L6 - Insulin Control in Health and Diabetes

Flashcards to review the function of glucose, cell types involved in diabetes, and treatments.

Glucose Homeostasis

Keeps blood glucose at a level of about five to five and a half millimolar, critical for brain function.

Skeletal Muscle and Fat

Major sites for glucose storage.

Liver

Organ capable of both making and releasing glucose into the blood.

GLUT4 Transporters

Transporters present on fat cells and skeletal muscle for glucose uptake.

GLUT2 Transporter

Transporter present in the liver, facilitating glucose uptake when blood glucose is high and release when it is low.

Beta Cells

Cells in the islets that secrete insulin, possessing GLUT2 transporters to detect high or low glucose levels.

Alpha Cells

Secrete glucagon and require the detection of low glucose levels, with the mechanism still being unraveled.

Type 1 Diabetes

An autoimmune disease where beta cells are destroyed.

Type 2 Diabetes

A metabolic disease where beta cells are still present.

Insulin

Hormone that regulates blood glucose, and without it, there is no control over glucose levels.

Most of the Pancreas

Secrete digestive enzymes (exocrine function).

Islets of Langerhans

Small structures dotted throughout the pancreas, consisting of endocrine cells responsible for the endocrine function.

Beta Cell

Predominant cell in the Islet of Langerhans, responsible for detecting changes in blood glucose.

Primary Function of a Beta Cell

Looking at changes in blood glucose and stimulating the beta cell to respond and increase insulin when glucose levels go above 5.5 millimolar.

Rise in Amino Acids

Can drive insulin secretion through an alternate route.

Hormones

Can change the beta cell's behavior; can increase or decrease insulin secretion.

Stimulus Secretion Pathway

The primary stimulus in a beta cell is glucose; the primary output is the secretion of insulin.

GLUT2 Transporter in Beta Cells

Same transporter as in the liver, allowing glucose to come into the cell, and the beta cell needs to know if glucose is too high or too low.

Metabolism of Glucose

Normal metabolic process in the beta cell, where glucose goes through the mitochondria and leads to the generation of ATP.

KATP Channel

Detects the change in ATP; sensitive to ATP on its internal surface; when ATP goes up, the channel closes.

Potassium Channels

Maintain a negative membrane potential.

Action Potentials in a Neuron

Triggered due to the closure of potassium channels and the opening of sodium channels.

Voltage Dependent Calcium Channel

Main conductance activated when cells go more positive; abbreviated to VDCC.

Elevation of Cytosolic Calcium

Triggers the fusion of insulin-containing granules with the cell membrane, releasing insulin to the outside.

Beta Cell Function

What a beta cell is doing: looking at changes in blood glucose, and if it detects changes above that set point of 5.5 millimolar, that will stimulate the beta cell.

Secretion in Response to an Injection of Glucose

Secretion in response to glucose. That's a normal control.

Ozempic

Was specifically developed to help with type two diabetes and increase the amount of insulin that's being secreted in type two diabetes.

Content in Gut

Stimulates secretion of the hormone GLP-one.

GLP-one

Can enhance calcium channel activity.

Before the Glucose Goes In

The beta cells are ready for it; they've got the GLP-one there, they know that something's coming, you've upregulated the cyclic AMP.

Autoimmune Disease

The body is not recognizing the beta cells as being part of the body. They're treating them as if the beta cells are foreign.

T Cell Response

The T cells are actually specifically targeting the beta cells and kill them.

Continuous Glucose Monitor

The continuous glucose monitor is telling you about that would be hidden if you were just sampling five times a day.