Physiology 2 Flashcards by Lauren Clegg

What are the muscles of active expiration?

contract only during active expiration

Internal intercostal muscles

Abdominal muscles

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What are the accessory muscles of inspiration?

contract only during forceful inspiration

Sternocleidomastoid

Scalenus

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What are the major muscles of inspiration?

contract every inspiration, relaxation causes passive expiration

Sternum
Ribs
External intercostal muscles
Diaphragm

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What is tidal volume?

Volume of air entering or leaving lungs during a single breath

500ml

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What is inspiratory reserve volume? (IRV)

Extra volume of air that can be maximally inspired over and above the typical resting tidal volume

3000ml

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What is inspiratory capacity? (IC)

Maximum volume of air that can be inspired at the end of a normal quiet expiration (IC =IRV + TV)

3500ml

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What is expiratory reserve volume? (ERV)

Extra volume of air that can be actively expired by maximal contraction beyond the normal volume of air after a resting tidal volume

1000ml

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What is residual volume? (RV)

Minimum volume of air remaining in the lungs even after a maximal expiration

1200ml

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What is functional residual capacity? (FRC)

Volume of air in lungs at end of normal passive expiration (FRC = ERV + RV)

2200ml

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What is vital capacity? (VC)

Maximum volume of air that can be moved out during a single breath following a maximal inspiration (VC = IRV + TV + ERV)

4500ml

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What is total lung capacity?

The maximum volume of air that the lungs can hold

Total lung capacity = Vital Capacity + Residual Volume.

Average value approximately 5700 ml

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Can you measure residual volume and total lung volume by spirometry?

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When does residual volume increase?

When the elastic recoil of the lungs is lost… e.g. emphysema

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What is FVC and FEV1?

FVC = Forced Vital Capacity - maximum volume that can be forcibly
Expelled from the lungs following a maximum inspiration

FEV1 = Forced Expiratory volume in one second. Volume of air that can be expired during the first second of expiration in an FVC (Forced Vital Capacity) determination.

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What is the FEV1/FVC ratio?

The proportion of the Forced Vital Capacity that can be expired in the first second = (FEV1/FVC) X 100% - Normally more than 70%

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What is lung parenchyma?

The portion of the lung involved in gas transfer - the alveoli, alveolar ducts and respiratory bronchioles.

What would the FVC, FEV1 and ratio be in a person with airway obstruction? (e.g. asthma, COPD)

FVC = Low or normal 
FEV1 =  Low 
Ratio = Low

What would the FVC, FEV1 and ratio be in a person with lung restriction? (e.g. emphysema????)

FVC = Low 
FEV1 =  Low 
Ratio = NORMAL

What is airway resistance and what is the primary determinant of it?

It is the resistance to flow in the airway - normally this is low and so the air moves with a small pressure gradient

Primary determinant = RADIUS of the conducting airway

What does para/sympathetic stimulation cause in terms of the bronchioles?

Para = bronchoconstriction
Sympathetic = bronchodilatation

If you have airway resistance is it harder to breath in or out?

Harder to breath out

Describe what happens to intrapleural pressure during inspiration and expiration

Inspiration = Intrapleural pressure falls
Expiration = intraplerual pressure rises

What is dynamic airway compression?

The rising pleural pressure during active expiration compresses the alveoli and airway

Pressure applied to alveolus that helps to push air out of the lungs

The pressure applied to airway is not desirable - tends to compress it

(pressure on the alveoli is okay as it pushes air out)

When does dynamic airway compression cause a problem?

Its fine in normal people.

Causes a problem in patients with airway obstruction.

What does the increased airway resistance cause? (normal people)

an increase in airway pressure upstream. This helps open the airways by increasing the the driving pressure between the alveolus and airway (i.e. the pressure downstream)

What happens in terms of dynamic airways if there is an obstruction?

the driving pressure between the alveolus and airway is lost over the obstructed segment. This causes a fall in airway pressure along the airway downstream resulting in airway compression by the rising pleural pressure during active expiration Diseased airways are also more likely to collapse

When would the problem become worse? (in terms of obstruction and dynamic airways)

The problem becomes worse if the patient also have decreased elastic recoil of lungs (e.g. a patient with emphysema and obstructed airway caused by COPD)

What is peak flow?

Its a test useful in patients with obstruction lung diseases (COPD). Measured by giving a short sharp breath into the flow meter. Best of 3.

What is pulmonary compliance?

Compliance is measure of effort that has to go into stretching or distending the lungs. As during inspiration the lungs are stretched.

What does it mean the less complaint the lungs are...?

the more work is required to produce a given degree of inflation

What factors decrease pulmonary compliance?

pulmonary fibrosis, pulmonary oedema, lung collapse, pneumonia, absence of surfactant

What does decreased pulmonary compliance mean?

greater change in pressure is needed to produce a given change in volume (i.e. lungs are stiffer). This causes shortness of breath especially on exertion

What can decreased pulmonary compliance cause of spirometry graphs?

restrictive pattern of lung volumes

How can you get increased pulmonary compliance?

Compliance may become abnormally increased if the elastic recoil of the lungs is lost

When does increased pulmonary compliance occur?

Increased compliance occurs in emphysema. Patients have to work harder to get the air out of the lungs – hyperinflation of lungs (compliance also increases with age)

What percentage of total energy expenditure is usually needed for quiet breathing?

When is work of breathing increased?

When pulmonary compliance is decreased When airway resistance is increased When elastic recoil is decreased When there is a need for increased ventilation