Gaseous Exchange Cell Lab Report

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Introduction
Cellular respiration - the process to make energy and fuel life processes - creates a constant demand for oxygen and elimination of carbon dioxide. This is carried out in the gaseous exchange system. The gases first dissolve (in the fish and mammals) and then diffuse (in mammals, fish and insect) through a moist and thin, (thickness of a cell) semi-permeable membrane with a large surface area to volume ratio. Dissolved gases are transported by a circulatory system (in mammals and fish) to cells in the body. In insects, oxygen and carbon dioxide are transported directly to each individual cell. The gaseous exchange surfaces for each animal that we will be covering are the lungs (mammals), gills (fish) and tracheoles (insects).
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The gaseous exchange system (lungs) are situated deep within the bodies due to the risk of desiccation; where the gaseous exchange membrane exposed to air dries out. The percentage of oxygen (21%) is very high in the air, so mammals do not need a highly efficient gaseous exchange system. When the oxygen concentration gradient in the air is greater than inside the body, oxygen is easily diffused through gas exchange membrane. Similarly, when carbon dioxide concentration gradient is greater inside the body than outside the body, carbon dioxide is expelled out of the body.
Structures and Adaptations
Lungs are organs that allow mammals to gain oxygen and remove carbon dioxide required for respiration through the process of inhalation and exhalation need to take place. In the inhalation process, air moves in through the nasal cavity. The mucous secreting membrane and beating cilia in the nasal cavity moisturizes and filters off dust/pathogens from the air before it reaches the lungs. Damaging particles/pathogens are filtered from inhaled air to protect the sensitive respiratory cells inside the gaseous exchange system. The air moves from the nasal cavity into a large tube trachea. The horseshoe shaped cartilage rings holds the trachea open and upright to allow continuous air flow in and out of the
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The oxygen is diffused from outside the alveoli through to the blood in the capillaries.

The difference in concentration gradient of oxygen and carbon dioxide outside and inside the membrane is important for increasing the rate of gas diffusion; whereby gas from higher concentration area diffuses to a lower concentration area until both areas between the membrane reach equilibrium.

Breathing in (inspiration) contracts the diaphragm and intercostal muscles. This increases air volume and decreases air pressure in the thoracic cavity as compared to the atmospheric pressure. The difference in air pressure gradient between the atmosphere and within the alveoli causes air rich in oxygen to rush into the body.

When exhaling (expiration), the diaphragm and intercostal muscles relax. This decreases air volume and increases air pressure within the thoracic cavity. The difference in air pressure gradient between the atmosphere and within the alveoli causes carbon dioxide to be expelled from the

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