Chapter 19 Regulation of Mammalian Fuel Metabolism and signaling Flashcards
Following a meal, the liver takes up _______ and converts it into _______
glucose
glycogen for storage
Muscle cells take up glucose when
it is available and store it as glycogen
Excess glucose and amino acids are catabolized to
acetyl-CoA
Acetyl-CoA is used to synthesize
fatty acids
Fatty acids are esterified to ______ and are exported to ______
triacylglycerol
adipose tissue
During a fast, the liver
mobilizes glucose from glycogen stores and releases it into the circulation for other tissue to use
What organ deals with lactate and alanine produced by muscle activity
liver
converts into glucose and disposes of Amino groups through urea synthesis
In a shortage of glycogen, triacylglycerols are broken down into
acetyl-CoA
converted into ketone bodies to power brain and heart
The cori cycle involves what two organs
liver and muscle
What does the cori cycle do
transfers free energy from the liver to the muscles
The glucose-alanine cycle includes what two organs
liver and muscle
Role of the glucose-alanine cycle
transport nitrogen from muscles to the liver
The human body buffers itself against fluctuations in fuel supply by
storing metabolic fuels, mobilizing as needed and replenishing them after a meal
The activities of organs that store and release fuels are coordinated by
hormones
The most important hormone involved in fuel metabolism are
insulin
glucagon
catecholamines-epinephrine and norepinephrine
Insulin’s role
regulating fuel metabolism by stimulating glucose uptake and inhibiting glycogen breakdown
lack of insulin or inability to respond to it results in
diabetes mellitus
increase in circulating glucose triggers
insulin release
Effect of insulin on muscle and other tissues
promotes glucose transport into the cell
stimulates glycogen synthesis
suppresses glycogen breakdown
Effect of insulin on adipose tissue
activates extracellular lipoprotein lipase
increases level of acetyl-CoA carboxylase
stimulates triacylglycerol synthesis
suppresses gluconeogenesis
Effect of insulin on the liver
promotes glycogen synthesis
promotes triacylglycerol synthesis
suppresses gluconeogenesis
In short insulin signals
uptake of glucose and storage of glucose and fats
Insulin is synthesized in the
beta cells of pancreatic islets
The rate of glucose transport into cell increases, not because insulin alters the intrinsic catalytic activity of the transporter but because
insulin increases the number of transporters (GLUT4) at the cell surface
Kinases transfer a
phosphoryl group from ATP to another molecule
How do the two tyrosine kinase domains of insulin receptor tyrosine kinase get phosphorylated
they phosphorylate each other using ATP as the source of phosphoryl groups
the insulin signaling pathway alters the activity of glycogen ____ and glycogen _____
synthase
phosphorylase
synthesis carried out by glycogen synthase
UDP-glucose + glycogen (n residues) ->
UDP + glycogen (n+1 residues)
glycogen phosphorylase
glycogen (n residues) + Pi ->
glycogen (n-1 residues) + glucose-1-phosphate
mTOR is activated by
insulin
affects of mTOR being activated
ribosome production
protein synthesis
nucleotide synthesis
lipid synthesis
glycolysis
reduced autophagy
reduced proteasome assembly
When the liver must mobilize glucose in order to keep blood glucose concentrations constant what hormones govern this
epinephrine and norepinephrine
Glucagon
G protein coupled receptors bind
guanine nucleotides
GTP and GDP
Antagonist of adenosine receptor
natural adenosine
caffeine also antagonizes
What is the second messenger of G protein coupled receptors
cyclic AMP
What enzyme is used to turn ATP into cyclic AMP
adenylate cyclase
AMP dependent protein kinase (AMPK) is activated by
cAMP
AMPK in the hypothalamus does what
increases food intake
AMPK in the liver does what
increases glycolysis
increases FA oxidation
decreases glycogen synthesis
decreases gluconeogenesis
What turns off cAMP-dependent signaling
phosphodiesterase
how does phosphodiesterase turn off cAMP-dependent signaling
hydrolyzing cAMP to AMP
Brown adipose is full of
mitochondria for generating heat especially in newborns and hibernating animals
The aldose reductase reaction does what
turns glucose into sorbitol
During fuel abundance, excess ____ is (are) catabolized to acetyl-CoA, which is used in fatty acid synthesis
glucose and amino acids
insulin is released from pancreatic __ cells in response to ____ blood glucose
beta
high
Which enzyme is the better sensor of glucose concentration
glucokinase
The initial effect of insulin binding on muscle cells is the translocation of
GLUT4
The reaction of adenylate cyclase produces the molecule
cAMP
Which organ has the capacity to generate glucose through gluconeogenesis
liver
kidneys
The cori cycle functions to synthesize
glucose in the liver to replenish glucoses in the muscle
Glycogen phosphorylase is allosterically ____ by ATP
inhibited
The hormone _____ stimulates liver to generate glucose by glycogenolysis and gluconeogenesis
glucagon
The hormone ___ stimulates lipolysis in adipocytes
glucagon
The hormone ____ stimulates muscle to generate glucose by glycogenolysis
epinephrine
The G protein that responds to epinephrine binding to the beta 2-adrenergic receptor
mediates the activation of second messenger production
Insulin receptor can ______ and is a _____
auto phosphorylate
tyrosine kinase
