Composition of bone
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Composition of bone

October 17, 2019


hello everyone in this presentation we
are talking about composition of bone or biochemistry or bone or chemical
composition of bone. Before going to the directly composition of bone, so let me
write one bone and we’ll see just what are the major structure of the
bone, just for example imagine this is a bone, long bone, it has got different
parts its central shaft cylindrical shaft is called cortical bone, cortical
are also called compact bone, compact bone and it’s very
dense in the center it has got bone marrow and it is very dense and it has
80% of mass of the bone, 80% of bone mass is compact bone or
cortical bone, periphery, whatever this is called trabecular bone or cancellous
bone, which is not dense when compared to cortical bone, it is also called a spongy
bone and also called trabecular bone okay , which is actually 20% of bone mass
because which is not dense as compared to cortical bone. It is porous,
spongy it’s also called honeycomb appearance. In order to understand
composition and remodeling, you should know there are two types, one is
central shaft or cylindrical shaft is called
compact bone, another one is spongy bone. or cancellous bone are also called
trabecular bone which is actually the porous. Coming to the components of
bone or composition of bone, bone has got an organic component and inorganic
component, this organic component accounts for approximately about 20% again depending
upon the type of bone, whereas inorganic components roughly around 80%, in this
water accounts for, water is also classified under inorganic, so we can
make this inorganic 60% and water 20%. So when I said 20% it is approximately
it is 10 to 20% is water, together with water as well as other ions it will be 80%.
First, we’ll see organic, this most part about any component of bone is protein
in this protein has got major part is collagen, collagen and again it has got
type I collagen and type V collagen. The major organic component of bone is type I college, it accounts for about 90 to 95 percent. It’s very minor. So the protein
component of the organic composition of the bone or organic part of the bone is
collagen, collagen protein and also we have non-collagen protein, the protein
component which is not collagen or non-collagen protein. So non-collagen
proteins are, we studied under carbohydrate chemistry, what is called
proteoglycan, proteoglycan can also call glycoprotein or you can call them
as glycosaminoglycan, carbohydrates are also there and also their protein also there and we
have another non collagen protein is called osteocalcin, it is not collagen
but it is a protein component. Similarly we have osteopontin and bone sialoprotein. So these are an organic component of bone, it is
collagen, that is type I collagen and it it accounts for 90 to 95 percent of organic component, of the bone, then small amount of type V and non-collagen protein like glycosaminoglycan, osteocalcin, osteopontin and bone sialoprotein. Coming to
the major component or composition of bone is inorganic including water in the
living bone, so the major part of the inorganic component is calcium and
phosphorus okay, phosphorus in the form of phosphate. This calcium and phosphorus is the major inorganic component of the bone, which is present in the form of
calcium phosphate and hydroxyl group. We can call this, you can see here, there is a hydroxyl group, there is a specific name for this as hydroxy appetite, hydroxy
appetite okay. This is the name given to inorganic component, which is present in
crystalline form, whatever the strength for the bone is due to the presence of this
hydroxyapatite. Hydroxyapatite is nothing but calcium and phosphate they
combine, they form a crystalline structure, the hardness or the strength
or the resilience of the bone is due to this form, calcium phosphate hydroxyl
apatite and in fact about 99 percent of body calcium is present in the bone itself. Bone and teeth are rich in calcium and phosphorus Apart from calcium and phosphate we also have other inorganic components. Our bone also contains sodium, magnesium, fluoride, carbonate, even potassium, chloride all these components are also present in our bone, so zinc also
present, selenium, so many inorganic components are also present,
major part is our calcium and phosphorus they are present in the form of
hydroxyapatite, in the form of crystalline hydroxyapatite, which is
actually the for the strength or resilience of the bone. Apart from these we also have bone cells there are three types okay,
osteoblasts, osteocytes and osteoclasts. When you say bone, there is a continuous remodeling of the bone, so I am going to explain this remodeling
of the bone in the next video, at this At this moment you should know, apart from organic and inorganic component, bone also contains three types of cells and this moment you
remember osteoblasts are actually responsible for bone formation, it is
called mineralization or deposition and osteoclasts actually it is whole
destruction or it is called resorption or bone destruction in our
body there is continuous bone formation and bone destruction
okay so old cells are continuously they undergo destruction and there will be
new bone formation. The new bone formation is called
osteoid, we are going to study how this new bone formation in the next video
and these osteoblasts and osteoclast they are present in the surface of the bone.
So I am going to explain in the next video, where is exactly the location of
these cells okay surface, whereas osteocytes actually they derive from
osteoblast they are inside the bone. Inside the bone, which is
not in the bone marrow inside the dense part of the bone. It is called actually present in the lacuna, lamellar bone. There are three types of cells, osteoblasts are responsible for new bone formation or deposition of the bone, whereas osteoclasts are responsible for destruction or resorption on the bone.
This with respect to the composition of bone That’s about the composition of bone. Thanks for watching.

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  1. बहुत अच्छा है सर जी आप हिंदी में भी वीडियो बनाइए

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