Exchnged Surfaces

Question 1

Need for exchange surfaces

Answer 1

Excrete waste prod eg co2, urea to prev build up and toxicity
Absorb o2 and nutrients for metabolic reactions

Question 2

SA, size, metabolic activity

Answer 2

Big sa needed as large org vol inc quicker than surface area size
Multicellular has layers of cells, long dp= too slow comp to single where cells close to enviro
Active= good supply of o2 and nutrients for energy and warmth+ use up quick

Question 3

Features of efficient exchange surface

Answer 3

Large sa= space for mol pass eg folds wg hair inc abs rate for water
Thin= red dp eg thin alv ep dec dd of co2 and o2 diff= high ror
Good blood supply/ventilation= steep conc grad eg alveloi and gills

Question 4

Lung structure

Answer 4

Trachea >2 bronchi>bronchioles>alveoli
Inter muscles hold ribcage which protects lungs

Question 5

Structure and function of exchange system

Answer 5

Goblet cells= secrete mucus, traps dust and prev reaching alv
Cilia= wafts mucus upw, swallowed
Elastic fibres= stretch inhale, recoil
Sme= constrict diameter, less resist
Cartilage = support, strong, flexible prev collapse of trachea and bronchi when air p low

Question 6

Lung adaptations for thin barrier

Answer 6

Alv, narrow cap wall= 1 cell thick, squam alv,cap close to alv wall= short dp,
Moist walls= gasses diffuse and dissolve

Question 7

Lung adaptations

Answer 7

Many alv = large sa 70
Surfactant= red cohesion prev alv collapse
Good blood supply = steep conc grad eg conc of co2 in blood is higher than in air of alv
Permeable barrier to 02 and co2