Overview of the Skeletal System

(http://www.stpeters.k12.nf.ca)





Introduction: Welcome to the second part of unit three! This unit is going to look through the skeletal and muscle systems. We are going to start with the skeletal system. This section will delve into the functions of the system, the different types of bones formed, what cartilage is and what it does, as well as the tissues involved. Let's dig in!

Functions:

1. Supports the Body

2. Protects soft body parts

3. Produces blood cells

4. Stores minerals and fat

5. Skeleton, with muscles, permit flexible body movement

Bones:

*Anatomy of a long bone

~Medullary Cavity: Cavity within the diaphysis of a long bone containing

marrow that stores fat

~Diaphysis: Middle length of the bone

~Epiphyses: Expanded region at the end of the bone

~Hyaline (articular) cartilage: Covers end of bones to stop hard bones rubbing

On each other in the joint

~Periosteum: Covers entire long bone (except where hyaline cartilage is) and

Contains blood vessels, lymphatic vessels, and nerves

Now for a look at the compact bone. This picture was found at http://upload.wikimedia.org.

*Compact Bone: Type of bone that is highly organized and composed of

Osteons that house osteocytes in lacunae

Last but not least, is the spongy bone. Above, the picture used for compact bone, also shows spongy bone. It kind of looks like a sponge, huh?

*Spongy Bone: An unorganized appearance containing a lot of trabeculae. Is

Lighter than compact bone and designed for strength

There will be much more on the different types of bones when it gets to the bone formation section. Next, let us look at red bone marrow. The picture below, from http://www.lpch.org is a Earlier in the semester, we talked some about red bone marrow because that is where the red blood cell is made.

*Red Bone Marrow: often fills spongy bones’ spaces; a specialized tissue that

Produces all types of blood cells

Technically, marrow should be placed in the tissues section.

Cartilage:

Cartilage is all over our body. It covers bones and makes part of our nose as well as forms our ear lobes! The below picture is from http://www.botany.uwc.ac.za. It shows the three different types of cartilage.

*Cartilage: Not as strong as bone, but more flexible

~Has gel-like matrix containing collagenous and elastic fibers

~Chondrocytes lie within lacunae that are irregularly grouped

~Has no nerves

~Great for padding joints

~No blood vessels, so it heals slowly

~3 Types

1. Hyaline: Firm, somewhat flexible; found at ends of long bones, nose,

End of ribs, and in larynx and trachea

2. Fibrocartilage: Stronger than Hyaline because matrix has wide rows of

Thick, collagen fibers; withstands tension and pressure; found in

Disks between vertebrae and cartilage of knee

3. Elastic Cartilage: More flexible than Hyaline because matrix has

Mostly elastin fibers; found in ear flaps and epiglottis

Tissues:

Below is a picture from http://www.cartage.org.lb. It simply points out the tibia bone and muscles involved in the foot and toes. It also picks out ligaments and tendons.

*Fibrous Connective Tissue: rows of cells, fibroblasts, separated by bundles of

collagenous fibers; makes up ligaments and tendons

~Ligaments: Connect bone to bone

~Tendons: Connect muscles to bone

Conclusion: That ends the first section of major topic two! Now that we know the basics of the skeletal system, it is time to delve a little deeper. With bones being such a huge part of our body, it is good to know how they are formed, repaired, and sometimes deteriorated.