Disease Seminar Handbook W12

18 inflammatory bowel disease you have been

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Unformatted text preview: ody, and in a way as an internal line of defense. As a result, any disease that causes a change in the structure or function of the liver can cause significant problems for the entire body. Of interest here, the liver is able to store excess glucose as glycogen during feeding time. This glycogen can later be broken back down to glucose and use as energy fuel for the entire body during fasting or in-between meals. b) The Principles Behind Glucose Homeostasis Why is it important to regulate blood glucose concentrations? Glucose, a simple carbohydrate, is the main source of energy for our body and allows growth, thinking, physical activity, temperature regulation, etc. Every organ (e.g. skeletal muscle, liver, adipose tissue) in our body can use glucose to function, but the brain uses ONLY glucose as an energy source. Therefore, maintaining blood glucose concentrations within a safe range is crucial for health and well ­being. In healthy individuals, blood glucose concentrations vary between 4 ­7 mmol/L throughout the course of a day. Blood glucose levels falling below this range may be dangerous for cognitive functions and can lead to fainting and coma. Blood glucose levels above this range may lead, in the long ­term, to renal, visual, and nerve problems. How do hormones (insulin and glucagon) help in regulating blood glucose concentrations? When we ingest carbohydrates, they are broken down into glucose (among others), and absorbed from the small intestine into the blood stream. Glucose is a major source of energy used by the brain, skeletal muscle, liver, etc. However, before glucose can be used as an energy substrate by the cells, it needs to enter the cells. This is one of the main roles of insulin. As we eat, glucose builds up in the circulation, and this sends a signal to the pancreas to release insulin, a hormone. Once insulin is released into the blood, it binds to receptor on the cell surface of many tissues. Here, let’s talk about skeletal muscle, as it is one of the main tissues involved in T2DM (but the same process also occurs in liver and adipose tissue). Insulin binds to its receptor on skeletal muscle the same way a key would fit into a lock. This enables the transport of glucose from the blood into the skeletal muscle cell. The cell can then use the glucose to produce energy, or store it as glycogen for later use. Between meals, the levels of glucose in the blood stream decreases: this is the signal to the pancreas to secrete glucagon, another hormone. Glucagon’s role is opposite to that of insulin: it sends a message to the cells to release glucose into the circulation. Glucagon mostly...
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This note was uploaded on 01/27/2014 for the course BIOL 1080 taught by Professor Dyck during the Winter '11 term at University of Guelph.

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