Basic Control Mechanisms of Thermoregulatory Process in Livestock Essay Example for Free

Basic Control Mechanisms of Thermoregulatory Process in Livestock Essay Introduction Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different (Wikipedia, 2012). Thermoregulation could also be referred to as the mechanisms and control systems used by the body to balance thermal inputs and thermal losses so as to maintain its core temperature nearly constant (Monique, 2002). This process is one aspect of homeostasis: a dynamic state of stability between an animals internal environment and its external environment (the study of such processes in zoology has been called ecophysiology or physiological ecology) (Wikipedia, 2012). If the body is unable to maintain a normal temperature and it increases significantly above normal, a condition known as hyperthermia occurs and any prolonged exposure (longer than a few hours) at this temperature without control mechanisms to bring it back to normal is tantamount to death of the animal. The opposite condition, when body temperature decreases below normal levels, is known as hypothermia. Most body heat is generated in the deep organs, especially the liver, brain, and heart, and in contraction of skeletal muscles (Guyton and Hall, 2006). Animals and humans have been able to adapt to a great diversity of climates, including hot humid and hot arid. High temperatures pose serious stresses for the animal body, placing it in great danger of injury or even death. For animals, adaptation to varying climatic conditions includes both physiological mechanisms as a byproduct of evolution, and the conscious development of cultural adaptations (Harrison et al., 1988; Weiss and Mann, 1985). There are four avenues of heat loss: convection, conduction, radiation, and evaporation (Wikipedia, 2012). If skin temperature is greater than that of the surroundings, the body can lose heat by radiation and conduction. But if the temperature of the surroundings is greater than that of the skin, the body actually gains heat by radiation and conduction. In such conditions, the only means by which the body can rid itself of heat is by evaporation. So when the surrounding temperature is higher than the skin temperature, anything that prevents adequate evaporation will cause the internal body temperature to rise (Guyton, 2006). During sports activities, evaporation becomes the main avenue of heat loss (Wilmore et al., 1999). Humidity affects thermoregulation by limiting sweat evaporation and thus heat loss (Guyton and Arthur, 1976). The skin assists in homeostasis (keeping different aspects of the body constant e.g. temperature). It does this by reacting differently to hot and cold conditions so that the inner body temperature remains more or less constant. Vasodilation and sweating are the primary modes by which humans attempt to lose excess body heat. The brain creates much heat through the countless reactions which occur. Even the process of thought creates heat. The head has a complex system of blood vessels, which keeps the brain from overheating by bringing blood to the thin skin on the head, allowing heat to escape. The effectiveness of these methods is influenced by the character of the climate and the degree to which the individual is acclimatized. Classification of Animals by Thermal Characteristics Based on thermal characteristics, animals could be classified into four broad groups: †¢ Endotherms: These are animals that create most of their heat via metabolic processes, and are colloquially referred to as warm-blooded. Most mammals and humans belong to this group. †¢ Ectotherms: These are animals that use external sources of temperature to regulate their body temperatures. They are colloquially referred to as coldblooded despite the fact that body temperatures often stay within the same temperature ranges as warm-blooded animals. Examples of animals that belong to this group are fish, amphibians and reptiles. †¢ Homeotherms: These are animals or organisms with stable body temperature which is independent of the temperature of the surrounding environment. Most endothermic organisms are homeothermic, like mammals. Although, fish are ectotherms because all of their heat comes from the surrounding water. However, most are homeotherms because their temperature is very stable. †¢ Poikiotherms: These are animals or organisms with variable body temperature. The body temperature varies according to the temperature of the surrounding environment. Animals with facultative endothermy are often poikilothermic, meaning their temperature can vary considerably. Examples of poikilotherms include amphibians, reptiles and fish. The Hypothalamus as a Thermoregulatory Centre Thermoregulation in both ectotherms and endotherms is controlled mainly by the preoptic area of the anterior hypothalamus (Romanovsky, 2007). In general, the posterior hypothalamus controls responses to cold, and the anterior hypothalamus controls responses to heat (Martha, 2010), hence, both serving as thermoregulatory centres. This area receives input from temperature receptors in the skin and mucous membranes (peripheral thermoreceptors) and from internal structures (central thermoreceptors), which include the hypothalamus itself (Dominika, 1998). The temperature sensory signals from the preoptic area and those from the periphery are combined in the posterior hypothalamus to control the heat producing and conserving reactions of the body. The hypothalamic thermostat works in conjunction with other hypothalamic, autonomic and higher nervous thermoregulatory centers to keep the core temperature constant. Some of these thermoregulatory responses are involuntary, mediated by the autonomic nervous system, some are neurohormonal and others are semi-voluntary or voluntary behavioral responses (Dominika, 1998). The brain receives signals regarding body temperature from the nerves in the skin and the blood. These