SKELETAL SYSTEM CHAPTER 7

BONE SHAPES LONG VS. FLAT BONES

BONE STRUCTURE- MACROSCOPIC Ø  Epiphysis

Ø  Diaphysis Ø  Periosteum

Ø  Compact bone

Ø  Spongy bone

Ø  Medullary cavity

Ø  Notice articular cartilage

Ø  what type?

LONG BONE STRUCTURE

Ø  Bone marrow Ø  Yellow

Ø  Medullary cavity Ø  Stores fat

Ø  Red Ø  Spongy bone Ø  Creates blood

cells

Head of femur- notice spongy bone

BONE STRUCTURE- MICROSCOPIC Ø  Compact bone

Ø  Osteocytes Ø  Osteon Ø  Osteonic canals

Ø  a.k.a. Haversian Ø  Communicating canals

Ø  a.k.a. Volkmann’s Ø  Spongy bone

Ø  Not around canals Ø  Irregular latticework Ø  Cells nourished by diffusion

Ø  from surface of bony plates Ø  only a few cells thick

Haversian canals (a.k.a. osteonic canals)

FUNCTIONS OF BONES Ø  Support & protection

Ø  Shape & form for structures Ø  Protect softer underlying tissues

Ø  Storage of inorganic salts (in matrix)

Ø  Calcium phosphate & calcium carbonate Ø  Needed for metabolic processes Ø  Low blood calciumà osteoclasts break down bone tissue Ø  High blood calcium à osteoblasts form bone tissue

Ø  Store lesser amounts of Mg, Na, K, etc. Ø  May accumulate lead

BODY MOVEMENT

Ø Bones & muscles function together as levers

Ø Bones=levers Ø  Joints = fulcrum Ø Consider knee

Ø  Rod Ø  Pivot (fulcrum) Ø  Object/weight that is moved Ø  Force that supplies energy

Ø  Levers- EnchantedLearning.com (third-class lever)

HEMATOPOIESIS (OR HEMOPOIESIS) BLOOD CELL FORMATION

Ø Red marrow (yolk sac, liver, spleen in young)

Ø Adult spongy bone (ribs, sternum, vertebrae, pelvis, epiphyses)

Ø  Produces erthyrocytes, leukocytes & thrombocytes

Ø  Yellow marrow inactive in hematopoiesis Ø  Stores fat

Notice this shows red marrow in medullary cavity. This would be in young children only!

OSSIFICATION- 2 TYPES (BONE FORMATION)

OSSIFICATION- 2 TYPES (BONE FORMATION) INTRAMEMBRANOUS OSSIFICATION

§  Broad, flat bones

§  Layers of connective tissue

§  Chondroblasts differentiate into osteoblasts

§  Osteoblasts form in all directions within layers

§  Osteocytes (mature) surrounded by matrix by end

§  Spongy bone forms in middle, surrounded by thin layer of compact bone on surface

OSSIFICATION- 2 TYPES (BONE FORMATION) ENDOCHONDRAL OSSIFICATION

§  Long bones

§  Cartilage model serves as template

§  Primary ossification center

§  Secondary ossification center §  Bone tissue replaces cartilage except 2 regions

§  Articular cartilage §  Epiphyseal disk (plate)

Where is primary ossification center? Bone tissue forms toward ends Osteoblasts deposit layers on outer surface (collar thickens) Marrow cavity formed Where is secondary ossification center? Spongy bone formed here

ENDOCHONDRAL OSSIFICATION

BONE GROWTH 1.  Epiphyseal disk (plate)

2.  Rate of growth

1.  Hormones (GH)

3.  Other Factors

1.  Calcium & phosphorus 2.  Vitamin D