Overview of Metabolism Flashcards
catabolic
breakdown of compounds to produce energy
examples of catabolic pathways
glycolysis, TCA cycle, oxidative phosphorylation, fatty acid catabolism, amino acid oxidation
anabolic
use energy to produce biomolecules
anabolic pathways
gluconeogenesis, lipid biosynthesis, amino acid biosynthesis, nucleotide biosynthesis
regulated steps
reactions are far from equilibrium (can not go forward and reverse with same molecules)
allosteric effectors mediate _
local effects (cell status)
hormones mediate _
systemic effects (needs of body/organism)
glycolysis
glucose –> 2 pyruvate
gluconeogenesis
pyruvate –> glucose
What stimulates PFK?
F2,6BP and AMP
What inhibits PFK?
ATP, citrate, H+
What inhibits F-1,6-bisphosphatase?
F2,6BP and AMP
What stimulates F-1,6-bisphosphatase?
citrate
What activates pyruvate kinase?
F-1,6-BP
What inhibits pyruvate kinase?
ATP and alanine
What activates pyruvate carboxylase?
acetyl CoA
pyruvate carboxylase
pyruvate –> oxaloacetate
What inhibits pyruvate carboxylase?
ADP
What inhibits PEP carboxykinase?
ADP
PEP carboxykinase
oxaloacetate –> PEP
proteins kcal
4kcal/gram
carbohydrates kcal
4kcal/gram
fats kcal
9 kcal/gram
US dietary guidelines
45-65% carbohydrates
10-35% proteins
>10% fats
energy balance equation
calories consumed-calories used
biggest factor in weight gain
carbohydrates
biggest factor in weight loss
resting metabolic rate
average male calorie intake
2700 kcal/day
average female calorie intake
2200 kcal/day
resting metabolic calorie use
60-70% of total calories (20% in brain)
glycogen
provides energy for muscles and brain (quick energy)
adipose
provides long term storage energy
brain can only use _ as fuel
glucose, lactate, or ketone bodies (no fat)
What can not use ketones for fuel?
RBC, WBC, marrow
Why does muscle store glycogen?
to supply glucose for contraction
leptin
inhibits appetite
leptin is release by _
fat cells
leptin acts on _
hypothalamus
ghrelin
stimulates appetite
ghrelin is produced by _
stomach in response to food intake
ghrelin acts on _
hypothalamus
cholecystokinin
acts as neuropeptide in CNS and suppresses appetite
cholecystokinin is released by _
duodenum
cholecystokinin action
stimulates release of bile and secretion of digestive enzymes and inhibits gastric emptying (prevents food from leaving to allow enzymes to act)
peptide Y
suppresses appetite
peptide Y is released by _
ileum and colon in response to food intake
peptide Y action
inhibits gastric motility, increases nutrient, water, and electrolyte absorption
incretins (GLP-1, GIP)
stimulate insulin secretion in response to food intake
incretin effect
oral glucose elicits a higher insulin response than intravenous glucose
saliva produces _
alpha-amylase and lingual lipase
alpha-amylase
catalyzes hydrolysis of starch into di- and trisaccharides
lingual lipase
catalyzes hydrolysis of medium and long chain triglycerides
parietal cells
secrete HCl, lowering pH
chief cells
secrete pepsinogen
What induces secretion of gastric acid?
acetylcholine, histamine, and gastrin
rantidine
H2 anatagonist, preventing histamine from activating protein kinase pathway, making the stomach less acidic
digestion occurs in _
small intestine
secretin
regulates pH of duodenum and inhibits secretion of gastric acid by parietal cells; stimulates bicarbonate production in pancreatic duct cells
pancreas secretes _ in the aid of protein digestion
trypsinogen, chymotrypsinogen, and procarboxypeptidase
stomach secretes _ to aid in digestion of proteins
pepsin
digestion of carbohydrates
pancreatic alpha-amylase breaks starch and glycogen into disaccharides (maltose, lactose, sucrose)
sucrase
breaks sucrose into fructose + glucose
maltase
breaks maltose into 2 glucose
maltase
breaks maltose into 2 glucose lactase
lactase
breaks lactose into glucose + galactose
digestions of fats
bile acids, lipase, colipase
bile acids
synthesized in liver and secreted from gallbladder; solubilize fats in small intestine
lipase and colipase
bile inhibits lipase so colipase binds to keep active; secreted by pancreas and cleaves triglycerides
exocrine pancreatic insufficiency
enzymes not released properly –> food is not digested –> no nutrients absorbed
exocrine pancreatic insufficiency treatment
pancreatic enzyme replacement, high-calorie high-fat diet, and vitamins
exocrine pancreatic insufficiency symptoms
weight loss, abdominal pain, bloating, diarrhea, vitamin K and D deficiency
absorption of monosaccharides
facilitated diffusion (fructose) or secondary active transport (glucose)
absorbed monosaccharides leave epithelial cells by _
facilitated diffusion to enter blood (passive)
lipid uptake
lipids cross freely through membrane due to hydrophobicity; form chylomicrons that enter lacteal and are transported away from intestine
increased iron in blood
activates HFE for hepcidin production –> hepcidin induces endocytosis of ferroportin –> ferroportin is in the cell and iron can not get out
water soluble vitamins
B and C; absorbed directly into blood and excreted in urine
fat-soluble vitamins
A, D, E, K; absorbed first into lymph then blood but requires protein carriers; not excreted, stays in fat-storage sites