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Nathan
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Bored again.
Insulin 101
Insulin is a small protein molecule that functions as a hormone in the body. It is synthesized in large quantities in only beta cells found in the pancreas. An interesting fact is that the amino acid chain sequence of insulin is very particular among vertebrate animals. So, the insulin found in one mammal will almost certainly be biologically active in another mammal. That's why people with diabetes are sometimes given insulin obtained from the pancreases of pigs - in case you ever wondered and give a shit. Anyway, insulin is usually secreted in response to elevated blood glucose levels since it's "job" is to shuttle glucose into cells. Actually, insulin is also released in response to elevated blood concentrations of other fueling molecules like amino acids and fatty acids and, interestingly enough, it is also secreted in response to certain stimuli like seeing or tasting food - so go stare at some pork chops and you'll be a monster in no time.
Like all protein hormones, the receptor for insulin is found bounded in the plasma membrane of cells. The insulin receptor works as an enzyme to transfer phosphate groups from ATP molecules to remnants of tyrosine on target proteins found within cells. Phosphorylation of these proteins changes their function and so something happens biologically.
Alright, so insulin facilitates the uptake of glucose into muscle cells, adipocytes and some other tissues. It does this by making GLUT4, the major transporter of glucose, available in the plasma membrane of cells. Insulin doesn't do this for all tissues, for instance it doesn't facilitate glucose uptake into liver or brain cells cause they don't utilize GLUT4.
What's more, insulin causes the liver to store glucose as glycogen. I don't really remember how exactly (my memory is pretty good but some of this stuff is too technical so fuck it) but the bottom line is that when there is lots of glucose in the blood, insulin tells the body to go to the bank (i.e. the liver) with that shit. When the liver is getting too filled with glycogen then insulin causes the synthesis of fatty acids in the liver. When insulin levels drop, the liver stops synthesizing glycogen and enzymes become active to break it down. Also, when insulin levels become low, the body turns to other sources of fuel for energy like fatty acids.
Insulin also inhibits the breakdown of fat (damn, eh?) by inhibiting triglycerides to release fatty acids. It can slow fat loss in yet another way, namely by causing the uptake of glucose into adipocytes which can then be synthesized into glycerol, and that in turn causes the synthesis of triglycerides.
Alright then. Carry on.
Insulin 101
Insulin is a small protein molecule that functions as a hormone in the body. It is synthesized in large quantities in only beta cells found in the pancreas. An interesting fact is that the amino acid chain sequence of insulin is very particular among vertebrate animals. So, the insulin found in one mammal will almost certainly be biologically active in another mammal. That's why people with diabetes are sometimes given insulin obtained from the pancreases of pigs - in case you ever wondered and give a shit. Anyway, insulin is usually secreted in response to elevated blood glucose levels since it's "job" is to shuttle glucose into cells. Actually, insulin is also released in response to elevated blood concentrations of other fueling molecules like amino acids and fatty acids and, interestingly enough, it is also secreted in response to certain stimuli like seeing or tasting food - so go stare at some pork chops and you'll be a monster in no time.
Like all protein hormones, the receptor for insulin is found bounded in the plasma membrane of cells. The insulin receptor works as an enzyme to transfer phosphate groups from ATP molecules to remnants of tyrosine on target proteins found within cells. Phosphorylation of these proteins changes their function and so something happens biologically.
Alright, so insulin facilitates the uptake of glucose into muscle cells, adipocytes and some other tissues. It does this by making GLUT4, the major transporter of glucose, available in the plasma membrane of cells. Insulin doesn't do this for all tissues, for instance it doesn't facilitate glucose uptake into liver or brain cells cause they don't utilize GLUT4.
What's more, insulin causes the liver to store glucose as glycogen. I don't really remember how exactly (my memory is pretty good but some of this stuff is too technical so fuck it) but the bottom line is that when there is lots of glucose in the blood, insulin tells the body to go to the bank (i.e. the liver) with that shit. When the liver is getting too filled with glycogen then insulin causes the synthesis of fatty acids in the liver. When insulin levels drop, the liver stops synthesizing glycogen and enzymes become active to break it down. Also, when insulin levels become low, the body turns to other sources of fuel for energy like fatty acids.
Insulin also inhibits the breakdown of fat (damn, eh?) by inhibiting triglycerides to release fatty acids. It can slow fat loss in yet another way, namely by causing the uptake of glucose into adipocytes which can then be synthesized into glycerol, and that in turn causes the synthesis of triglycerides.
Alright then. Carry on.
