The human body relies on many chemical elements for structure and biological processes. Among these, nitrogen and phosphorus are essential, found in nearly every cell and molecule. Their widespread presence highlights their importance to our biological existence.
Nitrogen’s Crucial Contributions
Nitrogen makes up about 2.6% to 3.2% of the human body’s mass and is a component of organic molecules. It is a defining characteristic of amino acids, the building blocks of proteins. Proteins perform functions like catalyzing biochemical reactions, providing structural support in tissues (e.g., muscle, skin, hair, nails), and transporting substances (e.g., oxygen via hemoglobin).
Beyond proteins, nitrogen is a constituent of nucleic acids, DNA and RNA. The nitrogenous bases (adenine, guanine, cytosine, and thymine or uracil in RNA) contain nitrogen and form the rungs of the genetic ladder. These nucleic acids carry genetic information and are involved in protein synthesis. Without nitrogen, inheritance and protein production would not be possible.
Nitrogen also plays a role in the body’s energy currency, adenosine triphosphate (ATP). The adenine part of ATP is nitrogen-containing, involved in energy transfer. ATP provides energy for cellular activities, from muscle contraction to nerve impulse transmission. Nitrogen is also a precursor for neurotransmitters, chemical messengers that transmit signals between nerve cells. These compounds regulate mood, sleep, and other brain functions.
Phosphorus: A Foundation for Life
Phosphorus is the second most abundant mineral in the human body, making up 1% to 1.4% of body mass. About 85% is found in the skeletal system, primarily bones and teeth. Here, it combines with calcium to form calcium phosphate, a crystalline structure providing rigidity and strength to bone and tooth enamel. This structural role supports and protects the body.
Phosphorus is also essential for energy transfer, found in ATP. The high-energy phosphate bonds within ATP store and release energy, powering cellular processes. This enables functions like muscle movement, active transport, and synthesis of complex compounds.
Phosphorus forms part of the sugar-phosphate backbone of DNA and RNA. This framework provides stability and integrity to nucleic acid strands, which carry the genetic code. The consistent structure of this backbone is important for accurate replication and transcription of genetic information.
Phosphorus is a component of cell membranes as phospholipids. These molecules form a bilayer, creating the selective barrier that encloses cells and organelles. This membrane structure maintains cell integrity, regulates substance passage, and facilitates cell communication. Beyond structural roles, phosphorus participates in cell signaling through a process called phosphorylation. This mechanism adds a phosphate group to proteins, activating or deactivating them, thereby regulating cellular processes.
Acquiring and Regulating These Elements
The human body cannot produce nitrogen or phosphorus, so it must acquire them through diet. Nitrogen is obtained from protein-rich foods as amino acids. Sources include meats, fish, legumes, nuts, eggs, milk, and dairy.
Phosphorus is also widely available in the diet, found in foods like dairy, meats, fish, eggs, nuts, and seeds. While widely available, phosphorus absorption can vary based on its chemical form, with some plant-based forms being less readily absorbed.
Once ingested, the body regulates these elements to maintain homeostasis. For nitrogen, the body recycles amino acids; excess converts to urea and is excreted by the kidneys. Phosphorus levels are controlled by hormones, including parathyroid hormone and vitamin D, which influence its absorption and excretion.