Bony Tissue | Anatomy of a Long Bone

hi everyone dr. Mike here in this video we're going to take a look at bony tissue so remember bone is just like cartilage just like blood just like tendons and ligaments it is another connective tissue and that means it's going to contain cells gels and fibers remember cells gels and fibers make up connective tissue now the skeleton which is going to be made up of bones is there to provide structural support for the body protection but also is a housing unit for very important minerals of the body and we're going to talk about those in a sec but first let's have a look at the cells gels and fibers that make up bony tissue so the cells are bony tissue include osteo progenitor cells osteo is a prefix means bone progenitor means it's going to create something so these are basically the stem cells of our bony tissue then we've got osteoblasts the blast tells you it's building so these are the bone building cells they release a substance called osteoid which helps build bone osteoclast think of the class result means crushing this breaks bone down and the last one is the osteocytes that's the mature osteoblasts the mature bone cell now our bone is constantly been remodeled that means it's constantly building itself up breaking itself down building up breaking down the more you use bone the more this remodeling process occurs also the more you use bone the more the building process occurs to make the bone stronger now osteoporosis is a disease in which this remodeling process of building and breaking is imbalanced and you have more braking and less building and you get holes in your bones I'll talk more about that later on okay so these are the cell types within bony tissue what about the gels so the gels include the glycoproteins and also the glycosaminoglycans remember they're the carbohydrates now if we look at bony tissue 15% of its entire mass is water okay 15 percent of bony tissue the rest is what we call dry weight now of that 75 odd 80 percent of that dry weight what you're going to find is that 30% of it is going to be the gel portion so that extracellular matrix the ground substance what we call the glycoproteins and the glycosaminoglycans that's 30% of the dryer weight the remaining 70% of the dry weight is actually something that bony tissue has that other connective tissues don't have these are the mineral depositions so 70% of the dry weight of bone is made up of something called hydroxyapatite and it's predominantly calcium and phosphate okay so bone has all these minerals dissolved into it and this is what makes bone hard and these minerals are calcium and phosphate so that's very very important you'll also find that we can break up the gels and fibers together we call the organic components of bone and the minerals are the inorganic components of bone so this is again important as well I'll talk about that shortly now when it comes to fibers the major fiber type within bone is collagen so together the organic components of bone make up 30% of its dry weight and the inorganic components of bone make up 70% of its dry weight all right now what we're going to do is look at the anatomy of a long bone so we've got a long bone here and you can see that this long bone I've sort of cut and we're looking inside of that long bone and you can see that it's made up of two bone types this is what we call cortical bone and spongy bone okay this cortical bone is a very dense bone this spongy bone by name is a spongy in appearance looking bone it's not spongy to feel still very hard but not as hard as the cortical bone okay so what you're going to find is you're going to have the cortical bone sitting on the very outside of a long bone and then you're gonna have the spongy bone sitting more so in the middle of the long bone now deep within the middle of a long bone is actually hollow and we call that the medullary cavity so there is a cavity deep inside of long bones that's hollow and it's called the medullary cavity and what is inside of that hollow area a lot of our blood vessels but also in the adult it's going to be what we call yellow bone marrow okay so you've got two types of bone marrow yellow bone marrow that's fat and red bone marrow which helps us create blood now in adults the medullary cavity is yellow bone marrow okay but in an infant the long bones have red bone marrow so that means in infants their long bones are the primary site for red blood cell production so the question may be where's our primary site for red blood cell production now that we're adults it's predominately in our flat bones so flat bones are going to be bones of our skull for example and other sternum and there are some other places that you'll find what we call the red bone marrow now the other thing is that if we were to take a look at the spongy bone and the cortical bone a couple of things firstly would the spongy bone you can see that there's these holes in them and you'll find the endosteum is the most inside portion of a bone the periosteum is the most external portion of a bone in the endosteum you're going to have certain cell types that's these cell types you're gonna have the osteoprogenitor cells producing osteoblasts then you're gonna have osteoblasts building the bone up so that means you can build bone from the inside okay Ostia bus then you have the osteo class which start to eat and break the bone up okay when we look down at the cortical bone which is sitting more on the outside you'll find that you can peel away the outside layer of the bone that's called the periosteum and underneath that peeled layer you can see that some of the cells sit so you can build bone from the outside as well so from the endosteum you can build bone from the periosteum you can build bone for adults most of it happens on the endosteum inside the bone you can also see that as the osteoblasts start releasing all that substances an actual fact that osteoblasts they secrete the organic components they secrete the gels and the fibers the inorganic components well that comes from when we ingest foods for example all right so we've got the osteoblasts secreting all this osteoid the gels and fibers and laying it down and it's like put setting concrete around it and once it sets concrete around it it's stuck and once it's stuck it matures into an osteosarcoma so you can see the osteocytes sitting between these layers like the layers of a tree okay now another thing that you're going to find is that bone is highly vascularized there's a lot of blood vessels cartilage on the other hand does not have any blood vessels so there's a big difference between two connective tissue types if you look at what we call the macroscopic anatomy of the long bone you've got two ends of the bone they're called the epiphysis okay so you got the proximal epiphysis that's closest to the side of attachment and the distal epiphysis that's farthest away from the side of attachment then you've got the long middle portion of the bone which we call the diathesis and then in between the diathesis and the epiphysis we've got the metathesis the other thing is you can see this green line that I've drawn here basically between the metathesis and the epiphysis that we call the epiphysis line this epiphany line is all in all of our long bones as an adult and it's hardened but it used to be cartilage it's actually when we grow from an infant to an adult there's cartilage in here that actually starts to lay down tissue and then hardens over time to form bone so to our growth plates if you break in here as an infant the growth plate it may stunt or alter the way that an individual grows so what we've got here overall is an outlook or a general outlook or overview of bony tissue

Channel: Dr Matt & Dr Mike

Views: 24,012

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Keywords: bone, skeleton, bony tissue, bone tissue, osteoblast, osteoclast, osteocyte, osteoprogenitor cell, osteopathy, bone remodelling, long bone, skeletal system, diaphysis, metaphysis, epiphysis, medullary cavity, bone marrow, yellow bone marrow, white bone marrow, usmle, nursing, physiotherapy, medicine

Id: S5b4NvdT1ds

Length: 8min 8sec (488 seconds)

Published: Sun Mar 24 2019