The Osteon and Compact Bone Structure

buon is a very rigid type of connective tissue so that basically means bones are dense bones are strong and bones are hard so they have the ability to resist both tensile as well as compressive forces the question is why what exactly is found inside the bone that gives bone these types of properties so basically it's the extracellular matrix that is found surrounding ourselves and in between our cells that actually gives the bone these types of properties so before we discuss the different types of cells inside the bone and the structure of the bone let's discuss the extracellular matrix of the bone so the extracellular matrix consists of organic matter as well as inorganic matter the organic component consists predominantly of a type of protein known as collagen and it's the collagen that gives the bone the ability to resist tensile forces it gives the bone tensile strength on the other hand the inorganic component of the extracellular matrix of the bone gives our bone the ability to resist compressive strength compressive force and it gives the bone compressive strength and that's because in our inorganic component of the extracellular matrix we have crystals known as hydroxyapatite and hydroxyapatite crystals themselves consist of calcium phosphate eggs as well as hydroxide ion so the collagen gives the bone tensile strength but it's the hydroxyapatite of the extracellular matrix that gives the bone compressive strength so now let's discuss the different types of cells found inside our bone so we have osteoblasts we have Ostia sites and we also have osteoclasts so let's begin with the osteoblasts so the osteoblasts are basically those cells inside the bone that are responsible for building that bone for building and sick creating the extracellular matrix so that means these osteoblasts are capable of secreting collagen into our extracellular matrix and these cells are capable of taking up calcium as well as phosphate from the blood and depositing into the extracellular matrix so basically these are the cells that are responsible for building bones they secrete organic as well as inorganic matter such as collagen calcium as well as phosphates and are responsible for creating the extracellular matrix that we just discussed above now eventually when these cells completely surround themselves and enclose themselves with the matrix they basically become they differentiate into a second type of cell known as an osteocyte now what exactly is an osteocyte well basically the osteocyte is the most common type of cell found in the bone and the osteocyte is responsible for providing the bone with nutrients that the bone actually needs to survive so the osteocyte is connected to the blood vessels that carry the different types of nutrients as we'll see in just a moment so osteocytes are the most common types of cell found inside bone and they are responsible for obtaining nutrients from the blood as well as dumping any type of waste products into our blood so that those waste products are recycled so osteocytes contain extensions that are known as processes so these two purple regions are the osteocytes and these blue extensions are our processes now these processes radiate outward and eventually they connect with canals and these canals are known as canal e-coli so these canaliculi basically are canals that connect one osteocyte to a second osteocyte and these canaliculi basically are responsible for exchanging different types of materials between our between our adjacent osteocytes now the final type of cell that I'd like to mention is our osteoclasts so if these osteoblasts basically build bone and one way to remember osteoblasts building bone is the fact that we have a be in osteoblasts so the B stands for building so osteocytes build bones but osteoclasts do this opposite of building they basically resorb our bone they break down the extracellular matrix of the bone and they secrete that into the blood for example they can break down our hydroxyapatite and they can release the calcium the phosphate back into the blood so osteoclasts are the cells responsible for resorbing bone and that basically means they break down bone and they break down the extracellular matrix and release the minerals such as calcium and phosphate into the blood now at times that can actually be helpful because let's say our muscle cells require calcium to contract and if we need our calcium this is how our bone basically releases the calcium so that the muscles can actually contract and when we discuss the process of reforming and remodeling our bone the osteoclast and the osteoblasts basically play a crucial role in that process so the bone is a living tissue it's continually being reformed so that means it's continually being broken down and reformed and that's exactly why these two cells are crucial now what about the structure of the bone so just like our muscle cells our skeletal muscle cells and cardiac muscle cells consist of individual units known as sarcomeres the bone also consists of individual units known as osteons now the osteon consists of concentric rings centric circles that are known as lamellae and these lamellae are basically our extracellular matrix that we spoke of earlier so this is the top view of our osteon we have these concentric circles we called lamellae so this is one lamellae a second lamellae a third lamellae these are the regions shown and why and the lamellae is basically our extracellular matrix that consists of collagen and our hydroxyapatite now along our lamellae we basically have these spaces these spaced regions known as our lacuna and these lacuna are basically shown in black so these are the spaces and within these spaces we basically have the osteoblasts that secreted our extracellular matrix and eventually became our osteocytes so these purple dots are basically our Ostia sites and these blue extensions are the processes as well as our canals known as our a canal e.coli so we have these blue extensions we have our canals known as canaliculi and we also have this central region at the center of our Ostia known as a haversian canal now this haversian canal is basically a central canal that consists of lymph vessels it consists of blood vessels and it also consists of neurons so nerve cells so in the center of the osteon the building block of the bone we have a canal known as our version canal or the central canal and this canal contains the blood vessels our lymph vessels that basically carry away different types of waste products the blood vessels bring different types of nutrients and we also have neurons that basically innervate our bone now bone contain many of these individual osteon so if we actually take a small cross-section of our bone we basically get the following diagram so we have many of these osteons in this case we have one two three four five six of these concentric cylindrical regions we call osteons and at the center of each osteon we have our central canal known as the haversian canal and within this haversian canal we basically have the blood vessels lymph vessels and our nerve cells our nerve fibers now what about the connecting regions between these are versioned canals so the her version canal of one osteon is connected to the harvard canal of a different adjacent osteon via a canal known as our Volkmann canal so the Volkmann canal is basically our canal that bridges that connects adjacent perversion canals as shown in the following cross sectional diagram so once again the building of the building unit of our bone is known as an osteon and the osteon consists predominantly of this matrix the extracellular matrix that is created by osteoblasts and once we create this matrix the osteoblasts basically differentiate into our osteocytes shown by these purple regions these osteocytes basically have these extensions known as processes and these processes connect to one another via these canals known as our canaliculi and these canaliculi basically connect and allow adjacent osteocytes to exchange important types of materials important types of nutrients now within our central region of the osteon we have our version canal which contains our blood vessels lymph vessels as well as our nerve cells our neurons now these concentric regions of matrix is known as our lamellar and the space is where we have the osteocytes that is known as lacuna now inside the matrix we have collagen as the main organic matter and we have the hydroxyapatite as the main in organic matter and inside bone we have three types of cells osteoblasts that build the matrix and build a bone osteocytes that allow the exchange of the exchange of nutrients between other osteocytes as well as our blood and lymph vessels and we have the osteoclasts that basically resorb our bone break down the bone and release the different types of materials minerals into our blood

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Keywords: bone structure, microscopic bone structure, osteon, osteocytes, osteoblasts, osteoclasts, types of cells in bone, Haversian canal, lamellae, lacunae, processes, Volkmann's canal, structure of the osteon, anatomy of bone, extracellular matrix of bone, hydroxyapatite, collagen

Id: PQpYZ0RcAKM

Length: 11min 39sec (699 seconds)

Published: Tue Sep 30 2014