4.2 Gas Exchange Flashcards
(31 cards)
Surface Area : Volume
The smaller an organism is the bigger their SA : Vol ratio is
Factors Affecting the Rate of Diffusion
Surface Area
Steepness of Concentration Gradient
Thickness of Membrane
Surface Area
The bigger the surface area the more particles can be exchanged at the same time
Steepness of Concentration Gradient
The steeper the CG the faster the molecules of a substance will diffuse
Thickness of Membrane
The thinner the membrane the faster diffusion can take place
Mammals gas exchange system
Nose/ Mouth
Epiglottis
Larynx
Trachea
Bronchus
Bronchioles
Alveoli
Nose/ Mouth
Ways that air enters the gas exchange system
Epiglottis
Flap of tissue that prevents food from entering the gas exchange system
Larynx
Uses the flow of air to produce sounds
Trachea
Airway to bronchi
Lined with mucus secreting cells that trap microorganisms
Bronchus
Tubes leading to lungs
Bronchioles
Small tubes that spread through lungs + end in alveoli
Alveoli
Main site of gas exchange
Alveoli Adaptations
Epithelial wall of alveoli is 1 cell thick
Capillaries surrounding alveoli are 1 cell thick
Elastic tissue holding capillary to alveoli which helps force air in + out
Lung surfactant coats the alveoli which prevents them from collapsing
Inhalation Steps
Active Process Uses ATP
1) Diaphragm contracts + flattens
2) Intercostal muscles contract + move ribs up + out
3) Increased volume + decreased pressure
4) Air rushes in to equalise the pressure
Exhalation Steps
Passive Process No ATP
1) Diaphragm relaxes + compacts
2) Intercostal muscles relax + move ribs down + in
3) Decreased volume + increased pressure
4) Air moves out to equalise pressure
Gas Exchange in Insects
Spiracles
Tracheae
Tracheoles
Spiracles
entry/ exit point
Can be opened or closed to prevent water loss
Tracheae
Carry air directly into the body
Run into but also along the body
Supported by chitin which holds the vessels open
Chitin makes the vessels impermeable so no gas exchange happens
Tracheoles
Single elongated cells with no chitin
Permeable to gases
Spread throughout the insect tissues
Methods to increase gas exchange for respiration
1) Mechanical Pumping
2) Collapsible Tracheae
Mechanical Pumping
Insect moves its thorax in a muscular pumping motion
Draws air in + out of spiracles
Collapsible Tracheae
Acts as air reservoirs
Movement of thorax can inflate + deflate them
Gas Exchange in Fish
1) Water flows in through mouth
2) Water flows over gills
3) Water flows out through the operculum
