Lung structure

Question 1

Feature of good exchange surface?

Answer 1

• large surface area
• thin membrane to reduce diffusion distance for faster exchange
• maintain steep gradient by supplying molecules on one side and remove on other (good blood supply and ventilation)

Question 2

What is the pathway of air

Answer 2

Trachea
bronchus
bronchioles
alveolar duct
alveolar sac
alveoli

Question 3

Structue of alveoli

Answer 3

elastin fibres and collagen for stretch and recoil to expel air
macrophage (white blood cell)
squamous epithelial cell for wall for short diffusion distance as one cell thick
fluid layer of surfactant (moist for diffusion and reduce surface tension)

Question 4

Relationship between capillary and alveolus

Answer 4

very close for short diffusion distance

Question 5

What is the capillary network

Answer 5

pulmonary capillaries
dense
alveolar macrophages (phagocyte) digests foreign particles that have reached alveoli

Question 6

The epithelial cells?

Answer 6

squamous
type 1 (squamous) and type 2 (secrete surfactant) pneumocytes

Question 7

What does connetive tissue do

Answer 7

forms supporting layer
collagen and elastin together with fibroblast cells
stretch and recoil to allow room for gases and help expel air

Question 8

Function of the surfactant

Answer 8

mix of lipids and protiens coating inner lining of alveoli
- reduce surface tension to prevent collapse
- kill bacteria
- speeds up transport

no surfactant for initial breath then collapse