Carbohydrate Metabolism Flashcards
(28 cards)
What are monosaccharides and what 3 molecules are they?
Simplest carbohydrates that are aldehydes or ketones with 2 or more hydroxyl groups
Glucose, fructose and galactose
What are disaccharides and what 3 molecules are they?
2 sugars joined by an a-glycosidic bond
Lactose (glucose-galactose)
sucrose (glucose-fructose)
maltose (glucose-glucose)
What are polysaccharides and what molcules are they?
2 or more sugars joined by glycosidic bonds eg starch, glycogen and cellulose
What is glycogen?
The storage form of glucose
Where in the body is glycogen stored?
In the liver and muscle
Where in the cell is glycogen stored?
In the cytosol in the form of granules
What do glycogen granules contain and what are they used for?
Enzymes for degredation of glycogen (glycogen phosphorylase) and glycogen synthesis (glycogen synthase)
What are the different functions of liver and muscle glycogen?
Liver glycogen regulates blood glucose
Muscle glycogen supplies energy
What hormone promotes glycogen synthesis?
Insulin
What hormone promotes glycogen breakdown?
Glucagon and adrenalin
What are the 5 different fates of glucose when uptaken into cells?
Converted to and stored as glycogen in the liver
Metabolized to CO2 and H20 to provide energy
Converted to ketone bodies
Converted to amino acids/proteins
Converted to fat (triglycerides) and stored as adipose tissue
What is glycogenesis?
The conversion of glucose to glycogen
What is glycogenolysis?
The breakdown of glycogen to glucose
What is gluconeogenesis?
The synthesis of glucose from non carbohydrate sources eg amino acids, glycerol, lactate
What is glycolysis?
Glucose to pyruvate or lactate
What range are blood glucose levels maintained in?
4.4-6.6mM (4.4 before meal, 6.6 after meal)
Blood glucose levels are primarily maintained by what organ?
The liver
Where is insulin synthesized?
By the B-cells of the pancreas
What does release of insulin stimulate/inhibit?
Glycogen synthesis in liver and muscle
Uptake of glucose by muscle and adipose tissue
Stimulates glycolysis in liver (inhibits gluconeogenesis in liver)
Stimulates triglyceride storage in adipose tissue
Overall lowers BG concentrations
What enzyme does insulin activate to lower blood glucose levels?
Glycogen synthase
When is insulin secreted?
When blood glucose levels rise
Where is glucagon secreted?
By the a-cells of the pancreas
When is glucagon secreted?
In response to low blood glucose levels
Glucagon targets what main organ?
The liver
