Simple squamous epithelium is a single layer of flat cells that is found in areas where passive transfer takes place. This includes the blood vessels (capillaries), the alveoli, and the glomerulus. The capillaries and alveoli are specialized for diffusion and osmosis, while the glomerulus is specialized for filtration.

Absorption is typically associated with simple columnar epithelium (found in the small intestine) and simple cuboidal epithelium (found in the nephrons).

The stratum corneum encompasses the very top two layers of cells in the epidermis. It consists almost entirely of dead, keratinzed skin cells that have been pushed to the outermost layer. The stratum corneum forms a protective, waterproof barrier against the outside environment.

Stratified squamous epithelium is primarily associated with protection of the body, and is found in areas that commonly encounter stress. These areas include the skin, the tongue, and the esophagus. The small intestine is associated with absorption, and is lined with simple columnar epithelium.

All of these mechanisms are used to either increase or decrease body temperature, allowing for proper temperature regulation. When your body becomes cold, shivering (the result of involuntary muscle contractions) helps increase body temperature. Constriction of blood vessels diverts warm blood to the most critical organs and away from extremities. In hot temperatures, blood vessels dilate to allow more blood to the surface of the skin where heat exchange can occur. Sweating allows excess heat to be released through the evaporation of water. Without all of these mechanisms, humans would have difficulty surviving in all the environments we currently inhabit around the world.

Endothelial cells are specialized to prevent clotting in their intact form. When disrupted, the endothelium retracts to expose the basement membrane. Proteins in this region will activate the clotting cascade.

Arterioles are the main type of vessel that regulates vessel size and pressure, and exchange over endothlieum can occur with or without fenestrations.

The skin is part of the integumentary system, and is also partly responsible for thermoregulation.

In warm climates, the skin helps lower body temperature by sweating and promoting vasodilation. It is able to open up pores to secrete sodium, which is followed by chloride and water. When water evaporates on the skin, it lowers the temperature of the skin because the water requires an input of thermal energy to transition to the gaseous state. Vasodilation in hot climates allows blood to exchange heat with the environment by flowing close to the skin.

In cold climates, the skin helps raise body temperature by promoting vasoconstriction and goose bumps (cutis anserina). Vasoconstriction helps prevent heat loss to the environment by reducing blood flow to regions of high surface area. Goose bumps raise the hairs in the skin to prevent convection from transferring heat away from the skin.

Thermoregulation is a homeostatic mechanism for regulating body temperature in varying conditions. This is accomplished by physiological, structural, and behavioral mechanisms. For example, many mammals will shiver as a result of small muscle contractions to generate heat. Many of the other possible answers sound similar, but are incorrect. Thermoregulation is a type of environmental adaptation, but "adaptation" is too broad of an answer in this case.

The stomach produces bicarbonate along the mucosal layer to neutralize the high acidity of the stomach. Without proper neutralization of the acid along the mucosal layer, the acid can directly destroy the barrier. When the acid destroys the mucosal layer, gastric ulcers may occur.

This question is asking for a thermoregulatory mechanism that is NOT active in response to an increase in temperature. Preference for a cooler environment would be an apt response to increased temperature. Activation of sweat gland excretion would secrete liquid onto the skin's surface—the evaporation of this liquid carries heat away from the skin. Dilation of arteriole sphincters would increase overall blood flow, which carries heat, to the skin; this heat can dissipate to the environment. Decrease in skeletal muscle activity would lead to less metabolic activity and subsequent heat production.

The pilorection of hairs on the skin surface would not be an appropriate response to a temperature increase. This is because when erect, hairs would reduce the flow of air over the skin and retain body heat. Goosebumps are formed in pilorection, and this is typically seen in a response to cold temperatures.

The arrector pili muscles are responsible for raising the hair shafts, producing "goose bumps" around the follicle. Arrector pili muscles are mostly vestigial, used for thermoregulation in mammals with more fur. In humans, the hair raise function is associated with fear and sexual arousal.