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44 Cards in this Set

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What are the three main types of fuels?
carbohydrate, protein, and fat
What element is the common crossroad for getting energy from fats, proteins, and carbohydrates?
acetyl-CoA
What happens to acetyl-CoA?
it is used up in the TCA cycle
What does Acetyl-CoA being used in the TCA cycle produce?
2CO2, 3 NADH, and FADH2
What are the four stages of producing energy from carbohydrates, proteins, or fat?
Stage 1: Glucose, amino acids, and fatty acids…………………………….Stage 2: Acetyl-CoA………………….Stage 3: TCA Cycle………………….Stage 4: Electron Transport Chain
How are electrons given to the electron transport chain?
they are given by the 3 NADH and FADH2 from the TCA cycle (Krebs cycle)
In addition to the electrons, what is another requirement for the electron transport chain to occur?
oxygen has to accept the electrons at the end of the chain
What is glycolysis?
the conversion of glucose to pyruvate
In which tissues does glycolysis take place?
ALL: red blood cell, muscle, adipose, brain, and liver
What does pyruvate change to?
Acetyl CoA
In the well fed insulin world, what happens to Acetyl CoA?
it goes through Krebs cycle and electron transport chain to produce CO2 and ATP
What is involved in the conversion of pyruvate to acetyl CoA?
Pyruvate Dehydrogenase, THIS IS A VERY IMPORTANT ENZYME
How do red blood cells get their energy?
They get all their energy from the conversion of glucose to pyruvate.
Why do red blood cells only get their energy from the conversion of glycolysis, the conversion of glucose to pyruvate?
The lack PDH because they lack mitochondria. Because PDH, Krebs cycle, and the electron transport chain all occur in the mitochondria, the red blood cell lacks all these stages.
What happens in the well fed insulin world when the liver has made all of the ATP it needs?
The ATP sends negative feedback to the processes that produced it (electron trans. Chain, Krebs cycle, PDH, glycolysis), and it will MAKE STORAGE FORMS OF ENERGY. With the shut down of these processes, glucose and Acetyl-CoA accumulates and will be stored by the liver as glycogen
What is glycogen?
it is basically a branched polymer of glucose
When the liver has enough ATP and stops the Krebs cycle and electron chain and Acetyl CoA and glucagon build up, what does it do with the build up of acetyl CoA?
It forms polymers of Acetyl CoA known as fatty acids
Where is the glycogen and the fatty acids, both produced in the liver stored?
the glycogen is stored in the liver while the fatty acids are stored in the adipose tissue
What will the liver put out after a meal and what is it composed of?
After it has made its full amount of ATP the Acetyl CoA is made into fatty acids which bind to apoproteins and are secreted as VLDL
What is fat made of?
fatty acids and glycerol-P
What is glycerol-P made of?
glucose
Why do diabetics have hyperlipidemia?
Without glucose in the adipose cell, it is unable to make glycerol, which along with fatty acids is a necessary component of fat. Thus, because it does not have glycrol, the adipose cell is unable to store fat and thus there is hyperlipidemia
Why do diabetics have a fatty liver?
They are unable to store fat in adipose tissue and thus have hyperlipidemia and try to store fat in the liver instead.
What is the main hormone in the postabsorptive state (between meals)?
glucagon
Where will Red Blood Cells and Brain cells get their glucose from between meals?
glucose from the liver……it is the liver that is responsible for distributing glucose in between meals
What does the liver use to get it’s ATP in the glucagon world (between meals)?
?????
What did it use in the well fed state?
Between meals, the liver uses fat to make the Acetyl-CoA and get it’s energy, while in the well fed insulin world it used glucose
How will the liver get the fatty acids to use between meals?
it is realesed from the adipose tissue and carried on albumin back to the liver
How does the liver know when it has enough energy to start making glucose to secrete between meals?
When enough ATP is produced is stopps the Krebs cycle and the electron chain, and thus the Acetyl CoA builds up. The build up of Acetyl CoA is the signal that tell the liver cell that it can not start to make glucose.
What are the sources of the glucose made between meals.
The main sources are the conversion of pyruvate to glucose and the breakdown of the stored glycogen
Does the Acetyl CoA building up between meals change to pyruvate and then to glucose?
NO, sugar will turn to fat through the PDH, but this does not go the other way. Fat cannot turn to sugar.
If Acetyl CoA cannot turn to sugar when it builds up in the liver between meals, what does it do?
When the liver is completely satisfied with it’s energy, the accumulation of Acetyl CoA will into Ketone bodies which will be put into circulation at the same time as the glucose is being released by the liver
What are the ketone bodies used by?
The muscle cells love using ketone bodies. The heart muscle functions almost exclusively on ketone bodies in between meals
How does tissue take advantage of ketone bodies?
it converts the ketone bodoes back into acetyl CoA
What are the sources of energy for muscle between meals?
ketone bodies, fatty acids, glycogen, etc. they will use anything they can get their hands one to make energy if they need to
What are the major sources of pyrovate (beginning of gluconeogenesis) between meals
lactate and alanine
Where does the lactate, which is converted to pyruvate between meals come from?
it is the lactate from the glycolysis in the red blood cell…the glucose converts to pyruvate which is converted to lactate in the red blood cell
What is the source of the alanine used to make pyruvate and thus gluconeogenesis between meals?
it is the result of protein breakdown in the muscles
What is the Cori cycle?
It is the cycle of glucose to pyruvate to lactose and then back to pyruvate and then back to glucose. This cycle goes in between the liver and the red blood cell
How does glucose get into cells?
Glucose transporters
In what tissues are glucose transporters 1 and 3 found in and what do they do?
These transporters are found in most tissues, especially brain and red blood cells and are responsible for basal uptake of glucase
Where is GLUT2 found and what is the significance of this transporter?
GLUT2 is found on the liver and Beta cells of the pancreas and it is a low affinity transporter so that all of the glucose from the gut is not absorbed and used by the liver. It allows a great deal of the absorbed glucose to pass the liver and go into the circulation. These transporters are are the Beta cells of the pancrease to insure that insulin will only be released when the blood glucose level is very high
Where is GLU4 found and what does it do?
it is found on akeletal muscle and adipose tissue. It is the glucose transmitter that responds to insulin. It only works when insulin is in the blood stream
How do the GLU4 transporter increase intake of glucose in response to insulin?
When there is no insulin, the transporter are stored on vesicles in the cytoplasm of cells. When insulin is present these vesicles fuse with the membrane, thus adding more transporters to the membrane