mammalian gas exchange

Question 1

describe the nasal cavity

Answer 1

• large SA & good blood supply = warms air to body temperature
• hairy lining = secrets mucus and traps bacteria
• moist = increases humidity and reduces evaporation

Question 2

describe the trachea

Answer 2

• c shape cartilage rings = prevents collapse and allows food down oesophagus
• ciliated epithelium = beat and move mucus to back of throat
• goblet cells = secrete mucus

Question 3

describe the bronchioles

Answer 3

• no cartilage
• smooth muscle = contracts and constricts to change air reaching bronchioles
• flattened epithelium = allows gas exchange

Question 4

describe the alveoli

Answer 4

tiny air sacs composed of flattened epithelial cells, collagen and elastin which allows elastic recoil

Question 5

what is the approximate size of alveoli?

Answer 5

200-300 micrometres

Question 6

describe the adaptations of alveoli

Answer 6

• large SA = maximum diffusion
• thin layers = short diffusion distance
• good blood supply = steep conc gradient
• good ventilation = breathing moves air in and out to maintain steep conc gradient
• lung surfactent = keeps alveoli inflated and prevents collapse

Question 7

describe the bronchus

Answer 7

smaller than trachea, branch off it, similar structure