What are the most common elements in the human body?

EUGE...QVav

31 Jul 2023

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Have you ever wondered what makes up your body? What are the basic building blocks of life? How do they work together to keep you alive and healthy?

In this article, we will explore the fascinating world of the chemical composition of the human body. We will learn about the most common elements in the human body, their functions, their sources, and their variations.

We will also look at some of the techniques and tools that scientists use to measure and analyze the body composition. By the end of this article, you will have a better understanding of your own body and its amazing chemistry.

The four big ones: oxygen, carbon, hydrogen, and nitrogen

The human body is composed of about 60 chemical elements, of which six make up 99% of the mass: oxygen, hydrogen, carbon, nitrogen, calcium, and phosphorus. These elements are mostly found in water and organic molecules, such as proteins, carbohydrates, fats, and nucleic acids.

The remaining elements are either trace elements, which are necessary for life, or contaminants or toxins, depending on the amount and function.

The four most abundant elements in the human body by mass are oxygen, carbon, hydrogen, and nitrogen. Together, they account for 96.2% of the body mass. So what do these elements do in the body? Let’s take a closer look at each one.

Oxygen (O)

Oxygen is the most abundant element in the human body by mass, making up 65% to 67% of the total weight. That’s because our bodies are mostly water — around 50% to 60% — so most of the oxygen is the “O” in H2O. Oxygen is also critical for energy production and metabolism, or the chemical processes that occur within the body.

Oxygen is used by cells to break down glucose and other nutrients into ATP (adenosine triphosphate), which is the main energy carrier in cells. Oxygen is also involved in many other key organic compounds, such as amino acids, fatty acids, hormones, neurotransmitters, and DNA.

Oxygen is obtained from the air we breathe through the respiratory system. The lungs take in oxygen and transfer it to the blood, which carries it to all parts of the body. The blood also removes carbon dioxide, a waste product of metabolism, from the cells and brings it back to the lungs for exhalation. Oxygen levels in the blood are regulated by sensors in the brain and other organs that signal the breathing rate and depth.

Oxygen deficiency or excess can cause serious health problems. For example, hypoxia is a condition where there is not enough oxygen reaching the tissues, which can lead to tissue damage or death. Hypoxia can be caused by high altitude, lung diseases, anemia, or poisoning.

On the other hand, hyperoxia is a condition where there is too much oxygen in the blood, which can cause oxidative stress or damage to cells. Hyperoxia can be caused by breathing pure oxygen for too long or by certain medical conditions.

Carbon (C)

Carbon is the second most abundant element in the human body by mass, making up around 18.5% to 19% of the total weight. Carbon has four bonding sites for other atoms, which makes it the key atom for organic chemistry. Carbon chains are used to build carbohydrates, fats, nucleic acids, and proteins. These molecules are essential for storing energy, providing structure, transmitting information, and performing functions in the body.

Carbon is obtained from the food we eat through the digestive system. The carbohydrates we eat are broken down into glucose and other simple sugars that can be used by cells for energy or stored as glycogen or fat. The fats we eat are broken down into fatty acids and glycerol that can be used for energy or stored as triglycerides or cholesterol. The proteins we eat are broken down into amino acids that can be used for building new proteins or converted into glucose or fat.

Carbon dioxide is a waste product of metabolism that is removed from the body through respiration. Carbon dioxide is also involved in maintaining the acid-base balance of the blood and other fluids. The normal pH of blood is around 7.4, which means it is slightly alkaline or basic. Carbon dioxide reacts with water to form carbonic acid (H2CO3), which can dissociate into bicarbonate (HCO3-) and hydrogen (H+) ions. These ions can act as buffers to neutralize excess acids or bases in the blood.

Carbon imbalance can cause metabolic disorders or acid-base disorders. For example, diabetes mellitus is a condition where there is too much glucose in the blood due to insufficient insulin production or action. This can lead to hyperglycemia, ketoacidosis, or coma. On the other hand, starvation or fasting can cause too little glucose in the blood, leading to hypoglycemia, ketosis, or brain damage.

Hydrogen (H)

Hydrogen is the third most abundant element in the human body by mass, making up around 10% of the total weight. Hydrogen is mostly found in water, which accounts for about two-thirds of the body mass. Hydrogen is also a component of many organic molecules, such as carbohydrates, fats, proteins, and nucleic acids. Hydrogen can form single, double, or triple bonds with carbon, as well as bonds with other elements such as oxygen, nitrogen, and sulfur.

Hydrogen is obtained from the food and water we consume through the digestive system. The water we drink is absorbed by the intestines and distributed throughout the body. The hydrogen atoms in water can participate in various chemical reactions, such as hydration, hydrolysis, and acid-base reactions. The hydrogen atoms in organic molecules can be used for energy production or biosynthesis of new molecules.

Hydrogen gas is a byproduct of some metabolic processes, such as fermentation in the colon or methanogenesis in some bacteria. Hydrogen gas can be expelled from the body through flatulence or breathing. Hydrogen gas can also be produced artificially by electrolysis of water or by reacting metals with acids.

Hydrogen imbalance can cause dehydration or edema. Dehydration is a condition where there is not enough water in the body, which can lead to thirst, dry skin, headache, fatigue, or kidney failure.

Dehydration can be caused by excessive sweating, vomiting, diarrhea, fever, or insufficient fluid intake. Edema is a condition where there is too much water in the body, which can lead to swelling, weight gain, shortness of breath, or heart failure. Edema can be caused by kidney disease, liver disease, heart disease, or high salt intake.

Nitrogen (N)

Nitrogen is the fourth most abundant element in the human body by mass, making up around 3% of the total weight. Nitrogen is mainly found in proteins and nucleic acids, which are essential for growth, repair, and maintenance of cells and tissues. Nitrogen is also a component of some hormones, neurotransmitters, and vitamins.

