The Circulatory System and Homeostasis The Circulatory System , which contributes to homeostasis by serving as the body's transport system consists of the heart, blood vessels, and blood The walls of the heart are composed primarily of cardiac muscle,  which is self excitable; it initiates its own contractions.  The heart serves as a double pump to continually circulate blood between the lungs  where Oxygen is picked up and Carbon Dioxide is removed, and other body tissues, which use oxygen to support their energy generating chemical reactions, producing carbon dioxide in the process. 

Components of the circulatory system include blood: a connective tissue of liquid plasma and cells heart: a muscular pump to move the blood blood vessels: arteries, capillaries and veins that deliver blood to all tissues

The circulatory system is sometimes referred to as the cardiovascular system or blood vascular system. This system consists of a muscular pump, the heart (cardio), and a network of blood vessels - arteries, veins and capillaries (vascular). The transport medium in this system is blood which is pumped throughout an organism through a closed circuit of blood vessels. This closed system keeps blood contained as it passes through various “circulations” of the body.

The capillaries, which are tiny blood vessels connecting arteries and veins, are in contact with extra cellular fluid surrounding each individual cell. In these microscopic vessels, blood performs its ultimate homeostatic function. Nutrients and other essential materials pass from capillary blood into fluids surrounding the cells as waste products are removed. Therefore, homeostasis within extra cellular fluid and the cells is facilitated

Numerous control mechanisms ensure a constant internal environment surrounding each body cell regardless of differing demands for nutrients or production of waste products. All sorts of factors affect the suitability of our body fluids to sustain life; these include properties like temperature, salinity, acidity (carbon dioxide), and the concentrations of nutrients and wastes (urea, glucose, various ion, oxygen). Physiological mechanisms, in conjunction with the circulatory system, ensure that the above properties are maintained at ideal levels. These physiological mechanisms are controlled by various organs in the body.

Thermal Regulation The skeletal muscles can shiver to produce heat if the body temperature is too low. Non-shivering, thermogenesis, involves the decomposition of fat to produce heat. Sweating cools the body by taking advantage of the cooling effect of evaporation.

Temperature Regulation in Homeotherms Animals capable of temperature regulation within a given range are deemed homeotherms (alternatively homiotherms or homotherms). They have the ability to regulate temperature via negative feedback control which is outlined below Temperature fluctuations in the body are recognized by thermoreceptors in the hypothalamus. Other thermoreceptors which detect temperature fluctuations in the external environment are present in the skin. When a temperature change is detected the information is relayed from the skin to the hypothalamus which in turn transmits messages causing corrective mechanisms to return body temperatures to a stable state.

Corrective Mechanisms in Temperature Control Increased perspiration is a corrective mechanism which can reduce elevated body temperatures through the cooling action of evaporation. Vasodilation is a corrective response where the blood vessels close to the skin surface become more dilated in response to increased core body temperatures. The larger surface area of dilated vessels allows more heat to escape from overheated blood to the external environment. Vasoconstriction is the opposite of this and occurs when temperatures in an organism drop. The blood vessels become constricted so that minimal heat loss occurs.

The hairs on your body also play an important role in temperature regulation. A corrective response to decreased temperatures can occur where the hairs 'stand on end', and trap a layer of air between the hair and the skin. This insulation of warmer air next to the skin reduces heat loss. Hair flattened to the skin in response to increased temperatures means there is a minimal layer of insulation, which would increase heat loss. Other corrective mechanisms are involved, such as a drop in metabolic rate and shivering when temperatures drop.