{"id":2470,"date":"2021-09-25T16:14:50","date_gmt":"2021-09-25T16:14:50","guid":{"rendered":"https:\/\/notesbard.com\/?p=2470"},"modified":"2021-09-25T17:36:10","modified_gmt":"2021-09-25T17:36:10","slug":"regulation-of-organic-metabolism-growth","status":"publish","type":"post","link":"https:\/\/notesbard.com\/regulation-of-organic-metabolism-growth\/","title":{"rendered":"Regulation of Organic Metabolism, Growth and Energy Balance"},"content":{"rendered":"\t\t
The period in which ingested nutrients enter the blood is called the absorptive state. In this state, some of the nutrients fulfill the energy need of the body while the extra nutrients remain stored. When the GI tract is empty of nutrients and required energy supplied by body storage, the state is called the post-absorptive state.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t Our body absorbs carbohydrates and proteins as monosaccharides and amino acids. These absorbed nutrients enter into the blood while the lymph absorbs fat as triacylglycerols.<\/p> \u2022 Absorbed carbohydrates: the primary source of energy for our body is glucose that is absorbed in the absorptive state. The glucose is stored as glycogen in the liver and skeletal muscles. Glucose is converted by adipose tissue into fat.<\/p> \u2022 Absorbed triacylglycerols: The capillaries of adipose tissue release fatty acids of plasma chylomicrons and from triacylglycerols.<\/p> \u2022 Absorbed amino acids: the major function of amino acids is to synthesize proteins. The excess amino acids are converted into carbohydrates and fat.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t The state includes net catabolism of glycogen, fat, and proteins. The glucose level in blood plasma is maintained by:<\/p> \u2022 Glycogenolysis: the process includes hydrolysis of glycogen.<\/p> \u2022 Lipolysis includes the conversion of triacylglycerols into glycerol and fatty acids.<\/p> \u2022 A catabolic reaction converts protein into glucose.<\/p> \u2022 Gluconeogenesis, synthesis of glucose.<\/p> \u2022 The glucose sparing, process includes an increase in fat utilization and a reduction in glucose metabolism.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t \u2022 Insulin:<\/strong> The beta cells of islets of Langerhans in the pancreas secrete a hormone named insulin. The absorptive state increases the secretion of insulin while the secretion decreases during the post-absorptive state. The major functions of insulin include increase the movement of glucose into cells, increase facilitated diffusion, increase glycogen synthesis, and inhibit or decrease the rate of glycogen catabolism. The secretion of insulin secretion is stimulated by parasympathetic fibers.<\/p> \u2022 Glucagon:<\/strong> The alpha cells of the pancreas secrete glucagon. The action of glucagon is the opposite of insulin. It helps in increasing the rate of glycogen breakdown and gluconeogenesis. Glucagon increases the level of sugar in blood plasma in the condition of hypoglycemia. The glucagon secretion is stimulated by sympathetic nerves.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t Deficiency of insulin or hyporesponsiveness of the hormone results in diabetes mellitus. It can be of two types: type I diabetes, and type II diabetes. Type I diabetes or insulin-dependent diabetes mellitus results in a low level of insulin in the body.<\/p> The cause of type I diabetes is mainly the destruction of beta cells. It results in an increasing amount of glucose in blood plasma. The problem can be treated by the administration of insulin. Type II diabetes or noninsulin-dependent diabetes mellitus causes hyporesponsiveness to insulin. In this condition, the insulin level is normal but the target cell does not respond to insulin. This condition of also known as insulin resistance is related to obesity.<\/p> The condition in which plasma glucose level decreases in the blood is called hypoglycemia. The increasing insulin or deficiency of glucagon arises the condition of hypoglycemia in the body.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t Diet and synthesis by the liver are two major sources of cholesterol in our bodies. The plasma cholesterol is regulated by homeostatic control, which involves hepatic synthesis. Animal fats or saturated fats increase the level of plasma cholesterol while it is decreased by unsaturated fatty acids.<\/p> The cholesterol is delivered to cells by low-density lipoproteins while the excess cholesterol is removed by high-density lipoproteins. HDL delivers extra cholesterol to the liver for excretion. Thus, the ratio of HDL and LDL is important for the regulation of cholesterol in our bodies.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t Two major growth regulators are (1) environmental factors, and (2) hormonal influences.<\/p> \u2022 Growth hormone and insulin-like growth factors:<\/strong> The growth hormone is the most important hormone for postnatal growth, which is secreted by the anterior pituitary. Gigantism is caused by an excess of GH, whereas deficiency of GH causes dwarfism. The increasing level of GH also results in bone thickening without lengthening, which is called acromegaly. GH stimulates the secretion of IGF-I from the liver that further promotes cell division and also stimulates protein synthesis.<\/p> \u2022 Thyroid hormone:<\/strong> It is an important hormone that controls metabolism. It also plays important role maintenance of the nervous system and normal development.<\/p> \u2022 Insulin:<\/strong> It inhibits protein degradation and promotes cell division and differentiation.<\/p> \u2022 Sex hormones:<\/strong> Levels of GH and IGF-I are stimulated by sex hormones. Testosterone also stimulates protein synthesis and exerts an anabolic effect.<\/p> \u2022 Cortisol:<\/strong> It stimulates protein catabolism and exerts antigrowth effects.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t Energy is liberated by the breakdown of organic molecules. The bodily cells use this energy to perform biological work, active transport, and molecular synthesis. Breakdown of an organic molecule liberates (\u2206E) energy that can either appear as heat (H) or can be used to perform work (W).<\/p> \u2206E = H + W <\/strong><\/p> This energy is incorporated into ATP, which is further used by cells.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t The total energy expenditure per unit of time is defined as metabolic rate. The metabolic rate under certain standardized conditions is called the basal metabolic rate. The activity of the heart, brain, liver, and kidney contributes most of the activity to the basal metabolic rate.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t They are used as an important determinant of BMR. They increase oxygen consumption and heat-production in body tissues that increase BMR.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t Epinephrine increases metabolic rate by calorigenic effect. The catabolism of glycogen and triacylglycerols is stimulated by Epinephrine.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t Body temperature is raised by ingestion of food. Proteins have the greatest effect in producing temperature changes.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t It increases muscle contraction. The examples of muscle contraction can be seen during exercise or shivering, which increases the metabolic rate.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t Energy stored = energy from food intake – (internal heat produced + External work)<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t The adipose tissue synthesizes a hormone called leptin. The hormone is released in a proportion of fat in adipose tissue. It inhibits the release of neuropeptides that cause a reduction in food intake. The hormone also increases the metabolic rate, which results in control changes in energy expenditure. The duration and frequency of meals in short term are regulated by various signals such as insulin, body temperature, presence of food in the GI tract, etc.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\tAbsorptive State<\/h2>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
Postabsorptive State<\/h3>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
Endocrine and Neural Control<\/h6>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
Diabetes Mellitus and Hypoglycemia<\/h6>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
Regulation of Plasma Cholesterol<\/h6>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
Growth Regulators<\/h6>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
Energy Balance<\/h5>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
i. Concepts of Energy Expenditure<\/h6>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
ii. Metabolic Rate<\/h6>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
iii. Thyroid Hormones<\/h6>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
iv. Epinephrine<\/h6>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
v. Food-induced Thermogenesis<\/h6>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
vi. Muscle Activity<\/h6>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
Regulation of Body Energy<\/h5>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
i. Control of Food Intake<\/h6>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t