Skeleton system

The skeleton of human being os composed about 206 bones.

Types of tissue that form the skeleton of human being: connective tissue proper, cartilage

Function of the skeleton: - to support (to protect rib cage and heart, lungs

- framework

       - attachment per muscles, to keep a shape

       - passive body movement

       - blood formation - haemopoiesis

       - mineral storage (Ca, P)

Structure of a bone

Composition of a bone: - a solid network of organic materials (25% - 30% of whole bone) - flexibility:

a) osteocytes

b) living tissue (spongy bone and compact bone)

c) collagenous fibres

    - a matrix (innorganic content, about 50%-55% of whole body) - strength + hardness:

a) minerals - Ca, P

b) H₂O - about 20 % of whole structure of bone

    - with the growing age the amount of inorganic substances is decreasing - bones are more           breakable

Structure of a bone:

1. epiphysis

2. body (diaphysis)

3. periosteum - connective tissue, covers bone, contain many blood vessles, responsible for nourishment, nerve endings - sensitivity, responsible for external bone grow

4. spongy bone - quite porouse, cavities are filled by bone marrow, placed in epiphases of long bones and in short bones

5. red bone marrow - haemopoiesis, found in each bone of newborn but in adult it´s replaced by yellow bone marrow (is found in sternum, vertebra, pelvis, ribs and at the end of long bones)

6. cartilage - covers epiphases of bones, prevent friction

7. compact bone - very hard and dense

8. medullary cavity

9. yellow bone marrow - it contains fat

Internal bone growth

A bone is forming durong the process of ossification by the activity of osteoblasts that change cartilage to bone, ossification starts in the special platces = ossification centres.

The growth occurs in the epiphyseal disc = Growth plates (found in ossification centres) - it is under the control of growth hormone. It starts from the outside part and also inside part of the bone.

Classification of bones

according to the shape: a) short bones

     b) long bones

     c) flat bones

     d) irregular bones

Types of Joints

- place where 2 bones come together

Classification is based on the amount of movement possible:

1. Fixed joint = synarthrosis

   - immovable joint

   - allows no movement between bones

   - is held together by vonnective tissue

     a) Connective tissue proper e.g. bones of skull

     b) Cartilage e.g. ribs and sternum

     c) Bone tissue e.g. pelvis, sacral bone

2. Semimovable joints = amphiarthrosis

   - slightly movable joint

   e.g. tibia + fibula

3. Freely movable joints = enables movement