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Describe and explain the structure of spiracles in insects
- Series of openings on the side of the insects abdommen.
- Valves which open to let O2 into the tracheae so gas exchange can happen.
- Valves can close when the insect is in an inactive state to help with water loss.
Describe and explain the stucture of Trachea in Insects
- Trachea are the tubes the spiracles open in to.
- Rings of chitin line the trachea to keep it open and prevent it from collapsing due to gravity of pressure and obstructing the flow of O2
Describe and explain how the structure of Tracheoles in Insects
- Tracheoles are located at the end of the trachea and are the site of gas exchange.
- Moisture is secreted at the tips of the tracheoles so that the gases can dissolve and diffuse.Tracheole membrane is only one cell thick meaning gases can rapidly and efficently diffuse across the membrane.
Describe and explain the structure of gill rakers in Fish
- The gill raker is located on the gill arch.
- The gill rakers protect the gills from by sifting the water to filter out things like sticks and leaves.This prevents the gas exchange system from damage
Describe and explain the structure of lamellae in Fish
- Lamellae are the folds of the filament and are the source of gas exchange.
- Large amounts of lamellae on each filament mean that a large surface area is created.Thin membrane one cell thick
Describe and explain the structures of Trachea and Bronchi in Mammals
- The trachea and bronci are the tubes which lead from the mouth to the lungs.
- They are lined with rings of cartilege which support the tubes and prevent them from collapsing due to gravity or pressure.
Describe and explain the stucture of alveoli in mammals.
- The alveoli are the air sascs at the end of thee bronchioles in the lungs
- Lined with blood capillaries. A very thin, semi-permeable membrane seperates the blood capillaries from the air flowLarge number of alveoli in the lungs creating a combined large surface area
Describe and explain the structure of diaphragm and intercostal muscles in Mammals
- The diaphragm and intercostal muscles create breathing movements which force air in and out of the lungs.
- When a human breathes in, the diaphragm pulls down and the intercostal muscles pull up and out. This increases the volume of the lungs and so air rushes in. When a human breathes out the diaphragm and intercostal muscles relax decreasing the volume of the chest cavity and forcing air out.Being able to increase the volume of the chest cavity means that optimum levels of gas exchange are able to happen.
Discuss how fishes gas exchange system solves the challenges of diffusion
- Gills are external meaning that they are always moisturiesed and so the gases are always able to dissolve and then diffuse.
- There is a one cell thick membrane seperating the lamellae from the blood capillaries.There is a large surface area created by the large number of folded lamellae on the filaments
Discuss how mammals gas exchange system solve the challenges of diffusion.
- The lungs are internal which prevents them from drying out and so they are kept moist.
- There is a thin membrane seperating the capillaries from the alveoliThere are large numbers of alveoli in the lungs creating a large surface area
Discuss fishes need for a concentration gradient and why mammals don't need one
- Fish have a very efficent system to gain maximum amount of oxygen from water. They can use 80% of the available O2 . The flow of water over the gills is constant and in one way. The blood capillaries flow in the opposite way. This means the concentration of the water is always higher than the concentration in the fish and so a concentration gradient is maintained(see diagram)
- Humans live in a high oxygen enviroment-21% of air and so a concentration gradient is maintained naturally.
Discuss why mammals have higher metabolic needs than fish.
- Mammals need an efficent gas exchange system because they have high metabolic needs. Mammals are homeothermic (maintain constant body temperature) and so have large oxygen requirements.
- Fish are poikiothermic (body temp varies with enviroment) and do not have such high oxygen needs. Gills therefore are efficent for their needs
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