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Human Systems and Anatomy > VQ relationships and disorders > Flashcards

VQ relationships and disorders Flashcards

1
Q

what is the VQ ratio

A

the relationship between ventilation and perfusion (ventilation to blood flow)

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2
Q

what is ventilation

A

process by which air moves in and out of the lung

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3
Q

what is perfusion

A

process by which deoxygenated blood passes through the lung and becomes oxygenated

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4
Q

what does the VQ ratio determine

A

the level of partial pressure of oxygen and carbon dioxide in the blood

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5
Q

describe the pleural pressure distribution in the lungs

A

more negative at the apex than at the base

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6
Q

what is compliance

A

how much effort is required to stretch the lungs and the chest wall

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7
Q

what are some pulmonary conditions that lead to reduced compliance

A

scarring in the lung tissue
fluid in the lungs
deficient surfactant production
destruction of elastic fibres

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8
Q

what is resistance

A

narrowing or obstruction in the airway that may reduce airflow

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9
Q

what are some conditions that lead to an increase in resistance

A

asthma
obstruction or collapse of airways due to COPD

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10
Q

what is COPD

A

chronic obstructive pulmonary disease including ephysema or chronic bronchitis

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11
Q

what are the two types of dead space

A

anatomical dead space or physiological dead space

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12
Q

what is anatomical dead space

A

volume of gas during each breath that fills the conducting airways

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13
Q

what is physiological dead space

A

total volume of gas in each breath that does not participate in gas exchange eg alveoli that are perfused but not ventilated

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14
Q

describe pulmonary blood flow distribution

A

pulmonary circulation is a low pressure and low resistance system, influenced by gravity more than systemic circulation

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15
Q

describe pulmonary circulation when sat upright

A

greater blood flow to the base than to the apex

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16
Q

what can influence flow and the VQ ratio

A

the variations in arterial and venous pressure

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17
Q

summarise pressure and resistance of pulmonary circulation

A

low pressure
low resistance

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18
Q

what is the VQ ratio defined as for a single alveolus

A

alveolar ventilation divided by capillary flow

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19
Q

what is the VQ ratio defined as for the lungs as a whole

A

total alveolar ventilation divided by cardiac output

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20
Q

what is the VQ for lungs in healthy people

21
Q

what does the perfect model for VQ ratio actually mean

A

where the alveolar partial pressure of oxygen and arterial partial pressure of oxygen are the same

22
Q

what is the arterial blood gas for someone with arterial hypoxemia

A

arterial partial pressure of oxygen is less than 80mmHG

23
Q

what is the partial pressure for hypoxia

A

less than 60mmHg

24
Q

what is hypoxia

A

this is when there is insufficient oxygen to carry out metabolic functions

25
what is the partial pressure for hypercapnia
over 40 mmHg
26
what is the partial pressure for hypocapnia
less than 35 mmHg
27
what is anatomical shunting
this is when mixed venous blood is shunted directly into arterial blood when this happens, the alveolar ventilation is the same, but the distribution of blood flow is changed
28
what is a right to left shunt
blood being shunted is deoxygenated
29
where do most anatomical shunts occur
in the heart, where the blood from the right ventricle or atrium crosses the septum to the left atrium or ventricle
30
what does anatomical shunting lead to
hypoxemia
31
does anatomical shunting affect the partial pressure of carbon dioxide
no, because central chemoreceptors are very sensitive to carbon dioxide changes to increase ventilation. this leads to a reduction in partial pressures of carbon dioxide
32
describe physiological shuntings impact on VQ
the alveolar ventilation is different, but the distribution of the blood flow is the same
33
what is the VQ ratio in physiological shunting
0
34
what is physiological shunting
blood perfusing non ventilated alveolus is mixed venous blood, and the blood leaving continues to be mixed venous then mixes with arterial blood
35
what is atelectasis
obstruction of ventilation due to mucous plugs, airway oedema, foreign bodies and tumours in airways
36
what is the most frequent cause of artieral hypoxemia in patients with respiratory disorders
VQ mismatching
37
what does VQ mismatching lead to
varying alveolar and capillary gas contents
38
what is encompassed in COPD
emphysema and chronic bronchitis
39
what are the symptoms of COPD
chronic cough chest tightness shortness of breath increased mucous production
40
what is the most frequent cause of COPD
long term smoking
41
what is emphysema
structures in the alveoli are inflated, and the lungs lose their elasticity and cannot fully expand and contract patients can inhale but exhalation is difficult due to decreased elastic recoil
42
describe chronic bronchitis
inflammation of the bronchi causes mucous production and excessive swelling shortness of breath with mild exertion
43
what is pulmonary fibrosis
this is a type of interstital lung disease, and leads to scarring and thickening of tissue. there is decreased elasticity and decreased gas exchange
44
what is used to measure lung volume
vitalograph or spirogram
45
what are the four major results obtained from vitalograph
forced vital capacity forced expiratory volume in one second ratio of forced expiratory volume to forced vital capacity average mixmaximal expiratory flow
46
what is the main cause for the regional differences between ventilation and perfusion
gravity
47
what is the VQ when ventilation exceeds perfusion
over one
48
what is the VQ ration when perfusion exceeds ventilation
less than one

Human Systems and Anatomy (57 decks)

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