The Skeletal System

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The Skeletal System by Mind Map: The Skeletal System

1. Bone Function

1.1. Support

1.2. Store minerals

1.3. Produce blood cells

1.4. Protection to various organs of the body

2. Types of bones

2.1. Long Bone

2.1.1. Strong

2.1.2. Broad at the ends where they join with other bones

2.1.3. Have large surface for muscle attachment

2.1.4. They are found in thighs, lower legs and upper and lower arms

2.2. Short bones

2.2.1. Small

2.2.2. Irregular shapes

2.2.3. They are found in wrists and ankles

2.3. Flat Bone

2.3.1. They cover soft body parts

2.3.2. They are found in shoulder blades, ribs and pelvic bones

2.4. Irregular bones

2.4.1. Do not fit above categories

2.4.2. They are found in vertebrae and some facial bones

2.4.3. Osteogenesis: The formations of bone Intramembranous ossification: Form membrane bones(skull+clavicles) directly from mesenchyme. Ossification centers appear in the fibrous connective tissue membrane, derived from mesenchymal cells differiating into osteoblasts. Ossification centers appear in the fibrous connective tissue membrane, derived from mesenchymal cells differiating into osteoblasts Hyaline cartilage model is formed and at it's diaphysis a bone collar begins to form.

3. Macroscopic Structure

3.1. Parts of a long bone

3.1.1. Diaphysis The shaft or middle region of long bones Made up mostly of compact bone

3.1.2. Epiphysis The end of long bones Mostly spongy bone

3.1.3. Epiphyseal line An area of cartilage tissue that is constantly replaces by new bone tissue as the bone grows Also known as the growth plate

3.1.4. Metaphysis Flared portion of the bone It is adacent to the epiphysis plate It lies between the epiphysis and the diaphysis

3.1.5. Articular cartilage hyaline cartilage at joint Smooth, strong, slich tissue It covers ends of bones that form a joint

3.1.6. Periosteum It has extensive nerve supply Strong, fibrous, vascular membrane Fibrous covering over most of bone

3.1.7. Medullary cavity (marrow) With fat and blood cells

3.1.8. Endosteum Membrane lining medullary cavity

3.1.9. Compact Bone Function/composition: Dense outer layer of bone present for protection/support. Contain passage way for blood vessels and nerves. Contain osteons (long cylindrical structures functioning in support) Location: surrounding all bones

3.1.10. Spongy Bone Function/composition: Internal honeycomb of small needle-like/ flat pieces, composed of trabeculae. The trabeculae helps bone resist stress and stores red(produces blood cells) and yellow blood marrow(stores energy as fat) Location: Within short, flat, irregular bones. At the epiphyses of long bones.

4. Microscopic Structure of Bone

4.1. Cell Components

4.1.1. Osteocytes (mature cell-located in the lacunae)

4.1.2. Osteoblasts(secrete collagen fibres and ground substance of matrix)

4.1.3. Osteogenic cells: Stem cells that later differentiate into osteoblasts

4.1.4. Osteoclasts: Multinucleate cells responsible for the resorption of bone

4.2. Matrix components(Ground substance+fibers

4.2.1. Gel-like ground substance( secreted by osteoblasts):(Occupy 35%) Gel-like ground substance calci ed with inorganic salt making the matrix hard and able to contribute to it's function in supporting the body.

4.2.2. Fibers: collagen(Occupy 65%) Collagen fibres: Composed of amino acids (Glycine, Proline, Hydroxyproline and Arginine). Fibres contribute to the strength of tissue, this strength is derived from the bundling and cross linking of fibrils within bundles, again within larger bundles.

5. Compact Bone Structure

5.1. Arranged in osteons (haversian systems)

5.1.1. Cylinders running parallel to long axis of bone

5.2. Central canal

5.2.1. Through center of osteon

5.2.2. Contains blood vessels, nerves, lymphatics

5.3. Concentric lamellae

5.3.1. Layers of matrix

5.4. Lacunae

5.4.1. “lakes” between lamellae

5.4.2. Contain osteocytes (bone cells)

5.5. Canaliculi (“little canals”)

5.5.1. Contain extensions of osteocytes

5.5.2. Permit flow of ECF between central canal and lacunae

5.6. Compact bone is covered by periosteum

5.7. Perforating (Volkmann’s) canals

5.7.1. Carry blood and lymphatic vessels and nerves from periosteum

5.7.2. They supply central (Haversian) canals and also bone marrow

6. Growth: Embryonic; Post natal

6.1. Post-natal growth:focusing on puberty, the effect of hormones, and remodeling

6.1.1. Bones lengthen by the growth of epiphyseal plates. During lengthening process cartilage is replaced with bone connective tissue at a approximate that of growth. Epiphyseal plates: Initially promote growth while retaining a constant thickness. Nearing the end of adolescence the chondroblasts divide less often, as a result the plates begin to thin and are eventually gone, at which the diaphysis and epiphyses fuse and the bone stops lengthening. Stimulated by a growth hormone produced by the pituitary gland. Epiphyseal termination is later stimulated by sex hormones.

6.1.2. Bone widening is the result of osteoblasts through appositional growth where bone tissue is added to the surface of bones, specifically the diaphysis.

6.1.3. Growth hormones Thyroid hormone: Ensures that proper proportions are retained within the skeleton as it grows. Sex hormones(estrogen and testosterone): Promote growth and growth termination. Bone remodelling: Deposition and removal occurs at the periosteal and edosteal surfaces, which are the result of osteoblasts and osteoclasts. Pituitary gland:Contains hormone that stimulates epiphyseal plates.

7. Types of Fracture

7.1. Greenstick Fracture

7.1.1. Incomplete and the break occurs on the convex surface of the bend in the bone

7.2. Fissured Fracture

7.2.1. Involves an incomplete longitudinal break

7.3. Comminuted Fracture

7.3.1. Complete and Fragments the bone

7.4. Transverse Fracture

7.4.1. Complete and the break occurs at a right angle to axis of the bone

7.5. Oblique Fracture

7.5.1. Occurs at an angle other than a right angle to the axis of the bone

7.6. Spiral Fracture

7.6.1. Caused by twisting a bone excessively