Roesler final section Flashcards
Glucose can ultimately be converted into what three metabolic fuels?
glycogen
amino acids
fatty acids/ triacylglycerols
Fatty acids can be converted into what other fuel in humans?
ketone bodies
Amino acids can be converted into what 3 fuels?
Glucose / glycogen
fatty acids/ triacylglycerols
ketone bodies
What is the most highly concentrated form of stored biological energy?
triacylglycerols
Explain the major metabolic processes in the liver involving glucose?
- glucokinase in liver is not inhibited by glucose 6p
- liver has a high capacity for glucose metabolism
- glucose 6 phosphate is the main metabolism in the liver
- liver exports glucose to maintain blood sugar levels for brain
In a fed state, what is the liver using glucose for?
glucose will go towards:
- ATP production (small %)
- glycogen
- fatty acids
- cholesterol
- NADPH
- nucleotides
In a fasting state, how is the liver maintaining blood sugar levels?
- glycogen and gluconeogenesis are making glucose
What 3 unique features of the liver contribute to it acting as a glucose sensor?
- liver has a specific glucose transporter GLUT2 which has a high KM for glucose meaning it can respond to high glucose concentrations
- liver has a specific hexokinase called glucokinase that has a high KM for glucose and is not inhibited by glucose 6p
- Liver glycogen phosphorylase A is inhibited by glucose
In a fed state, what is the liver using amino acids for?
- to make proteins in the liver
- to make nucleotides
- exports excess amino acids elsewhere
In a fasting state, what is the liver using amino acids for?
- making glucose
- making a small % of ATP
In a fed state, what is the liver using fatty acids for?
- converting them to triacylglycerols and phospholipids
In a fasting state what is the liver using fatty acids for?
- MAJOR source of ATP
- Ketone body formation when needed
during prolonged fasting, what provides as much as 70% of the energy in the brain?
ketone bodies
In a fed state, what are fat cells using glucose for?
- making a small % of ATP
- making acetyl COA and DHAP which eventually get converted into triacylglycerols
- making NADPH
In a fasting state, what do fat cells do to triacylglycerols?
breaks them down to get energy, making fatty acids and glycerol
What are the major metabolic processes in muscle cells?
- maximum activity - glucose is the main fuel
- since muscle lacks glucose 6 phosphatase, the glucose released from glycogen is metabolized through glycolysis
- rate of glycolysis exceeds that of the TCA cycle making excess lactate
- cori cycle uses lactate to make glucose in the liver
- basically every metabolic proesses in muscle makes ATP or expels waste (lactate)
The heart obtains most of its ATP through oxidative phosphorylation using _____
fatty acids
What are the three major metabolic hormones?
insulin, glucagon and epinephrine
Which two metabolic hormones are synthesized in the pancreas?
- insulin and glucagon
Does muscle respond to glucagon?
no because muscle cells do not have glucagon receptors
the most common fuel used by most tissues isssss
fatty acids
What are the two targets of glucagon?
liver and adipose tissue
What gets synthesized under extreme fasting?
ketone bodies
What metabolic processes increase when glucagon is released? (4)
- glycogenolysis
- triacylglycerol hydrolysis - lipolysis
- gluconeogenesis
- ketogenesis
What are the three main targets of epinephrine?
liver, muscle, adipose
What does epinephrine do in liver?
stimulates glycogen breakdown and glucose release
What does epinephrine do in adipose tissue?
- stimulates TAG breakdown and fatty acid release
What does epinephrine do in muscle?
stimulates glycogen breakdown and glycolysis
What is the main difference between epinephrine and glucagon?
epinephrine acts on muscle whereas glucagon doesn’t because muscle has no glucagon receptors
What is the only metabolic pathway that is inhibited by epinephrine?
glycogen synthesis
insulin stimulates ___ uptake by tissues
glucose
Most cases of diabetes in north America are type ___
II
What is the blood glucose level in mM that may indicate diabetes?
7mM
What test measures the amount of blood sugar attached to your hemoglobin proteins?
HbA1C
If insulin is absent or non functioning, glucose cannot enter cells so all energy must be derived from ___, leading to the production of _____. What does this mean / lead to?
- derived from fats, leading to acetyl coa production
- because glucose is used to make oxaloacetate (?) there is insufficient amounts to react with acetyl coa from fatty acid oxidation
- so acetyl CoA builds up bc oxaloacetate cannot replenish the TCA cycle
- acetyl coa will be used for ketone body production
- can lead to diabetic ketoacidosis
What two processes does insulin stimulate in the liver?
glycolysis and fatty acid synthesis
What two tissues are not insulin dependent?
brain and liver
