Blood, Sweat, and Tears: Human Anatomy

Bones: The Skeletal System

Functions

1. Structure
While a function of the  integumentary system was holding everything IN, the skeletal system's main function is to hold everything UP. the system is made up of stiff, rigid parts to keep the body upright.
2. Protection
Going hand in hand with structure, the form of the system - the rigid, strong bones - lends itself well to also protecting the soft tissue and organs of the body from impact, among other things. 
3. Movement
Bones also allow for movement by providing an anchor point for muscles to contract and relax. Furthermore, they can absorb the shock of intense movement. 
4. Storage
A less obvious function, the insides of bones can actually store a number of minerals and lipids that are then distributed to the body for other functions. 
5. Synthesis of Blood Cells
The insides of bones also house the materials necessary to form both white and red blood cells.  

A Brief Intro into the Skeletal System

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Bones: The Breakdown

1. Periosteum
This is a thin, membranous layer that covers all bones. In it are embedded blood vessels. 
2. Compact Bone
Right underneath the periosteum is the compact bone. This is the part of the bone you know and love, hard and compact from the dense osteocytes, and is what provides the main structural strength of bones. 
3. Spongy Bone
While not actually soft, this part of the bone is slightly hollowed out and has the appearance of a sponey. It is, however, still relatively strong. It lies towards the ends of bones.  
4. Medullary Cavity
This is the very inside of the bone, a hollow space that houses the yellow and red marrow's, which synthesize the white and red blood cells, respectively. 
5. Endosteum
This is like a periosteum, but lines the medullary cavity. 
6. Epiphyses (Singular: Epiphysis)
This is the rounded part at the ends of bones. These also store red marrow. 
7. Diaphysis
The shaft of the bone, this is basically anything that isn't the epiphyses, and encompasses the periosteum, compact bone, and some of the spongy bone.   

Types of Bones

1.  Long Bones
These bones are, as the name says, longer. This category of bones is also usually thicker/wider, and is meant for movements on a larger scale (like walking) as well as heavy support. This means bones like the femur, which is an especially long bone and supports the upper half of the body.
2. Short Bones
These bones are not only short, but far smaller. They are far less for support and more for dexterity and simple motion. As such, you'll have bones like the carpals, tarsals, and other small extremities fit into this category.
3. Flat Bones
Flat bones are shaped essentially like large, flat plates, like armor, to protect organs. The main example would be the ribs, which are thin, curved "sheets" of bone.
4. Irregular Bones
This is the broadest category, as it is essentially a "dump" for any bones that don't fit into any of the three previous categories. For example, vertebrae provide support, but aren't long and don't provide dexterity that short bones do or the protection of long bones. So, they're irregular bones.