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Flashcards in Physiology Deck (89)
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1

What does internal respiration refer to?

The intracellular mechanisms which consume O2 and produce CO2

2

What does external respiration refer to?

Events that lead to the exchange of O2 and CO2 between the external environment and the cells of the body

3

What are the 4 steps of external respiration?

Ventilation
Gas exchange (alveoli-blood)
Gas transport
Gas exchange (blood-tissues)

4

Which 3 body systems are involved in external respiration?

Respiratory
Cardiovascular
Haematological

5

Define ventilation

The mechanical process by which air is moved between the atmosphere and the alveolar air sacs

6

Air flows from a region of ___ pressure to ___ pressure

High, low

7

Intra-alveolar pressure must be greater than atmospheric pressure for air to flow into the lungs. True/False?

Intra-alveolar pressure must be less than atmospheric pressure, since air flows from high to low pressure

8

At constant temp, as the volume of a gas increases, the pressure exerted _____ (Boyle's Law)

Decreases

9

Before inspiration, intra-alveolar pressure = atmospheric pressure. True/False?

True

10

Which 2 forces hold the lung and thoracic wall in close opposition?

Intrapleural fluid cohesiveness
Negative intrapleural pressure

11

Describe intrapleural fluid cohesiveness

Water molecules present in intrapleural fluid are attracted to each other/resist being pulled apart
This causes pleural membranes to stick together

12

Describe the effect of sub-atmospheric intrapleural pressure

Creates a transmural pressure gradient across the lung and chest wall, causing lungs to expand outwards while the chest squeezes inwards (inspiration)

13

Intra-alveolar pressure = 760
Intrapleural pressure = 756
What happens across the lung wall?

Lungs expand outwards

14

Intrapleural pressure = 756
Atmospheric pressure = 760
What happens across the thoracic wall?

Chest squeezes inwards

15

Contraction of the diaphragm causes the volume of thorax to increase in which direction?

Vertically

16

What is the function of external intercostal muscle in inspiration?

Lifts ribs up, pushes out sternum

17

What is a pneumothorax?

Air in the pleural space

18

What is the function of surfactant?

Reduces alveolar surface tension

19

Smaller alveoli have a smaller tendency to collapse. True/False?

False
More likely to collapse

20

What secretes surfactant?

Type II alveoli

21

What cause respiratory distress syndrome in new borns?

Not enough surfactant, leading to high alveolar surface tension

22

Describe alveolar interdependence

When one alveoli starts to collapse, surrounding alveoli recoil in resistance, pulling the collapsing alveoli open

23

What are the 2 main accessory muscles of respiration?

Scalenus
Sternocleidomastoid

24

What is meant by tidal volume?

Volume of air entering/leaving the lungs in a single breath

25

What is meant by inspiratory reserve volume?

Volume of air that can be maximally inspired beyond the tidal volume

26

What is meant by inspiratory capacity?

TV + IRV

27

What is meant by expiratory reserve volume?

Volume of air that can be maximally expired beyond the tidal volume

28

What is meant by residual volume?

Volume of air remaining in lungs after maximal expiration

29

What is meant by functional residual capacity?

Volume of air remaining in lungs following normal expiration
ERV + RV

30

What is meant by vital capacity?

Volume of air that can be maximally expired following maximal inspiration
TV + IRV + ERV