Lung Function & Respiratory Gases 1

Question 1

What are the general functions of respiratory systems?

Answer 1

Gas exchange

Metabolism

Acid-base balance

Phonation

Pulmonary defence

Question 2

What are the metabolic functions of the respiratory system ?

Answer 2

Metabolism of vasoactive hormones in the lung are selective

Angiotensin I- bradykinin, serotonin, prostaglandin

Angiotensin II- E1, E2 & F2

Question 3

What is the function of the respiratory zone?

Answer 3

End of the respiratory tree (respiratory bronchioles, alveolar ducts, and alveolar sacs)

Gas exchange surface

Epithelial surface and an extracellular matrix

Surrounded by capillaries

Question 4

What is the function of conducting zone?

Answer 4

Air flow into and out of the lungs (nose to terminal bronchioles)

• Heat, hydrate and clean
• Heat exchange, water vapor pressure equilobration, and remove particulate load
• Mucocilloary load

Question 5

Whaat is the 8mportance of bulk flow?

Answer 5

Gas moves from the trachea to the alveoli via bulk flow

I’m the alveoli gas moves across the alveolar capillary membrane by diffusion

Question 6

What is fick’s Law?

Answer 6

V- rate if gas diffusion

A - surface area available for exchange of gas

T- diffusion barrier thickness

D-diffusion coefficient

Vgas= D x A/T (P1-P2)

Question 7

What is the surface area of the pulmonary blood-gas barrier?

Answer 7

Gas exchange occurs in the over 300 million closed air sacs called alveoli (75 m2)

Pulmonary circulation- most extensive network of capillaries in the body

Question 8

How thick is the diffusion barrier ?

Answer 8

The pulmonary blood-gas is about 0.5 um thick

Formed by the alveolar capillary membrane of the terminal respiratory unit

Question 9

What does the diffusion barrier consist of?

Answer 9

1. Thin layer of surface liquid
2. Alveolar epithelium cells (type 1 pneumocytes), plus associated basement membrane
3. Thin layer of intestinal fluid
4. Pulmonary capillary endothelial cells, plus associated basement membrane

Question 10

What are the types of alveolar cells?

Answer 10

Two types of cells in alveolar epithelium

• Type 1 pneumocytes
• Type 2 pneumocytes

Ratio is 1:1
Type 1 pneumocytes occupy most of the surface area
Type 2 pneumocytes make surfactant

Question 11

What is the surfactant of alveolar cells?

Answer 11

Surface active agent

Secreted by type II pneumocytes

Main component
Dipalmitoykphohatidyl choline

Reduces surface tension greatly- increasing lung compliance