Respiration during Exercise (1)

Question 1

What is the primary purpose of the respiratory system?

Answer 1

To maintain arterial blood-gas homeostasis

Question 2

maintenance of arterial blood-gas
homeostasis is accomplished by a 4-step process. What are the 4 steps?

Answer 2

1. Pulmonary ventilation
2. Alveolar gas exchange
3. Gas transport
4. Systemic gas exchange

Question 3

What does the epiglottis do?

Answer 3

Separates the upper and lower respiratory tracts.

Question 4

The lungs are enclosed within membranes called..?

Answer 4

Pleura

Question 5

Is intrapleural pressure > or < than atmospheric pressure?

Answer 5

Intrapleural pressure < atmospheric pressure, which prevents the alveoli from collapsing

Question 6

There are ~23 airway generations. What is the main bronchi?

Answer 6

The main bronchi is Z1; the conducting zone extends to the terminal bronchioles (Z16)

Question 7

In terms of the airways, where does gas exchange occur?

Answer 7

Gas exchange occurs in the respiratory zone (Z17-23)

Question 8

Where does pulmonary gas exchange take place?

Answer 8

Across the pulmonary capillary

Question 9

How do O2 and CO2 move between air and blood?

Answer 9

Simple diffusion (high to low partial pressure)

Question 10

There are 2 types of alveolar cell (pneumocytes), what are they?

Answer 10

o Type I cells cover ~95% of the internal
surface of the alveolus and are critical for gas exchange
o Type II cells release surfactant—a molecule that lowers the surface tension (like soap) - without surfactant alveoli would collapse.

Question 11

What is the volume of gas passing through a sheet dependent upon?

Answer 11

1. Surface area (A)
2. Thickness (T)
3. Diffusion coefficient (D)
4. Pressure gradient (alveolar to arterial)

Question 12

Alveolar gas has a diffusion path to the erythrocyte and includes 5 layers, what are these ?

Answer 12

1. Surfactant (not shown)
2. Alveolar epithelium (EP)
3. Interstitium (IN)
4. Capillary endothelium (EN)
5. Plasma

The blood-gas barrier is very thin (0.3 μm) and has a vast surface area (50-100 m2) making it ideal for gas exchange/diffusion (Fick’s law)

Question 13

The mechanics of breathing is concerned with the movement of air into and out of the lungs by changes in..?

Answer 13

pressure, flow and volume
contraction length = change in volume
contraction velocity = change in flow
contraction force = change in pressure

Question 14

What does the bucket handle motion do?

Answer 14

increases the transverse (lateral) diameter of the thorax during
inspiration

Question 15

What does the pump handle motion of the ribs do?

Answer 15

increases the anteroposterior diameter of the thorax during inspiration

Question 16

What muscle is responsible for the majority of pulmonary ventilation at rest?

Answer 16

Diaphragm contraction (expiration is passive)

Question 17

During exercise, what muscle are the diaphragm assisted by?

Answer 17

external intercostal muscles, scalenes,
sternocleidomastoid and many others in
order to increase pulmonary ventilation 10 20-fold above resting levels

Question 18

When expiration become active, contraction of what muscles happen?

Answer 18

contraction of the rectus abdominis, internal intercostal muscles and external oblique (among others)

Question 19

What is Ohm’s law?

Answer 19

o Current = voltage/resistance, applied to breathing
o Airflow is dependent upon a pressure gradient and airway resistance

Question 20

What is Poiseuille’s law?

Answer 20

o Resistance is dependent upon length and radius of a tube
o Radius is raised to the fourth power, thus the major determinant of airway resistance

Question 21

What is the difference between a volume and a capacity?

Answer 21

• A volume is one segment
• A capacity is two or more segments

Question 22

What is ‘dead space’?

Answer 22

Not all air breathed reaches the alveoli; the volume of air not participating in gas
exchange is called dead space.

Question 23

What is forced vital capacity ?

Answer 23

the maximum volume air that can be forcefully expired after a maximum inspiration

COPD is characterised by increased airway resistance and a reduced FEV1/FVC