Carbohydrate Metabolism Overview

Abundant organic molecules, primarily found in plants, providing energy as sugars and starch. They also have structural roles in cells and tissues, and are components of RNA and DNA.

Carbohydrates composed of monosaccharides and disaccharides.

Polymers of saccharide units linked by glycosidic bonds. Oligosaccharides have 3-10 units; polysaccharides have more than 10.

The small intestine has folds (Kerckring's folds), villi (finger-like projections), and microvilli (extensions of cells) that increase its surface area for nutrient absorption.

Finger-like projections in the small intestine, lined with cells (enterocytes), containing blood capillaries and lymph vessels for nutrient transport.

Cells lining the villi in the small intestine that absorb nutrients and transport them into the bloodstream or lymph.

Hair-like extensions of enterocyte plasma membranes on the villi, significantly increasing the surface area for nutrient absorption.

The part of an enterocyte's membrane facing the intestinal lumen (inside of the gut).

Process of transferring simple sugars from the gut into the bloodstream.

The thin boundary layer surrounding a cell.

Membrane proteins that actively transport glucose and sodium together into cells.

Membrane proteins that facilitate glucose transport across cell membranes by passive diffusion.

Primarily responsible for absorbing glucose and galactose from the gut (intestine) into enterocytes.

Movement of molecules across a membrane that requires energy input from the cell.

Movement of molecules across a membrane from high to low concentration, with help from carrier proteins, but no energy required.

A glucose transporter that crosses the blood-brain barrier and is essential to the developing brain.

Supplies glucose to erythrocytes, brain endothelial cells, and fetal tissues.

Causes seizures early in infancy due to lack of glucose to the brain, requiring a ketogenic diet.

Low-affinity, high-capacity transporter of monosaccharides in pancreas, liver, intestine, & kidney. Transports glucose/fructose when levels are high.

Sensitive glucose level indicator and involved in insulin release.

High-affinity glucose transporter in brain and neurons, also in spermatozoa, placenta, and early embryos.

Insulin-dependent glucose transporter in muscle and adipose tissue, not in liver, kidney.

Insulin moves GLUT4 from storage vesicles to the cell membrane for glucose uptake.

Specific fructose transporter, primarily in small intestine; also in kidney, brain, muscle, and adipose.

A coordinated effort of multiple organs (intestine, liver, kidney, muscle, adipose) to maintain normal blood glucose levels.

GLUT2 is involved in the movement of monosaccharides from enterocytes into the portal blood. This process is important for the absorption and distribution of these crucial nutrients.

The process of converting glucose into glycogen, which is a storage form of glucose primarily in the liver and skeletal muscles. This allows the body to store energy for later use.

The process of converting stored glycogen back into glucose. This occurs mainly in the liver, releasing glucose into the bloodstream to maintain blood sugar levels.

Muscle glycogen is primarily used as an energy source within the muscle itself, while liver glycogen is released into the bloodstream to maintain blood glucose levels.

A phosphorylated form of glucose, produced by the enzyme hexokinase in most cells. This molecule is a key intermediate in various metabolic pathways.

Hexokinase, the enzyme that converts glucose to glucose-6-phosphate, is regulated by the product of the reaction. This means that when cells have enough glucose-6-phosphate, the entry of glucose into the pathway is slowed down.

The process of maintaining stable blood glucose levels through hormonal and metabolic actions.

The primary hormone that lowers blood glucose by promoting glucose uptake into cells, especially muscle and adipose tissue.

The primary hormone that raises blood glucose by stimulating glycogen breakdown in the liver.

The process of converting glucose into glycogen for storage in muscle and liver.

The process of breaking down stored glycogen into glucose, primarily in the liver.

The process of synthesizing glucose from non-carbohydrate sources, such as amino acids and fatty acids, in the liver.

A condition where cells are less responsive to insulin, leading to impaired glucose uptake and potentially elevated blood glucose levels.

High blood glucose levels, often associated with diabetes.

Insulin is released, promoting glucose uptake into cells, lowering blood glucose levels.