Respiratory 2

Question 1

Which 3 things affect alveolar gas exchange

Answer 1

O2 reached to the alveoli

Diffusion pathway

Perfusion

Question 2

What affects o2 reaching alveoli for exchange

Answer 2

Composition of air

Alveoli/pulmonary ventilation

Question 3

Which 4 things affect alveolar ventilation (how much o2)

Answer 3

Lung compliance

Rate and depth of breaths

Airway resistance

Alveolar surface tension

Question 4

Flow rate is pressure/ resistance , which factors affect resistance

Answer 4

Length of path

Viscosity of gas

Diameter of airway

Question 5

Which kind of flow and resistance is at the upper respiratory tract/ down trachea

Answer 5

Turbulent flow

Question 6

Which kind of flow is at the lower respiratory tract from the bronchioles down

Answer 6

Laminar flow

Question 7

Which area is resistance highest and why

Answer 7

Bronchi

Smallest area

Trachea is wider and bronchioles have a large cross sectional area for lower resistance

Question 8

Which 3 events can cause resistance

Answer 8

Mucus

Inflammation

Tumour

Question 9

What causes smooth muscle bronchoconstriction in bronchioles

Answer 9

Parasympathetic ach binding to M3

Question 10

Why is there surface tension in alveoli which affects their ventilation and therefore exchange

Answer 10

Liquid inside which h20 can form cohesive H bonds

The gases are non polar so can’t form bonds

Creates surface tension at gas water boundary

Question 11

When is surface tension highest

Answer 11

In expiration where diameter is lowest

Question 12

What does surface tension cause

Answer 12

Obstruction to alveolar inflation

Question 13

Which substance do type 2 cells need to produce to reduce surface tension in small alveoli (they have largest ST)

Answer 13

Surfactant

Question 14

What does surfactant do

Answer 14

Reduces tension by disrupting H2O bonds

Allows alveolar inflation

Question 15

What is RDS produced by which means alveoli can’t inflate

Answer 15

Late production / lack of surfactant

Can’t inflate due to high ST

Question 16

What does lung compliance affecting ventilation and therefore exchange mean

Answer 16

Ability of lungs to stretch

Question 17

What allows lung compliance

Answer 17

Increase in surfactant to cause inflation of alveoli

Swelling of elastic tissue around lungs

Ability of chest wall to move up in inspiration

Question 18

What is lung compliance triggered by

Answer 18

Increase in pressure from the air in atmosphere ie in inspiration

Question 19

What is the max amount of lung compliance called

Answer 19

Vital capacity

Question 20

What limits lung compliance

Answer 20

Elastic recoil

Question 21

What happens to lung compliance in emphysema

Answer 21

Large compliance even at a lower atmospheric pressure

due to lack of elastic recoil

Question 22

Why does fibrosis cause lack of compliance

Answer 22

They have lack of elastic tissue to stretch the lungs

This is replaced with scar tissue

Affects compliance / has a lower vital capacity

Question 23

What is the rate and depth of breathing affecting ventilation measured by

Answer 23

Spirometer

Question 24

What is tidal volume

Answer 24

Volume of air in and out in a normal breath

Question 25

What is expiratory reserve volume

Answer 25

Amount of extra air which can be breathed out along with every normal breath (tidal volume)

Question 26

What is Inspiratory reserve volume

Answer 26

Extra amount of air breathed in alongside the normal breath (tidal volume)

Question 27

What is the air called left inside the lungs after even expiratory reserve volume

Answer 27

Residual volume

Question 28

How do you work out vital capacity of the lungs (max air in and out)

Answer 28

Tidal volume + ERV + IRV

Question 29

How do you work out total lung capacity

Answer 29

Residual volume + erv + irv + tidal volume

Question 30

What is forced vital capacity and what other measure does it use

Answer 30

Measure of Total amount of air expired after a forced breath over time Uses the FEV (forced expiratory volume)

Question 31

What does FEV1 mean

Answer 31

Forced expiratory volume in 1 second

Question 32

Which types of lung disease have lower FVC

Answer 32

Restrictive lung disease Their vital capacity is lower due to low compliance (lack of elastic)

Question 33

Why would the FEV in 1 second be slower in those with obstructive lung diseases like asthma

Answer 33

They have an obstruction to expiration and so the expiration rate is slower (FEV)

Question 34

What is anatomic dead space

Answer 34

Volume of air in conducting airways which isn’t used for exchange

Question 35

What is physiologic dead space

Answer 35

Vol of air in airways and also alveolar space which isn’t used for exchange

Question 36

Why is conducting airways volume (anatomic dead space) not always used for exchange

Answer 36

Because it is expired via the tidal volume expiration | Only some inspired air reaches alveoli

Question 37

How do you work out pulmonary ventilation

Answer 37

Ventilation rate(eg 12 breaths) x tidal volume (500ml)

Question 38

Why is alveolar ventilation a better measure

Answer 38

It accounts for dead space volume

Question 39

How do you work out alveolar ventilation rate

Answer 39

Ventilation rate x (tidal volume - dead space vol)