The role of homeostasis is to maintain a constant internal environment within the body despite changes in the external environment. For example, the body is able to keep its core temperature, blood sugar levels, and water balance relatively constant. This ensures the survival and functioning of cells, organs and tissues. If homeostasis were to cease and the human body temperature decreased or increased, vital organs crucial to human survival would be severely damaged. Furthermore, tissue fluid must remain constant if the cells within it are to remain functional and capable. Homeostasis is a complex and delicate process as cells can stop functioning and die due to minimal changes in energy sources, temperature, electrolyte balance, and pH (Saylor, 2012). This makes homeostasis one of the most important physiological functions of the human body, which is often exposed to changes in conditions, temperature and nutritional intake (Saylor, 2012). Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an Original Essay The components responsible for maintaining homeostasis are known as homeostatic control mechanisms. All systems and organs of the body are involved in this and must have adequate control mechanisms when necessary. These mechanisms will respond to the changing needs of restoring and maintaining the ideal internal environment. In order for this self-regulation to continue, the body requires a complex communication system called a feedback control loop (Saylor, 2012), and information is communicated by the neuroendocrine system. These feedback control loops will always have the same fundamental components and function almost identically despite facilitating different information for different functions (Saylor,2012). Control systems are composed of three components: the detector, the control center and the effector. The control center regulates the limits within which the variable factor must be maintained. The detector is what sends the input to the control center, which then integrates the information. If the input signal indicates a necessary adjustment, the control center will respond to alter its output to the effector. This process allows for constant readjustment of a variety of physiological variables. The impact that the effectors can have on the sensors will be negative or positive feedback. This means that homeostatic control mechanisms will be classified into negative or positive feedback systems (Saylor, 2012). Negative feedback systems are necessary to ensure that the body is in a consistent internal environment. An action is triggered that will counteract a change that triggered the system (Saylor, 2012). Positive feedback is not designed to help the body maintain a homeostatic condition. For this reason it can be harmful or even lethal to the functioning of the body. While negative feedback will resist changes in the internal environment, positive feedback will enhance changes. Using the example of home temperature, positive feedback would detect the drop in temperature and react by decreasing the temperature further, creating a cycle in which the temperature constantly drops. If this were to happen, bodily functions would cease to function properly and homeostasis would be disrupted. This means that negative feedback is the more crucial and used of the two homeostatic control mechanisms. However, sometimes positive feedback can be helpful. Examples include the formation of blood clots, which means positive feedback canoccasionally promote survival. There are two ways signals are sent throughout the body. One of these ways is through the nerves in the nervous system. Signals are sent as nerve impulses that travel through nerve cells known as neurons (Long, 2015). These impulses are sent to other neurons or specific target cells at a specific location in the body to which the neuron extends. Most of the signals that the body uses to regulate temperature are sent through the nervous system. The second way is through the circulatory system, where specific molecules called hormones produced by endocrine glands (diagram 1) travel through the circulatory system and transmit signals (Long, 2015). In addition, detectors are thermoreceptors of the skin and hypothalamus. The regulator is the heat loss and generation center of the hypothalamus, and effectors include sweat glands, arterial muscles, hair follicles, and the hormones adrenaline and thyroxine. When the body temperature is too high, temperature detectors signal the hypothalamus to initiate cooling mechanisms. The hypothalamus then sends signals to the circulatory system to vasodilate the arterioles and produce sweat via the sympathetic nervous system. This allows the body to lose heat more quickly. It also prevents the production of adrenaline and thyroxine, reducing basal metabolism and muscle activity. This means that less heat is generated during rest. When the body temperature is too low, thermodetectors signal the hypothalamus to initiate mechanisms that increase its temperature. It then signals the circulatory system to initiate vasoconstriction to retain more body heat (diagram 7). It also signals the adrenal glands to produce adrenaline, which increases basal metabolic rate and therefore the creation of body heat. It will also cause shivering and piloerection where the hairs stand