Lecture 2

Question 1

What is Tidal Volume?

Answer 1

The volume of air breathed in and out of the lungs at each breath at rest. Typically 500ml, approx at 1/2 total lung capacity.

Question 2

What is Expiratory Reserve Volume (ERV)

Answer 2

The maximum volume of air which can be expelled from the lungs at the end of a normal expiration. 1100ml av. men, 900ml av. women.

Question 3

What is Inspiratory Reserve Volume (IRV)?

Answer 3

The maximum volume of air which can be drawn into the lungs at the end of a normal inspiration. Average 3L for men 1900ml for women.

Question 4

Residual Volume (RV)

Answer 4

The volume of gas in the lungs at the end of a maximal expiration. 1200ml av. men, 1100ml av. women. Prevents alveoli collapse, which would take a lot more energy to open when collapsed. Also provides place for gas exchange to take place even between breaths.

Question 5

What is Vital Capacity (VC)?

Answer 5

tidal volume + inspiratory reserve volume + expiratory reserve volume. Used to measure lung funtion. 4600ml av men, 3100ml women , max. amount of air voluntarily expire.

Question 6

What is Total Lung Capacity (TLC)?

Answer 6

vital capacity + the residual volume

Question 7

What is Inspiratory Capacity?

Answer 7

tidal volume + inspiratory reserve volume

Question 8

What is Functional Residual Capacity (FRC)?

Answer 8

expiratory reserve volume + residual volume.

Question 9

FEV1:FVC =

Answer 9

Fraction of forced vital capacity expired in 1 second.

Question 10

What lobes are the lungs divvied into?

Answer 10

RIght Lung: Superior, Middle, Inferior

Left lung: Superior and Inferior

Question 11

How many pleural sacs are there

Answer 11

2 - left and right

Question 12

What is the differenc ebetween parietal and visceral pleura?

Answer 12

Parietal pleura is the outer layer lining inner surface of ribs/deep surface of chest wall
Visceral is the inner layer lining lungs

Think parietal brain is the upper outermost part therefore parietal pleura is outermost too

Question 13

What fills pleural cavity?

Answer 13

intrapleural fluid

Question 14

Are lungs effectivelystuck to rib cage through relationships of pleural membranes with ribs/lungs?

Answer 14

Yes

Question 15

What causes unforced exhalation?

Answer 15

the elastic connective tissue in the lung leads to recoil of the chest wall

Question 16

What is Boyles law?

Answer 16

Pressure exerted by a gas is inversely proportional to its volume (big volume low pressure, small volume high pressure)

BP - Boyle=Pressure

Question 17

What law states that the total pressure of a gas mixture is the sum of the pressures of the individual gases?

Answer 17

Daltons Law (SID the sloth - Sum of Individ gasses = Daltons)

Question 18

What law states that the volume occupied by a gas is directly related to the absolute temperature (v a T)

Answer 18

Charles law (Prince charles checking temparature)

Question 19

Which law states that the amount of gas dissolved in a liquid is determined by the pressure of the gas and it’s solubility in the liquid?

Answer 19

Henry’s law - finding Henry (the underwater law)

Question 20

What muscles does inspiration use?

Answer 20

External Intercostals and diaphragm, accessorary muscles inc : sternocleidomastoid and scalenes

Question 21

What muscles does expiration use?

Answer 21

Passive at rest, but uses internal intercostals and abdominal muscles during severe load.

Question 22

What shape is the diaphragm when it is relaxed?

Answer 22

Dome shaped.

Question 23

What is Intra-thoracic (Alveolar) Pressure (PA):

Answer 23

pressure inside the thoracic cavity, (essentially pressure inside the lungs). May be negative or positive compared to atmospheric pressure

Question 24

What is Intra-pleural Pressure (Pip)

Answer 24

pressure inside the pleural cavity, typically negative compared to atmospheric pressure (in healthy lungs at least!)

Question 25

What is Transpulmonary pressure (PT):

Answer 25

difference between alveolar pressure and intra-pleural pressure. Almost always positive because Pip is negative (in health). PT = Palv – Pip

Question 26

State the role of pulmonary surfactant

Answer 26

It stops water molecules being able to “see” each other (blocks intermolecular forces) therefore reduces surface tension urge (tendency) of alveoli to collapse. Water and other fluid is required as gasses can only move across in solution

Question 27

What is the Law of Laplace?

Answer 27

P=2T/r P=Pressure T=surface Tension r=radius

Surface tension is the same across different alveoli because water droplets are attracted to each other with same attractive force across alveoli regardless of big or small alveoli.

T without surfactant =3??? T with surfactant = proportional to size (more cocentrated in smaller alveoli)! Therefore pressure should be the same in big and small alveoli with functioning surfactant.

Question 28

Define the term compliance

Answer 28

change in volume relative to change in pressure
i.e. how much does volume change for any given change in pressure
It represents the stretchability (ability to get air in) of the lungs (not the elasticity - recoil!)
HIGH COMPLIANCE = large increase in lung volume for small decrease in ip pressure (not much effort to increase lung vol. (inspire))
LOW COMPLIANCE = small increase in lung volume for large decrease in ip pressure (hard to inspire!)

Question 29

What factors affect compliance

Answer 29

Changes in disease states/age

Is determined, in part, by action of surfactant

Question 30

What are the 2 cell types make the alveolar walls?

Answer 30

Thin walled “Type I” cells which permit gas exchange

Specialised “Type II” cells which secrete surfactant fluid

Question 31

What is Pleurisy?

Answer 31

Inflammation of the Pleura, making any movements/breaths etc painful as the pleural membranes don’t slide over each other as much

Question 32

How much pleural fluid is between the pleural membranes?

Answer 32

About 3mm

Question 33

At the end of a normal expiration at rest what forces are in equilibrium?

Answer 33

Outward force of chest wall (through pleural membrane stuck to rib cage) and inward force of elastic fibres wanting to recoil further

Question 34

What is Pneumothorax

Answer 34

When pleural membranes are pierced and so the elastic fibres in the lung recoil the lung and it shrivels up as it can no longer help and pushes out in the opposite direction by the chest wall which is now able to move freely as the plural membrane is no longer cohesive.

Question 35

What is the Hilum of the lungs

Answer 35

The region where the bronchi, arteries, veins, and nerves enter and exit the lungs.

Question 36

Which nerve innervates the diaphragm?

Answer 36

Phrenic nerve

Question 37

During inspiration/expiration what happens to the airways?

Answer 37

Inspiration = increase diameter
expiration = decrease diameter,

Question 38

How does asthma affect the bronchiole smooth muscles?

Answer 38

Inappropriate constriction, aggravated on expiration. Restricts air flow even more. Asthma wheeze on expiration .

Question 39

Why is surfactant more effective in smaller alveoli compared with larger alveoli?

Answer 39

Surfactant molecules come closer together and therefore more concentrated.

Question 40

When does surfactant production start and when is it complete? What is it stimulated by? What do premature babies suffer from?

Answer 40

25 weeks gesation start - 36 weeks complete (40 weeks full term). Stimulated by thyroid hormones and cortisol which increase towards end of pregnancy. Premature babies suffer Infant Respiratory Distress Syndrome (IRDS) as they dont have adequate surfactant (before 36 weeks). These days is overcome with synthetic surfactant aerosol.