Compare And Contrast The Stimulus For Insulin And Glucagon Release From The Pancreas

Question 1: How does the insulin and glucagon secreted by the pancreas function in glucose metabolism?

eventually become insulin dependent due to the loss of pancreatic beta cells.3 Glycemic control is

The insulin signaling cascade is initiated when insulin binds to insulin receptors located on the cell 's surface. The insulin receptor has four subunits: two alpha subunits located on the outside of the cell and two transmembrane beta subunits (3 & 4). When insulin binds to the alpha subunit receptors, it transmits a signal across the plasma membrane and activates tyrosine residues that are attached to the beta subunits. The activation of the tyrosine residues causes it to autophosphorolate and then phosphorolate other proteins that also have tyrosine residues attached to them. These phosphorylated proteins then move on to trigger cellular responses such as translocation of GLUT4 vesicule to the cell membrane. The vesicule becomes a transporter to allow glucose to come into the cell so that it can continue on and be stored as glycogen (3).

In Glucose Homeostasis, the Pancreas is responsible for releasing Insulin and Glucagon that control blood Glucose. The Pancreatic cells that produce Insulin are called BC (beta) Cells.

The pancreas detects the intake of glucose and secretes insulin to help manage the uptake of glucose. When the blood glucose levels decrease, the pancreas inhibits the insulin. In this example the function of negative feedback is to help maintain blood glucose

The pancreatic hormone glucagon is a peptide secreted by the alpha cells in the islets of Langerhans, a region located in the tail of the pancreas ("Glucagon..."). Similar to the other major pancreatic hormone insulin, glucagon helps to regulate the levels of glucose in the body. While insulin works mainly to reduce high blood glucose levels, glucagon does the opposite and works to increase low blood glucose levels by seeking other sources of stored glucose in the body. When blood glucose is low—like in between meals or during exercise—alpha cells secrete glucagon into the bloodstream. The protein then travels to the liver, where it is recognized by G protein coupled receptors on the hepatocytes ("Glucagon - New World Encyclopedia"). Glucagon

 Diabetes mellitus is a metabolic disease which is characterized by, hyperglycemia, the increase in the blood glucose level. Glucose is an important source of energy for the body cells but its level should be controlled in the blood. When the glucose concentration increases in the blood (for example after eating a meal) then it stimulates pancreas to release a hormone called insulin. Insulin is made and secreted by the beta cells, located in clusters called pancreatic islets, of the pancreas. After releasing in the blood stream Insulin binds to their receptors on different body tissues and organs which allow the glucose to enter inside them. Inside the tissues glucose is used for different purposes such as energy production by cellular respiration, converted into glycogen or converted into fat and then stored. When the insulin does not produce at all, does not produce in sufficient amount (hyposecretion) or body tissues do not respond to insulin then the glucose level in the blood remains high at all times. Such condition can be defined as diabetes mellitus or diabetes (Cartailler, n.d.).

Normally when we eat food, in particular carbohydrates (starches and sugars) the level of glucose in our blood increases. In response to this the pancreas produces insulin which brings the level of glucose back to normal. Insulin is a hormone which is produced by a small organ in the body called the pancreas.

When a person’s body becomes immune to insulin or when the pancreas stops making insulin that’s when it progresses. No one really knows the cause, but genetics and environmental factors, such as excess weight and inactivity, appear to provide a part in it. Insulin is a hormone that comes from the pancreas.18 When the pancreas produces insulin it goes into bloodstream. So when insulin moves around it lets sugar go into the cells. Then insulin lowers the quantity of sugar into the bloodstream. When the blood sugar level trickles so does the production of insulin in the pancreas.18

However, the level of insulin is inappropriately low relative to their elevated blood glucose concentration. According to the American Diabetes Association (2015), type 2 diabetes has been classified as an illness due to the progressive insulin secretory defect on the background of insulin resistance. Insulin and glucagon are known to be the key mediators in balancing plasma glucose in a healthy body. Insulin is a hormone from the pancreatic β-cell that decreases plasma glucose by driving tissues uptake of glucose from the blood stream and suppressing hepatic glucose production. On the other hand, glucagon stimulates hepatic glucose production which then raises glucose level in the body. Amylin, a hormone, is co-secreted with insulin from the pancreatic β-cells that are responsible for modulating the rate of gastric emptying and suppresses the release of glucagon.

The regulation of the cornerstone of the whole body energy, glucose, in blood stream by the pancreas, specifically the islets of Langerhans, is very critical through the secretion of insulin and glucagon. Insulin, which is secreted from beta cells of the islets of Langerhans in response to high blood glucose levels, has an anabolic effect via its stimulation of glucose uptake in peripheral, skeletal muscle, as well as central, brain, tissues to be stored in the form of glycogen and fat [2]. On the other hand, low glucose levels enhance pancreatic alpha cells secretion of Glucagon that plays the catabolic role through stimulation of stored glycogen breakdown and formation of glucose from non-carbohydrate sources via glycogenolysis and hepatic gluconeogenesis, respectively [2]. This mechanism is well controlled through the opposite secretion of these hormones in response

The main stimulus for insulin release is a high glucose concentration (hyperglycemia), however insulin release is also stimulated by other factors, such as high amino acid and fatty acid levels in the blood, hormones released from the stomach and intestine as well as neurotransmitters (Lang, 1999). Glucose entrance into pancreatic beta cell and its further metabolism in mitochondria alters the adenosine triphosphate (ATP)/ adenosine diphosphate (ADP) ratio that leads to closure of ATP-sensitive K+ channels. It results in membrane depolarisation and opening of voltage-dependent calcium channels. The subsequent increase in cytosolic free Ca+2 coupled with the multiple phosphorylation events modulated by protein kinase C and protein kinase A (PKA) induce exocytosis and insulin secretion [(Ashcroft et al., 1994 and Lang, 1999), see Fig.

One of the body's feedback systems is the reaction to a rise in blood sugar or glucose. This is a negative feedback system since there is something that is threatening the body and it needs to be fixed and regulated. When blood sugar rises above the "ideal" want/need for the body, the receptors in the body sense a change and send a message to the "control center". The control center in this feedback system in the pancreas. The pancreas receives this message and begins to release insulin- this will begin to lower the blood sugar. When enough insulin has been released to lower the amount of sugar in the blood the pancreas will stop secreting insulin because homeostasis is back in balance. This is an important feedback system because you can have

Glucose is obtained from the food that we eat which are starch -rich foods. Insulin and glucagon are responsible for controlling the concentration of glucose in the blood, insulin controls the high sugar level in our body and secreted by beta cells while glucagon control the low level of the glucose and secreted by Alpha cells.

In Diabetes blood glucose levels raise after a meal and remain above normal levels because insulin is either inadequate or ineffective. Type 2 diabetes is the most common form of diabetes, it accounts for 90 to 95% of cases.(1) The primary defect is insulin resistance or a lack of sensitivity to insulin in eight main areas which includes muscle, adipose cells, liver, beta cell in the pancreas, alpha cells in the pancreas, intestine, kidney and brain. Muscle is affected by becoming resistant to insulin and then cannot take up glucose for energy needs. Adipose cells or fat cells start to breakdown contributing to insulin resistance and deposit fat throughout the body. The liver recognises the difficulty of dealing with glucose and increases