Insects and bony fish Flashcards
why do insects have specialized features to help with oxygen adn co2 exchange
Active
High oxygen requirements
Tough exoskeleton - no gaseous exchange can take place
Don’t have blood pigment that can carry oxygen
Oxygen travels directly to cells that need it
Why is radius of insects body lmited
Diffusion of co2 and o2 through air in the tracheal tubs is only fast enoguh for distances less than 10mm from the bdoies surface -
Spiracles
Small openings i Air enters adn leaves, water lost Opened and closed by sphinctos Kept closed to prevent water loss Whn insects inactive= closed
Trachae ( insects)
Leading away from the spiracles
Largest tubes of insect respiratory system
Up to 1mm in diameter , carry air into body
RUn into and along body
Lined with chitin which keep them open if bent or pressed
Chitin impermeable = little gas exchange
Tracheoles ( insects)
Trachae branch into tracheoles 0.6-0.8um Sinlge, greatly elongated cell with no chitin freely permeable Small size Most of gas exhange takes place
Tracheole fluids
Limits the penetration of air for diffusion
When o2 demands build up- water moves ut of brachnioles by osmosis = greater sa
Increasing level of gaseous exchange
Mechanical ventilation of tracheal system - air actively oumeped into system by muscular pumping movements of throax, change the volume of body and pressure in trachea = air drawn in or forced out
Collapsible enlarged bronchae or air sacs, which act as air reservoirs = increase air moved through system, inflate and deflate by ventilating moment of thorax
Why do bony fish need specialised system
SA:V ratio means diffusion not enough o supply inner cells
Scaly covering doesn’t allow for gaseous exchange
Flow in ONE direction over gills
WHy is water harder to get oxygen from than oxygne in the air
Denser
Thicker (viscous)
Lower oxygen Continent
Gills adaptations
Large surface area
Good blood supply
Thin layers
Contained in gill cavity, covered by flap called operculum ( protective)
Lamellae
Rich blood supply and large surface area, main side of gaseous exchange
Filaments
Occur in large gill plates and need a flow of water to keep them apart, exposing large SA
How are the gills effective?
Tips of adjacent gills overlap = increases resistance to flow of h20 over gill surfaces and slows movement of water = more time for gaseous exchange to take place
Counter current exchange
Counter current exchnage - gills
Blood and h20 flow in opposite directions
Steep concentration gradient
80% of oxygen in water removed compared to parallel systems in cartilaginous fish ( 50%
Oxygenated bood + max conc h20
Deoxygneated blood + less conc h2o
Water flow over gills - for when they arent swimming
When open mouth, buccal cavity lowered Increases volume Decreases pressure Water enters Close mouth Raise buccal vacity Pressure increased adn volume decreased Water leaves over gills