Nitrogen is obtained from the food we eat through the digestive system. The proteins we eat are broken down into amino acids that can be used for building new proteins or converted into other compounds. The nucleic acids we eat are broken down into nucleotides that can be used for synthesizing new DNA or RNA. The nitrogen-containing compounds we eat are broken down into ammonia (NH3), which is toxic to the body.

Ammonia is converted into urea (CO(NH2)2) by the liver and transported to the kidneys for excretion. Urea is the main nitrogenous waste product of humans and other mammals. Urea is dissolved in water and forms urine, which is eliminated from the body through urination.
Nitrogen imbalance can cause protein deficiency or excess.

Protein deficiency is a condition where there is not enough protein intake or absorption to meet the body’s needs, which can lead to muscle wasting, growth retardation, edema, anemia, or immune deficiency. Protein deficiency can be caused by malnutrition, malabsorption, infection, or chronic disease.

Protein excess is a condition where there is too much protein intake or breakdown to exceed the body’s capacity to eliminate nitrogenous waste products, which can lead to dehydration, acidosis, or kidney damage. Protein excess can be caused by high protein diet, catabolic stress, or genetic disorders.

The two big ones: calcium and phosphorus

The next two most abundant elements in the human body by mass are calcium and phosphorus. Together, they account for 2.8% of the body mass. These elements are mostly found in the bones and teeth, which make up about 15% of the body mass.

Calcium and phosphorus are also involved in many other vital processes, such as muscle contraction, nerve transmission, blood clotting, and enzyme activation.

Calcium (Ca)

Calcium is the fifth most abundant element in the human body by mass, making up around 1.5% of the total weight. Calcium is the most abundant mineral in the body, accounting for about 2% of the body weight. About 99% of the calcium in the body is stored in the bones and teeth, where it provides strength and structure. The remaining 1% of calcium is found in the blood and other fluids, where it plays important roles in cell signaling, muscle contraction, nerve transmission, blood clotting, and enzyme activation.

Calcium is obtained from the food we eat through the digestive system. The main sources of dietary calcium are dairy products, such as milk, cheese, and yogurt. Other sources include green leafy vegetables, such as kale, broccoli, and spinach; fish with edible bones, such as sardines and salmon; nuts and seeds, such as almonds and sesame; and fortified foods, such as cereals and orange juice.

Calcium levels in the blood and other fluids are regulated by hormones, such as parathyroid hormone (PTH), calcitonin, and vitamin D. These hormones control the absorption of calcium from the intestines, the reabsorption of calcium from the kidneys, and the release or deposition of calcium from the bones. The normal range of calcium in the blood is between 8.5 to 10.5 mg/dL.

Calcium deficiency or excess can cause bone disorders or electrolyte disorders. For example, osteoporosis is a condition where there is a loss of bone density and strength, which can lead to fractures, pain, or deformity. Osteoporosis can be caused by aging, menopause, low calcium intake, or hormonal imbalance.

On the other hand, hypercalcemia is a condition where there is too much calcium in the blood, which can lead to nausea, vomiting, confusion, kidney stones, or cardiac arrest. Hypercalcemia can be caused by hyperparathyroidism, cancer, or excessive vitamin D intake.

Phosphorus (P)

Phosphorus is the sixth most abundant element in the human body by mass, making up around 1.2% of the total weight. Phosphorus is mainly found in two forms: phosphate (PO4) and phospholipid (PL).

Phosphate is a component of many organic molecules, such as nucleic acids (DNA and RNA), ATP (the energy currency of cells), phosphoproteins (such as casein and albumin), and phosphates (such as creatine phosphate and pyrophosphate). Phospholipid is a component of cell membranes, which are made of a double layer of phospholipid molecules.

Phosphorus is obtained from the food we eat through the digestive system. The main sources of dietary phosphorus are protein-rich foods, such as meat, poultry, fish, eggs, dairy products, nuts, seeds, and legumes. Other sources include grains, cereals, fruits, vegetables, and soft drinks.

Phosphorus levels in the blood and other fluids are regulated by hormones, such as PTH, calcitonin, vitamin D, and FGF23 (fibroblast growth factor 23). These hormones control the absorption of phosphorus from the intestines, the reabsorption or excretion of phosphorus from the kidneys, and the release or deposition of phosphorus from the bones. The normal range of phosphorus in the blood is between 2.5 to 4.5 mg/dL.

Phosphorus deficiency or excess can cause bone disorders or electrolyte disorders. For example, rickets is a condition where there is a lack of mineralization of bone tissue, which can lead to softening, bending, or deformation of bones. Rickets can be caused by vitamin D deficiency, malabsorption, or renal disease.

On the other hand, hyperphosphatemia is a condition where there is too much phosphorus in the blood, which can lead to calcification of soft tissues, such as blood vessels, heart valves, or lungs. Hyperphosphatemia can be caused by renal failure, hypoparathyroidism, or excessive phosphorus intake.

Conclusion

We have learned a lot about the most common elements in the human body and their roles and functions. We have seen how oxygen, carbon, hydrogen, and nitrogen make up the bulk of our body mass and are involved in many vital processes, such as energy production, metabolism, cell signaling, and information transmission.

We have also seen how calcium and phosphorus are mainly found in our bones and teeth and are important for muscle contraction, nerve transmission, blood clotting, and enzyme activation. We have also learned about some of the sources, regulation, and imbalance of these elements and their effects on our health.

I hope you enjoyed this article and gained some new insights into your own body and its amazing chemistry. If you want to learn more about the other elements in the human body, such as sodium, potassium, magnesium, iron, zinc, copper, iodine, selenium, and more, stay tuned for our next article.

Thank you for reading and have a wonderful day! 😊

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