Bone Growth And Structure Lecture 5 Flashcards
What bones do you have when your young
Don’t have bone, you are a skeleton that is made up of cartilage
When does the cartilage model start to form
6 weeks after fertilisation, the cartilage model starts to form and after years your bone will ossify and grow
What is ossification
This is turning into bone, turning. Cartilage into bone
What is Edochondral ossification
This is turning cartilage into bone
How does turning cartilage into bone happen and where does it take place
It starts off with calcification which is just cartilage and then the blood vessels and osteoblast will surround the wall of the cartilage but we want these inside so after the blood vessels and osteoblasts push their way inside, and once they are inside they can now start to turn that bone cartilage into bone tissue. And this happens in the primary ossification centre
What is the primary ossification centre ( thinking about long bones )
If we are thinking about the long bone This is where the formation of cartilage into bone takes place. We start off at the Diaphysis, this is where the osteoblasts will end up first and this is where the process of turning cartilage into bone starts and this is what’s called the primary ossification centre.
While for the end of the bones they remain as cartilage for a bit longer
Secondary ossification centre
Because there is a primary there must be a secondary. So once the Diaphysis has started to turn into bone from the osteoblasts and the blood vessels, we can move onto the ephithysis, this is the ends of the long bone. This is basically the same process that happens in the diaphysis but as it is turning the cartilage into bone tissue not all of the cartilage is going to be used up. And that cartilage that is not used up is called the GROWTH PLATE
What is the growth plate
This is when not all of the cartilage is used up in the secondary ossification centre. The growth plate is for the length of your bones, we need this so that the bone can grow in length as we are getting older and older. After about 18 years to 20 your growth plate won’t be there anymore and so there will be no more cartilage and the bone will be fully grown
What is the name for bone growth in the WIDTH direction and what is the cell used to help that ?
Appositional growth ! This is the building of bone outwards, using osteoblast as the call
How does the bone grow in the width direction
So basically what building bone outwards is called APPOSITIONAL GROWTH, this is done by osteoblast, osteoblast on the outside of the bone ( on the bone surface ) are going to start adding more bone tissue, making the bone wider and wider, but this adds a lot of weight and we don’t want it to be so heavy. So therefore in the MEDULLARY CAVITY osteoclast are going to break the bone from the inside to hallow it out and make sure that we are getting balance of growth without the weight of the bone changing too much.
How does the skeleton move
Joints
What are 4 types of things in joints that helps a skeleton move
Hold bones together
Bone end touch each other
Involves soft tissue allowing things to attach to each other
Allows control and movement
What are the key soft tissues
Cartilage , there are 2 forms of cartilage, Hyaline And fibrocartilage
DFCT , these have a lot of fibres and are mostly Collagen that are closely packed together and they make multiple structures like, ligaments, tendons and joint capitals.
What are chondrocytes
These are a part of cartilage, they sit in the lacuna and they maintain the extracellular matrix of the cartilage and produce the cartilage matrix
What is ground substance
In the matrix there is something called the ground substance and this is what the collagen frites stick onto.
What are collagen fibres
They are dense and kind of like the strongest rope that you can think of
What kind of tissue is the cartilage and explain what that tissue is
It is an AVASCULAR TISSUE!
so there is no blood vessels and this may cause problems as we need the nutrients and we get the nutrients from the blood, so in order for the cartilage to get the nutrients that it needs the nutrients will fuse through the matrix by JOINT LOADING
What happens in joint loading
Joint loading happens at the end of the joints where you move your bone, there is a fluid that has nutrients in it and so every time we move it squishes the fluids that have the nutrients in it into the cartilage and gives it its nutriends
What is the function of the HYALINE cartilage
This is found at the ends of the bones, so its main function is to Resist compression, so if you were to push on the bone it won’t crumble into pieces, it does this by having a high water content in its extracelleiour matrix as water is great for resisting compression
So basically Hyaline cartilage is slippery and smooth which helps your bones move smoothly past each other in your joints. It’s flexible but strong enough to help your joints hold their shape this is important because every time we move we are going to apply pressure and so the bones will rub with each other if it didn’t have the hyaline cartilage. And this will hurt really bad
What is the hyaline cartilage was not there
Bones will rub against each other and the blood vessels and the nerves in the bone and so it will just hurt
What is Fibrocartilage
It is a transitional tissue, Its main function is to act as a cushion within joints, where it helps manage compression forces and reduces stress placed on joints. So relaxing the stress can be like it makes the bone be able to fit together more nicely
It resist both compression and tension while hyaline cartilage only resist compression
What is DFCT ( dense fibrous connective tissue)
Fibrous connective tissue supports, protects, and holds bones, muscles, and other tissues and organs in place. Ligaments, tendons, the inner layer of the skin, and the sclera (the white outer layer of the eye) are all types of dense connective tissue. Also called fibrous connective tissue, so this means that they are made from the fibroblast, and its main function is to resist tension
What are some things that DFCT can make
LIGAMENTS
They are made of DFCT that has a lot of fibres in, connecting bone to bone, they are made of collagen and elastin
TENDONS
Tendon is a fibrous connective tissue that attaches muscle to bone.
What is BONY CONGRUENCE
This is how much the bone touches each other, if the bone was not to touch as much then we would need a lot of soft tissue to support it, for example the knee needs a lot of soft tissues
What are the 3 joint CLASSIFICATIONS
Fibrous
Cartilaginous
synovial
What are fibrous JOINTS and give an example
They are the joints that have the less movement, and the tissue here is DFCT
Fibrous joints, such as the cranial sutures which connect cranial bones and protect the brain, are made of ligaments, formed of DFCT. As ligaments are able to tightly hold bones together and resist tension because of the tightly packed collagen fibres, this limits movement completely, ensuring stability and protection.
What is the cartilaginous JOINT and give an example
Thus has a little bit of movement and the tissue here is fibrocartilage
An example can be, such as in the pubic symphysis, which connects the two hip bones together. The slight movement allows for the bones to move a little during walking, and also for the joint to soften during childbirth to widen the pelvic cavity. Cartilaginous joints are made of fibrocartilage. Similar to fibrous joints, the collagen fibres in the fibrocartilage resist tension, but the ground substance component allows it to also resist compression.
What is the synovial joints and give an example of it
These are the joints that provide the most movement and it has many tissues
There are 7 types of synovial joint, with each type differing based on the bone shapes and planes of movement possible at each joint.
One example is the knee, which is a condylar synovial joint. Synovial joints contain many tissues, including a joint capsule of DFCT which surrounds the joint and holds it together, and is lined with a synovial membrane that secretes fluid important for lubrication and nutrient provision to avascular structures. Also ensuring smooth, frictionless movement is l the hyaline cartilage which covers the articulating bone surfaces.
