Endotherms are described as organisms that are able to maintain a stable internal temperature, irrespective of the outside influence. This ability to control inner temperature is considered an important biological advancement in the evolutionary development because it allowed animal life to develop in environments with temperatures significantly different from those of the body. (9) It is the major feature of mammal and bird life that distinguishes them from reptiles and other vertebrates. Endothermy provides distinct psychological and ecological advantages, which allows for successful survival of mammals in wide range of aerial, aquatic and terrestrial environments. It allows them to maintain level of activity, which is beyond the capacity of endotherms. (6)
Mammals maintain a constant body temperature mostly by two ways. First, minimizing thermal conductance with fur, or storing large amounts of subcutaneous fat; Second, by maintaining a metabolic heat production which is equivalent to the rate at which body is losing heat to the environment. They tend to increase the amount of oxygen consumption significantly in cold temperatures to compensate for accelerated heat loss. Mammals also shiver in response to exposure to cold environments. However, there are placental mammals as well who rely on non-shivering thermogenesis for increased rate of metabolic heat production during long-term cold exposure. Brown adipose tissue is a specialized thermogenic tissue associated with hibernating and cold adapted mammals. (4)
It has been observed that the mechanisms used by homeothermic species to produce heat and maintain body temperatures are not new. They antecede homeothermy, which is supported by presence of similar mechanisms in lowe...
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...ansition. (7)
It is possible that one or multiple of the theories providing explanations to the evolution of complex characteristic of endothermy could be correct, however there is not enough fossil record to recover small changes associated with the evolution of fully expressed mammalian homeothermy. The correlated progression hypothesis supports that evidence from living amniotes or from fossils cannot be enough to reveal the sequence of mammalian endothermy because the ectotherms show few relevant signs of early endothermy, and mammals evolved from ancestors who had fully evolved endothermic mechanisms. There are several individual structures, processes and definable functions of endothermy, which evolved in a correlated progression. Endothermy cannot be separated as a single function from its integration with rest of the biological features of an organism. (7)
The various modes of heat loss during this phase include radiation, convection, conduction and evaporation. Radiation contributes to maximum heat loss (approximately 40%) and is determined by the fourth power of difference between ambient and core temperature. Convection is the next most important mode of heat loss (upto 30%), and is due to loss of heat to air immediately surrounding the body. It is proportional to the square root of the velocity of the air currents. Evaporation contributes to less than 10% of heat loss and occurs from cleaning fluids as well as skin, respiratory, bowel and wound surfaces. Conduction accounts for least heat loss (upto 5%) and is due to cold surfaces in contact with the body such as operating room table. After 3-4 hours, a plateau phase is realized when core heat production equals heat loss to the periphery and core temperature reaches a
Levis, N. A., Yi, S. X., & Lee, R. E. (2012). Mild desiccation rapidly increases freeze tolerance of the goldenrod gall fly, eurosta solidaginis: evidence for drought-induced rapid cold-hardening. Manuscript submitted for publication, Available from Journal of Experimental Biology. (215, 3768-3773)Retrieved from http://jeb.biologists.org/content/215/21/3768.full
Williams, C. T., Goropashnaya, A. V., Buck, C. L., Fedorov, V. B., Kohl, F., Lee, T. N., and Barnes, B. M. (2011). Hibernating above the permafrost: effects of ambient temperature and season on expression of metabolic genes in liver and brown adipose tissue of arctic ground squirrels. J Experi Biol. 214, 1300-1306.
While the respiratory and cardiovascular systems are most reliant on one another, all body systems require a functioning circulatory cycle in order to thrive. Blood circulation and consistent transfer of oxygen to cells is required to maintain cell and tissue life. Disturbances to this process will cause cells and tissues to die (Red Cross 48). This state of balance and functioning body systems is referred to as homeostasis, defined as a “condition of equilibrium in the body’s internal environment due to constant interaction of body’s many regulatory processes” (Tortura 8). Changes or disruptions to homeostasis are regulated by the Endocrine and Nervous systems of the body. The endocrine system is made up of glands placed throughout the body
Metabolic rate is directly linked to the core temperature in an animal. An ectotherm, or cold blooded animal, warms its body mainly by absorbing heat from its surroundings. The amount of heat it derives from its metabolism is negligible. In contrast, endotherms derive most or all of its body heat from its own metabolism (Campbells,p899). Because ectotherms do not produce their own heat, they cannot actively ensure their ideal temperature for an ideal metabolic rate (aquacult.htp).
VanPutte, C., Regan, J., & Russo, A. (2014). Seeley's anatomy & physiology(10th ed.). NEW YORK, NY: MCGRAW-HILL.