signals go to the hypothalamus, which coordinates thermoregulation in the body. Both sets of information are needed so that the body can make appropriate adjustments. The thermoregulatory centre sends impulses to several different effectors to adjust body temperature. The signals from the hypothalamus control the sympathetic nervous system, which affects vasoconstriction, metabolism, shivering, sweating, and hormonal controls over temperature to bring the increased or decreased temperature back to normal (Wikipedia,2012) Figure 1: Schematic representation of the thermoregulatory centre role in thermoregulation (IHW, 2006) Feedback Control Mechanism for Thermoregulation in Hot Condition When the surroundings are hot or when the animal body is vigorously exercising, the following could be described as the summary of the feedback control system responsible for regulating the temperature back to normal: †¢ As the body core temperature starts to rise, the increase in temperature is detected by heat receptors in the body. †¢ †¢ These receptors send signals to the hypothermic thermostat. The thermostat inhibits the adrenergic activity of the sympathetic nervous system and stimulates the vasomotor system to dilate the capillaries underlying the skin. †¢ Arteriolar vasodilation occurs. The smooth muscle walls of the arterioles relax allowing increased blood flow through the artery. This redirects blood into the superficial capillaries in the skin increasing heat loss by convection, conduction and radiation. †¢ If the heat is sufficiently intense, the cholinergic sympathetic fibers, wh ich innervate sweat glands release ACh, stimulating sweat. †¢ The eccrine sweat glands under the skin secrete sweat (a fluid containing mostly water with some dissolved ions) which travels up the sweat duct, through the sweat pore and onto the surface of the skin. This causes heat loss via evaporative cooling; however, a lot of essential water is lost (Wikipedia, 2012). †¢ The hairs on the skin lay flat, preventing heat from being trapped by the layer of still air between the hairs. This is caused by tiny muscles under the surface of the skin called arrector pili muscles relaxing so that their attached hair follicles are not erect. These flat hairs increase the flow of air next to the skin increasing heat loss by convection. †¢ Behavioral responses to heat, such as lethargy, resting, lying down with limbs spread out or wallowing in pool of water or mud, decreases heat production and increases heat loss †¢ As the animal body gets cooler, the hypothalamic receptors detect this and diminish the heat loss prevention responses . †¢ The body core temperature returns to normal. It should be noted that most animals cant sweat efficiently. Cats and dogs have sweat glands only on the pads of their feet. Horses and humans are two of the few animals capable of sweating. Many animals pant rather than sweat because the lungs have a large surface area and are highly vascularised. Air is inhaled, cooling the surface of the lungs and is then exhaled losing heat and some water vapour. Figure 2: Schematic representation of thermoregulatory process in the body of an animal (IHW, 2006) Feedback Control Mechanism for Thermoregulation in Cold Condition When the surroundings are cold or when the animal body is resting, the following could be described as the summary of the feedback control system responsible for regulating the temperature back to normal: †¢ As the body core temperature starts to drop, this is detected by cold receptors in the body. †¢ These receptors send signals to both the hypothalamic thermostat and higher cortical centres in the CNS. †¢ The activation of the sympathetic centre results in several response which slow down the activity of the sweat glands. †¢ This lowers the production of sweat and it decreases the evaporation of sweat, which reduces heat loss by evaporation. †¢ The muscles under the surface of the skin called arrector pili muscles (attached to an individual hair follicle) contract (piloerection), lifting the hair follicle upright. This makes the hairs stand on end which acts as an insulating layer, trapping heat. †¢ The hypothalamus also signals the vasomotor system to constrict the capillaries underlying the skin. †¢ Arterioles carrying blood to superficial capillaries under the surface of the skin can shrink (constrict), thereby rerouting blood away from the skin and towards the warmer core of the body. This prevents blood from losing heat to the surroundings and also prevents the core temperature dropping further. This process is called vasoconstriction. It is impossible to prevent all heat loss from the blood, only to reduce it. In extremely cold conditions excessive vasoconstriction leads to numbness and pale skin. Frostbite only occurs when water within the cells begins to freeze, this destroys the cell causing damage (Wikipedia, 2012). This reduces heat loss by conduction, radiation, and convection. †¢ A Shivering Center in the hypothalamus is also activated which activates the brainstem motor centers to initiate involuntary contraction of skeletal muscles causing shivering. This increases heat production as respiration is an exothermic reaction in muscle cells. Shivering is more effective than exercise at producing heat because the animal remains still. This means that less heat is lost to the environment via convection. There are two types of shivering: low intensity and high intensity. During low intensity shivering animals shiver constantly at a low level for months during cold conditions. During high intensity shivering animals shiver violently for a relatively short time. Both processes consume energy although high intensity shivering uses glucose as a fuel source and low intensity tends to use fats. This is a primary reason why animals store up food in the winter (Wikipedia, 2012). †¢ There is also epinephrine secretion from adrenal medulla that increases thermogenesis.

