Respiratory Physiology- Intro

Question 1

Steps of External Respiration

Answer 1

Ventilation
Gas exchange between alveoli and blood
Gas transport in blood
Gas exchange at tissue level

Question 2

Systems involved in external respiration

Answer 2

Respiratory
Cardiovascular
Haematology
Nervous

Question 3

Ventilation

Answer 3

Mechanical process of gas being moved in and out of lungs

Question 4

Gas exchange between alveoli and blood

Answer 4

Exchange of O2 and CO2 between air in alveoli and blood in pulmonary capillaries

Question 5

Gas transport

Answer 5

Binding and movement of O2 and CO2 in circulating blood

Question 6

Gas exchange at tissue level

Answer 6

Exchange of O2 and CO2 between blood in systemic capillaries and body cells

Question 7

Boyle’s Law

Answer 7

Pressure exerted by a gas is inversely proportional to the volume of gas at any constant temperature

Question 8

Two forces which hold thoracic wall and lungs in close opposition

Answer 8

Intrapleural fluid cohesiveness

Negative Intrapleural pressure

Question 9

Intrapleural fluid cohesiveness

Answer 9

Water molecules in intrapleural fluid resist pulling apart, causing pleural membranes to stick together

Question 10

Negative intrapleural pressure

Answer 10

A transmural pressure gradient is created across the lung wall and chest wall by the sub atmospheric inreapleural pressure. therefore lungs are forced to expand and chest to squeeze in

Question 11

Important pressures in ventilation

Answer 11

Atmospheric
Intra-alveolar/ intrapulmonary
Intrapleural/ intrathoracic

Question 12

Atmospheric pressure

Answer 12

Pressure caused by weight of gas in the atmosphere on the Earth’s surface
Average: 760mmHg/ 101kPa

Question 13

Intra-alveolar pressure

Answer 13

Pressure in the lung alveoli

760mmHg when equilibrated with atmospheric pressure

Question 14

Intrapleural

Answer 14

Pressure exerted outside lungs within the pleural cavity

Usually less than atmospheric pressure

Question 15

Inspiration

Answer 15

Active process caused by constriction of inspiratory muscles

Question 16

Why does intralveolar pressure fall during inspiration?

Answer 16

Lungs inflate, causing size to increase and pressure to fall
*Boyle’s Law

Question 17

Expiration

Answer 17

Passive process (in normal circumstances) caused by relaxation of inspiratory muscles

Question 18

Types of pneumothorax

Answer 18

Spontaneous
Traumatic
Iatrogenic

Question 19

Why does a pneumothorax cause lung to collapse?

Answer 19

The transmural pressure gradient is abolished as air from outside or from lungs enter the pleural space

Question 20

Signs and symptoms of a pneumothorax

Answer 20

Signs:
hyperressonant percussion
decreased/ no breath sounds

Symptoms:
SOB
chest pain

Question 21

What causes lungs to recoil during expiration?

Answer 21

Elastic connective tissue in lungs

Alveolar surface tension (more significant)

Question 22

Alveolar surface tension

Answer 22

A foster is produced (due to attraction between water molecules at liquid-air interface) which resists lung stretching

If alveoli were only lined with water, the surface tension would be too high and they would collapse

Question 23

LaPlace’s Law

Answer 23

P=2T/r 
P= inward directed collapsing pressure
T= surface tension
r= radius of alveoli/bubble
smaller r=higher tendency to collapse

Question 24

Pulmonary surfactant

Answer 24

Mix of lipids and proteins which type 2 alveoli produce

Lowers alveoli surface tension by dispersing themselves between water molecules

Question 25

Why are premature babies prone to developing RDS?

Answer 25

developing foetal lungs do not make pulmonary surfactant until late pregnancy

Question 26

Alveolar interdependance

Answer 26

Surrounding alveoli will start to stretch and recoil if an alveolus starts to collapse. Therefore expanding forces are exerted on collapsing alveolus