The blood glucose level rises after we consumefood which is digested and the nutrientsare absorbed. The beta cells of pancreas respond to the rise in glucose leveland secrete a Insulin promoted the cellsto increase their glucose intake and increase the cellular rate to breakdownglucose to produce ATP. However, In liver and muscle cells, the formation ofglycogen from glucose is increased. Furthermore, insulin stimulates thesynthesis of fats in adipose tissue. All these activities would cause theglucose level to fall back into the normal level. Another negativefeedback mechanism is blood glucose level regulation.
The cells in our bodybreak down glucose as their main source of energy. The break glucose moleculesare broken down by the cells to produce Adenosine Tri-phosphate (ATP) which areenergy-rich molecules used to perform multiple cellular processes. The glucosemolecules are transported to the cells via circulation of blood.
The glucoselevel should thus be maintained at constant levels. The normal range is 70-110milligrams of glucose per deciliter of blood. Disturbance in the blood glucoselevel can lead to life-threatening situations.
Maintaining constant glucoselevel is necessary for the survival of the cells and health of the body. On the contrary, when the temperature of thebody falls below the set point because of low environmental temperature, theheat-promoting centre of hypothalamus is activated which then initiates aseries of events. The skin surface blood vessels are vaso-constricted to reduceheat loss, sweating is inhibited, and hairs of the skin are raised to increaseinsulation. To produce more heat, the skeletal muscles are activated, and thebody tends to shiver and produce heat. Again, once the temperature increases tooptimal temperature, the heat-promoting center of the hypothalamus is shut off.
But if the homeostatic mechanism fails, the positive feedback mechanism woulddecrease the temperature to the point of hypothermia, which is a conditionwhere the body temperature falls below 32ºC.Temperature regulation is an examples ofnegative feedback mechanism. The optimal body core temperature is about 36.8 ºC which is the homeostatic set point. This optimal temperature is closelyregulated due to factors like enzymes works best at certain temperatures. Ifthe temperature raises to 43ºC, itmay be fatal and cause death. Whereas, ifthe temperature falls below 32ºC, theindividual may go into coma and die.
The changes in the temperature aredetected by nerve-endings in the skin and the hypothalamus of the brain. Whenblood temperature raises above the optimal temperature, the heat-loss centre inthe hypothalamus is activated which then initiates an autonomic response. Thisresponse triggers changes to the effectors like the blood vessels whichvasodilate and increase blood flow to the skin so that there is increase inradiation, conduction and convection to lose heat. Subsequently, metabolic rateand muscular activity are decreased to slow down further heat production. Thesweat glands, additional effectors, are activatIn negative feedback loop, has acounteraction effect on its own influence. Therefore, the negative feedbackmechanism can increase or decrease the stimulus. If the level is high, the bodydecreases it and if it is too low, it elevates it and thus it is known asnegative feedback.
Homeostasis always tends to provide optimal internalenvironment in which the body can function best. Another positive feedback mechanism is bloodclotting. When a blood vessel is damaged, platelets arrive to the site andstick to the site of the injury. They release chemical signals that attractmore platelets to the site and accelerate the process of clotting.
Thiscontinues until the clot repairs the damaged vessel.During labor, the oxytocin hormone isreleased by the hypothalamus and released by posterior pituitary. The oxytocinstimulates and intensifies the contraction of the uterus, forcing the head ofthe baby into the cervix. Subsequently, more oxytocin is release when stretchreceptors that are in the cervix are activated. In turn, more oxytocin isreleased causing more contractions and maintaining labor.
This cycle continuesuntil the baby is born. Once the baby is born, the stretch receptors aredeactivated and since the stimulus is not present anymore, the release ofoxytocin is stopped ending the positive feedback mechanism.In positive feedback mechanism, the output isamplified to maintain homeostasis. They are designed to push levels out ofnormal ranges. This is achieved by initiating a series of events, whichoriginates to amplify the effect of the stimulus.
This mechanism can be usefulbut are rarely used due to its ability to become uncontrollable. For instance,child birth and blood clotting are paramount examples of the use of positivefeedback mechanism. ed to release perspiration and evaporate bodyheat.
Hairs on the skin are flattened to reduce insulation. When the bodytemperature falls back to the set point, the heat-loss centre is shut off. Ifby any reason this thermoregulation mechanism fails, the body temperature canexceed 41ºC causing Hyperthermia.
The endocrine system plays a vital role inhomeostasis as it is responsible for releasing hormones that regulate thecellular activities. The release of hormones is affected by the stimulus. Thestimulus may cause an increase or decrease in the amount of hormones released.The response to the stimulus then changes the internal environment when is thenconsidered a new stimulus. This mechanism where the hormones self-adjust isknown as feedback mechanisms. Any feedback regulation takes place when theresponse to a stimulus influence the original stimulus.
According to the typeof effect the response has on the original stimulus, there are two types offeedback mechanisms: positive and negative feedback. Positive feedback is whenthe response increases the initial stimulus; and negative feedback is when theresponse increases and decreases the original stimulus.Regulation of homeostasis itself isaccomplished by control system which have three basic components: detector,control center and effectors. The detector sends input to the control centrewhich assesses it and if any change is required, it changes its output to theeffectors accordingly. The control systems set limits for which the variablehas to be maintained. When the control centre detects changes, it responds toany changes in the internal environment. This dynamic process maintains thehomeostasis. Opdells depend on diffusion and osmosis.
These processes rely on the body’s salt and water concentration, which aremaintained by homeostasis. In addition to that, the cells also rely on variousenzymes that carry out the chemical reactions that cells need to survive andfunction. These enzymes require temperatures to work which are also maintainedby homeostasis. The internal environment needs to be constantfor the proper function of cells and the maintenance of a stable environment isknown as Homeostasis. The concept of “homeostasis” was first coined by ClaudeBernard, a French physiologist in 1865.
In literal sense it means unchanging,but practically, it is a dynamic and Thehuman body is a complex yet single entity that is made up of variousindependently operating systems. various tissues and organs work together toform systems that work interdependently undertaking specific functions. Thesurvival and maintenance of a healthy of a body is greatly affected by the external environment that surrounds usand the internal environment which isthe water based medium or interstitial fluid where the cells exist. Theexternal environment supplies the body with nutrients and oxygen that the cellsneed and the waste products from cellular activities are excreted back into theexternal environment. The transportation of oxygen, carbon dioxide, nutrientsand waste products occurs in the internal environment such as interstitialfluid.