Part BHomeostasisThe importance of homeostasis within the human bodyHomeostasis is the maintenance of a constant internal environment within an organism or cell to maintain equilibrium, usually using a system of feedback controls to stabilise health and proper functioning. Homeostasis can control steady water levels, blood sugar level and temperature which are vital in survival as they can be changed depending on the external environment, whether being in a cold or hot climate, the body will adapt internally in order to keep itself functioning. The human body has receptors to detect stimuli, processing centers which receive information, a coordinator which receives and controls the information from the receptor and triggers the response that will correct the change and an effector that carries out the action that will bring about the change.For example, the body’s temperature must remain at 37 degrees Celsius as this is the temperature at which enzymes can function optimally. There are temperature receptors found within the skin which detect change in the external environment and then this information is passed onto the hypothalamus as it is the brain’s processing centre and it also has receptors that can detect change in blood temperature. Whenever the internal or external temperature changes, the hypothalamus will trigger a change in the body’s effector (in this case sweat glands and muscles) to maintain the correct temperature. If it discovers that the body is too hot, glands within the skin will secrete sweat onto its surface to increase heat loss by evaporation. If the body is too cold, muscles in the skin contract, causing the hair on the arms to stand up straight which in turn traps a layer of warm air next to the skin to prevent heat loss. This happens all over the body in many different ways in order to maintain stability in the body or the body could malfunction.How the endocrine system is involved with homeostasisThe endocrine system has glands that secrete hormones, which are chemical messenger molecules, into the bloodstream to be used in another part of the body. The endocrine has an important role within homeostasis because it is the hormone’s job to regulate the activity of body cells which can be changed to achieve homeostasis. Release of hormones is controlled by a stimulus which either increases or decreases the number of hormones secreted, depending on what is needed for a specific situation. The endocrine system is involved with certain homeostatic regulations such as osmoregulation, where antidiuretic hormones (ADH) are released from the pituitary glands in the kidneys. ADH balances the concentration of urine by absorbing water, so too much water in the blood will increase ADH release, while too little water will decrease ADH release. The endocrine system is also involved in thermoregulation as the hypothalamus can detect change in blood temperature.Examples of homeostasis within the bodyGlucose level within the bloodstream must be maintained in homeostasis, so when this level changes, the body will react to correct it. When there is an increase in glucose levels in the blood, for example, eating glucose rich food such as fruit and vegetable, the increase of the glucose level in the blood will be detected by the beta cells found in the pancreas. The pancreas then releases insulin into the bloodstream which helps the liver to take up the glucose and break it down into glycogen to be stored. Insulin increases the rate of respiration within the body cells, therefore increasing the glucose uptake which helps in the regulation of the glucose level in the blood. This is a negative feedback loop because the change detected was an increase and this had to be reduced. When there is a decrease in glucose level in the blood, for example, not eating for an entire day, the alpha cells in the pancreas will detect this change and glucagon will be released. The glucagon will facilitate the break down of glycogen stored to glucose within the liver and released into the bloodstream, therefore increasing the glucose level in the blood.Hyperglycemia is when the glucose level is above the normal range (980mg – 100mg / 100ml), this can be a result of type 1 diabetes where the body cannot make insulin, or type 2 diabetes where the body cannot respond to insulin properly, so the glucose builds up in the blood. This can result in damaging the vessels that supply blood to vital organs, increasing risk of heart disease/stroke, kidney disease, vision problems and nerve problems for diabetic people. Hypoglycemia is the opposite, where the level of glucose in the blood is lower than the normal range which can be a result of not eating, or not taking diabetic medicine and can result in confusion, seizures or death.The blood oxygen level is also maintained through homeostasis, as the kidneys constantly measure how much oxygen is in the blood, if they discover that there is a decreased red blood cell count, then there is a low blood oxygen carrying affinity, leading to decreased haemoglobin, meaning that there is a decreased availability of oxygen. Erythropoietin (EPO, a hormone produced by a specialised cell in the kidney) is secreted by the kidneys which will then stimulate red bone marrow. Red blood cells are then produced by the red bone marrow as it is the effector which will in turn increase the red blood cell count, meaning the oxygen level is increased, maintaining homeostasis. Carbon dioxide is a waste product of respiration, in order to leave the body, it travels in the blood stream from the cells to the lungs where it leaves the body during exhaling. Carbon dioxide forms an acidic solution when it dissolves in water, so the carbon dioxide levels must be controlled to prevent the blood from becoming too acidic or too alkaline. If carbon dioxide levels get too high, the pH of the blood can be affected, resulting in blood proteins and enzymes being affected too which can result in blood clotting. During a feedback loop, the CO2 level increases, decreasing the pH and oxygen levels in the blooddecrease as well as cerebrospinal fluid. The reflex response has the chemoreceptors being stimulated,resulting in the respiratory response where the medulla oblongata (Lowest part of the brainstems thatcontrols the heart and lungs) is stimulated, increasing the respiratory rate, therefore restoring homeostasiswith the CO2 level decreasing, pH increasing, oxygen levels in the blood and CSF increasing. How each key organ system works together and contributes to overall functioning of the human body Digestive System Endocrine System Excretory System Nervous SystemCardiovascular System Transports nutrients gathered from digestion from all around the body Uses the blood streams to transport hormones around the body to where they are required Filtration in the kidneys to remove wastes and helps removing carbon dioxide The autonomic system regulates heart rate and blood pressureDigestive System Insulin is produced in the pancreas to regulate glucose levels in the blood Kidneys and liver activate vitamin D and water from the digestive system can be excreted from the kidneys Autonomic system controls the size and tone of the digestive tractEndocrine System Hormones can be released to produce more or less urine and the adrenal gland is located on the kidneys Reproductive hormones affect the development of the nervous systemExcretory System The brain signals the excretory system when to release waste Compare and contrast how the endocrine system and nervous system help control our body functionsThe endocrine and nervous systems have both similarities and differences, the largest difference is that thenervous system uses chemical impulses through a continuous network of neurons to relay messages inboth chemical and electrical forms and are much quicker but shorter lasting. The endocrine system uses chemical messengers called hormones which are transported through the cardiovascular system using theblood stream towards their target cells and while this signal transmission is slow, the functions are longer lasting. There are countless different types of hormones in the endocrine system, whereas in the nervous system, there are only three different types of neurons: sensory neurons which carry information from the sensory receptors, motor neurons, which transmit information from the brain to the muscles of the body and interneurons which communicate between different neurons within the body.Both systems regulate bodily functions, however the nervous system mainly transmits informationregarding external stimuli, meanwhile the endocrine system transmits information affecting the interior and well being of the interior of the body. They are both connected via the pituitary glands which is connected tothe hypothalamus which allows the nervous system to send and receive information from the endocrinesystem, which in turn, regulates reactions going on around the body. The nervous system can detect changes in the environment which can activate a response from the endocrine system in order to carry outa change.