The Photographers Eye Essay -- Photography

In Szarkowski’s essay ‘The Photographer’s Eye’, he discusses how photography has taught us to see from the unexpected vantage point, as well as how ‘photography’s ability to challenge and reject our schematized notions of reality is still fresh’ (Szarkowski. 1966. Page 11). When thinking about vantage point myself, two very different ideas of this characteristic of photography came to mind, which I will discuss and compare in this essay. Firstly, perhaps the more obvious, was the concept of where a photograph is taken from, for example looking at a subject or scene from a position that allows the photographer a favourable view. A very literal approach. Therefore I decided to think more about how Szarkowski said photography teaches us to see from the unexpected vantage point, and on a visit to the V&A Museum I found Fred Zinnemann’s photograph ‘Empire State Building from the Subway’ (1950) which I think begins to address this idea; the photograph certainly shows an unexpected position for the artist to have photographed the subject from. With the title of the image being ‘Empire State Building’, this surely suggests that Zinnemann intended this to be the main subject and focus point for the viewer, making the position that the artist chose to photograph from very interesting. The empire state building itself is actually set in the background of the image, allowing the viewer to take in the maybe unconventional framing of it, notably the blacked out railings of the subway that are so prominent. Whether Zinnemann intended this or not, I think the vantage point in this image allows for the viewer to re late to the scene more, as it is from a perspective that they could see everyday, when at the same time I feel it also directs the v... ...Brooklyn Family going for a Sunday Outing. [photograph] (Tate Modern Collection) Zinnemann, F., 1950. Empire State Building from the Subway [image online]. Available at: http://www.mutualart.com/Artwork/Empire-State-Building-from-the-Subway--c/AD8E090F77375033 [Accessed January 2012]. Calle, S., 1981. The Hotel, Room 47 [image online]. Available at: http://www.tate.org.uk/servlet/ViewWork?cgroupid=999999961&workid=26559&searchid=10437&tabview=image [Accessed January 2012]. Arbus, D., 1970. Jewish Giant at Home with His Parents in the Bronx [image online]. Available at: http://masters-of-photography.com/A/arbus/arbus_jewish_giant_full.html [Accessed January 2012]. Arbus, D., 1966. A Young Brooklyn Family going for a Sunday Outing [image online]. Available at: http://www.studio-international.co.uk/studio-images/arbus/82364761_b.asp [Accessed January 2012].

