CHP 7 Bone Tissues

Osteology

the study of bone

Skeletal system

• made of bones

• made of cartilages; forerunner of most bones

• ligaments; hold bones together at joint (DIFFERENT THAN tendons; attach muscle to bone)

Functions of the skeleton

• support

• protection

• movement

• electrolyte balance; calcium/phosphate levels

• acid-base balance; buffers blood against large pH changes by altering phosphate and carbonate salt levels

• blood formation; red bone marrow = blood cell maker

Bones + Osseous Tissue

-mineralization/calcification; hardening process of bone

• connective tissue w matrix hardened by calcium phosphate and other minerals

-bones are osseous tissue, but also technically an organ

Types of Bone (shape)

• Long bones = longer than wide, only type with a marrow cavity

• Short bones = approx. equal length/width, glide across each other

• Flat bones = thin curved plates, filled with spongy bone, protect soft organs

• Irregular bones = all others w weird shapes

Types of bones (tissue)

• Compact bone = dense outer shell of bone

  • lamellae surround central canal (longitudinally)

  • perforating canals (transverse/diagonal passageways)

• Spongy (cancellous) bone = loosely organized bone tissue

  • made of trabeculae and the space filled with red bone marrow

  • found in the centers of bones and specially at the ends of long bones

  • few osteons and no central canal

Bone cells

-osteogenic cells

-osteoblasts

-osteocytes

-osteoclasts

Osteogenic cells

-stem cells found in endosteum and inner layer of periosteum

-CREATION of bone cells

Osteoblasts

-bone BUILDERS
-form a single layer of cells under endosteum and periosteum by synthesizing soft organic matter of matrix

How does stress make our bones stronger

-stress stimulates osteogenic cells to multiply rapidly and increase the number of osteoblasts which in turn reinforce bone

-osteocytes also act as strain sensors that produce biochemical signals that regulate bone remodeling

Osteocytes

-former osteoblasts that have become trapped in the matrix

-MAINTENANCE cells; when stressed produce biochemical signals that regulate bone remodeling

includes:

• lacunae = tiny cavities that hold the osteocytes

• canaliculi = little channels that connect lacunae together

osteoclasts

• bone dissolving cells found on bone surface

• CLEANING cell; dissolves bone tissue by hydrochloric acid

• multinuclear from the fusion of stem cells

the matrix of bones

-1/3 organic, 2/3 inorganic

• Organic matter = synthesized osteoblasts, collagen!

• Inorganic matter = 85% hydroxyapatite (crystalized calcium phosphate salt), 10% calcium carbonate, other minerals

-the MINERAL portion gives stiffness; deficiency= soft bone

-the POLYMER (protein) gives flexibility

• Osteogenesis imperfecta (brittle bone disease); results from a defect in collagen deposition

Bone Marrow

-soft tissue occupying marrow cavities of long bones and small spaces of spongy bone

• Red Marrow (myeloid tissue)

  • makes blood cells

  • nearly every bone in a child

• Yellow Marrow

  • marrow found in adults

  • fat storage

osteogenesis

the formation of bone

• Intramembranous ossification

• Endochondral ossification

Intramembranous ossification

endochondral ossification