Physiology 1 - Forces of Respiration

Question 1

Is inspiration active or passive?

Answer 1

Inspiration is active

Question 2

Which three factors keep alveoli open?

Answer 2

Transmural pressure gradient
Pulmonary surfactants
Alveolar interdependence

Question 3

Which 2 forces allow lungs to adhere to the chest?

Answer 3

Transmural pressure gradient

Intrapleural cohesion

Question 4

State the mmHg for Atmospheric Pressure, Alveolar Pressure and Intrapleural pressure

Answer 4

Atmospheric Pressure - 760 mmHg
Alveolar Pressure - 760 mmHg
Intrapleural Pressure - 756 mmHg

Question 5

During inspiration, which two muscles help most?

Answer 5

Diaphragm - contracts to become flat

External Intercostal Muscles - Lifts ribs upwards and outwards

Question 6

How does a pneumothorax abolish transmural pressure gradient? What is the result?

Answer 6

Pneumothorax allows air entry into the pleural space and raises pleural (intrathoracic) pressure gradient.
The lung collapses.

Question 7

What are symptoms of pneumothorax?

Answer 7

shortness of breath

chest pain

Question 8

what are the physical signs of pneumothorax?

Answer 8

hyperressonant percussion note

decreased/absent breath sounds

Question 9

Which law states that at constant temperature the pressure exerted by a gas is inverse to the volume of gas?

i.e. when volume of gas increases the pressure exerted by gas decreases

Answer 9

Boyle’s Law

Question 10

Why is Boyle’s law important to respiration?

Answer 10

For air to flow down its pressure gradient, intra-alveolar pressure should become less than atmospheric pressure.
This happens during inspiration when lungs expand.

Also needed for expiration

Question 11

Which 2 factors cause lungs to recoil during passive expiration?

Answer 11

Elastic connective tissues

Alveolar surface tension

Question 12

What reduces alveolar surface tension?

Answer 12

Surfactants

Question 13

What produces surfactants?

Answer 13

Type 2 alveoli

Question 14

Name the two major inspiratory muscles

Answer 14

Diaphragm

External intercostal muscles

Question 15

Name the 3 accessory muscles of inspiration used during forceful inspiration?

Answer 15

Sternocleidomastoid
Scalenus
Pectoral

Question 16

Name 2 muscles of active expiration?

Answer 16

Abdominal muscles

Internal intercostal muscles

Question 17

Volume of air entering or leaving lungs during a single breath?
0.5L

Answer 17

Tidal Volume (TV)

Question 18

Extra volume of air that can be maximally inspired over and above the typical resting tidal volume
3.0L

Answer 18

Inspiratory reserve volume (IRV)

Question 19

Extra volume of air that can be actively expired by maximal contraction beyond the normal volume of air after a resting tidal volume
1.0L

Answer 19

Expiratory reserve volume (ERV)

Question 20

Minimum volume of air remaining in the lungs even after a maximal expiration
(1.2L)

Answer 20

Residual volume (RV)

Question 21

Maximum volume of air that can be inspired at the end of a normal quiet expiration
(3.5L)

Answer 21

Inspiratory Capacity (IC)

IC = Inspiratory Reserve Volume + Tidal Volume

Question 22

Volume of air in lungs at end of normal passive expiration (2.2L)

Answer 22

Functional Residual Capacity (FRC)

FRC = Expiratory Reserve Volume + Residual Volume

Question 23

Maximum volume of air that can be moved out during a single breath following a maximal inspiration (4.5L)

Answer 23

Vital Capacity (VC)

VC = Inspired Reserve Volume + Tidal Volume + Expired Reserve Volume

Question 24

Total volume of air the lungs can hold (5.7L)

Answer 24

Total Lung Capacity (TLC)

TLC = Vital Capacity + Reserve Volume.

Question 25

Which three lung volumes and two lung capacities can spirometry measure?

Answer 25

Tidal Volume Inspiratory & Expiratory Reserve Volume Inspiratory Capacity Vital Capacity

Question 26

What is the normal Fev1/FVC ratio?

Answer 26

>75%

Question 27

Maximum volume that can be forcibly expelled from the lungs following a maximum inspiration

Answer 27

Forced vital capacity (FVC)

Question 28

Volume of air that can be expired during the first second of expiration in an FVC (Forced Vital Capacity) determination

Answer 28

Forced expiratory volume in one second (FEV1)

Question 29

In diagnosing restrictive vs obstructive diseases, which measurement differs and which stays the same?

Answer 29

FVC differs | FEV1 same

Question 30

A peak flow meter is used for obstructive or restrictive lung disease?

Answer 30

obstructive lung disease (e.g. asthma/COPD)

Question 31

Which nerve innervates the major inspiratory muscles? Name its levels.

Answer 31

Phrenic nerve | C3, 4, 5