Concepts Of Lifetime Fitness :: essays research papers

Concepts of Lifetime FitnessHomeostasis is the state of equilibrium in which the internal environment of thehuman form remains relatively constant. Two excellent examples of homeostasis be how the body maintains a constant temperature and blood pressure duringstrenuous physical activity or exercise. Although there are many otheractivities in the body that display homeostasis, I will only discuss these two. Temperature in the human body is usually kept at approximately 37 degreesCelsius. To maintain such a strict temperature, the body has a few functions tocombat the outside elements. People can non make themselves cold as readily asmake themselves hot, save I will mention both homeostasis functions. Whenthe external temperature decreases, a portion of the brain called thehypothalamus detects the drop by means of the blood. To compensate, the brainsends chemical and electrical impulses to the muscles. These impulses specialise themuscles to begin to contract and relax at very hig h intervals. This is commonlyknow as shivering. The production of Adenosine Triphosphate or ATP in themitochondria of the muscles produces heat. If the body temperature does notrise immediately after this, then a second function begins. The brain willsignal the blood vessels near the skin to constrict or narrow in diameter. Thisoccurs so the heat deep in the muscles is conserved. Since the vessels are nowsmaller in diameter, slight blood is involve to fill them. Since less blood isneeded through the vessels, the heart begins to slow. If the body remains inthis slowed state, hypothermia could result. Hypothermia is the condition inwhich metabolic processes are inhibited. The medical world has taken favourof this by inducing hypothermia in patients that are undergoing organtransplants.To fight temperatures higher than normal, as in exercise or on hot days, thebody reacts in the opposite way than with cold. Again, the hypothalamus detectsthe change of temperature in the blood. The b rain signals blood vessels not toconstrict, but to dilate. This increases the diameter of the vessels, andresults in the need for more blood. Since more blood is needed to fill thevessels, the heart pumps faster and that causes respiration to increase. Theincreased respiration will make the body exhale some of the internal heat, likeplacing a winnow in a window to cool a room. The blood vessels are dilated so theheat deep in the muscles is easily released. Another commonly known mechanismto fight heat is sweating. Sweat glands found throughout the body arestimulated by the hypothalamus to excrete sweat and when the sweat evaporates,