Essay On Gas Exchange

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The process of gas exchange is very important in living things as it allows the production of energy which is required in body cells in order for life process such as reproduction to take place. Oxygen and carbon dioxide are the main gases involved in this process. Gas exchange is the diffusion of oxygen and carbon dioxide in and out of the cells. It is essential for respiration to occur. A carbon dioxide build up in the body is extremely dangerous so this must be removed from the body. Respiration is a process which is required for living things as it removes carbon dioxide from the body and replaces it with oxygen, this being a requirement for survival.

In order for gas exchange to be efficient and effective, there must be a large surface …show more content…

These include:
Direct diffusion from the atmosphere
Wind and wave action
Photosynthesis
Of these, the process of photosynthesis (this done through aquatic plants and phytoplankton) is the most important.
Oxygen, which is derived from the process of photosynthesis, is produced during daylight hours when sunlight shines on the plants in the water. Oxygen levels will drop at night due to respiration by aquatic plants and animals (fish). These are predictable changes in dissolved oxygen levels which occur every 24 hours. This is commonly known as the diurnal oxygen cycle (diagram 1).

Diagram 1 illustrates how the dissolved oxygen concentration within water fluctuates on a 24-hour basis in a lake in which the blue cod that were used to illustrate the information gathered are located. The blue cod which are commonly seen and known in Wairarapa’s location tend to live in salt waters which would show slightly varied results. The fluctuation is referred to as a diurnal oxygen cycle. Dissolved oxygen levels are shown to increase during daylight hours when photosynthesis is occurring and decrease at night when respiration continues to occur while photosynthesis does …show more content…

During the gas exchange process, fish will open their mouths to allow water in, it will then close its mouth which forces water to travel through the gills and out through the operculum/gill cover (illustrated in diagram 3). During inspiration, the mouth opens causing muscles to lower to the floor of the buccal (mouth) cavity, as well as causing the opercula to bulge outwards. This process will increase the internal volume whilst lowering the internal water pressure located within the mouth. During this, the opercula remain closed, thus ensuring that water enters through the mouth. During expiration, the mouth will close which causes muscles to raise the floor of the buccal cavity and push the walls of the operculum inwards. This process reduces the internal volume whilst increasing the internal water pressure located within the mouth. From this point, the opercula will open causing water to be pushed out over the gill surface. This ensures that water flows through the gills in one direction, further allowing a more efficient gas exchange in comparison to if the water were to have to travel in and out the same way. This is key for the survival of the fish due to the low oxygen concentration in water. Due to the fact that water enters the gas exchange surface in the same way which food enters the fish's body, unwanted food particles are likely to be present in the water.

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