Insulin: Difference between revisions

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[[Image:Glucose insulin day.png|300px|left|thumb|Schematic of daily changes of blood sugar (red) and insulin (blue)]]

Our blood sugar level (i.e. glucose concentration) varies over time with food intake and exercise, but has to remain in a narrow range so we stay healthy (not become hyperglycemic or hypoglycemic). Insulin, together with [[glucagon]], regulates blood sugar levels by changing fuel metabolism in all cells <ref>https://www.yourhormones.info/hormones/insulin/</ref> on a timescale of minutes and hours. In simplest terms, the presence of insulin in the blood signals the well-fed stage, while the presence of glucagon signals the fasting stage.

Our blood sugar level (i.e. glucose concentration) varies over time with food intake and exercise, but has to remain in a narrow range so we stay healthy (not become hyperglycemic or hypoglycemic). Insulin, together with [[glucagon]], regulates blood sugar levels by changing fuel metabolism in all metabolic cells (e.g. liver, fat, kidney, muscle and nerve cells) <ref>https://www.yourhormones.info/hormones/insulin/</ref> on a timescale of minutes and hours. In simplest terms, the presence of insulin in the blood signals the well-fed stage, while the presence of glucagon signals the fasting stage.

Biosynthesis and processing of insulin occurs in the [https://en.wikipedia.org/wiki/Beta_cell beta cells] of the pancreas. The beta cells are found in the islets of Langerhans, which also contain the alpha cells that synthesize glucagon. Insulin is made as a 110 amino acid pre-proinsulin, which is processed to the mature 51 amino acid insulin and targeted to secretory vesicles. In a healthy adult, about 200 units of insulin are available in the pancreas, of which 30-50 units are secreted daily<ref>https://www.britannica.com/science/insulin</ref>. With a unit of insulin corresponding to 0.0347 mg mature insulin <ref>https://www.who.int/biologicals/expert_committee/BS_2143_Human_Recombinant_Insulin_final.pdf</ref>, the body contains only about 7 mg of insulin. In its stored form, insulin is a hexamer complexed to zinc ions.

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@@ Line 30: / Line 30: @@
 [[Image:Glucose insulin day.png|300px|left|thumb|Schematic of daily changes of blood sugar (red) and insulin (blue)]]
-Our blood sugar level (i.e. glucose concentration) varies over time with food intake and exercise, but has to remain in a narrow range so we stay healthy (not become hyperglycemic or hypoglycemic). Insulin, together with [[glucagon]], regulates blood sugar levels by changing fuel metabolism in all cells <ref>https://www.yourhormones.info/hormones/insulin/</ref> on a timescale of minutes and hours. In simplest terms, the presence of insulin in the blood signals the well-fed stage, while the presence of glucagon signals the fasting stage.
+Our blood sugar level (i.e. glucose concentration) varies over time with food intake and exercise, but has to remain in a narrow range so we stay healthy (not become hyperglycemic or hypoglycemic). Insulin, together with [[glucagon]], regulates blood sugar levels by changing fuel metabolism in all metabolic cells (e.g. liver, fat, kidney, muscle and nerve cells) <ref>https://www.yourhormones.info/hormones/insulin/</ref> on a timescale of minutes and hours. In simplest terms, the presence of insulin in the blood signals the well-fed stage, while the presence of glucagon signals the fasting stage.
 Biosynthesis and processing of insulin occurs in the [https://en.wikipedia.org/wiki/Beta_cell beta cells] of the pancreas. The beta cells are found in the islets of Langerhans, which also contain the alpha cells that synthesize glucagon. Insulin is made as a 110 amino acid pre-proinsulin, which is processed to the mature 51 amino acid insulin and targeted to secretory vesicles. In a healthy adult, about 200 units of insulin are available in the pancreas, of which 30-50 units are secreted daily<ref>https://www.britannica.com/science/insulin</ref>. With a unit of insulin corresponding to 0.0347 mg mature insulin <ref>https://www.who.int/biologicals/expert_committee/BS_2143_Human_Recombinant_Insulin_final.pdf</ref>, the body contains only about 7 mg of insulin. In its stored form, insulin is a hexamer complexed to zinc ions.