Exchange surfaces 3.1.1
- Created by: adamss
- Created on: 29-05-17 13:17
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- Exchange surfaces
- The need...
- absorb certain substances
- Single-celled organisms
- Exchange necessary gases, nutrients and minerals.
- Large SA:V ratio
- Metabolic activity low. Oxygen demands, CO2 production low
- Multicellular organisms
- Smaller SA:V ratio
- Need more supplies, have more cells
- Nutrients and gases have to travel a larger distance to centre
- Efficient exchange surface
- Large (increased) SA
- More area needed for exchange
- Example: root hair cells (plants) villi
- More area needed for exchange
- Thin layer
- Short diffusion distance
- Speeds up process
- Example: alveoli (lungs) and villi (small intestine)
- Speeds up process
- Short diffusion distance
- Good blood supply
- steeper conc. gradient, faster diffusion
- Substances constantly delivered -exchange surface
- Example: alveoli (lungs) gills (fish), villi (small intestine)
- Substances constantly delivered -exchange surface
- steeper conc. gradient, faster diffusion
- Ventilation maintain diffusion gradient
- gases, ventilation system maintain conc. grad
- Processes more efficient
- Example: alveoli (lungs) gills (fish), villi (small intestine)
- Processes more efficient
- gases, ventilation system maintain conc. grad
- Large (increased) SA
- Structures and functions MAMMALIAN GASEOUS EXCHANGE SYSTEM
- Cartilage (trachea)
- Main airway carrying clean, warm, moist air. Nose to chest.
- Wide tube supported by CARTILAGE, stop trachea collapsing.
- Ciliated epithelium
- Move in a synchronised pattern to waft mucus up the airway to the back of the throat (away from throat)
- Goblet cells
- Secrete mucus, onto lining of trachea
- Trap dust and microorganisms escaped nose lining
- Secrete mucus, onto lining of trachea
- Smooth muscle
-
Can contract to restrict airway
- Prevents harmful substances from reaching the alveoli
-
Can contract to restrict airway
- Elastic fibres
-
Reverses the effect of the smooth muscle
- Smooth muscle contracts = deforms elastic fibres
- Smooth muscle relax = elastic fibre recoils
- Smooth muscle contracts = deforms elastic fibres
-
Reverses the effect of the smooth muscle
- Cartilage (trachea)
- The need...
- Single-celled organisms
- Exchange necessary gases, nutrients and minerals.
- Large SA:V ratio
- Metabolic activity low. Oxygen demands, CO2 production low
- Larger organisms = large area, exchange more substance. Combine w/ transport system
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