Nutrition Metabolism Review - Skildum Flashcards
What accounts fro the majority of the chemical energy in your body?
Triacylglycerol
What is the brain’s primary energy sources?
Glucose and ketone bodies
What is the storage form for glucose, AA, and fats?
Glucose = glycogen, TAG AA = protein Fats = TAG
How long is the fed state? What is the hypercatabolic state?
Fed: Lasts 2-4 hours after a meal
Fasted: Overnight without eating
Starved: Prolonged fasting
Hypercatabolic: Trauma, sepsis, etc.; not related to meals
What process dominates the starvation state?
Fatty acid metabolism
Insulin is released from what type of cell?
Pancreatic beta cells
(T/F) The relative amount of carbohydrates in the meal doesn’t determine the ratio of insulin to glucagon.
The relative amount of carbohydrates in the meal determines the ratio of insulin to glucagon.
High carbs More insulin
High protein Less insulin, more glucagon
After feeding, what does the liver do?
The liver is the primary organ responsible for maintaining glucose homeostasis. After eating a carbohydrate rich meal, . . .
. . .biosynthetic pathways that produce glucose (glycogenolysis, gluconeogenesis) are inhibited.
. . .metabolic pathways that store glucose (fatty acid biosynthesis, cholesterol biosynthesis, protein synthesis, glycogenogenesis) are activated.
After eating a protein rich meal, elevated amino acids in the blood increase the secretion of glucagon by pancreatic alpha cells. In this case, excess amino acids are used by the liver for gluconeogenesis.
After feeding, what is the function of these organs?
Brain:
RBCs:
White adipose cells:
Brain:
Oxidizes glucose to CO2 to make ATP through oxidative phosphorylation.
Red blood cells:
Ferments glucose to pyruvate; exports lactate.
White adipose cells:
Ferments glucose to glycerol 3-phosphate, the backbone for triacylglycerol synthesis.
Fed or fasted state?
Skeletal muscle
Glycolysis, fatty acid beta oxidation, glycogenogenesis, protein synthesis
Cardiac muscle
Fatty acid beta oxidation (60-80%); Oxidation of glucose and lactate (20-40%).
Fed
What is the function of these cells during the fed state?
Intestinal epithelial cells:
.
Colonocytes:
Intestinal epithelial cells
Convert glutamine, glutamate and aspartate from the diet to a-ketoglutarate.
Colonocytes (gut epithelial cells of colon)
Use short chain fatty acids produced by gut bacteria.
What cells produce glucagon and what are its downstream effects?
The glucagon receptor is a seven transmembrane domain heterotrimeric G protein coupled receptor.
Ligand binding causes activation of adenylate cyclase, production of cAMP, and activation of PKA.
During the fed state, what does the liver do with respect to glycogenolysis, gluconeopgenesis, ATP, and acetyl CoA?
The liver increases production and export of glucose for use by other tissues.
Glycogenolysis uses hepatic glycogen stores.
Gluconeogenesis uses carbon skeletons from amino acids, lactate, and glycerol to produce glucose.
The ATP to power gluconeogenesis comes from the FAD(2H) and NADH reduced by fatty acid beta oxidation.
The acetyl CoA produced by fatty acid beta oxidation is a substrate for ketone body synthesis.
After an overnight fast, what’s happening in these organs?
Skeletal muscle
Cardiac muscle
Skeletal muscle:
Proteolysis produces free amino acids. Branched chain amino acids are used by the muscle as fuel. Alanine and glutamine are exported for use as gluconeogenic substrates by the liver.
As the fast prolongs, skeletal muscle can use ketone bodies for energy.
Cardiac muscle:
Fatty acid beta oxidation increases; glycolysis decreases.
Do gut epithelial cells still use glutamine as their primary fuel in the fasted state?
Yes. Gut epithelial cells still use glutamine as their primary fuel in the fasted state, but it comes from the blood, not the lumen of the gut.
