ventilation and compliance

Question 1

what is residual volume and why is it important?

Answer 1

it is the volume of air that stays in a person’s lungs after fully exhaling. It stops the alveolar from collapsing and allows for gas exchange between breaths

Question 2

what does a lung capacity value mean?

Answer 2

it is a sum of 2 or more volumes

Question 3

what is total lung capacity?

Answer 3

everything including residual volume, tidal volume, expiratory and inspiratory reserves

Question 4

what is the anatomical dead space volume and what is it in general?

Answer 4

150 ml

air that doesn’t participate in gas exchange but fills conducting airways

Question 5

what is the average tidal volume and what does it mean?

Answer 5

500 ml on average
ie we breathe in 500 ml of air and breathe out 500 ml of air

no matter how much you squeeze your lungs to let air out you are always going to breathe out this tidal volume

Question 6

what is vital capacity?

Answer 6

max amount of air you can expel from the lungs after a max inhalation.
ie. inspiratory reserve volume (what you take in to get max breath) + tidal volume (always there) + expiratory reserve volume (air that you can let out if you need to)

Question 7

What does ventilation mean?

Answer 7

the movement of air in and out of the lungs

Question 8

pulmonary ventilation

Answer 8

total air movement into/ out of the lungs - doesn’t tell us anything about dead space

Question 9

alveolar ventilation

Answer 9

amount of fresh air getting to alveoli and therefore available for gas exchange

Question 10

Dalton’s Law

Answer 10

total pressure of a gas mixture is the sum of pressures of the individual gases

Question 11

what is partial pressure? units?

Answer 11

pressure of a gas in a mixture of gases is equivalent to the % of that particular gas in the entire mixture multiplied by the pressure of the whole gaseous mixture
mmHg or kPa units

Question 12

why does the body get rid of CO2?

Answer 12

it is poisonous to cells
CO2 is the main reason you hyperventilate ie to get it out of the body
we produce CO2 it is not obtained from the air we breathe

Question 13

PO2 and PCO2 stand for what?

Answer 13

partial pressure of oxygen and CO2

Question 14

what happens at end of inspiration?

Answer 14

350 ml of fresh air goes into alveoli

150 ml fresh air enters DEAD SPACE

Question 15

what happens at the end of expiration?

Answer 15

dead space is filled with STALE air

Question 16

what happens to P02 and Pc02 during hypo-ventilation?

Answer 16

P02 falls (30)
Pc02 rises (100)

Question 17

what happens to P02 and Pc02 during hyper-ventilation?

Answer 17

P02 rises (120)
PC02 falls (20)

Question 18

what are the normal ventilation values for PO2 and PCO2

Answer 18

PO2 100
PCO2 40

these remain fairly constant in resting alveolar ventilation

Question 19

what do type 2 alveolar cells produce and what does it do?

Answer 19

surfactant fluid

it reduces surface tension on alveolar surface membrane which reduces the tendency for alveoli to collapse

Question 20

define compliance

Answer 20

change in volume relative to change in pressure i.e. how much does volume change for any given change in pressure

Question 21

what does compliance represent?

Answer 21

stretchability of the lungs ie how to get air in by stretching open, it tells us nothing about getting air out

Question 22

what is surface tension?

Answer 22

when water molecules line the alveoli they create an inwardly directive force that makes the alveoli want to collapse. During inspiration this needs to be overcome as air needs to fill the alveoli.

Question 23

how does surfactant reduce surface tension

Answer 23

surfactant sits between water molecules and reduces the attraction between the water molecules therefore decreasing the inward force and preventing the alveoli from collapsing.

Question 24

when does surfactant production start? and describe it

Answer 24

about 25 weeks gestation

it is stimulated by thyroid hormones and cortisol which increase towards end of pregnancy

Question 25

what is IRDS and why are premature babies at risk of this

Answer 25

infant respiratory distress syndrome | due to insufficient surfactant production and structural immaturity in the lungs.

Question 26

where happens to air in smaller alveolus when there is no surfactant?

Answer 26

it flows into the larger alveolus and therefore collapses losing that surface area

Question 27

what is the law of LaPlace equation and what does it mean?

