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Available at: http://www.slideshare.net/Urendersingh/regulation-of-blood-glucose Accessed 19 Jan. 2017.References:In conclusion, the human body is a complex and sophisticated machine.There is a lot of process continually and successfully going on inside ourbodies without our knowledge. Individual systems achieve a great deal inmaintain homeostasis but achieve better outcomes working in synergy.
Each cell, organ and system are always atwork with other systems to accomplish a stable environment. One can appreciatethat homeostasis is one of the most important mechanisms that are keeping usalive. Despite, the endocrine and nervous system working together to achieve a homeostaticenvironment, they diverge in terms of how they function. The nervous systemuses neurotransmitters to signal while the endocrine system uses hormones releaseby glands to do so. Other differences is the response rate of each system.
Forinstance, the nervous systems has a faster response rate when compared to theendocrine system. This is due to the nervous system having neurotransmitterswhich only travel across small synaptic distances. However, in the endocrinesystem, the hormones travel over longer distance in the bloodstream beforereaching the target organ. Furthermore, the hormones from the endocrinerequire targeting and binding to the respective receptor.
Although, the endocrine system sustains longerresponse than the nervous system due to the secreted hormone continuing tocirculate in the bloodstream and has a variable time of inactivation followingits metabolisation. For example, specific hormones can last forfew minutes while others can last up to a whole week. The nervousand endocrine systems are organ systems that work in synergy to maintainhomeostasis. These systems regulatebodily functions and relay information. Both are key systems in carrying outautonomic process of the body.
The nervous system mediates informationregarding external stimuli, while the endocrine system releases hormone inresponse to the external stimuli. The hypothalamus is the connection betweenthe nervous and endocrine system. Accordingly, the nervous system can send and receive information from the endocrine. The endocrine system then regulates activitiesthroughout the body. Regularly, externalstimulus received by the nervous system have effect on the endocrine systemwhich induces a hormone response which targets specific organs.
The endocrinesystem is a collection of glands that secrete hormones that target distantorgans. The endocrine system is recognized to have a key role in maintain bodyhomeostasis by using chemical signals (hormones). The hormones are released by the cell intothe blood stream and travel throughout the body. These hormones directlyinfluence organs to function or they influence those organs to produce otherhormones that target secondary organs. The endocrine system helps to controlgrowth and development, maintain the body’s homeostasis, metabolism (bodyenergy levels) reproduction, response to stimuli (stress and /or injury). In situations such as starvation or all the absorbed nutrients beingused by the cells, the glucose levels in the blood decrease. To elevate theblood glucose levels to normal, insulin is inhibited which prompt the alphacells in the pancreas to release glucagon. Glycogen initiates a cascade ofreaction to produce more glucose.
Forinstance, the glycogen store in liver cells are broken down to glucosemolecules, the adipose tissue is broken down to glycerol and fatty acids. Thisis followed by stimulation of liver cells to synthesize glucose from glycerolabsorbed from the blood. The liver produced glucose is then returned to the bloodand glucose levels are increased to optimal setpoints. Theblood glucose level rises after we consume food which is digested and the nutrients areabsorbed. The beta cells of pancreas respond to the rise in glucose level andsecrete a Insulin promoted the cells toincrease 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.