Bone Growth
How is bone formed in a growing infant? Calcified bone matrix replaces the cartilage. The bone is remodeled. The cartilage bone serves as a mold
Bone Development in a Newborn
Bone Remodeling
What roll do osteoblasts and osteoclasts have in bone formation? Osteoblasts = bone-forming cells –These cells form the cells needed to form a bone Osteoclasts = bone-resorbing cells –These cells absorb the important nutrients needed to form bone
What hardens a bone? The laying down of calcium salts in the matrix
Why is it that athletes have stronger denser bones than non-athletes? Stresses on bones during exercise increases the rate of bone deposition
What do all bones start out as? Cartilage models –Infants have such soft skeletons –Infants and toddlers are extremely flexible. –Their skull has not fully ossified yet Soft spot
What is the process of endochondral ossification and which direction does it occur? Bone is formed inside a cartilage “mold” –The process is ossification. Bone grows inside out and at the ends. Blood vessels penetrate the cartilage model to provide nutrients to the Osteoblasts & Osteoclasts to sustain their growth & function
A –Catilage Mold B –Blood vessels invade Diaphysis –Osteoblast and Osteoclast action Medullary Cavity forms Calcification Bone Tissue
C –Continuing of Osteoblast and Osteoclast action Medullary Cavity more defined Greater Calcification D –Epiphyseal calcification begining
E –Ossification continues in the epiphysis F –Growth Plate appears showing dividing the Epiphysis and Diaphysis G –Growth Complete, Growth plate calcified
When does bone growth cease? When all the epiphyseal cartilage is converted into bone. The growth plate closes
What roll does the growth plate (epiphyseal plate) have in bone growth? The diaphysis grows towards the epiphysis at the plate. When the growth plate is still visible, growth is still occurring –The Diaphysis and Epiphysis haven’t fused
Spinal Cord
4 ConcaveConcave –Cervical / Lumbar ConvexConvex –Thoracic / Sacral How many curves do you have in your spine? Where are the convex curves? Where are the concave curves?
How is an infants spine different from an adult? In infants, the spine is a continuous convex curve. As they develop muscle strength to hold their head up, the concave curve develops at the neck. As they learn to stand and strengthen their legs and abdomen, they get a convex curve in the lumbar region
What function to these curves have in your spine? Strength to support the weight of the body Balance for standing and locomotion Curves re-disdribute the forces of gravity and stress