Gas exchange Flashcards
Features of an efficient gas exchange system
1) Large SA:V
2) Short diffusion distance
3) Steep concentration gradient
How does SA:V relate to an organisms size?
The smaller the organism the larger the SA:V.
How does SA:V relate to organisms metabolic rate?
The smaller the SA:V the higher the metabolic rate.
Why do multicellular organisms need gas exchange systems?
Smaller SA:V means more distance needs to be crossed for substances to reach cells.
What are insect adaptations to limit water loss?
a) Small SA:V of place where water can evaporate
b) Have chitin waterproof lipid coated exoskeleton so water doesn’t evaporate across body
c) Spiracles can open and close
Describe parts of the insect gas exchange system
SPIRACLE: Small valve opening across abdomen which lets O2 in and CO2 out.
TRACHEA: Internal tubing with disks to hold shape.
TRACHEOLS: Extended tubing to respiring tissue/cells
How are insects adapted for large SA:V?
Lots of tracheoles.
How are insects adapted for short diffusion distances?
Walls of tracheoles are thin + small in size so short distance between spiracles and tracheoles.
How are insects adapted for steep diffusion distances?
Constant intake of O2 and production of CO2.
Explain the process of gas exchange in insects
1) Simple diffusion: Cells make CO2 and use up O2 which makes a concentration gradient from atmosphere-inside.
2) Mass transport: Contraction and relaxing of abdominal muscles pumps gases across.
3) Pressure gradient: during flight when there is anaerobic respiration = lactate = lower water potential = water osmosis from tracheoles-cells = less volume in tracheoles = less pressure = air enters.
Describe the parts of a fish’s gas exchange system
GILLS: 4 layers on each side of head.
GILL FILAMENTS: V shape stack together to make a gill
GILL LAMELLAE: Cover the gill filaments at right angles.
How are fish adapted to large SA:V?
Many gill filaments covered by many gill lamellae at right angles.
How are fish adapted to short diffusion distances?
Very thin lamellae + capillary bed in every lamellae.
How are fishes adapted to steep concentration gradient?
Using the counter current flow mechanism.
Explain the counter current flow mechanism
Water flows over gills in the opposite direction to the blood flow in capillaries so water is always slightly more concentrated than the blood. This ensures equilibrium is never reached and diffusion gradient is maintained across entire lamellae.
Explain concurrent flow mechanism
Water flows in the same direction as blood ( water= 100% - blood= 0%)
So starts with rapid diffusion but reached 50% so not across entire lamellae.