Module 3 Flashcards
Why don’t single celled organisms need a transport system?
Low metabolic demands
High SA:V
Short diffusion distance
How are exchange surfaces specialised for their function?
High surface area
Thin layers
Good bloody supply
Ventilation to maintain concentration gradient
What are important features of the nasal cavity ?
Large surface area and good supply, which also increases temperature
Hairy lining that secretes mucus
Moist surfaces which increases humidity of air which reduces evaporation from exchange surfaces
What are the main features of the trachea?
C shaped cartilage rings to stop it collapsing
Ciliated epithelium with goblet cells
What are the main adaptations of alveoli?
Composed of elastin That allows stretch to allow more air in, and elastic recoil to help expel it Large surface area Think layers Good blood supply Good ventilation Lung surfactant keeps alveoli
Explain the process of inspiration
Diaphragm contracts and flattens
External intercostal muscles contract, moving the rib cage up and out
Volume increases, so pressure decreases compared to atmosphere, so air rushes in
How can the air capacity of the lungs be measured ?
Peak flow meter- measures the rate at which air can be expelled from the lungs
Vitalograph- more sophisticated version of a peak flow meter
Spirometer
What are the different aspects of lung volume that can be measured
Tidal volume- volume of air in a resting breath
Vital capacity- maximum possible air in one breath
Inspiratory reserve volume- maximum air you can breath in above the normal inhalation
Expiratory reserve volume- extra air you can force out over w normal breath out
Residual volume- volume of air left in lungs when you have exhaled as hard as possible
Total lung capacity- vital capacity+residual volume
What is ventilation rate?
Total volume of air inhaled in one minute
Ventilation rate=tidal volume x breathing rate
How does gas exchange take place in insects?
Along the thorax there are spiracles that let air in. Sphincters open and close spiracles to balance water loss vs gas exchange
Tracheae carry air into the body, then split into tracheoles. These are elongated cells with walls permeable to gas as they have no chitin
How can larger insects with higher metabolic demands maintain higher levels of gaseous exchange?
Air actively pumped into the ventilation system by muscular pumping movements
Why is it more difficult to obtain oxygen from water than air?
water is denser, more viscous and has a much lower oxygen content
describe the structure of gills?
gill lamellae are site of gaseous exchange, contained in gill filaments. These occur in large stacks called plates that need flow of water to keep them apart and expose the large surface area
describe how fish keep water flowing over their gills
Mouth opens and buccal cavity floor lowered, raising the volume, water moves in. Opercular cavity expands with the valves shut, lowering opercular pressure, and buccal floor moves up, increasing buccal pressure and forcing water over the gills. Both the buccal and opercular cavities constrict to increase pressure, forcing water out
How are gills well adapted to gaseous exchange, further than those for all exchange surfaces
Tips of adjacent gill filaments overlap, increasing resistance to water flow to allow for more gaseous exchange
Countercurrent system to maintain a steep concentration gradient throughout gaseous exchange
