Deconstructing Mammalian Thermoregulation

Question: Discuss about the Deconstructing Mammalian Thermoregulation. Answer: Introduction: Homeostatic regulation of decreased body temperature is a vital aspect in maintaining a normal body temperature. Endothermic animals such as mammals are capable of maintaining a fairly constant body temperature of 37.5? C. The thermoregulatory centre located in the hypothalamus is responsible for controlling the body temperature. Two sets of thermoreceptors sends the impulse to the hypothalamus, core temperature is regulated by the receptors in the hypothalamus itself while the receptors in the skin monitor the temperature changes relevant to the external environment. Thus these both sets of information are essential to make appropriate adjustments (Liedtke, 2017). Adjustments in the body temperature are maintained by means of relaying of impulses by the hypothalamus to the various effectors. The responses to lowered body temperature cause the stimulation of the thermoregulatory centre that in turn is under the control of the autonomic nervous system and therefore involuntary respons es take place. In situations of extreme cold or decreased body temperature, hypothalamus triggers the response pertaining to the conservation of heat through stimulation of the heat conservation centre. However some of the responses pertinent to the low temperature leads to actual production of heat inside the body by a mechanism termed as thermogenesis whilst other responses include the conservation of heat. Hence depending upon the internal as well as external body temperature, a wide range of bodily responses occurs that render suitable adjustments in the body. The responses are all evident at the effectors. As response to low temperature the smooth muscles located in arteriole in the skin undergo vasoconstriction through contraction of the muscles. Due to this vasoconstriction less heat is transferred from the core to the bodily surface thereby maintaining the core temperature (Romanovsky, 2014). Chances of the extremities turning blue coupled with the feelings of cold and damag e due to frostbite might take place at this point. No sweat production occurs in response to decreased body temperature as the sweat gland effectors remain non-functional. Further changes occur as the erector pili muscles of the skin contract raising the hairs in the skin thereby trapping an insulating layer of warm, still air right by the side of the skin. In humans, this mechanism is not very prominent and leads to the formation of goose bumps. Repeated contraction and relaxation of the skeletal muscles causes shivering in response to lowered temperature whereby heat generation occurs as a result of friction and other metabolic reactions. The endocrine glands like adrenal and thyroid glands become active causing secretion of adrenaline and thyroxine respectively that in turn accentuates the metabolic rate in various tissues in the body particularly like that of liver thereby generating heat (Houdas Ring, 2013). Therefore the homeostatic regulation of decreased body temperature in volves the interactions and interplay of various bodily organs with the hypothalamus as the chief regulator. Normal carbohydrate digestion results in glucose being absorbed into the blood and elevating blood glucose levels. Cells need to glucose to allow the body to utilize the carbohydrate in this form thereby aiding in the functioning of several metabolic reactions along with the physiological mechanisms. Glucose is responsible for storing of energy in the form of adenosine tri phosphate (ATP) that takes part in majority of the cellular processes. By virtue of cellular respiration glucose may also be broken down into ATP that in turn is again capable of being readily taken up by the cells in order to carry out various functions. Moreover glucose is considered as the chief metabolic fuel for the brain tissue particularly as the number of ATP molecules produced as a result of per oxygen consumption when glucose is completely oxidized to CO2 is quite high. Furthermore, glucose is the only molecule that is capable of supplying ATP even in absence of oxygen through the anaerobic glycolysis pat hway (Brosnan, 1999). The homeostatic feedback system is responsible for regulating the elevated blood glucose levels that gets activated in response to such metabolic alterations in the body. Elevated blood glucose level is detected by the pancreas that leads to the secretion of insulin from the ? cells in response. Insulin allows for the body cells to take up more glucose while the bulk portion is taken up by the liver thereby converting and storing them into glycogen. Ultimately this leads to the lowering of the blood glucose and the pancreas receives the signal for inhibiting the secretion of insulin (Ariyachet et al., 2016). Insulin is characterized of having the blood sugar lowering effect and is therefore considered as a hypoglycemic factor and its hypoglycemic action is achieved in the following manner. Insulin increases the permeability of different tissues to glucose so as to facilitate transport of glucose from blood to tissues. It helps in utilization of glucose in the c ells by stimulating glycogenesis (formation of glycogen from glucose), lipogenesis (conversion of glucose to fat) and oxidation of glucose for yielding energy. Insulin also inhibits formation of glucose through glycogenolysis and neoglucogenesis in liver and its entry into the blood (Brereton et al., 2014). Thus the glucose regulation is carried out by the pancreas along with the glucose receptor cells that are responsible for maintaining the blood glucose concentration in conjunction with the endocrine tissues of the Islets of Langerhans that maintain the glucose levels by virtue of secreting the hormones. Vitamins and minerals are important for body system health. Calcium and vitamin D are essential in the maintenance of bone health. Sources of calcium include milk, cheese, curd, hard water, lime, dark green leaves, carrot, cabbage and others. Besides this, the sources of Vitamin D include fatty fishes and their liver oils, dairy products such as chicken, egg, milk, butter and others. Furthermore Vitamin D is synthesized by the body and produced in the skin by exposure to sunlight. Calcium is an important constituent of bones and teeth and is responsible for imparting hardness, strength and concrete like module to them. They occur in the matrices of bone, dental enamel, dentin and cementum mainly as rod or platelet shaped crystals of calcium hydroxyapatites and carbon apatites. Vitamin D promotes the mineralization and remodeling of bones by coordinating the actions of osteoblasts and osteoclasts in several ways. It enhances the retention and deposition of calcium in bones by inducing the synthesis of calcium binding proteins. It further stimulates the differentiation of osteoclasts and induces calcium carrier proteins in them enhancing bone resorption (Bouillon Suda, 2014). If there was a lack of either calcium or Vitamin d in the body, the bone health would suffer major consequences. Deficiency of Vitamin D would cause rickets in which malformation of bones take place in case of children and young, while osteomalacia would occur in adult where fragility of bones is common. Deficiency of calcium would have culminated in similar outcomes where tetany and dental decay would have been a common consequence characterized by neuromuscular hyperexcitability, muscle spasm, paresthesia (Zidenberg-Cherr, 2016). Thus calcium ions and Vitamin D play crucial roles in bone health. References Ariyachet, C., Tovaglieri, A., Xiang, G., Lu, J., Shah, M. S., Richmond, C. A., Shivdasani, R. A. (2016). Reprogrammed stomach tissue as a renewable source of functional cells for blood glucose regulation. Cell stem cell, 18(3), 410-421. Bouillon, R., Suda, T. (2014). Vitamin D: calcium and bone homeostasis during evolution. BoneKEy reports, 3. Brereton, M. F., Iberl, M., Shimomura, K., Zhang, Q., Adriaenssens, A. E., Proks, P., Gribble, F. M. (2014). Reversible changes in pancreatic islet structure and function produced by elevated blood glucose. Nature communications, 5, 4639. Brosnan, J. T. (1999). Comments on metabolic needs for glucose and thea role of gluconeogenesis. European journal of clinical nutrition, 53, S107-S111. Houdas, Y., Ring, E. F. J. (2013). Human body temperature: its measurement and regulation. Springer Science Business Media. Liedtke, W. B. (2017). Deconstructing mammalian thermoregulation. Proceedings of the National Academy of Sciences, 201620579. Romanovsky, A. A. (2014). Skin temperature: its role in thermoregulation. Acta Physiologica, 210(3), 498-507. Zidenberg-Cherr, S. (2016). Nutrition and Health Info Sheet: Calcium.