Gas Exchange Essay

Living organisms all need energy to carry out their life processes. Respiration is the chemical process of releasing energy from glucose, and in the case of aerobic respiration, in the presence of oxygen. Gas exchange is the physical process by which the oxygen n is absorbed from the air and into the blood stream and carbon dioxide is released.

Gas exchange is a two-way diffusion of oxygen and carbon dioxide into and out of cells across a semi permeable membrane. Gas exchange efficiency can be increased by a number of variables, there must be a large surface area to volume ratio, a concentration gradient for the gases to diffuse down, a thin surface so that the gases can diffuse rapidly and a moist surface that gases can dissolve in and out

Water entering the mouth with high oxygen saturation meets the blood with low oxygen saturation. This allows oxygen to diffuse from the water and across the lamellae into the capillaries. As the water flows across the lamellae it gradually loses more oxygen but will still allow for diffusion as it flows across incrementally deoxygenated and unsaturated blood in the capillaries where the concentration and partial pressure of oxygen is still lower than that of the dwindling concentration in the water. This is more effective then regular flow, in which blood flows the same way as water. Because there is less oxygen in water it requires fish to

The tracheae is held open by reinforced rings of cartilage called chitin (featured right, fig 2). Insects do not breathe through their mouths as mammals do, nor do they have gills as fish do. Instead, gases pass into and out of the insect through small openings called spiracles that are found on the underside of the insect’s thorax and abdomen. These are placed on the underside to reduce exposure and thus limiting chances of drying out, to also aid this, they can close to prevent water loss, although this can limit gas exchange, especially