gas exchange Flashcards
what are the components of an insects tracheal system
spiracles
trachea
tracheoles
what are spiracles
round valve like openings that run along the lenght of the abdomen
what is the function of the spiracles
they open and close to allow gases such as oxygen and carbon dioxide into and out of the body, as well as have little hairs to further reduce water loss
explain the structure of the trachea
lined with rings of chitin that reinforce the trachea to keep them open and prevent collapsing, providing spaces so filled with air, fast diffusion takes place
explain the function of tracheoles
smaller tubes which extend through all tissues in the insect to deliver oxygen to respiring cells. the tracheal fluid is important in maintaining water potential in the cells and creating air pressure so air moves down into tracheoles
how does diffusion occur in insects
in respiring tissues the release of CO2 and use of O2 creates a gradient. O2 moves into the trachea down the gradient and CO2 moves out along the gradient
How does mass transport occur in insects
As the muscles in their abdomen contracts the spaces inside the tracheae and tracheoles squeezes. This decreases volume and increases pressure, forcing gas out of the insects body
Explain how the movement of fluid at the end of the tracheoles is a method of gas exchange
During flight cells begin to respire anaerobically due to lack of oxygen, producing lactate in the cells which lowers the cells water potential. The fluid in the tracheoles moves down a water potential gradient by osmosis into the cells. This loss of water reduces the pressure of tracheoles drawing air in.
Why is gas exchange essential in insects
Oxygen is essential for respiration
Carbon dioxide changes the acidity of tracheal fluid if dissolved
What are issues with the tracheal system
Water can be lost as spiracles open resulting in dehydration
Mostly relies on the passive movement of gases along their concentration gradient
Diffusion pathway must be short (why insects are small)
How do insects and the tracheal system reduce water loss
Small surface area to volume ratio reducing the area from which water could evaporate
Waterproofing the chitin exoskeleton with a waterproof cuticle
Voluntary closing of the spiracles
What do fish use energy from respiration for
Catabolism
Anabolism
Movement
Explain the inhalation of water in fish
Floor of mouth is lowered as operculum is shut, and water enters buchal cavity due to increased volume and decreased pressure. Operculum opens and floor of mouth is raised, water is forced out of buchal cavity due to decreased volume and increased pressure.
Explain the full structure of the gills
Consist of branches called gill filaments which branch off of a gill bar (held open by water pressure), filaments contain blood vessels which branch into capillaries in the lamellae for gas exchange. At right angles to gill filaments are gill lamellae, which are one cell thick and increase the surface area of gills.
Explain the principle of counter current flow
Water flows in opposite direction to the flow of blood so water with high oxygen concentrations always meets blood with slightly lower oxygen concentrations. Therefore diffusion gradient is maintained along the length of the lamellae
