Glutamine's Role in Kidney Function and Acidosis

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Questions and Answers

What is the goal of protein intake for healthy, non-pregnant adults?

To increase muscle mass

To maintain a positive nitrogen balance

To build new tissue

To replace what is used every day (correct)

What is the primary reason whole proteins are not absorbed in the digestive system?

They are too large to pass through cell membranes (correct)

They are toxic to the body

They are not soluble in water

They are not broken down by digestive enzymes

What is the purpose of the urea cycle in protein metabolism?

To remove excess nitrogen from the body (correct)

To break down amino acids for energy

To store amino acids for later use

To synthesize new amino acids

What is the term for the balance between protein intake and protein breakdown in the body?

Nitrogen balance Signup and view all the answers

What is the term for the breakdown of amino acids to produce energy?

Amino acid catabolism Signup and view all the answers

In the kidneys, what is the primary role of glutamine?

To provide a source of NH3 to buffer excess H+ Signup and view all the answers

What is the primary function of cortisol in regulating glutamine metabolism?

Stimulating glutamine synthetase activity Signup and view all the answers

In rapidly dividing cells, what are the three main roles of glutamine?

Fuel source, nitrogen donor, and substrate for protein synthesis Signup and view all the answers

What is the end result of glutamine metabolism in the kidneys?

Production of ammonia to buffer excess H+ Signup and view all the answers

What is the relationship between the Krebs cycle and the urea cycle?

The Krebs cycle produces carbon skeletons for the urea cycle Signup and view all the answers

What is the main site of amino acid oxidation?

Liver Signup and view all the answers

Where is ammonia converted to urea?

Liver Signup and view all the answers

What is the primary transporter of ammonia in the blood?

Alanine Signup and view all the answers

What is the fate of glutamine in the kidney, liver, and intestine?

It is deaminated by glutaminase Signup and view all the answers

What is the end product of the urea cycle?

Urea Signup and view all the answers

What is the primary destination of nitrogen derived from amino acid catabolism in other tissues?

Liver and kidney Signup and view all the answers

Study Notes

Protein Metabolism

Protein metabolism involves the breakdown and synthesis of proteins, which is crucial for maintaining nitrogen balance in the body.

Nitrogen Balance

Nitrogen balance refers to the equilibrium between the amount of nitrogen consumed and the amount of nitrogen utilized by the body.
There are two types of nitrogen balance: positive nitrogen balance (when the body builds new tissue) and negative nitrogen balance (when the body breaks down existing tissue).

Dietary Proteins and Amino Acid Metabolism

Proteins are broken down into amino acids, which are then absorbed and utilized by the body.
There are two sources of amino acids in the body: exogenous (from dietary proteins) and endogenous (from protein turnover).

Amino Acid Pool

The amino acid pool refers to the total amount of amino acids available in the body, which can be used for various bodily functions.

Protein Digestion

Whole proteins are not absorbed by the body; instead, they are broken down into smaller peptides and amino acids.
The kidney plays a crucial role in excreting excess nitrogen in the form of urea.

Glutamine

Glutamine is an amino acid that plays a crucial role in various bodily functions, including:
- Providing fuel for the kidney
- Acting as a buffer against excess hydrogen ions (H+)
- Serving as a nitrogen donor for biosynthetic reactions
- Being used as a substrate for protein synthesis
Glutamine is also involved in the regulation of acid-base balance and is stimulated by cortisol.

Transamination and Deamination

Transamination is the process by which an amino group (-NH2) is transferred from one amino acid to another.
Deamination is the process by which an amino group is removed from an amino acid, resulting in the formation of ammonia.

Urea Cycle and Krebs Cycle

The urea cycle is a pathway by which ammonia is converted into urea, a non-toxic and water-soluble compound that can be excreted in the urine.
The Krebs cycle (also known as the citric acid cycle or tricarboxylic acid cycle) is a pathway by which amino acid carbon skeletons are oxidized to produce energy.

Amino Acid Catabolism

Amino acid catabolism is the process by which amino acids are broken down to produce energy.
The liver is the major site of amino acid oxidation, but most tissues can oxidize branched-chain amino acids (i.e., leucine, isoleucine, and valine).
The carbons from amino acid degradation are converted to pyruvate, intermediates of the TCA cycle, acetyl-CoA, or acetoacetate.

Quiz Questions

The keto acid that generally accepts the -NH2 group from amino acids during transamination is alpha-ketoglutarate.
One transamination reaction of glutamate is the conversion of glutamate to alpha-ketoglutarate and alanine.
The complete deamination reaction of asparagine involves the conversion of asparagine to aspartate and ammonia.
The relationship between the Krebs cycle and urea cycle is that the Krebs cycle produces fumarate, which is converted to arginine in the urea cycle.

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Description

Learn about the functions of glutamine in the kidney, including its role in buffering excess H+ ions, providing fuel, and regulating acid-base balance. Discover how cortisol stimulates glutamine synthesis and export.