3.1.1 Exchange surfaces

Question 1

4 features of a specialised exchange surface

Answer 1

• increased SA
• thin layers
• good blood supply
• ventilation to maintain diffusion gradient

Question 2

Pathway of oxygen in a human

Answer 2

mouth/nostril,nasal cavity->larynx->trachea->bronchus->bronchioles->alveolus

Question 3

features of the nasal cavity

Answer 3

-large SA w/good blood supply to warm air to body temp
- moist surfaces which increase the humidity of the incoming air reducing evaporation

Question 4

structure of trachea?

Answer 4

• wide tube supported by incomplete rings of strong flexible cartilage
• lined with a ciliated epithelium w/goblet cells

Question 5

Structure of bronchus

Answer 5

similar to trachea but smaller rings of cartilage

Question 6

structure of bronchioles

Answer 6

• no cartilage rings
  -walls contain smooth muscle
  -lined with a thin layer of flattened epithelium

Question 7

structure of alveoli

Answer 7

• layer of thin flattened epithelial cells
• • collagen and elastic fibres

Question 8

lung surfactant

Answer 8

Lung surfactant reduces surface tension in the alveoli, preventing collapse and aiding efficient gas exchange

Question 9

What happens in inhalation?

Answer 9

-diaphragm: contraxts + lowers
-EIM’s cotract moving ribs up + out
- thorax vol increases, pressure reduces
- lower than atm so air drawn in

Question 10

What happens in passive exhalation

Answer 10

• diaphragm muscles relax
• EIM’s relax so ribs move down
• thorax vol decreases, pressure increases
• higher than atm so air moves out

Question 11

What happens in forced exhalation?

Answer 11

• IIM’s contract
  -ribs pulled down
  -abdominal muscles contract forcing diaphragm up
• lung pressure increases rapidly

Question 12

tidal vol

Answer 12

vol of air that moves in and out of the lungs with each resting breath

Question 13

vital capacity

Answer 13

vol of air breathed in when strongest possible exhalation followed by deepest intake of breath

Question 14

inspiratory reserve vol

Answer 14

max air in after a normal inhalation

Question 15

expiratory reserve vol

Answer 15

extra air forced out above normal

Question 16

residual vol

Answer 16

vol air left in lungs after hardest exhalation

Question 17

ventilation rate formula

Answer 17

tidal vol X breathing rate (per min)

Question 18

gas exchange in insects

Answer 18

-air enters/leaves from spiricales
- flows throgh tracheae, lined by spirals of chitin
- tracheoles w/no chitin lining
- tracheal fluid