Digestion Lab
In the digestive system, there are two hormones that control the intake of food. These include GLP-1 and ghrelin, which are secreted in the stomach. The function of the GLP-1 hormone is to promote the feeling of satisfaction during food intake, by stimulating the release of insulin so as to limit the amount of food intake. Insulin converts glucose into glycogen, thereby giving the feeling of satiety. The function of ghrelin is to stimulate the release of glucagon so as to promote hunger and increase food consumption. The glucagon converts glycogen to glucose and releases it into the bloodstream, thereby increasing hunger in a living organism.
Agonists are used in place of native hormone peptides since their shapes are similar to that of the endogenous ligand and is thus able to bind to the receptor and produce effects similar to that of native hormone peptides. The agonist used in the experiment for GLP-1 was Exendin-4 while the agonist used to ghrelin was GHRP-2. During the experiment, the rats were fasted for GLP-1 treatment to decrease their food intake, while fed for ghrelin to increase their food intake. From the experiment, the importance of control fasted and control fed rats is to compare the results obtained and assess the effects of the agonists.
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Endocrinology Lab
In the endocrine system, the difference between the endocrine and exocrine pancreas is in their functions. The exocrine pancreas is a tissue that produces enzymes which aid in digestion. The endocrine pancreas consists of cells known as Islets of Langerhans that secrete hormones which regulate level of blood sugar and secretions from the pancreas. The hormones secreted are insulin and glucagon. The function of insulin is to stimulate lipogenesis, glycogenesis and glycolysis for the purpose of reducing sugar concentration in the blood while the function of glucagon is to stimulate glycogenolysis, lipolysis and gluconeogenesis for the purpose of increasing sugar concentration in plasma. Insulin dominates in the fed state where it causes net anabolism to occur by converting excess sugar to glycogen or fats for storage, while glucagon dominates in the fasted state where it converts glycogen to glucose to increase the concentration of plasma glucose to sustain energy.
Factors that stimulate and inhibit the production of insulin hormone include increase in plasma glucose, increase in plasma amino acids, presence of GI hormones such as GLP-1 and GIP and parasympathetic and sympathetic activities. In lowering blood sugar level, the insulin hormone inhibits enzymes that break down proteins, converts excess glucose into triglycerides which is stored in the adipose tissue and increases the transportation of glucose in insulin-sensitive cells. Insulin is useful in skeletal muscle and adipose tissue since it stimulates the production of GLUT4 transporters by the cytoplasmic vesicles which are useful for glucose uptake. Since insulin results in low plasma glucose, streptozotocin kills beta cells of the pancreas, thereby inhibits the secretion of the insulin hormone. In the experiment the rat group treated with insulin had low plasma glucose concentration while the group treated with STZ had high plasma glucose concentration.
Reproduction
The male reproductive system contains the testes which contains the seminiferous tubule and the epididymis. The seminiferous tubule is in charge of production of sperm, while the function of the epididymis is to store the sperms produced. On the other hand, the female reproductive system is made up of follicles which contain follicular cells and oocytes. The follicular cells surround the oocyte until it matures.
Similar to the female menstrual cycle is the estrous cycle which occurs in rodents. This cycle occurs between four to six days and occurs in four stages namely protestrus, estrus, metestrus and diestrus. In protestrus, the body of the rodent produces nucleated epithelial cells. At this stage, there is significant rise in the level of estradiol due to increase in the number of developing follicles. The next stage is estrus, which is characterized by presences of non-nucleated, cornified epithelial cells. At this stage, the level of estradiol is constant and the female rodent starts to ovulate. The next stage is metestrus which is characterized by the low number of cells and debris. During this stage, follicle cells are transformed into luteal cells after ovulation. These luteal cells form the corpus luteum. The final stage is diestrus, characterized by increase in the level of progesterone hormone and a corpus luteum that is fully functional.
Orchidectomy is a procedure done to separate the cauda epididymis from the seminiferous tubules, epididymis and sperms, while ovaridectomy is a procedure used to check the estrous by removing and observing the follicles, oviduct and vaginal smear.
