anatomy - bones

functions of bone

1. structure/support

2. protection of vital organs

3. serves as levers for movement

4. mineral storage

5. hemopoeisis

6. yellow marrow

structure/support function

serves as framework for the body and supports a lot of weight

protection of vital organs

cage

serve as levers for movement

gives a way for muscles to attach

mineral storage

calcium and phosphorous - if we get a signal for more calcium, osteoclasts break down bone

hemopoesis

bone makes blood, so forms blood cells (RBCs/WBCs/platelets)

yellow marrow

serves as a storage point for marrow, stores fat and there are stem cells there too

vascularity of bone

very vascular, heal well because there’s a good blood supply

parts of long bones

diaphysis, epiphysis, metaphysis, articular cartilage, periosteum, endosteum

diaphysis

shaft

epiphysis

ends

metaphysis

area between diaphysis and epiphysis, where growth plates are located

epiphyseal line

growth plate ossification; like a scar

articular cartilage

ends of bone where joints are located, made of hyaline cartilage and provides lubrication

periosteum

around the bone, fibrous membrane that surrounds the bone, there are two layers with protection and have blood vessels

2 layers of periosteum

1. dense CT - outside layer

   1. mesenchymal (stem) cells

endosteum

lines the medullary cavity; also contains stem cells, houses yellow marrow

medullary cavity

hollow cavity within the diaphysis

bone is…

connective tissue, made of cells and IC substance

IC substance of bone

concrete, has collagen and elastic fibers/calcium salts to make it hard, secreted by osteoblasts, help make strong in tension/compression forces e

exterior bone

compact bone

interior bone

spongy bone/cancellous bone

bone cells

osteoprogenitor, osteoblast, osteoclast, osteocytes

osteoprogenitor

mesenchymal stem cells, can become anything, generates new cells associated with bone

osteoblasts

form bone, make IC substance

osteocytes

mature osteoblasts, responsible for maintaining cellular environment, sends signals to clasts and blasts to build/break down bone, secretes enzymes, surround themselves with lacunae

osteoclasts

bone eaters/reabsorption of bone, multinucleated cells, ruffled border

osteon/haversian system

functional unit of compact bone (what compact bone is made of), extends lengthwise through the bone

four major structures associated with an osteon

haversian canal, lamellae, lacunae, canaliculi

haversian canal

central canal, blood vessel/vein goes through center

lamellae

calcified matrix around central canal

canaliculi

little canals that radiate out to each lamellae to deliver nutrients to lamellae

lacunae

located between the lamellae in concentric arrangement, house the osteoblasts

volkmann’s canals

perforating canals, penetrate bone perpendicularly (horizontally) and bring blood vessels from the surface, interconnect osteon

spongy/cancellous/trabecular bone

deep to compact bone, contains no true osteons, consists of needle-like bony spikes called trabeculae

where is compact bone found

at the ends of long bone/flat bonew

what is compact bone missing

lamellae'/osteons

what does compact bone have still?

lacunae and canaliculiw

where does the blood supply come from

red marrow; surrounds and makes blood

red marrow

performs homopoeisis

types of bone

long bone, short bones, flat bones, irregular bones, floating bones, sutural bones

long bones

levers of system (even the metacarpals and hand bones are considered long bones)

short bones

cuboidal, found in places where we have limited range of motion, ex: carpals/tarsals

flat bones

2 thin layers of compact bone separated by spongy bone (ribs/scapula)

irregular bones

funny/peculiar shape, ex: sphenoid/ethmoid, vertebrae

floating bone/sesamoid bone

looks like a sesame seed, ex the patella and pisaform, float and aren’t really attached to much

sutural/wormian bones

only found in the skull, places where the sutures have an “extra suture”