SKELETAL SYSTEM: Bones and Joints
Components of the skeletal system:
- bones, cartilage, tendons, and ligaments (connective tissue)
- Their characteristics are largely determined by
The major functions of the skeletal system include:
1. Support.
2. Protection.
3. Movement.
4. Storage.
4. Blood cell production. (bone marrow)
EXTRACELLULAR MATRIX
The bone, cartilage, tendons, and ligaments of the skeletal system are all connective tissues.
Their characteristics are largely determined by the composition of their extracellular matrix.
The matrix always contains collagen, ground substance, and other organic molecules, as well as water and
minerals.
Collagen
- is a tough, ropelike protein.
Proteoglycans
- are large molecules consisting of many polysaccharides attaching to and encircling core proteins.
- form large aggregates and attract water
tendons and ligaments
- contains large amounts of collagen fibers, making these structures very tough, like ropes or cables.
cartilage
- contains collagen and proteoglycans. Collagen makes cartilage tough, whereas the water-filled
proteoglycans make it smooth and resilient.
- As a result, cartilage is relatively rigid, but it springs back to its original shape after being bent or
slightly compressed.
- It is an excellent shock absorber.
extracellular matrix of bone
- contains collagen and minerals, including calcium and phosphate.
- The ropelike collagen fibers lend flexible strength to the bone.
- The mineral component gives the bone compression (weight-bearing) strength.
, - Most of the mineral in bone is in the form of calcium phosphate crystals called hydroxyapatite
GENERAL FEATURES OF BONE:
There are four categories of bone, based on their shape: long, short, flat, and irregular.
Long bones
- are longer than they are wide.
- Most of the bones of the upper and lower limbs are long bones.
Short bones
- are approximately as wide as they are long;
- examples are the bones of the wrist and ankle.
Flat bones
- have a relatively thin, flattened shape.
- Examples of flat bones are certain skull bones, the ribs, the scapulae (shoulder blades), and the
sternum.
Irregular bones
- include the vertebrae and facial bones, which have shapes that do not fit readily into the other three
categories.
STRUCTURE OF A LONG BONE
Diaphysis
- central shaft
- (compact bone)
epiphysis
- ends
- (spongy tissue)
articular cartilage
- Covers epiphytes
- Reduces friction
epiphyseal plate
- Site of growth between epiphysis and the diaphysis
medullary cavity
- Center of diaphysis red or yellow marrow
Periosteum
- Membrane around bone’s outer surface
Components of the skeletal system:
- bones, cartilage, tendons, and ligaments (connective tissue)
- Their characteristics are largely determined by
The major functions of the skeletal system include:
1. Support.
2. Protection.
3. Movement.
4. Storage.
4. Blood cell production. (bone marrow)
EXTRACELLULAR MATRIX
The bone, cartilage, tendons, and ligaments of the skeletal system are all connective tissues.
Their characteristics are largely determined by the composition of their extracellular matrix.
The matrix always contains collagen, ground substance, and other organic molecules, as well as water and
minerals.
Collagen
- is a tough, ropelike protein.
Proteoglycans
- are large molecules consisting of many polysaccharides attaching to and encircling core proteins.
- form large aggregates and attract water
tendons and ligaments
- contains large amounts of collagen fibers, making these structures very tough, like ropes or cables.
cartilage
- contains collagen and proteoglycans. Collagen makes cartilage tough, whereas the water-filled
proteoglycans make it smooth and resilient.
- As a result, cartilage is relatively rigid, but it springs back to its original shape after being bent or
slightly compressed.
- It is an excellent shock absorber.
extracellular matrix of bone
- contains collagen and minerals, including calcium and phosphate.
- The ropelike collagen fibers lend flexible strength to the bone.
- The mineral component gives the bone compression (weight-bearing) strength.
, - Most of the mineral in bone is in the form of calcium phosphate crystals called hydroxyapatite
GENERAL FEATURES OF BONE:
There are four categories of bone, based on their shape: long, short, flat, and irregular.
Long bones
- are longer than they are wide.
- Most of the bones of the upper and lower limbs are long bones.
Short bones
- are approximately as wide as they are long;
- examples are the bones of the wrist and ankle.
Flat bones
- have a relatively thin, flattened shape.
- Examples of flat bones are certain skull bones, the ribs, the scapulae (shoulder blades), and the
sternum.
Irregular bones
- include the vertebrae and facial bones, which have shapes that do not fit readily into the other three
categories.
STRUCTURE OF A LONG BONE
Diaphysis
- central shaft
- (compact bone)
epiphysis
- ends
- (spongy tissue)
articular cartilage
- Covers epiphytes
- Reduces friction
epiphyseal plate
- Site of growth between epiphysis and the diaphysis
medullary cavity
- Center of diaphysis red or yellow marrow
Periosteum
- Membrane around bone’s outer surface
