The term “ammonia acid” is not a recognized chemical or biological phrase. Instead, this article will clarify two distinct, yet related, biological compounds: amino acids and ammonia. Amino acids serve as the fundamental building blocks of proteins, playing diverse roles within the body’s systems. Ammonia, conversely, is a metabolic byproduct that requires efficient removal due to its inherent toxicity. Understanding the nature and handling of these two substances is important for comprehending human biochemistry.
Understanding Amino Acids
Amino acids are organic compounds that combine to form proteins. These molecules contain both an amine group and a carboxyl group, along with a unique side chain that differentiates each specific amino acid. The human body utilizes these amino acids to synthesize new proteins, which are involved in breaking down food, promoting growth, and repairing body tissues.
There are 20 different amino acids that the human body needs to function properly. These are categorized based on whether the body can produce them internally or if they must be obtained through diet. Nine of these are considered “essential” amino acids because the body cannot synthesize them and thus they must come from food sources:
- Histidine
- Isoleucine
- Leucine
- Lysine
- Methionine
- Phenylalanine
- Threonine
- Tryptophan
- Valine
The remaining 11 amino acids are classified as “non-essential” because the body can produce them, even without dietary intake. Examples include:
- Alanine
- Arginine
- Asparagine
- Aspartic acid
- Cysteine
- Glutamic acid
- Glutamine
- Glycine
- Proline
- Serine
- Tyrosine
Some non-essential amino acids are also termed “conditionally essential,” meaning that under certain circumstances, such as illness or stress, the body may not be able to produce enough of them to meet its needs, requiring dietary supplementation. Beyond protein synthesis, amino acids also contribute to the formation of enzymes, hormones, and neurotransmitters.
Ammonia in the Body
Ammonia is a colorless gas with a pungent odor that readily dissolves in water, forming ammonium ions within the body. It is a natural byproduct of several metabolic reactions, primarily arising from the breakdown of amino acids and other nitrogen-containing compounds through a process called deamination. Bacteria in the intestines also contribute to ammonia production through the digestion of proteins.
Even a slight increase in blood ammonia concentration, from a normal level of less than 50 micromoles per liter to just 100 micromoles per liter, can lead to disturbances in consciousness. Concentrations around 200 micromoles per liter are associated with more severe neurological symptoms, including coma and convulsions.
Ammonia’s toxicity primarily stems from its detrimental effects on the central nervous system. It can damage brain cells and deplete neurotransmitters, leading to symptoms such as confusion, disorientation, excessive sleepiness, and difficulty concentrating. High levels can result in cerebral edema, a swelling of the brain, which can be life-threatening.
How the Body Handles Ammonia
The body has developed sophisticated mechanisms to manage and eliminate ammonia, primarily through a process known as the urea cycle. This biochemical pathway converts highly toxic ammonia into urea, a much less harmful substance, for excretion. The urea cycle takes place predominantly in the liver, with some activity also occurring in the kidneys.
The process begins in the mitochondria of liver cells, where ammonia is converted into carbamoyl phosphate. This compound then enters a series of five enzymatic reactions that span both the mitochondrial matrix and the cytosol of liver cells. Through these reactions, the nitrogen from ammonia is incorporated into urea.
Once formed in the liver, urea is released into the bloodstream. It then travels to the kidneys, where it is filtered out of the blood and ultimately excreted from the body in urine. A dysfunctional urea cycle can lead to hyperammonemia, a buildup of ammonia in the body, causing severe and irreversible damage, particularly to the brain.