Flashcards in B2.041 Metabolism and its Regulation Pt. 1 Deck (55)
what is caloric homeostasis?
in both the fed state and fasting, a healthy body keeps the same amount of "calories" available in the blood
what are calories?
fuel that can be metabolized to do work
what are the negative consequences of having too much fuel in the blood?
generation of too many electrons via oxidation that react with oxygen to produce ROS
what types of fuel does the body utilize?
carbs (glucose, fructose, galactose)
fat (triacylglycerols, free fatty acids, ketone bodies)
protein (20 amino acids)
where are fuels primarily stored?
adipose (triacylglycerol and triglycerides)
what drives the starve-feed cycle?
increase in ADP concentrations drives fuel oxidation and oxygen consumption (respiration)
conversion of glucose to pyruvate or lactate
conversion of glucose to glycogen
conversion of carbon of glucose and amino acids to fat
what is the function of the pancreas in the well fed state?
pancreatic B cells produce insulin
how does the liver process fuel in the well fed state?
liver is glycogenic, glycolytic, and lipogenic
how does the muscle process fuel in a well fed state?
muscle is glycogenic
how does adipose tissue process fuel in a well fed state?
adipose is lipogenic and stores TAG
how do red blood cells derive energy?
need constant supply of glucose for anaerobic respiration, no mitochondria
what is the function of the pentose phosphate pathway?
NADPH is a reducing agent that keeps glutathione reduced and fights oxidative stress
list the glucose transporters and their locations in the body
GLUT3- brain tissue
GLUT4- adipose, muscle, heart
how do blood glucose and liver glucose compare?
very similar bc all blood filtered through liver via portal vein
what do glucuronides do?
solubilize insoluble compounds
how does the body lower the amount of fuel in the blood during the well fed state?
synthesis and storage of glycogen in the muscle and liver
synthesis of fat in the liver, release of fat into the blood, uptake and storage of fat in the adipose tissue
what state is the body locked in during obesity?
due to overconsumption of high energy fuels
what is the relationship between insulin and glucagon in obesity?
insulin is very high
glucagon is very low
high I/G ratio
drives fat synthesis
what is the rate limiting enzyme for fatty acid synthesis?
acetyl CoA carboxylase
what is lipogenesis from glucose?
occurs in liver in well fed state
requires lots of glucose for glycolysis to produce pyruvate and for the pentose phosphate pathway to produce NADPH
why does lipogenesis require mitochondria?
formation of citrate which carries acetyl groups from the mitochondrial matrix space to the cytosol for fatty acid synthesis
for what tissues is glucose a primary fuel?
brain, RBCs, white muscle, kidney medulla, macrophages
for what tissues are fatty acids an important fuel?
heart, skeletal muscle, liver, kidney
why are ketone bodies important?
4 carbon compounds made from fatty acids
water soluble fat calories
important in heart, skeletal muscle, and kidney
for what tissues are amino acids an important fuel?
liver and gut (glutamine)
what is the distinction between heavy calories and light calories?
heavy calories: 1 lb of glycogen = 4 lbs total due to water uptake
light calories: 1 lb of fat = 1 lb due to fat being dry and not taking up water