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Gaseous Exchange in Different Organisms.

Gaseous Exchange in Different Organisms. . Lesson 2. Gaseous exchange in bony fish. . Spec Statements. . Gas exchange across the gills of a fish (gill lamellae and filaments including the counter current principal). . Imagine you are a fish…. Which of these statements are correct?.

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Gaseous Exchange in Different Organisms.

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  1. Gaseous Exchange in Different Organisms. Lesson 2. Gaseous exchange in bony fish.

  2. Spec Statements. • Gas exchange across the gills of a fish (gill lamellae and filaments including the counter current principal).

  3. Imagine you are a fish… Which of these statements are correct? You have a set of lungs. You have blood contained within a circulatory system. You need to come to the surface for oxygen. You only respire anaerobically so you don’t need oxygen.

  4. Gaseous Exchange in Fish. Outcomes: -Label a diagram of the gill system. -Describe the issues with gaseous exchange in fish. -Explain how the features of the gill system (surface area, counter-current principal) allow for efficient gaseous exchange.

  5. 1) Why the Gill System • Adapted to extract oxygen from water. • In water O2 concentration rarely exceeds 0.8%. This is compared to 20.9% in air and is lower in warmer waters than colder waters. • Swimming fish have high respiration demands. • Gill system allows up to 80% of oxygen to be extracted from the water.

  6. 2) The Gill System All covered by bony flap known as operculum Each lamellae had its own blood supply. Surface is a single layer of flattened cells

  7. 3) How it works • Fish swim along with their mouth open. This forces water into the buccal cavity (mouth) • The water leaves the buccal cavity and passes over the gills. It leaves at the end of the operculum. • This flow of water over the gills is opposite to the flow of blood through the gills. Counter Current Principal. • Maximising gaseous exchange. Which part of the gill system provides…. • large surface area? • short diffusion distance? • maximum concentration gradient?

  8. Maximising gaseous exchange. Which part of the gill system provides…. • large surface area? • Many gill filaments contain many lamellae. • short diffusion distance? • Each lamellae has its own blood supply. The surface of the lamellae contain a single layer of flattened cells.

  9. Maximising gaseous exchange. Which part of the gill system provides…. • maximum concentration gradient? • Counter Current Principal. Water flows across the lamellae is the opposite direction to blood flow. • This means that the blood with the greatest oxygen content is in contact with the water with the greatest oxygen content. http://www.kscience.co.uk/animations/anim_3.htm • This is maximised by the constant blood flow through the capillaries and the constant flow of water over the capillaries. Blood that is saturated with oxygen is replaced and water that has lost the oxygen is also replaced.

  10. Exam Question. June 09. Q8 A fish uses its gills to absorb oxygen from water. Explain how the gills of a fish are adapted for efficient gas exchange. 6 marks.

  11. Exam Question. June 09. Q8

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