Mechanics Of Breathing-1

Question 0

What are the secondary functions of respiration ?

Answer 0

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

Question 1

What is the primary function of respiration ?

Answer 1

Gas exchange

Question 2

What is internal respiration ?

Answer 2

Oxygen is essential for ATP production by oxidative phosphorylation

Question 3

What is external respiration ?

Answer 3

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

Question 4

What makes up the upper airways ?

Answer 4

Air passages in head and neck

- opening of larynx =glottis- covered by epiglottis to prevent food entering

Question 5

What makes up the respiratory tract ?

Answer 5

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

Question 6

What are the 2 zones of the respiratory tract ?

Answer 6

Conducting zone- conducts air from larynx to lungs

Respiratory zone- contains sites of gas exchange

Question 7

Describe the conducting zone

Answer 7

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

Question 8

How much mucus do you swallow each day?

Answer 8

1L

Question 9

Describe the respiratory zone

Answer 9

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

Question 10

What muscles are used in breathing ?

Answer 10

Diaphragm

Internal/external intercostal muscles

Question 11

What are the lungs surrounded by ?

Answer 11

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

Question 12

During inspiration is atmospheric or alveolar pressure greater ?

Answer 12

Atmospheric air is greate r

Question 13

During expiration is atmospheric or alveolar air greater ?

Answer 13

Alveolar

Question 14

What is normal atmospheric air pressure ?

Answer 14

760mmHg

Question 15

What is intraalveolar pressure ?

Answer 15

0 at rest

Because it is equal to atmospheric at rest

Question 16

What is intrapleural pressure ?

Answer 16

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

Question 17

What is transpulmonary pressure ?

Answer 17

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

Question 18

What prevents 2 pleura being pulled apart ?

Answer 18

Surface tension intrapleural fluid

Question 19

What is the functional residual capacity ?

Answer 19

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

Question 20

What is a pneumothorax ?

Answer 20

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

Question 21

What diseases increase chances of spontaneous pneumothorax ?

Answer 21

Emphysema and pneumonia

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

Question 22

What is boyles law ?

Answer 22

Gas pressure is inversely proportional to volume

Question 23

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

Answer 23

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

Question 24

What are the 2 determinants of intraalveolar pressure ?

Answer 24

Quantity of air in alveoli | Volume of alveoli

Question 25

Describe what happens during inspiration

Answer 25

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

Question 26

Describe what happens during expiration

Answer 26

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

Question 27

What respiratory muscles are involved in inspiration ?

Answer 27

External intercostal and diaphragm

Question 28

What respiratory muscles are involved in expiration ?

Answer 28

Internal intercostal and abdominal muscles

Question 29

What are the mechanics of inspiration ?

Answer 29

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

Question 30

What does transpulmonary pressure provide ?

Answer 30

Provides the force for the expansion of the lungs

Question 31

What is lung compliance ?

Answer 31

Ease at which lungs can inflate

Question 32

What does a large lung compliance mean ?

Answer 32

Reduces work of breathing

Question 33

What does lung compliance rely on ?

Answer 33

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

Question 34

During inspiration what effect does surface tension have ?

Answer 34

Acts to decrease lung compliance

Question 35

What is surfactant ?

Answer 35

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

Question 36

Where is surfactant more concentrated and why ?

Answer 36

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

Question 37

Why is airway resistance low in healthy lungs ?

Answer 37

Because total sa is relatively high at each levels of branching

Question 38

What does a low airway resistance mean ?

Answer 38

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

Question 39

What factors determine airway resistance ?

Answer 39

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

Question 40

What effect foes histamine have on the bronchioles ?

Answer 40

Causes bronchoconstriction