Anatomy Notes - Skeletal System

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Bone Growth

Bone growth in length

Occurs in the osteogenic zone

Lower part of bone tissue

Rapid division of upper cells

Calcification and replacement

Bone growth in width

Appositional growth

Deposit of bone matrix by osteoblasts under periosteum

Bone growth + hormones

Growth hormone from anterior pituitary gland stimulates growth plate

Moderated by thyroid hormone

Bone growth hormones (puberty)

Testosterone and estrogen promote growth spurt

But also influence closure of growth plate (RIP growth plate)

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Bone Remodelling

Adults: remodeling is balanced creation and removal

Greater rate when injured

Bone absorption: minerals of degraded bone move in blood

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Remodelling Control

Hormonal mechanism to maintain blood calcium homeostasis

Balances parathyroid hormone activity

Balances calcitonin (lessens amount of calcium in the blood)

Response to Natural Stressors

Bone grows or remodels to where it allows it to withstand experienced stress

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The Girls Who Couldn't Move Notes

Ashley's large toe was smaller than the rest of her toe w/ bunyon

Ashley hit developmental milestones

Ashley had a warm lump on her back

Ashley had IFM (infantile fibromatosis)

Growth spread to Ashley's right arm

Tumor had gone all around her body, doctor had to amputate arm and other extremities off

Another lump on left side

Ashley can't lift her arm up

Calcification in her spine

Ashley didn't have fibromatosis

Ashley actually had fibrodysplasia ossificans progressiva (or FOP for short)

FOP is a genetic condition

Gene alters normal bone instructions and causes unnecessary and sporadic bone growth (ossification) in muscle mass in body

Patient grows extra skeleton

Patient will become rigid and eventually immobile

No cure

Ashley exhibited signs as early as 2 months old:

Shortening and abnormal development of toes considered first signs

As bone develops in the muscle, areas of swelling that are tender will occur

Eventually loss mobility in left arm

Limited movement in neck and right hip