September 1, 1997Homeostasis is the state of equilibrium in which the internal environment of thehuman body remains relatively constant. Two excellent examples of homeostasisare 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 cannot make themselves cold as readily asmake themselves hot, however 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 tell themuscles to begin to contract and relax at very high intervals.Order now
This is commonlyknown 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, less blood is needed 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 advantageof 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 brain 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 fan 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,the skin is cooled.
If the body is not cooled by the time all of the internalwater supply is used, it could go into hypothermia. This is when the bodybecomes dehydrated and proteins begin to denature. Hypothermia can result incertain death if the water supply is not immediately replenished. Someadvantages to these mechanisms are the cleansing effect of sweating and weightloss.
Sweat, when excreted, removes waste materials such as bacteria and water. Fat material, during exercise, is actually “eaten” by the body thus reducingoverall weight. The second example of homeostasis is blood pressure regulation. When thehydrostatic pressure of blood is above normal, pressure sensors in the bloodvessels tell the brain through chemical means. The brain will then stimulatethe heart to contract or beat in slower intervals.
This will cause less bloodto enter the blood vessels and that will lower the hydrostatic pressure. If thepressure is lower than normal, the exact opposite happens. The sensors in thevessels tell the brain and the brain will then make the heart beat faster somore blood enters the vessels and the pressure is raised. The body uses many mechanisms to regulate temperature and blood pressure.
Be itstimuli to the heart from the brain or messages from the blood, the bodymaintains its internal environment through a process called homeostasis.Category: Miscellaneous .