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Flashcards in mechanics of breathing Deck (30):
1

Pulmonary ventilation consists of which two phases?

  • inspiration
  • expiration

2

Define intrapulmonary pressure

  • Ppul is the pressure within the alveoli

3

What pressure prevents the lungs from collapsing?

  • Transpulmonary pressure

4

How is transpulmonary pressure calculated?

Intrapulmonary pressure (Ppul) - Intrapleural pressure (Pip)

5

List the muscles of normal respiration

  • Diaphram
  • intercostal muscles

6

Name the physical factors influencing pulmonary ventilation

  • Airway resistance
  • Alveolar surface tension
  • Lung compliance

7

Name the four respiratory volumes

  • tidal volume
  • inspiratory reserve volume
  • expiratory reserve volume
  • residual volume

8

Define vital capacity

Vital capacity = total sum of IRV + ERV + TV

9

Define dead space

Amount of inspired air within the conducting zone that does not participate in gaseous exchange

10

Define intrapleural pressure

Pip = the pressure within the pleural cavity

11

Define total lung capacity

  • TLC is the maximum volume of air contained in the lungs after maximum inspiratory effort
  • TLC = TV + ERV + IRV + RV

12

Define Functional residual capacity

 

  • FRC is the sum of Expiratory reserve volume and Reserve volume
  • the volume of air remaining in the lungs after normal tidal expiration

13

Define minute volume

  • MV is the volume of air inspired and expired in a minute
  • MV = TV x RR

14

Define alveolar minute volume

  • Alveolar ventilation rate = RR x (TV - dead space)

15

Define nonrespiratory air movements

Nonrespiratory air movements are voluntary or reflex actions that clear the respiratory passageway or express emotions

16

What respiratory group of the respiratory centre controls inspiration?

Dorsal respiratory group

17

Which muscles of respiration does the Dorsal respiratory group control?

  • Diaphragm
  • External intercostal muscles

18

What nerves are responsible for initiating ventilation?

  • Phrenic nerves
  • Intercostal nerves

19

Describe phase 1 of inspiration

  • inspiratory muscles contract
  • diaphragm moves down
  • thoracic cavity expands and volume increases

20

Describe phase two of inspiration

  • intrapulmonary pressure decreases by 1mmHg
  • air flows into the lungs along the pressure gradient until Ppul = Patm

21

Describe phase 1 of expiration

  • inspiratory muscles relax
  • diaphragm rises
  • thoracic cavity recoils and volume decreases

22

Describe phase 2 of expiration

  • thoracic recoil causes an increase in intrapulmonary pressure by 1mmHg
  • air flows out of the lungs down the pressure gradient until Ppul = Patm

23

What is the normal value for tidal volume?

500ml

24

True or false? Adult males and females have the same total lung capacity

False

25

What is the value for normal intrapleural pressure?

756mmHg

26

In which air passages does the greatest resistance to airflow occur?

Medium-sized bronchi

27

Which factors diminish compliance?

  • reduced natural resiliance of lungs
  • blocked small respiratory passages
  • reduced surfactant production
  • decreased flexibility/expandability of thoracic cage

28

What device is used in hospital to measure a patient's lung volume and capacity?

A spirometer

29

Define Boyle's law

At a constant temperature , the pressure of a gas varies inversely with its volume

P1V1 = P2V2

30

How do you calculate physiological dead space?

anatomical dead space + alveolar dead space