The Staff Development

This paper will review the characteristics of a teaching program for a critical care department in a local community hospital. This will include a review of teaching strategies that focus on the adult learner based on their development stage. A teaching program for the critical care department would entail small group and student-centered teaching strategies that focus on communication enhancement and core skill competency development among learners. This teaching approach emphasizes more autonomy in the clinical care setting and encourages the teacher to consider learner characteristics among clinical and professional workers. The educational program described will be offered in hospital and other generic health care organizations where proactive team building skills and communication skills development are necessary to ensure a multi-disciplinary approach to learning and care giving. The teaching program provided will include a team approach to healthcare education encouraging participants to learn and adopt strategies for conversing and communicating with diverse populations including other professionals, students, clinical workers, patients, families and community members. Teaching Program for Critical Care Department Foundation Learner characteristics for employees in a critical care work setting are unique. Adult learners generally have specific characteristics that require use of effective strategies for learning and teaching the adult learner (Huttly, Sweet & Taylor, 2003). Studies suggest that multiple approaches may be more effective for helping critical care staff develop, including a â€Å"team healthcare approach† which educators can adopt and simulate in an educational setting â€Å"through interprofessional education and vertical integration of student years† (Huttly, Sweet & Taylor, p. 5). Teaching strategies must be based on learner characteristics and the place of employment students intend to pursue their career to be successful. Teaching strategies that are varied are most likely to be successful, and may include information technology training in skills development and writing genres and education about working in a multidisciplinary health care setting where a depth and range of activities and problems solving skills are nurtured among future healthcare practitioners (Biggs, 1999; Huttly, Sweet & Taylor, 2003). Teaching strategies must incorporate multiple aims including improving adult critical care workers perceptions and experiences of their education and learning environment and supporting learners at varying developmental levels (Curzon, 2000). Among the skills necessary include improving communication skills in a patient centered manner; this may require that educators focus on assessing the student practitioner and providing information based learning in small groups that emphasizes problem based and problem solving learning (Huttly, Sweet & Taylor, 2003). Many support teaching strategies that incorporate good communication, skills and core competency training and specialist options that are student based and emphasize group study skills to support ongoing learning at each development stage among adult learners; further research suggest that the ability of adult learners to discover information and understand subject matter in a clinical setting depends in part on their ability to uncover information about subjects important to them and their professional careers (Huttly, et al. 2003; Wilby, 2001). It is important that teachers adopt strategies that allow them to act as â€Å"agents of change† in the classroom, drawing on their own educational experience to provide students with a learning environment that is â€Å"condensed but focused† (Huttly, Sweet & Taylor, 150). The clinic provides an adequate learning environment for all medical students, and teaching strategies in this environment should focus on providing students with skills, knowledge, expertise and professional ability to treat patients correctly and efficiently (Huttly, Sweet & Taylor, 2003). Teaching strategies that tend to work well in a clinical environment reflect learner characteristics, are generally subject-centered, consider student's pre-clinical ability and education and enable students to tackle â€Å"problem-oriented, practical experiences† geared toward their developmental level (Townsend, et al. 1997; Huttly et al. 2003). Small group learning is also considered â€Å"the most meaningful learning experienced by adult learners† and useful for all curricula including medical, particularly when characterized by â€Å"active participation of all group members† (Huttly, Sweet & Taylor, 101). Further small group experiences can enhance learning by involving them in various processes including â€Å"relating, applying, generating ideas and recognizing and resolving problems† (Huttly, Sweet & Taylor, 101). It is a more active than passive form of teaching that provides students with more stimulating methods of interaction and developing, enabling better responsibility for learning among students, helping develop generic clinical skills and promoting all adult learning characteristics and styles (Biggs, 1999; Huttly, Sweet & Taylor, 2003). Particularly in clinical education student centered modes of teaching including small group work allow students to adopt more active and autonomous roles better preparing them to function as team members in their medical communities at later dates and times (Huttly, Sweet & Taylor, 2003). There is ample evidence supporting the role of active learning in the clinical environment. There is also ample evidence suggesting that student centered approaches to teaching help clinical student learn to communicate better in a team environment and help develop more comprehensive communication and problem solving skills, important attributes within the medical profession (Huttly, Sweet & Taylor, 2003). This compared with more teacher centered approaches, strategies that in the past have proven less successful among adult learners with varying learning characteristics, particularly those learning in a clinical environment where it is important that students adopt transferable and generic skills (Huttly, Sweet & Taylor, 2003).

Child Sexual Abuse Prevention Essay example - 1991 Words

Child Sexual Abuse Prevention The purpose of this literature review is to evaluate the information that has been collected in the area of child sexual abuse prevention. From the research studies critically examined, a decision will be made as to what areas improvements need to be made in, in order to adequately outfit children, teachers and child care workers with the skills and knowledge to help prevent child sexual abuse. An exploratory study entitled â€Å"Child Sexual Abuse Prevention† was conducted by Michele Elliott of Kidscape Charity for Children’s Safety, London England and also by Kevin Browne and Jennifer Kilcoyne of the School of Medicine, University of Birmingham, Birmingham England. The Nuffield Foundation sponsored the†¦show more content†¦The second interview asked the men a total of seventy-two questions and was conducted by a female research psychologist. Some of the questions were; the age and range of their victims, how they selected children, how they maintained them as victims and what suggestions they had for preventing child sexual abuse. The third interview was conducted six months after the second and the answers received were compared to those in the second interview to test for consistency. The offenders displayed a 90 percent consistency in the way they responded throughout the interviews. The study concluded that in order for prevention programs to become more affective and successful they need to include information about the specific ways that child molester operate. â€Å"It also stated that it is potentially dangerous for children to tell the abuser â€Å"no† once the abuse as started and that Child Safety Programs needed to be re-evaluated and information reassessed in light of the information that offenders have revealed.† (Elliott et al, 1995, page 593) The next research study that will be examined is entitled â€Å"Positive and Negative Effects of a Child Sexual Abuse Prevention Program†. The aim of this research is to study the intended and unintended affects of the â€Å"Right to Security† child sexual abuse prevention program. â€Å"The aim of the prevention program is toShow MoreRelatedChild Abuse Prevention and Control; Can Physical, Sexual or Psychological Abuse Be Controlled Within the Household?820 Words   |  4 PagesChild abuse is a serious and widespread problem throughout the world. It can take the form of sexual abuse, physical or psychological mistreatment , or child neglect. Can child abuse be prevented? Can the child abuser be rehabilitated? What can be done within your own home or community to prevent or control child abuse? Once discovered, child abuse can be addressed, but how does one report child abuse, and what are the legal requirements for reporting the abuse? Are you aware of the effect t hat theRead MoreChild Sexual Abuse And Children1301 Words   |  6 PagesChild sexual abuse effects tens of thousands of children, and young teens every year. 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