Endocrinal Regulation of Energy Metabolism in the Human Body Assignment Help
Explain Energy Metabolism & Endocrinology
Introduction:
Adipose tissue is one of the primary sources of energy reserves and is earlier estimated to be inert in terms of regulation of metabolic processes. The storage capacity of adipose tissues is evident thorough its hypertrophy of the adipocytes to accommodate the fat absorbed by the body. The significance of adipose tissue is manifested through the secretion of various endocrine hormones to control the energy intake and its expenditure post intake. In this essay the concept of leptin and adiponectin and their role in the regulation of energy metabolism are discussed (Havel, 2004).
Adipose tissue:
The dynamic nature of adipose tissue is evident through the synthesis of multiple endocrine hormones contributing to the process of homeostasis. The composition of the adipose tissue is not uniform in its cellular components. Endothelial cells, pericytes and precursor cells, immune cells primarily form the base of tissues and differ in the proportion based on the location of the tissue. Cells of adipose tissue belong to mesenchymal origin and are formed from the precursor cells through Adipogenesis. Mature adipocytes perform the major function is to accumulate the fat reserves to store and, in the process, they are morphologically transformed in the event of excessive fat intake. Adipocytes are classified as white and brown based on the difference in their phenotypical characteristics and functions. Brown fat is densely packed with mitochondria and is extensively supplied with blood vessels to aid in the transfer of heat involved with the maintenance of thermogenesis and is observed at the initial ages of an individual gradually transforming into white fat.
On the other hand, white fat is distributed through the entire body and has a complex role in the regulation of metabolism. The effects of Adipose tissue is observed through out the body as it serves as a major endocrine organ. Inflammation mediators such as tumour necrosis factor -alpha, interleukin-6 , adiponectin and acylation stimulation protein are synthesised in addition to leptin indicating a connection between the obesity, inflammation and insulin resistance (Coelho et al., 2013).
Role of Hypothalamus in energy regulation:
Hypothalamus is an integral portion of central nervous system and is majorly involved in the regulation of appetite. Peptides associate with hypothalamus such as neuropeptide and agouti peptide induce food intake once activated. On the other hand, the melanocortin receptors reduce the food intake. The dorsal vagal complex acts as a signalling link between the hypothalamus and the external signals. Vagal nerve is the sensory nerve involve in the transport of information of time and quantity of intake.
Leptin synthesis regulation:
Leptin hormone is majorly involved in the management of energy reserves. Insulin promotes the oxidative metabolism of glucose in the adipocytes post-prandial increase in the glucose levels. Insulin and leptin act in the opposite directions where insulin decreases leptin production and vice-versa. Intake of fructose rich diet stimulated the synthesis of fat precursors thereby the leptin production increases to influence the eating behaviour. The hormone ghrelin is a gastric hormone is known for its effects on stimulating the hunger. In the event of high glucose diet the ghrelin is inhibited whereas the fructose diets, does not affect ghrelin production thereby leading to excessive consumption of food and obesity.
Leptin is a hormone directly involved with the energy balance and is observed in substantial quantities in the subcutaneous tissue. Higher levels of leptin are linked to the reduced nutrition intake. The eating behaviour is regulated by hypothalamus region of Central nervous system through the signalling cascade influencing the production of liver steroyl CoA. Lower levels of leptin produce pronounced physiological effects such as increased eating urge and thereby contributing the obesity. Any mutation in the leptin receptor resulted in the similar results. A common signalling pathway exists between insulin and leptin. Insulin resistance is also linked to the deficiency of leptin. Metabolic role of leptin involves the regulation of the levels of hepatic triglyceride deposition (Coelho et al., 2013).
Action of acylation-stimulating protein:
Acylation-stimulating protein is a lipogenic factor in other words is responsible for the deposition of fat. Studies of ASP knock out mice showed reduced body weight and increased sensitivity towards insulin. It is majorly secreted in the cells adjacent to the site of triacyl glycerol synthesis. It increases the uptake of lipids from the bloodstream. This hormone is synthesized by the presence of chylomicrons in the bloodstream. ASP affects the GLUT-4 a glucose transporter and an enzyme catalysing the reaction of triacylglycerol synthesis thereby facilitating the synthesis of TAGs. Higher levels of this hormone are associated with obesity.
Adiponectin:
Adiponectin stimulates the transport of glucose in liver and restricts the process of gluconeogenesis, simultaneously increasing the oxidation of fatty acids thereby reducing the levels of fat. Adiponectin positively affects the insulin secretion promoting the glucose uptake by the cells. Adiponectin inhibits the lipolysis and is found to have a reciprocal function of leptin to maintain the energy reserve balance (Nigro et al., 2014)
Clinical applications in obesity:
Overweight and obesity is current epidemic threatening the health of the world nations with increased morbidity and mortality rate. The associated risks such as diabetes, arthritis, vascular diseases and their lethal consequences demand the attention towards the process of energy metabolism. The current available treatments are restricted to the lifestyle changes and reduction of the size of the stomach to stimulate a feeling of fullness and limit the overconsumption. However, the bariatric surgical procedure is ineffective in the long-term and has many health complications. Obesity is defined as the increase in the size and composition of fat in the adipose tissue. Recent evidence reflects the existence of inflammation and insulin resistance as a contributing factor of diabetes (De Silva and Bloom, 2012).
Conclusion:
Adipose is actively involved in the coordination of energy homeostasis in addition to the CNS. Among all the proteins in the fuel metabolism primarily leptin, adiponectin, ghrelin and peptide tyrosine tyrosine are involved. Synthesis of these hormones is initiated by the feeding status of an individual. Understanding the intricate biochemical pathways associated with these hormones has a major application in treating the eating disorders, diabetes and obesity (Coelho et al., 2013)
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