5 (cardiac output) = 1000

only 25% O2 used by tissue in resting state

75
Q

explain haemoglobins components

A

4 haeme groups, contain Fe2+

4 chains, 2 alpha, 2 beta HbA

76
Q

what affinity does CO have for haemoglobin

A

250x greater affinity and difficult to dissociate

77
Q

what is CO2 bound to in plasma

A

70% react to enzyme - carbonic anhydrase = carbonic acid, dissociate to bicarbonate ions and H+ ions

go into plasma, exchange Cl- ions, H+ ions bind to deoxyhaemoglobin

23% to deoxyhaemoglobin form carbamino comounds

7% dissolved in plasma

78
Q

whats myoglobin

A

O2 carrier molecule only in cardiac and skeletal muscle

higher affinity for O2, stores O2 more

79
Q

what are the dif types of hypoxia

A 
Hypoxaemic Hypoxia
Anaemic Hypoxia
Stagnant Hypoxia
Histotoxic Hypoxia
Metabolic Hypoxia
80
Q

what is hypoxia

A

Inadequate supply of oxygen to tissues

81
Q

what is Metabolic Hypoxia

A

oxygen delivery to the tissues does not meet increased oxygen demand by cells.

82
Q

what is Histotoxic Hypoxia

A

poisoning prevents cells utilising oxygen delivered to them e.g. carbon monoxide/cyanide

83
Q

what is Stagnant Hypoxia

A

Heart disease results in inefficient pumping of blood to lungs/around the body

84
Q

what is Anaemic Hypoxia

A

Reduction in O2 carrying capacity of blood due to anaemia (red blood cell loss/iron deficiency).

85
Q

what is Hypoxaemic Hypoxia

A

most common. Reduction in O2 diffusion at lungs either due to decreased PO2atmos or tissue pathology.

86
Q

in steady state, net vol of gas exchanged in lungs per unit time is equal to net vol gas exchanged in tissue

A

ccc

87
Q

the thoracic cavity increases volume on inspiration so the pressure decreases and is less than atmospheric pressure so air moves in

A

ddd

88
Q

on inspiration the diaphragm contracts (flattens out) so the volume increases

on expiration diaphragm relaxes so pressure increases above atmospheric pressure so air moves out

A

sss

89
Q

70% efficient breathing, 500ml of air exhaled is dead space air too - 150ml

A

sss

90
Q

greater tidal volume = greater alveolar ventilation (can be hyperventilation)

A

ddd

91
Q

in obstructive lung disease the rate air is exhaled is much more slow as much more pressure is required to push the air out the alveoli, low compliance

A

ww

92
Q

PP of O2 in plasma determines degree of O2 binding to haemoglobin

saturation complete after 0.25s contact w alveoli

total contact time - 0.75s

A

ww

93
Q

affinity of haemoglobin for oxygen changes under different conditions, affinity decreases when exercising to give off more O2 to tissue

A

www

94
Q

PaO2 not same as arterial O2 concentration

A

www

95
Q

what is ventilatory control

A

requires stimulation of the (skeletal) muscles of inspiration
via phrenic (diaphragm) and intercostal nerves (external)
is normally subconscious
entirely dependent on signalling from the brain (sever spinal cord above origin of phrenic nerve (C3-5) breathing ceases)

96
Q

where is ventilatory control located

A

within ill defined centres located in the pons and medulla (Respiratory Centres)

97
Q

what do respiratory centres have their rhythm modulated by

A

emotion
voluntary over-ride
mechano-sensory input from thorax
chemical composition of blood - detected by chemoreceptors

98
Q

whats do the Dorsal Respiratory Group of neurons innervate

A

Inspiratory muscles Via phrenic and intercostal nerves

99
Q

whats do the ventral Respiratory Group of neurons innervate

A

Tongue, pharnyx, larynx, expiratory muscles

100
Q

what are the 2 types of chemoreceptors

A

Central and Peripheral Chemoreceptors

101
Q

what are chemoreceptors

A

sensors that detect changes in CO2, O2, and pH that affect rhythm of breathing

102
Q

describe central chemoreceptors

A

medulla
respond directly to [H+] on CSF arounf brain (directly reflects PCO2)
- primary ventilatory drive
- reflex stimulation of ventilation by rise in [H+]

103
Q

describe Peripheral Chemoreceptors

A

carotid and aortic bodies
respond primarily to PO2 (not O2 content) and plasma [H+]
- secondary ventilatory drive

104
Q

what happens to individuals with chronic lung disease, what do they rely on to stimulate ventilation and why

A

usually rely on PaCO2 level to stimulate ventilation
in CLD PaCO2 becomes elevated chronically
become desensitised to PCO2 and rely on changes in PaO2 to stimulate ventilation

105
Q

What will happen to respiration rate in an anaemic patient with normal lung function, who has a blood oxygen content half the normal value?

