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)