1. Skeletal System
It's all about the bones
Mrs. Sheila Taylor

2. Alive? Yes they are And they work too... Here are some of the jobs
Point of attachment for muscles
Protect and support softer tissue
House blood producing cells
Store inorganic salts
It has canals for blood vessels and nerves
Bones have similar structure, development and function, they just differ in size and shapes

3. Structure of a long bone
Exhibits all the parts of the bones
Parts:
Epiphysis(s) – the end, expanded portion of the bone
Of course there is proximal and distal ones for each end of the bone
Articulates (forms a joint)
Made mostly of spongy bone (cancellous bone)
Lots of small bony plates connected together
Covered with thin plates of compact bone
Articular cartilage – a hyaline cartilage that coats the articulating portion of the epiphysis
Diaphysis- the shaft located between the epihyses (p)

4. Some more parts
The diaphysis is composed out of different types of bone tissue
Compact bone (AKA cortical) – makes up the outer walls
Has a continuous extracellular matrix with no spaces
Medullary cavity – hollow chamber inside the compact bone and goes into the spongy bone
Endosteum lines the areas
Filled with marrow which is a connective tissue
Periosteum – a tough fibrous tissue that covers the outside bone

6. Getting to the tiny details
Osteocytes – bone cells
In small areas called lacunae
In compact bone the make concentric circles around the central canals(aka Haversian canals)
Have blood vessels and nerves here
Are longitudinal through the bone
Volkmann's canals
the transvere version of the Haversian canals
They branch off them
Compact bone is made out of collagen and inorganic salts like calcium phosphate

7. So, how do they grow and develop?
Start to form during the first couple of week of prenatal development
Two main paths
Intramembranous bones
Originate between sheetlike layers of connective tissues
Endochondral bones
Originate as masses of cartilage that bone tissue later replaces

8. Intramembranous Bones
How created
Membranelike layer of connective tissue appear
Some of it enlarges and differentiates into bone-forming cells (osteoblasts).
Osteoblasts lay down bony matrix making spongy bone
Outside layer of connective tissue becomes periosteum
Found in skull bones

10. Endochondral Bones Development
Masses of Hyaline cartilage shaped kind-of like bones that grows rapidly
Cartilage starts to break down and disappear in the center as the periosteum forms and encircles the outside of the diaphysis
Osteoblast migrate from the periosteum into the disintegrating area of cartilage and start making bone. It is now called the primary ossification center.
Bone continues to form towards the ends

12. Endochondral bone formation continued
Osteoblast in the periosteum lays the foundation for the compact bone
Epiphyses remain cartilaginous and continue to grow until secondary ossification centers appear in them forming spongy bone.
The epiphyseal plates (metaphysis) are the bands of cartilage between the epiphysis and diaphysis .
Becomes known as the growth plate
When the cartilage is all ossified, no more growth occurs

14. Bone shaping Our bones are shaped continually as we live.
3-5%of the Ca is exchanged every year
Osteoclast dissolve the inorganic components of the calcium matrix with acid and lysosomal enzymes digests organic compounds
Digested out the medullary cavity
When they're done, osteoblast come in and make new bone.
What we put those bones through determines their shape and thickness as well as the amount of Ca in our blood stream

15. The physiology section
Protection and structure
Along with giving the shape to the skull, it also protects the eyes, ears, and brain
The pelvis not only supports our weight, but protects the lower abdominal organs
The ribs and shoulder girdle form a protective cage about the heart and the lung and the upper digestive organs

16. Body movement
With the aid of muscles, the bones act as a lever to move what ever we want them to.
Unless they can not exert the force need to over come the inertia of the object, of course. ^-^
The tendons attach to the processes that have formed on the bones. This allows the muscle to exert the force needed to move the bone.

17. Blood cell Formation Red bone marrow Yellow marrow Aka hematopoiesis
Starts in the yolk sac of the embryo, the liver and spleen take over the job until they are made in the red bone marrow.
Red bone marrow
In adults it is located in the spongy bone of in the skull, hip, sternum, ribs, clavicle, vertebrae
Makes all cellular components of blood
Yellow marrow
Stores fat
In the bones not mentioned above
Can turn back into red marrow if needed.

19. Bone marrow transplant

20. Storage of inorganic salts
Stored in the extracellular matrix of the bone tissue
Mainly calcium phosphate
Also has: magnesium, sodium, potassium, can carbonate ions
Will store harmful metals accidentally ingested here
Material is removed when we need it some where else in the body, and replaced when the body can.

22. Our skeleton Two main sections Axial skeleton Appendicular skeleton
The bony and cartilaginous parts the support and protect the head, trunk and neck regions.
Appendicular skeleton
The bony and cartilaginous parts that anchor the limbs to the axial skeleton and limbs.