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This set contains the content understandings, applications, skills and nature of science syllabus statements for IB Biology topic 6.6: Hormones, Homeostasis and Reproduction.
Terms in this set (93)
A hormone is a molecule released by a cell in a multicellular organism that influences the behavior of another cell within the same organism. Hormones are secreted from one cell and bind to a specific receptor on (or in) the target cell. Hormones are used to coordinate and control everything from metabolism to behavior. 

Insulin is a protein hormone secreted from β cells of the pancreas in response to high blood glucose levels. Insulin moves through the blood and binds to receptor proteins located in the membrane of target cells, major ones being liver, skeletal muscle and fat. Insulin helps reduce blood glucose levels by signaling the liver to
convert glucose to the storage molecule glycogen. Insulin causes muscle and fat cells to take in glucose from the blood.
convert glucose to the storage molecule glycogen. Insulin causes muscle and fat cells to take in glucose from the blood.

Glucagon is a protein hormone secreted from α cells of the pancreas in response to low blood glucose levels. Glucagon moves through the blood and binds to receptor proteins located in the membrane of liver cells (hepatocytes). When glucagon binds to the glucagon receptors, the liver cells convert the storage polysaccharide glycogen into individual glucose molecules and release them into the bloodstream, thereby increasing blood glucose levels.

Beta (β) cells are endocrine cells of the pancreas that produce and secrete the hormone insulin when blood glucose levels are high. Insulin promotes the storage of glucose as glycogen by liver cells and the uptake of glucose from the bloodstream of muscle and fat cells, thereby lowering the blood glucose levels.

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