User:SSergeant/Cutaneous respiration

Cutaneous respiration is the gas exchange in which takes place in the skin rather than their lungs or gills. In some organisms cutaneous respiration may be their only method of gas exchange for example ventilation. The various organisms that use cutaneous respiration includes insects, amphibians, turtles and some mammals. Cutaneous respiration is the process in which there are 2 simultaneous movements in an organism where one part carries the air to the body and the other helps with removing it from the organism. In this process about 90% of oxygen is intaked and the same amount exerted for carbon dioxide. In most fish groups cutaneous respiration is more predominant. It's known that even before gills were developed fishes developed the ability to breathe through their skin. How this works is there is a system of capillary networks that are located right underneath the epithelial layer. This covers the entire body surface giving them the ability to successfully perform gas exchange. In specific fish skin is harder for gas exchange to take place because of how thick the skin is, including the scales and mucus. This is because of the low potential it has for ventilation. In amphibians, there are 2 skin glands that exist, the mucous and the granular. The mucous glands are located all over the body's surface, this gives off a slimy type mucus in which helps support cutaneous respiration by keeping the skin moist. While the granular glands produce toxic repellent which helps the organism as a defensive mechanism towards predators. There are many species that have cutaneous respiration with the water- blood diffusion being from 50 to 400um, in addition to the fact that there's no direct relationship from the scales to the epidermal thickness to the rate of O2 transfer. Their skin is metabolically active in which secretory cells  exist and gets its nutrients from dermal capillaries. Cutaneous respiration could limit the stagnant water and minimize the diffusion process. Epidermal capillaries reduce the air to blood diffusion level, which is a specialization for respiration in various amphibious- air breathing fishes. In cutaneous respiration countercurrent exchange takes place, this is when the blood circulates through the organisms skin and would then flow in the opposite direction as it absorbs oxygen or water. An example of this process is our fingernails. Amphibians are vertebrates that live life partially on land and the other part in water. There are many amphibians that are dependent on only water, which means that they have dominant traits from their ancestors. However, most common amphibians now don't even have lungs! Alternatively, they use cutaneous respiration to breathe through their skin. This is usually how all of the carbon dioxide gets out of their bodies. The cutaneous respiration process is in each of the 3 groups of amphibians; Caudata (salamanders etc.), Anura (frogs & toads, etc.) and Caecilians (legless amphibians).