Lung Function Flashcards

1
Q

Why is it important to know about the respiratory system ?

A
  • integral to safe dental treatment of patients with respiratory problems
  • general anaesthetic can lead to hypoxia
  • analgesics and narcotics are respiratory depressants
  • drilling of the teeth can cause asthma attacks
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2
Q

What is the function of the respiratory system ?

A

• gas exchange - intake of oxygen and removal of carbon dioxide
• contributes to regulation of blood pH
• filters and heats inspired air
• metabolises inhaled chemicals
• receptors for sense of smell

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3
Q

What are the functions of the elastic fibres on the alveoli ?

A

They give the lungs elastic recoil

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4
Q

Describe the structure of the respiratory system

A
  • trachea > bronchi > bronchioles > terminal bronchioles > respiratory bronchioles > alveolar ducts > alveolar sacs
  • 2 zones : conducting zone and respiratory zone
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5
Q

Summarise the function of the conducting zone

A
  • no gas exchange taking place
  • transfers air to and from the alveoli
  • warms and humidifies inspired air
  • filters and removes foreign material
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6
Q

Summarise the function of the respiratory zone

A
  • gas exchange
  • oxygen delivery to the blood
  • carbon dioxide removal from the blood
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7
Q

Which structures of the respiratory system are part of the conducting zone ?

A
  • trachea
  • bronchi
  • bronchioles
  • terminal bronchioles
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8
Q

Which types of cells are found in the bronchial epithelium ?

A
  • ciliated cells
  • goblet cells (more)
  • basal cells
  • clara cells (less)
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9
Q

Which types of cells are found in the bronchiolar epithelium ?

A
  • ciliated cells
  • very very few goblet cells
  • lots of clara cells
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10
Q

Which types of cells are found in the alveolar epithelium ?

A
  • type 1 alveolar cells
  • type 2 alveolar cells
  • alveolar macrophage
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11
Q

Why is the conducting zone known as dead space ?

A

Because it is not involved in gas exchange

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12
Q

What are the 2 types of dead space ?

A
  • anatomical dead space
  • physiological dead space
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13
Q

Describe the function of the anatomical dead space

A
  • the conducting airways that deliver air to the alveoli
  • the volume is determined by the geometry of the airway network
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14
Q

Describe the function of the physiological dead space

A
  • volume of the lung that does not participate in gas exchange
  • measured by the functional assessment of the lung
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15
Q

What is the estimate for the volume of the anatomical and physiological dead space in healthy subjects ?

A

150 - 180 ml

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16
Q

How are lung volumes measured ?

A

A spirometer can be used to measure changes in the volume of air in the lungs

17
Q

What is the tidal volume ?

A

It is the normal air moving in and out of the lungs (normal breathing at rest)
- 0.5 litres

18
Q

What is the inspiratory reserve volume ?

A

The amount of air that can be breathed in (maximal inhalation)
- 3.1 litres

19
Q

What is the expiratory reserve volume ?

A
  • amount of air that can be breathed out (maximal exhalation)
  • 1.2 litres
20
Q

What is the difference between capacity and volume ?

A

capacity is the sum of volumes that can be divided into different volumes whereas volume is a set value which cannot be subdivided

21
Q

Which values can’t be measured using spirometery ?

A
  • functional residual capacity (2.4 litres)
  • residual volume (1.2 litres)
  • total lung capacity (6 litres)

They can’t be measured using spirometery because the air can’t be expelled

22
Q

What are the values of inspiratory capacity and vital capacity ?

A

• inspiratory capacity - 3.6 litres
• vital capacity - 4.8 litres

23
Q

What is functional residual capacity ?

A
  • air remaining at the end of normal exhalation
  • provides a buffer and prevents breath to breath fluctuations in alveolar gas composition
  • air entering the lungs mixes with air remaining in the lungs
  • 2.4 litres
24
Q

What is residual volume ?

A
  • air remaining in the lungs at the end of maximal exhalation
  • 1.2 litres
25
What is tidal volume ?
Tidal volume = air in the dead space + air in the alveoli (air entering the lungs ventilates both the dead space and the alveoli)
26
What is alveolar ventilation ?
- It is the volume of gas entering the alveoli every minute - alveolar ventilation = (tidal volume - dead space) x respiratory rate - typical value at rest =4200 ml/min
27
How can alveolar ventilation be increased ?
- increasing tidal volume - increasing respiratory frequency
28
What is the typical value of expired ventilation/minute ventilation ?
6000 ml/min
29
What is hypoventilation ?
- breathing in and out too slowly compared to what the body needs - decrease in ventilation without similar decrease in oxygen consumption or carbon dioxide production
30
How can hypoventilation occur ? (Hypercapnia)
- in disease states which physiological dead space - when respiratory muscles are paralysed or the chest wall is damaged - when tidal volume is reduced by CNS depression
31
What is hyperventilation ?
- breathing in and out too quickly for the bodies needs - ventilation in excess metabolic needs or carbon dioxide exhaled at a greater rate than production
32
How can hyperventilation occur ? (Hypocapnia)
- during acute asthma attacks - under conditions of stress - at altitude