Bone Tissue

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the study of bone

composed of bone, cartilage, and ligaments

hold bone to bone at joints

attach muscle to bone

• Support
• Protection
• Movement
• Electrolyte balance
• pH balance
• Blood formation

• connective tissue with matrix hardened by calcium
• Called Mineralization or Calcification

• Curved but wide and thin
• Example: Ribs
• Function: protect soft organs

• Longer than wide
• Functions: Rigid levers acted upon by muscles
• Example: Femur

• Equal in length and width
• Function: glide across one another in multiple directions
• Example: carpal bones

• Elaborate shapes that don't fit into other categories
• Example: vertabrae

Enlarged heads of long bones

• Also Dense Bone
• Outer shell of bones

• shaft of long bones
• cylinder of compact bone to provide leverage

• also Cancellous Bone
• always covered by compact bone
• lighter and less dense than compact bone

layer of hyaline cartilage that covers joint surfaces

Minute holes in the bone surface to allow blood vessels to penetrate

• external sheath that covers bone except where the articular cartilage is
• made of dense irregular CT
• Outer fibrous layer of collagen
• perforating fibers for strong attachment

Thin layer of reticular CT lining marrow cavity

• Line of hyaline cartilage that separates marrow space of the epiphysis and diaphysis
• Only seen in children who are still growing

• Flat bone composition
• Spongy layer sandwiched in between two layers of compact bone
• Absorbs shock

• Stem Cells found in periosteum, endosteum and central canals
• arise from mesenchym
• produce new osteoblasts

• Synthesis soft organic matter matrix which hardens through calcification
• nonmitotic

• Former osteoblasts that have become trapped in matrix
• Maintain bone matrix

Little cavities in bone matrix where osteocytes live

Little channels that connect lacunae

part of the osteocyte that reach into the canaliculi

• Bone-dissolving cell found on the bone surface
• Not a bone cell

results from combined action of the bone-dissolving osteoclasts and the bone-depositing osteoblasts

• 1/3 organic matter deposited by cells by weight
• 2/3 inorganic matter
• -85% hydroxyapatite
• -10% calcium

• Soft bones due to calcium salts
• Only found in children

• Brittle Bone Disease
• excessively brittle bones due to lack of protein, collagen

• Ceramic: hydroxyapatite and calcium
• Polymer: collagen
• makes bones tough but slightly flexible so they don't break

Transverse or diagonal canals carrying blood and nerves through bones

Run up and down long bones a carrying blood and nerves through bone

Slivers of spongy bone

• Thin plates in spongy bone
• Develop along lines of stress

soft tissue that occupies the marrow cavity of long bones and small spaces amid trabeculae of spongy bone

• Found in the skull, vertebrae, ribs, sternum, pelvic girdle, proximal heads of humerus and femur
• produces blood cells

• Only found in adults
• Composed of adipose tissue
• No longer produces blood

bone formation

• Formation of Flat Bones
• 1. Condensation of mesenchyme into soft sheets permeated with blood capillaries
• 2. Deposition of osteoid tissue by osteoblasts on mesenchymal surface; entrapment of first osteocytes
• 3. Honeycomb of bony trabeculae formed by continued mineral deposition; creation of spongy bone
• 4. Surface of bone filled by bone deposition, converting spongy bone to compact bone. Spongy bone in the middle

• 1. Early cartilage model consisting of perichondrium and hyaline cartilage
• 2. Formation of primary ossification center, bony collar, and periosteum
• 3. Vascular invasion, formation of primary marrow cavity and secondary ossification center
• 4. Bone at birth, with enlarged primary marrow cavity and appearance of secondary marrow cavity
• 5. Bone of a child, with epiphyseal plate at distal end
• 6. Adult bone with single marrow cavity and closed epiphyseal plate

zone of transition facing the marrow cavity

• 1. Zone of reserve cartilage
• 2. Zone of cell proliferation
• 3. Zone of cell hypertrophy
• 4. Zone of calcification
• 5. Zone of bone deposition

Bone growth in length from the epiphyseal line

Bone increase in width by laying down circumferential lamellae

Architecture of bone determined by mechanical stress placed on it and bones adapt to withstand those stresses

Long bones stop growing in childhood

• Lack of growth hormone
• Normal proportions

stimulates protein synthesis and cell growth throughout the body

stimulates cell metabolism and increase osteoblast activity

stimulate osteoblasts to produce bone faster causing epiphyseal plate to close

Bone deposition outside of bones

the process of dissolving bone and releasing minerals into the blood

• Too much calcium in the blood
• causes excessive excitability of nervous system leading to muscle spasms and tremors

• Too little calcium in the blood
• Sodium channels are less likely to open. depressing nervous system

• A form of Vitamin D produced from the skin, liver, and kidneys
• Allows body to absorb calcium from food

• Secreted by C ells of the thyroid gland when calcium levels in the blood are too high
• inhibits osteoclasts from dissolving bone
• increases the number of osteoblasts to deposit calcium into the skeleton

• Secreted by the parathyroid gland when blood calcium reaches too low
• Raises blood calcium level by stimulating osteoclasts

Break caused by abnormal trauma to a bone

break in a bone that has been weakened by some other disease

• 1. Hematoma formation
• 2. Soft callus made of collagen
• 3. Hard calls formation
• 4. Bone remodeling

Bone fragments are manipulated into their normal position without surgery

Opening a fracture surgically to put the bones back together using pins and plates

Branch of medicine that deals with prevention and correction of injuries and disorders of the bones, joints, and muscles

• accelerates bone repair
• suppresses effects of parathyroid hormone

severe loss of bone density