A

It will stay the same

if lungs working normally, diffusion will take place normally = the amount of oxygen in solution in the plasma (PaO2) will be normal.

PaO2 is what the peripheral receptors monitor there will be no increase in RR

106
Q

what effect do most gaseous anaesthetic agents have on RR, tidal volume and alveolar ventilation

A

increase RR,

decrease TV so decrease AV

107
Q

how can barbiturates and opioids affect respiratory centres

A

can depress respiratory centres

dec sensitivity to pH and therefore response to PCO2 . Also dec peripheral chemoreceptor response to decreasing PO2.

108
Q

what effect does nitrous oxide have on patients with chronic lung disease

A

could end up in respiratory failure as it blunts peripheral r chemoreceptor response to falling PaO2 and then no longer have ventilatory drive

109
Q

where does plasma [H+] originate from

A

H+ originates from CO2

CO2 + H2O  H2CO3  HCO3- + H+

110
Q

Changes in plasma pH will alter ventilation via the peripheral chemoreceptor pathways

A

fff

111
Q

what happens to ventilation if plasma pH falls ([H+] increases)

A

ventilation will increase (acidosis)

112
Q

what happens to ventilation if plasma pH increases ([H+] falls)

A

ventilation will decrease

less [H+] = less CO2, need to slow down ventilation to retain co2

113
Q

Normally pH is stable because all the CO2 produced is eliminated in expired air.

A

gg jj

114
Q

what does hypoventilation cause

A

causing CO2 retention, leads to increased [H+] bringing about respiratory acidosis.

115
Q

what does hyperventilation cause

A

blowing off more CO2, lead to decreased [H+] bringing about respiratory alkalosis

116
Q

Hyperventilation: Ventilation is reflexly inhibited by an increase in arterial PO2 or a decrease in arterial PCO2/[H+]

A

ggg

117
Q

where is resistance to air flow greatest

A

in largest airways

in small airways the cross sectional area is greater

118
Q

when does surfactant production begin in the foetus

A

25weeks gestation

complete at 36 weeks

119
Q

what is anatomical dead space

A

150mL

volume of gas occupied by the conducting airways and this gas is not available for exchange

120
Q

what gases is air composed of

A

nitrogen 79%
oxygen 21%
co2 0.03% (don’t breathe this in)

121
Q

All gas molecules exert same pressure, so partial pressure increases with increasing [gas]mixture

A

ghh

122
Q

during hyperventilation what happens to PO2 and PCO2

A

PO2 rises - 120mmHg

COS2 falls - 30mmHg

123
Q

during hypoventilation what happens to PO2 and PCO2

A

PO2 falls - 30mmHg

CO2 rises - 100mmHg

124
Q

at the apex of the lung is ventilation greater or less and why

A

ventilation declines

compliance is lower at apex

125
Q

what is the partial pressure gradient at alveoli and tissues

A

ALVEOLI:
in blood PO2 40mmHg to 100mmg
PCO2 46mmHg diffuse to 40mmHg in alveoli

TISSUE:
in blood 100mmHg diffuse through to 40mmHg in tissue
…

126
Q

what does the abbreviation A stand for

A

alveolar

127
Q

what does the abbreviation a stand for

A

arterial blood

128
Q

what is ventilation

A

air getting to alveoli

129
Q

why is blood flow higher than ventilation at the base of the lungs

A

because arterial pressure exceeds alveolar pressure

130
Q

why is blood flow less at the apex of the lungs

A

because arterial pressure is less than alveolar pressure. This compresses the arterioles.

131
Q

blood flow declines faster than ventilation meaning

blood flow>ventilation at the base

ventilation>blood flow at the apex.

A

hhh

132
Q

what is shunt used to describe

A

describe the passage of blood through areas of the lung that are poorly ventilated

ventilation

133
Q

what is pulmonary arterial pressure

A

25/8 mmHg

134
Q

what determines how saturated haemoglobin is with O2

A

partial pressure of oxygen in blood

135
Q

how quickly is haemoglobin saturated with O2 when at the alveoli

A

in 0.25s

total contact time 0.75s

136
Q

whats 2.3-DPG

A

affinity of haemoglobin for oxygen is decreased
this chemical increases in situations w inadequate O2 supply (high altitude, heart/lung disease) and maintain O2 release in tissues

137
Q

What is PaO2 and what is it determined by

A

O2 in solution in the plasma

determined by O2 solubility and the partial pressure of O2 in the gaseous phase that is driving O2 into solution

138
Q

how much oxygen is bound to haemoglobin

A

98%

Medicine Term 2 (5 decks)

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