on end to trap a layer of air on the skin keeping it warm and increasing thermogenesis. Negative feedback loops between detectors, control, and effects maintain the body's actions to shift body temperature up or down. proportional to the current variation from normal body temperature at any time. The human body maintains glucose levels via hormone signaling. Glucose is a monosaccharide and the main source of fuel for our body, but it is too large to only diffuse into cells. The pancreas produces insulin, a hormone that facilitates the transport of glucose into cells. By facilitating the transport of glucose into cells through the bloodstream, insulin lowers blood glucose levels and inhibits the production of glucose from amino acids, fatty acids, and glycogen. Insulin also stimulates the formation of glycogen from glucose. All functions of insulin help reduce blood glucose levels. Glucagon is a hormone also produced by the pancreas that increases blood glucose levels by stimulating the breakdown of glycogen into glucose, stimulating the production of glucose from fats and amino acids, and stimulating the release of glucose from the liver (Morris, 2014). This means that insulin and glucagon have antagonistic effects against each other, with glucagon promoting glucose production and release into the bloodstream while insulin promotes the transport of glucose into cells from the bloodstream by inhibiting glucose production (diagram 2). Blood glucose levels are usually measured in milligrams per deciliter with a normal range between 70 and 110 mg/dl (Morris, 2014). If glucose levels go out of this range, the pancreas will adjust the amounts of insulin and glucagon accordingly to bring the levels back up.of glucose in the set range. The pancreas will always produce insulin and glucagon, trying to find a balance between the release of glucose into the blood and the uptake of glucose into the cells, calling this process homeostasis. In blood sugar control, detectors are glucose-sensitive cells in the hypothalamus. The controllers are the islets of Langerhans and the effects are the hormones insulin and glucagon. The pancreas produces glucagon and insulin from the alpha and beta cells of the islets of Langerhans. When sugar is too high, beta cells secrete insulin which opens bonds with special receptors on cell membranes allowing glucose to be actively transported within them. This lowers blood sugar levels and leads to glycogenesis (glycogen production), lipogenesis (fat production), and faster protein synthesis. When blood sugar is too low, alpha cells produce glucagon which causes glycogenolysis. Glycogen is broken down into glucose, in gluconeogenesis, which circulates in the bloodstream and increases blood sugar levels. It also leads to ketogenesis (the breakdown of fats to form ketones) and proteolysis where proteins are broken down into amino acids to produce ATP. Through negative feedback, the secretion of each hormone is adjusted to match the change from normal blood sugar. In water balance the detectors are the osmoreceptors in the hypothalamus, the controller is the hypothalamus and the effectors are the hormones ADH and aldosterone. the human body is regulated by the renal system, composed mainly of the kidneys but which also involves the arteries, veins and urinary tract (scheme 3). The kidneys maintain water balance by controlling blood plasma concentration and salt levels. Inside the kidneys there are tiny filtering structures called nephrons (see diagram 4). These nephrons are the functional units of the kidneys and help remove excess waste, water, and other substances from the blood, while returning substances such as potassium, phosphorus, and sodium when supplies run low in the body (Saylor, -2012).Hormone Antidiuretic (ADH) is a hormone produced by the pituitary gland to control blood volume. The more concentrated it is, the greater the release of ADH, which causes the kidneys to retain more water. In dehydration, osmoreceptors detect a drop in blood volume detected by the hypothalamus. It releases ADH through the pituitary gland where it enters the bloodstream. When it reaches the kidneys, it causes them to retain water, thus reducing the volume of urine (diagram 5). As it increases, the amount of ADH in the blood decreases through negative feedback. When the blood volume is too high, ADH is not released into the blood. Therefore the kidneys do not reabsorb water and dilute urine is produced in abundance, which rapidly lowers blood volume to normal levels. As it lowers, more ADH will be made to prevent low blood volume. Aldosterone is another important hormone released by the adrenal cortex. Before it can be released, renin must be released by the kidneys in response to low renal blood flow. The renin and angiotensin converting enzyme stimulates the adrenal cortex to release aldosterone which regulates water and salt balance. When it is released and reaches the kidneys, it causes them to reabsorb water and sodium, so less is lost in the urine and blood volume increases. As it increases, less will be released into the blood (Diagram 6). Diabetes occurs in people whose blood glucose is not regulated properly and efficiently by their body (Diabetes, 2015). Diabetes can be type 1 or type 2. Both conditions are characterized by the fact that the..