Bone And Skeletal Growth Flashcards
Characteristics of the human skeleton and bone
• The human skeleton contains 10 – 12 kg of bone:
~ 1 – 2 kg of calcium (99% of the body total)
~ 0.5 – 0.75 kg of phosphorus (88% of the body total)
~ we require about 1 gram of each per day in the diet
~ 70% of bone is hydroxyapatite (calcium phosphate)
Hydroxyapatite
Ca10(PO4)6(OH)2
What % of the body is osetoid
-30% which is a matrix of collagen, hyaluronate, chondroitin sulphate, osteocalcin
How much and why in the first place does bone receive cardiac output
-the bone is a connective tissue that is highly metabolically active
-receives 12% of the cardiac output at rest (600ml/min)
List the types of bones
-long bones
-short bones
-flat bones
-irregular bones
-sesamoid bones
Long bones
~ metacarpals, metatarsals phalanges, humerus, ulna, radius, tibia fibula
Short bones
~ carpals and tarsals
Flat bones
~ rib, scapula, skull, sternum
Irregular bones
~ vertebrae and some facial bones
Sesamoid bones
Patella
Functions of the skeleton
• Mineral storage:
~ calcium and phosphate
• Support:
~ framework that supports the body and cradles soft organs
• Protection:
~ for delicate organs - brain, spinal cord, heart & lungs
• Movement:
~ bones act as attachment points and levers for muscles
• Blood cell formation:
~ bone marrow haematopoiesis
Parts of the bone
• Cartilage protects the ends of long bones
• An epiphysis / metaphysis is found at each end
• The epiphyseal line is a layer of growing cartilage
• Trabecular bone is on each side of an Epiphyseal line
• The shaft is cortical bone
• The shaft contains bone marrow where red and white blood cells form
Type of bone cells
Osteogenic
Osteoblasts
Osteocytes
Osteoclasts
Osteogenic cells
Form osteoblasts
Osteoblasts
Form new bone
Osteocytes
Entrapped ‘osteoblasts’
Mature bone cells
Osteoclasts
multinucleated cells that reabsorb bone using acids and enzymes
What do bone slips into
Epiphysis
Diaphysis
Epiphysis
-porous,high blood flow and high turnover
Diaphysis
Shaft of bone.lower turnover,less porous
Bone Growth in the Epiphyseal Plate (Bone Ends)
• Growing epiphyseal cartilage contain chondrocytes
➢epiphyseal bone growth is promoted by growth hormone (mainly during sleep)
➢sex steroid fuse the epiphysis towards the end of puberty preventing further growth
-Osteoblasts replace the chondrocytes and calcify the new bone matrix (osteoid)
-Osteoblasts become trapped in new calcified bone (osteoid) and become osteocytes with cellular inter-connexions
Chondrocytes
-cells found in healthy cartilage
-maintain healthy matrix Which consists mainly of collagen and proteoglycans
Endochondral ossification in long bones(creation of bone tissue)
1) Mesenchymal cells aggregate
2) Formation of cartilage model
3) Bone collar and primary ossification centre develop
4) Formation of marrow cavity
5) Epiphyseal cartilage begins ossification
6) Ossification of lower epiphyseal cartilage begins
7) Disappearance of epiphyseal cartilage & cessation of bone growth
What does aggregate mean
Combine/colllect
