Gas Exchange Flashcards
How are single-celled organisms adapted for gas exchange?
Short diffusion pathway, gases just diffuse across cell-surface membrane.
How are insects adapted for gas exchange?
Tracheal system consisting of spiracles, trachea and tracheoles.
What are insect spiracles?
Openings in the surface of the insect where air can enter and water can evaporate from.
How are insect spiracles adapted (for preventing water loss)?
Mostly stay closed to reduce water loss by evaporation. Have hairs to trap humid air and mainting a low water potential gradient.
How are insect trachea adapted?
Supported by strengthening rings to prevent collapse of trachea.
What are the 3 ways that gases move throught the insect tracheal system?
- Mass Transport
- Along a diffusion gradient
- The ends of tracheoles fill with water.
How does mass transport work in the insect tracheal system?
The contraction of muscles (in the abdomen) squeeze the trachea, enabling the movement of air in and out.
How does a diffusion gradient work in the insect tracheal system?
Ozygen enters respiring tissue away from the ends of tracheoles, creating an oxygen diffusion gradient between trachea. Carbon dioxide lost to atmosphere from spiracles creating concentration gradient betweeb trachea and atmosphere.
How does volume change in tracheoles work in the insect tracheal system?
Major activity causes anaerobic respiration which forms lactate in muscle cells, lowering their water potential. Water moves by osmosis from tracheoles into cells and air is drawn into the empty space in tracheoles.
How are insects adapted to balance gas exchange and water loss?
Small organisms have high surface area to volume ratio. Waterproof exoskeleton so water cannot evaporate from surface. Spiracles controlling exchange.
How else are insects adapted to prevent water loss?
Small Surface Area to Volume ratio and a rigid, chitin exoskeleton that is a waterproof outer covering.
How are fish adapted for gas exchange?
Through ventilation and they have gills consisting of gill lamallae, gill filaments and a counter-current flow.
What is the counter-current flow principle?
Water flows in the opposite direction to bloodflow meaning a concentration gradient is maintained and diffusion of gases continue along the whole length of the gill.
How do gill lamallae and filaments facilitate gas exchange?
Many lamallae are thin for short diffusion pathway and contain high blood supply for a large concentration gradient.
In water, filaments spread out so they are branched and have a high surface area to volume ratio.
How does a fish ventilate and how does it affect gas exchange?
As fish opens mouth, the pressure of the buccal cavity is lowering, meaning water rushes in. Then fish closes mouth to increase pressure again as water flows over gill and lamallae due to the pressure gradient between the mouth and operculum cavity.
