The ANS is part of the peripheral nervous system and is divided into sympathetic pathways, which prepare the body for action, and parasympathetic pathways, which prepare the body for rest. This automatically regulates the functions of the body and certain muscles. Sympathetic pathways alter nervous activity during periods of stress, exercise, hypoglycemia, excitement, or fear, due to the flight or fight response. These changes can affect homeostasis by increasing heart rate, increasing blood flow, dilating pupils, sweating, releasing glycogen, increasing oxygen delivery, and diverting blood flow from the gastrointestinal tract. The parasympathetic pathways are important for digesting and absorbing nutrients, slowing down and allowing for a restorative process. Parasympathetic pathways work opposite to sympathetic pathways. After a stressful situation, they stop the release of adrenaline and allow the body to relax by reducing heart rate, slowing breathing and constricting the pupils. Homeostasis involves the whole body, but certain organs play a more important role in maintaining balance. The liver and pancreas maintain proper blood glucose levels, the kidneys remove metabolic waste, and maintain proper salt and water levels in the blood. The skin and liver help maintain body temperature, with the lungs controlling the levels of oxygen and carbon dioxide in the blood, and the blood itself carrying nutrients and waste throughout the body. For homeostasis to work, the transport, respiratory, gastrointestinal, renal and cardiovascular systems must work together. Homeostasis works primarily through negative feedback, this is where the effector response diminishes the effects of the original stimuli...... middle of paper ...... on dioxide, in the body, affecting the pH balance of the blood. This will then affect proteins in the body, called enzymes, which can only function if their environment is in balance. Any alteration of this environment will prevent the enzymes from functioning effectively. The extra heat produced during metabolic exchange again increases body temperature, affecting enzymes and the heat is then carried away through sweating. If the body is not hydrated during exercise, dehydration will occur, causing the blood to become concentrated. When blood becomes concentrated, cells no longer have enough water to function. If homeostasis is not maintained, it will lead to disease and even death, because without each functional part of the body working together effectively, the body cannot function at a sufficient level. level to maintain survival.