lec 18-Glucose Homeostasis Practice Flashcards

These vocabulary flashcards cover the essential terms and concepts of glucose homeostasis, including metabolic pathways, enzymatic reactions, and hormonal regulation as discussed in Lecture 18 by Dr. Lauren Albee.

Physiological circulating concentration of glucose

The average range of blood glucose in a healthy individual, typically between $3.9-6.7\,mM$, with most adults fasting at $4.4-5\,mM$.

Pentose phosphate pathway

A metabolic pathway that converts glucose to pentose sugars for nucleotide synthesis and reduces $NADP$ to $NADPH$ for synthetic reactions requiring reducing power.

Osmotically active

A property of glucose that can cause water to move into or out of cells; in high concentrations, it can lead to cell damage or dehydration.

Liver glycogen

A medium-term fuel source ($100-120\,g$) sensitive to blood glucose concentration, used to maintain homeostasis under the control of insulin and glucagon.

Muscle glycogen

A fuel source for exercise ($250-300\,g$) sensitive to the energy needs of the tissue, regularized by adrenaline, calcium, $AMP$, and $ATP$.

$\alpha$-1,4 glycosidic bonds

The chemical bonds that link glucose units together in the main linear chains of a glycogen molecule.

$\alpha$-1,6 glycosidic bonds

The chemical bonds that create branch points in the glycogen structure, catalyzed by the branching enzyme.

UDP glucose

The 'activated' intermediate required for glycogen synthesis, formed from glucose 1-phosphate and $UTP$.

Glycogen synthase

The enzyme responsible for adding $UDP$-glucose to a pre-existing glycogen chain during synthesis; it is activated by insulin.

Glycogen phosphorylase

The enzyme that catalyzes the phosphorolysis of glycogen to produce glucose-1-phosphate during glycogen breakdown.

Glucose-6-phosphatase

An enzyme present ONLY in the liver and kidney that allows the release of free glucose into the blood from glucose-6-phosphate.

Gluconeogenesis

The synthesis of glucose from non-carbohydrate sources (lactate, glycerol, and glucogenic amino acids) in the liver during carbohydrate deprivation.

Pyruvate carboxylase

A mitochondrial enzyme that carboxylates pyruvate to yield oxaloacetate in a reaction requiring $ATP$.

PEP carboxykinase

An enzyme that converts oxaloacetate into phosphoenolpyruvate ($PEP$) in a reaction requiring $GTP$ and releasing $CO_2$.

Cori cycle

The metabolic process where lactate produced in the muscle is converted back to glucose in the liver and returned to the muscle.

Lactate dehydrogenase

The enzyme responsible for converting lactate to pyruvate during the Cori cycle.

Islets of Langerhans

The endocrine portion of the pancreas containing alpha cells (which secrete glucagon) and beta cells (which secrete insulin).

Anabolic hormone

A hormone, such as insulin, that promotes the synthesis and storage of fuel sources in the body.

Catabolic hormone

A hormone, such as glucagon, that promotes the degradation of stored fuels to increase blood glucose levels.

GLUT4

Glucose transporters that insulin causes to translocate from the cytosol to the cell membrane in muscle tissue to increase glucose uptake.