Signaling Mechanisms for Insulin

Signaling Mechanisms for Insulin

Insulin appears to work without second messengers generated when a hormone binds to a receptor on the plasma membrane of its tissue cells, referred to as target cells.

A hormone stimulus typically produces one or more of the following changes:

1. Alters plasma membrane permeability or membrane potential , or both, by opening or closing ion channels.

2. Stimulates synthesis of proteins or regulatory molecules such as enzymes within the cell.

3. Activates or deactivates enzymes.

4. Induces secretory activity.

5. Stimulates mitosis.

The insulin receptor is a tyrosine kinase enzyme that is activated by autophosphorylation (addition of the phosphate complex ion to several of its own tyrosines ) when insulin binds. This activated insulin receptor provides docking sites for intracellular relay proteins that, in turn, initiate a series of protein phosphorylations that trigger specific cell responses.

The phosphorylated proteins begin the cascade that leads to increased glucose uptake by the cells in the body.

After glucose enters a target cell, insulin binding triggers enzymatic activities that:

1. Catalyzes the oxidation of glucose for ATP production.

2. Join glucose molecules together to form glycogen.

3. Convert glucose to fat (particularly in adipose tissue.)

Signals, whether neural, hormonal or both are important to homeostasis and your health.

Nervous System and Endocrine System Connection

Central Nervous System and Endocrine System Connection

Whenever we get the "Devil" scared out of us...so to speak, our body instantaneously, it seems, prepares us to runaway, fight, or prepare for another reaction...right away. 

The system which is part of our Nervous System that does this is the Sympathetic Branch of our Autonomic Nervous System.

After we have had a moment to assess our emergency situation our Endocrine System prolongs the same preparedness that our Nervous System provided immediately.

This "dual" control helps keep us alive and well! Who wants Lucifer after us!

Our body is controlled by a whole series of "on-off" switches called negative feedback controls. Basically, if one control mechanism speeds us up there is another control that slows us down. Much like the autonomic nervous systems two branches.

The other branch of the Autonomic Nervous System that slows us down is the Parasympathetic Branch. Remember, the Sympathetic Branch is the one that prepares you for the "Flight, Fright, and Frolic" response. It doesn't know which one of those three it is preparing the body for...that is up to your mental reasoning to assess the situation and select accordingly.

For instance, if the danger passes the Parasympathetic Branch begins to return your body to its "relaxed state." If you want to make a comparison to the glucose in your body think of what glucose provides to each cell that makes up your muscles. Muscles that you may need to run away from danger.

Your body immediately begins to dump glucose into the bloodstream from the liver to provide each cell with glucose to maufacture ATP, a very important high energy chemical used to help muscles contract properly.

When the danger is past, insulin helps return any excess glucose (above the amount you normally use for everyday functions) back to the bodys storage centers for later use.

This whole process is part of something far larger called Homeostasis. Your body has a normal concentration for glucose in the bloodstream. During the course of a day this value flucuates slightly above and below the normal value. The attempts to regulate the normal values for everything associated with life is Homeostasis!

The Unknown Factor with Hormone Medication

Hormone Medication - It is Global

We hear, especially in Sports, steroid this-steroid that and how it does this and that. They forget one important word - Global. 

Endocrine glands secrete into the bloodstream. What the gland produces affects every cell in the body that is nourished by the circulatory system. 

This is very different from an exocrine gland that secretes its product into a duct, not the bloodstream.

 In many situations the uninformed that take steroids for anabolic purposes (building up muscle tissue)have no clue what might be happening in their brain tissue, for example. What happens when you stop taking a hormone suddenly? Does your body and personality change? Maybe. Maybe not. Ask as many questions as you can about the global affects of hormone treatment.

A very good example of that is the hugh database of information on the birth control pill. The statistics from a large number of women, on the pill, are reliable. Word of mouth isn't reliable, it is just an opinion. That is why pharmaceutical companies go to great lengths to put, in writing, all the possible warnings of what their drug may do in your body. It is protects the drug company from some legal actions.

Insulin is a hormone. Please see a Diabetologist about how insulin may result in other changes in you. It is "global" too.

Beta Cells can overstretch like a Slinky Toy!

Hyper-stimulation of Beta Cells in the Pancreas

We talked about how important Insulin is in Glucose control. If you contiually stimulate your Beta Cells in the Pancreas they will enlarge and lose their ability to produce Insulin. 

This is likened to stretching a Slinky Toy too much so it doesn't return to normal to perform its function...entertaining you!

By eating the "wrong" foods (consult your Diabetologist for the "right" foods) the Beta Cells enlarge (thats called hypertrophy) and lose the ability to produce insulin when you need it. (Beginning of Diabetes)

Your job is to watch what you eat, monitor your blood sugar as instructed, exercise and live your life! The Alpha Cells produce the hormone Glucagon. It causes glucose manufcturing to start when you blood glucose concentration drops below normal levels temporarily. That condition is called Hypoglycemia, a  word that means your blood sugar is too low. If you are taking insulin and you take too much, it can cause a temporary condition of hypoglycemia.