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Exchange and Transport
Systems
Created
Class

@February 13, 2025 12:25 PM
Cells to Systems

Exchanging Substances
Oxygen for aerobic respiration and nutrients
Waste product excretion like CO2 and urea
Heat exchange occurs so body temp stays the same

Organ Exchange and Mass Transport Systems
Single celled organisms
Substances diffuse across cell surface membrane
Quick process due to small distances
Multicellular organisms
Diffusion is too slow
Cells are deep in the body and too far from external environment for
quick diffusion process
Big animals have low surface area to volume ratio
Difficulty in exchanging enough substance to animal
Mass Transport

Exchange and Transport Systems

1

Good system required to carry substance from and to cells
Circulatory system uses blood to carry glucose and O2

Factors Affecting Heat Exchange
Size
Heat loss depends on surface area
Organisms with large volume have smaller surface area
Small organisms have bigger surface area making it easier to lose heat
Small organisms have higher metabolic rate to keep warm
Shape
Animals with compact shape reduces heat loss
Less compact shape has bigger surface area increasing heat loss
Shape of animal is dependent on temp or environment

Behavioural and Physiological Adaptations
Animals with higher surface area volume ratio lose more water due to
evaporation
Mammals in cold areas eat high energy foods to sustain high metabolic
rates
Smaller mammals have thick fur or hibernate in plummeting temps
Bigger animals in hot areas increase surface area maximising heat loss

Gas Exchange Adaptations

Exchange and Transport Systems

2

Larger surface area
Thin surfaces means shorter diffusion pathway

Single-celled Organism Gas Exchange
Absorbs and release gas via diffusion through outer surface
Has bigger surface area, thin surface and shorter diffusion pathway

Lungs Gas Exchange
Air is breathed in through trachea
Trachea divides into two bronchi that leads into lungs
Bronchioles
Smaller tubes branched off from bronchioles
Alveoli
Small air sacs on bronchiole end
Ribcage, intercostal muscles and diaphragm works in unity moving air in
and out

Ventilation Processes
Inspiration
Contraction of external intercostal and diaphragm muscles
Ribcage moves upwards and outwards, diaphragm flattens increasing
thoracic cavity volume
Cavity increase decreases lung pressure

Exchange and Transport Systems

3

Air flows from area of high to low pressures, down trachea into lungs
Process needs energy (Active Process)
Expiration
External intercostal and diaphragm muscles relax
Ribcage moves downwards and inwards
Thoracic cavity volume decreases increasing air pressure
Air moves down pressure gradient and out the lungs
Passive process
Forced Expiration
External intercostal muscles relax
Internal intercostal muscles contract

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