Simon, E. J., Reece, J. B., Dickey, J. L. (02/2012). Campbell Essential Biology with Physiology, 4th Edition [VitalSource Bookshelf version 6.2]. Retrieved from http://online.vitalsource.com/books/9781256902089
Endocrinology can be defined as the study of the structure and function of the endocrine system (Tortora & Grabowski 1996). The endocrine system is composed cells, known as endocrine cells, which are distributed around the body and produce the chemical messengers known as hormones. Following secretion by endocrine cells, hormones travel in the blood where they affect tissues outside of their tissue of origin - and are therefore a form of cellular communication. In multicellular organisms, such as humans, cellular communication is essential for a number of body processes and the maintenance of homeostasis (Campbell, N.A. et al. 2015). In this essay, I am going to outline some of a number of body
Ross, A. C. (2005). Physiology. In B. Caballero, L. Allen, & A. Prentice (Eds.), Encyclopedia of
The debate of whether dinosaurs were cold blooded or warm blooded has been ongoing since the beginning of the century. At the turn of the century scientists believed that dinosaurs had long limbs and were fairly slim, supporting the idea of a cold blooded reptile. Recently, however, the bone structure, number or predators to prey, and limb position have suggested a warm blooded species. In addition, the recent discovery of a fossilized dinosaur heart has supported the idea that dinosaurs were a warm blooded species. In this essay, I am going to give supporting evidence of dinosaurs being both warm and cold blooded. I will provide background information on the dinosaur that was discovered and what information it provides scientists.
The circadian rhythm is a predictable pattern that a species follows during a twenty-four-hour cycle. Circadian rhythms of species are associated with the external cues, which can be factors like sunlight, moisture, and temperature. When mammals are presented with an environment that does not have many external cues, the expectations are that there would be a weak or no evidence of a circadian rhythm. Contrary to this expectation, subterranean rodents have shown evidence of circadian rhythm, even though the environment they live in has few external cues. Prior scientific research done by other scientists indicated that the rodents acted in a predictable manner due to heat regulation against the hot and cold. In this study, the authors looked at the Ansell’s mole-rat (Fukomys anselli) to better understand whether social or environmental cues were more important in the creation of the circadian rhythm. Through this experiment, the authors attempted to answer five questions: is there a noticeable circadian rhythm that Fukomys anselli follows, is the circadian rhythm emerging due to the temperature of the environment, is the circadian rhythm emerging due to social effects, are Fukomys
There are two categories of organisms: poikilotherms and homeotherms. Poikilotherms’ internal temperature varies constantly because they are reliant on the external environment, while homeotherms’ internal temperature is maintained relatively constant regardless of the external environment (Pfleugal, 2014). Because fish are poikilotherms, it is easy for researchers to observe changes in their metabolism due to changes in the external environment. One aspect in the external environment of fish that can be manipulated is the amount of caffeine in the water. This experiment will examine changes in oxygen concentration inside a chamber as a method of comparing goldfishes’ respiration and metabolic rates in two different fish water environments: regular (control) and caffeinated. Because caffeine stimulates the respiratory center resulting in an increase in the oxygen consumption, it is predicted that goldfish will have a higher oxygen consumption and metabolic rate when exposed to caffeine (Brinley, 2014). Thus, our hypothesis states there will be a statistically significant change in oxygen consumption between the two environments, and our null hypothesis states tha...
They had similar features to today’s apes, such as a hairy body. The purpose of the vast amount of hair is to protect the body from the sun’s ultraviolet (UV) rays and to prevent overheating, mainly by acting as a barrier for the skin underneath the hair (Jablonski, 598). Some parts of the body, such as palms, were not covered with hair, but with sweat glands. Sweat glands allowed the body to cool off via evaporation at the surface of the skin; sweat glands were more efficient at thermoregulation. Over time, early humans with a high amount of sweat glands were selected since they had the best method at the time to keep themselves cool in warm environments (Kirchweger).
5. The genetic resemblance of mitochondria and chloroplasts to certain bacteria supports the endosymbiosis theory. The DNA within mitochondria and chloroplasts is also different than the DNA of the cell.
There are many enzyme-catalyzed reactions that occur in cells through control mechanisms, which keep humans in chemical balance. There are two systems that have a major responsibility for regulating body chemistry known as the endocrine system and nervous system. The endocrine system depends on chemical messengers that flow in the bloodstream known as hormones. Hormones travel to target cells, where they connect with receptors that initiate chemical changes within cells. The nervous system depends on neurotransmitters that are electrical impulses in nerve cells activated by its own chemical messengers. The nervous system counts on a much faster means of circulation. This cycle is what allows drugs to work so well, because they mimic the crucial role of hormones and neurotransmitters in the function of the human body.