Internal Respiration Essay

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During internal respiration, energy, known as ATP, is also released. This is used in many reactions within the cells. Energy needed by the body is stored in food and the process of tissue respiration releases this energy. The oxygen oxidises glucose and produces energy. This is known as aerobic respiration. The equation for the oxidation of glucose is;

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The main adaptation of the lungs is the extremely large surface area it has. This is created by the millions of tiny alveoli sacs and the ciliated epithelial cells lining them. This increases the contact surface area for the oxygen entering the lungs, allowing many more molecules to diffuse simultaneously. The capillaries are also divided up into a network covering a large area which also creates a larger exchange surface for the carbon dioxide and oxygen. The second adaptation is that both the alveolar membrane and the capillary wall are surrounded by a membrane which is only one cell thick. This is important for diffusion of oxygen and carbon dioxide gases as it means there is a much narrower distance for the molecules to pass through. The third way in which the lungs are adapted to increase the rate of diffusion is that both the capillary and the alveolus are made of a semi permeable membrane allowing smaller molecules such as oxygen and carbon dioxide to pass through easily.

Fick’s Law is used to measure the rate of diffusion. It explains that for diffusion to take place successfully the surface area needs to be as great as possible and there must be a significant difference between the concentration in each organ structure. The thickness o...

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... acids and glucose produced by digestion to the hepatic portal vein and the liver. Lacteals are small lymph vessels, and are present in villi. They absorb fatty acids and glycerol, the products of fat digestion. Layers of circular and longitudinal smooth muscle enable the chyme to be pushed along the ileum by waves of muscle contractions called peristalsis. The remaining chyme is passed to the colon (Christopher A Becker).

In conclusion, the body has many physiological adaptations to increase the rate of diffusion/absorption. This is specified using Fick’s law. The main features are the adaption of a large exchange surface area within each organ system and the close proximity of the surrounding capillary networks. Other adaptations include membranes of a single cell thickness and the evolution of cells within the membranes to create a moist layer to aid diffusion.