Mechanics Of Breathing-1 Flashcards Preview

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Flashcards in Mechanics Of Breathing-1 Deck (41)
0

What is the primary function of respiration ?

Gas exchange

1

What are the secondary functions of respiration ?

Acid-base balance
Vocalisation
Defence against pathogens
Avenue for water and heat loss
Enhancing venous return
Activating some. Plasma proteins

2

What is internal respiration ?

Oxygen is essential for ATP production by oxidative phosphorylation

3

What is external respiration ?

Oxygen uptake and carbon dioxide removal - requires circulatory system as well

4

What makes up the upper airways ?

Air passages in head and neck
- opening of larynx =glottis- covered by epiglottis to prevent food entering

5

What makes up the respiratory tract ?

Pharynx to lungs, starting with larynx - it's held open by cartilage

6

What are the 2 zones of the respiratory tract ?

Conducting zone- conducts air from larynx to lungs
Respiratory zone- contains sites of gas exchange

7

Describe the conducting zone

Trachea divide into 2 bronchi which divide into smaller bronchi and bronchioles
Volume is about 150ml
Air is warmed, humidified and filtered
- goblet cells secrete mucus to trap any pathogens
Trachea is surrounded by chapped cartilage to keep it open

8

How much mucus do you swallow each day?

1L

9

Describe the respiratory zone

Organised to have maximum surface area and mini is wall thickness
-about 300 million alveoli - total sa 100m squared
-alveolar wall is a single squamous epithelium layer with basement membrane membrane fused - 0.2 micrometers thick

10

What muscles are used in breathing ?

Diaphragm
Internal/external intercostal muscles

11

What are the lungs surrounded by ?

A pleura sac with a visceral pleura on the outside and a parietal pleura on the inside surface
Between these 2 pleura is intrapleural space contain 15ml intrapleural fluid

12

During inspiration is atmospheric or alveolar pressure greater ?

Atmospheric air is greate r

13

During expiration is atmospheric or alveolar air greater ?

Alveolar

14

What is normal atmospheric air pressure ?

760mmHg

15

What is intraalveolar pressure ?

0 at rest
Because it is equal to atmospheric at rest

16

What is intrapleural pressure ?

-4 at rest
Always less than intraalveolar
Always negative during normal breathing because opposing forces pull parietal and visceral pleura part

17

What is transpulmonary pressure ?

Alveolar pressure - intrapleural pressure
It is the distending pressure across the lung wall
At rest it's about 4

18

What prevents 2 pleura being pulled apart ?

Surface tension intrapleural fluid

19

What is the functional residual capacity ?

Volume of the air in the lungs t rest when all breathing muscles are relaxed

20

What is a pneumothorax ?

When the lung is punctured it causes the intrapleural pressure to equilibriate with atmospheric pressure causing lungs to recoil and collapse and chest wall recoils outward

21

What diseases increase chances of spontaneous pneumothorax ?

Emphysema and pneumonia
- these disease damage visceral pleura allowing air from lungs to enter intrapleural space

22

What is boyles law ?

Gas pressure is inversely proportional to volume

23

What is the driving force for air into and out of the lungs ?

The difference between atmospheric pressure and alveolar pressure
As atmospheric is constant it is the alveolar pressure which determines the direction of flow

24

What are the 2 determinants of intraalveolar pressure ?

Quantity of air in alveoli
Volume of alveoli

25

Describe what happens during inspiration

Lungs expand
Alveolar volume increases so pressure decreases
Pressure gradient drives air into lungs

26

Describe what happens during expiration

Lungs recoil
Alveolar volume decreases and pressure increases
Pressure gradient drives air out of lungs

27

What respiratory muscles are involved in inspiration ?

External intercostal and diaphragm

28

What respiratory muscles are involved in expiration ?

Internal intercostal and abdominal muscles

29

What are the mechanics of inspiration ?

Diaphragm contracts and flattens moving downwards
External intercostal contract and ribs pivot up and out
Volume increases
Intrapleural pressure decreases
Transpulmonary pressure increases
Lungs expand with chest wall
Air flows in until alveolar air is equal to atmospheric

30

What does transpulmonary pressure provide ?

Provides the force for the expansion of the lungs

31

What is lung compliance ?

Ease at which lungs can inflate

32

What does a large lung compliance mean ?

Reduces work of breathing

33

What does lung compliance rely on ?

Elasticity of the lungs - elastic fibres present in connective tissue of the lungs which recoil once lungs have been stretched
Surface tension of fluid lining alveoli - measure of the amount of work needed to increase SA

34

During inspiration what effect does surface tension have ?

Acts to decrease lung compliance

35

What is surfactant ?

Secretes by type 2 alveolar cells
It decreases surface tension by interfering with hydrogen bonds and so increases compliance

36

Where is surfactant more concentrated and why ?

In smaller alveoli to reduce surface tension and and the internal pressure so it prevents collapse of smaller alveoli

37

Why is airway resistance low in healthy lungs ?

Because total sa is relatively high at each levels of branching

38

What does a low airway resistance mean ?

Means during normal conditions it doesn't require a large difference between atmospheric and alveolar pressure to cause breathing

39

What factors determine airway resistance ?

Passive forces exerted on airways
- changes in transpulmonary pressure and tractivs forces exerted on airways
Secretion of mucus in the airways
- excessive secretion or reduced clearance causes accumulation which increases resistance
Contractile activity of bronchioles
- a decrease in bronchodilator radius increases resistance

40

What effect foes histamine have on the bronchioles ?

Causes bronchoconstriction