anatomy bones pt 2
what happens during endochondral ossification
- blood vessels form (cartilage is very vascular) - bone starts replacing cartilage - medullary cavity forms - secondary (in epiphyses) and primary ossification (center of diaphysis) centers - articular cartilage and epiphyseal plate
what happens during intramembranous ossification
- ossification center - calcification - formation of trabeculae - periosteum development
number one hormone which regulates blood calcium
PTH- parathyroid hormone
how does our blood calcium stay the same
balance between calcium storage in blood and bones
what's a simple fracture
bone breaks cleanly two steps to treatment - bone realignment and immobilization closed reduction (no surgical intervention)
what's a comminuted fracture
bone breaks into many fragments. open reduction may require surgical intervention for large bone fragments
what's a green stick fracture
bone breaks un completely (like a branch splintering on a tree)
what are osteoclasts
bone dissolving cells
what's an open or compound fracture
bone ends penetrate skin open reduction
What are osteoblasts?
bone forming cells
what's a compression fracture
bone is crushed
what's an impacted fracture
broken bone ends are forced into each other
what is the matrix made of
calcified matrix which is extremely vascular 25% water 25% collagen 50% crystallized mineral salts
what minerals are important to bone growth
calcium, phosphorus smaller amounts of magnesium, fluoride, and manganese
what tells PTH to be released
chemical receptors
where in the bone does cartilage remain
epiphyseal plate or line, articular cartilage
factors affecting bone growth
exercise and diet
when does bone growth occur
fetal development, infancy to toddler, adolescence
what triggers cell differenciation
genes
two major ways of embryonic bone formation
intramembranous ossification- simpler form- goes directly to bone - FLAT bones are created this way endochondral ossification- MOST bones are made this way- goes from cartilage (hyaline) to bone-
What is osteoporosis?
loss of bone mass resulting in calcium loss
What is PTH released in response to?
low blood calcium levels
What are osteocytes?
mature bone cells
what are osteogenic cells
only cells that undergo mitosis develop from stem cells
what is bone remodeling based on
osteoclastic and osteoblastic activity
what triggers promoter genes
photons of light
as the calcium increases in blood from pth...
pth levels slow; this is a negative feedback system. calcitonin TONES down blood calcium
we grow bone in what direction
radially
what's a spiral fracture
ragged break whereboth ends twist
4 types of bone cells
stem cell, osteogenic cells, osteoblasts and osteoclasts, and osteocytes
which organ plays a huge role in bone remodeling
the kidneys (retain calcium when it's low, hemoreceptors, can dispose of calcium)
how is blood calcium brought to normal when too low
through osteoclastic activity- bone is broken down to release calcium into blood
calcitonin comes from which gland
thyroid - tells calcium to go back to bone for storage
What are stem cells?
undifferentiated cells
which two body systems assist in bone remodeling
urinary and endocrine
what vitamins are important to bone growth and what do they do
vitamin A (stimulates osteoblasts) vitamin C (production of collagen), vitamin D (absorption of calcium)
how are bone calcium amts measured
xrays- areas of graying indicate bone loss, white indicated more dense material
four major parts of fracture repair
1. hematoma formation (blood vessels are ruptured when bone breaks. blood-filled swelling called hematoma forms. UNDER THE SKIN) 2. fibrocartilaginous callous formation (build up of bone. fibrocartilage model repairs. growth of new capillaries into clotted blood into site of damage. closes gap of fracture.) 3. bony callous formation (fibrocartilage callus is replaced by bony callus made of spongy bone) 4. bone remodeling
normal range for blood calcium
8.5- 10.5 mg/dL
what hormones are important to bone growth
IGHs (insulinlike growth hormones which help w energy production), T3 and T4 (thyroid hormones which speed up metabolism), sex hormones (peak during puberty), and parathyroid hormones and calcitonin (intimately involved w blood calcium)