Answer 27

``` P=2T/r P= pressure T= surface tension r= radius it describes the pressure required to keep alveoli open ```

Question 28

when surfactant is present what happens to the pressure in the large and small alveoli

Answer 28

they become equal

Question 29

where is pressure greater? the smaller or larger alveolus?

Answer 29

in the smaller alveolus

Question 30

high compliance

Answer 30

large increase in lung volume for small decrease in ip (interstitial pressure - pressure in pleural space) pressure ie a lot of air getting into alveoli in a smaller breath (not much decrease in thoracic pressure)

Question 31

low compliance

Answer 31

small increase in lung volume for large decrease in ip pressure (ie not much O2 getting to alveoli in a large breath)

Question 32

visceral pleura

Answer 32

the portion of protective tissue that is attached directly to the lungs

Question 33

parietal pleura

Answer 33

portion of the protective tissue that lines the inner surface of the chest wall and covers the diaphragm

Question 34

visceral pleura

Answer 34

portion of protective tissue that is attached directly to the lungs

Question 35

what is emphysema

Answer 35

a loss of elastic tissue (recoil) means expiration requires effort

Question 36

what is emphysema

Answer 36

a loss of elastic tissue means expiration requires effort

Question 37

what is fibrosis

Answer 37

inert fibrosis tissue means effort of inspiration increases- harder to get air in as scar tissue thickens walls and oxygen can't diffuse across as easily

Question 38

what is compliance like at the apex of the lung and why?

Answer 38

lowest compliance at the apex of the lung because the weight of the lung pulls the lung downwards stretching open the alveoli at the apex meaning their ability to change volume isn't good

Question 39

what is compliance like at the base of the lung and why?

Answer 39

highest compliance to ventilation because the weight of the lung compresses the alveoli against the diaphragm so their ability to change volume on inspiration is better.

Question 40

obstructive lung disease

Answer 40

obstruction of air flow, especially on expiration

Question 41

restrictive lung disease

Answer 41

restriction of lung expansion

Question 42

examples of obstructive lung diseases

Answer 42

asthma | COPD

Question 43

asthma

Answer 43

over-reaction of bronchial smooth muscle which reduces the diameter of the airways and reduces the ability to get air out

Question 44

COPD

Answer 44

Chronic Obstructive Pulmonary Disease Chronic bronchitis - Inflammation of the bronchi Emphysema -Destruction of the alveoli, loss of elasticity

Question 45

examples of restrictive lung diseases

Answer 45

``` loss of lung compliance- lung stiffness or incomplete lung expansion fibrosis infant respiratory distress syndrome oedema pneumothorax ```

Question 46

what is oadema of the lung

Answer 46

fluid building up between alveoli, creating space reduces diffusion

Question 47

what is pnuemothorax

Answer 47

punctured lung so air seeps into thorax leads to collapsed lung

Question 48

spirometry

Answer 48

technique used to measure lung function FEV1 and FVC are measured from a full forced experiation into a spirometer. Exhalation continues until no more breath can be exhaled FEV1/FVC ratio then gives a good estimate of the severity of airflow obstruction

Question 49

static measurement (Lung volumes that are not affected by the rate of air movement in and out of the lungs ie tidal vol etc)

Answer 49

only consideration made is the volume exhaled

Question 50

dynamic

Answer 50

time taken to exhale a certain volume is what is being measured- more helpful

Question 51

FEV1

Answer 51

forced expiratory volume in 1 second

Question 52

spirometry in obstructive lung disease

Answer 52

you have restricted air flow so FEV1 dramatically reduces ie the amount of air you can get out in 1 second reduces because there is a real problem with getting air out the lung

Question 53

spirometry in restrictive lung disease

Answer 53

reduction in FVC because there is a problem with lung expansion the total amount of air in lung will be less so although there is no problem getting air out, there is less air in the first place

Question 54

FVC

Answer 54

forced vital capacity | is the total amount of air exhaled during the FEV test.

Question 55

norm ratio of FEV1/FVC

Answer 55

80%

Question 56

why is surfactant more effective in small alveoli than large?

Answer 56

surfactant molecules come closer together and are therefore more concentrated.

Question 57

is high compliance healthy lungs or poor lungs?

Answer 57

healthy

Question 58

when is high compliance bad?

Answer 58

if it doesn't come with high elasticity

Question 59

what can spirometer not measure?

Answer 59

residual volume as that is always in your lungs