General, Research, Technology

How many bones are in the human body?

Did you know that at the time of birth, the numberare there much more bones in the human body than in adulthood? In fact, bones, although hidden from our eyes, allow Homo Sapiens to maintain our signature physical condition. The skeleton is not just a lifeless building frame needed to support internal organs and appearance. Although we tend to think of our bones as unchanging, in fact, they are constantly changing and evolving, even before we are born. So, the number of bones in the body of an adult is 206, but in newborns the bones can be more than 300. These, if I may say so, "extra" bones as the body develops merge together. Interestingly, most people's bones finish growing together around the start of puberty, although some lagging parts, such as the collarbone, are not fully formed until around age 25.

The number of bones in the body of an adult is 206, but some people may have more bones.

Inside the human body

The bulk of the bones in the human body isstrong bone substance, which contains a large amount of calcium - its weight can reach 70% of the weight of all bones. It is noteworthy that the bone substance is of two forms in the form of "compact bone substance" (a solid, dense mass of whitish color) and "cancellous bone substance", which consists of rather thin plates / bars. Although bones appear immobile, for example in a museum, inside the human body they are as alive as the lungs, liver or kidneys.

This is because the compact bone substance consists of mature cells - osteocytes... These cells have processes through whichthey connect to each other. Osteocytes also interact with young osteoblast cells (responsible for bone formation), and as a result of their joint work, new bones begin to form. As for the destruction of bone tissue, this happens with the help of cells called osteoclasts.

Over the past 125 years, the development of technologyallowed researchers to look inside living bodies and observe how bones behave in their familiar environment. The first such look came in 1895, when the inventor of X-rays, Wilhelm Roentgen, photographed the bones of the hand of his wife, Anna Berthe Ludwig.

Portrait of Wilhelm Roentgen, his wife Anna Bertha Ludwig and an X-ray of her hand.

Hidden from our eyes, the skeletal system is fed by a network of veins and arteries that carry oxygen and energy, as well as remove waste and substances formed in the bones. So, dense bone surrounds periosteum - a fibrous membrane that helpsrestore damaged bone tissue and form new one. The only places not covered by the periosteum are where the bone surrounds the cartilage (as in the joints), or where the ligaments and tendons attach that connect the bone to the muscles.

What are bones for?

It is believed that the reason why people and othersanimals have internal bones, primarily associated with the protection of the body. Today, this theory has received support from recent research on bone function. Thus, the skull and ribs protect vulnerable organs such as the brain and lungs from damage. Bones also protect soft bone marrownecessary for hematopoiesis.Recall that the bone marrow contains special stem cells that produce both red (erythrocytes) and white blood cells (leukocytes), which supply oxygen to all body tissues and fight germs. Scientists have known about this function since the 1950s.

Moreover, the bone marrow stores calcium andphosphate, though only as long as your body does not need them. Phosphate and calcium provide muscle and nerve function, but only in very specific amounts. Bone, which stores about 99% of calcium and about 85% of phosphorus, is a kind of "bank" from which the body can extract these resources, if necessary.

The human skeletal system contains 206 bones - but only after it has finished growing.

Research over the past two decades has revealed another surprising role that bones play: creation and regulation of the hormone osteocalcin. Research conducted in 2019suggests that, among its other roles, osteocalcin induces a fight-or-flight instinct - which makes some sense if you think bones play a large role in your body's ability to fight or flee.

Interestingly, osteocalcin is the onlya hormone that the bone produces is released by them in situations of acute stress. He is responsible for "turning off" the parasympathetic nervous system (the one we use when everything is in order). Then adrenaline and cortisol are used to help you get in the mood for a run or fight.

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Our unique bones

Bone growth and skeletal formation, likegenes are known to control, just as they control every part of your body. But this skeleton can also be "strongly influenced" by what you do. Scientific research by the NIH has shown that people who regularly exercise or engage in physical activity have a different bone shape, depending on the type of physical activity.

Physical activity is the key to health.

This is interesting: Why do vegetarians have fragile bones?

In turn Erin Waxenbaum, Associate Professoranthropology at Northwestern University, which has studied human osteology for more than a decade, believes that 206 bones are not common to everyone. The fact is that some people may simply have extra bones. About 10% of adults have an extra vertebra in the lower spine Is an abnormality that is often only detected by X-ray or MRI and usually does not cause discomfort.

It is also interesting that in some parts of the bodycontains a higher concentration of bones than others. So, the skull may appear to be one continuous segment, but in fact it consists of more than 20 different bones. The arms and legs, each made up of nearly 30 separate bones, contain more than half of all 206 bones in the human body.

In turn, the humerus (upper parthands) is initially formed as three or four separate cartilages. After birth, the cartilage that makes up each piece gradually turns into bone. After about three years, these cartilages meet and continue to fuse until puberty, when the upper arm finally has its own real bone.