skeletal system anatomy

support

bones provide a frameowrk that support and anchor all the soft organs

protection

protect our soft organs

movement

muscles use bones to help more the body

storage

bones store minerals (calcium and phosphorous) and 98% of calcium and phosphorus is stored in your bones

bone cell formation

all components of blood are formed inside certain bones

hormone production

osteocalcon deposited in bones to form them andsome hormones are produced in the bones

3 main components

bones, 206 bones in the body, divided into two divisons

axial skeletion (1st divison)

126 bones of the skull, chest, and spinal column

appendicular skeleton (2nd divison)

80 bones, bones of the limbs, gridles that attach them to the axial skeleton, cartilage, ligaments, and other connective tissues

bone classification based on shape

6 shapes

flat bones

thin, flat, and usually curved (rib bones, clavicle, scapula)

stutural/wormiam bones

irregular bones formed between the crancial bones

long bones

long and slender (femur,tibia, fibula,humerus, radius)

short bones

small and boxy (carpsals, tarsals)

sesamoid bones

small, flat, shaped like a seasame seed and develop in the tendons of the knees, hands, and feet (patella)

irregular bones

have complex shapes (vertebrae, hip bones, facial bones)

osseous tissue

bone tissue

1st type of bone tissue

compact/dense tissue

2nd type of bone tissue

spongey bone (cancellous/trabecular)

types of skeletal cartilage

consists of mostly water and has no nerves or blood vessels (hard to repair)

hyaline cartilage

provides support w/ flexibility and resilence

elastic cartilage

similar to hyaline but contains elastic fibers

fibro cartilage

highly compressable and very strong

epiphysis

top and bottom of bones w spongey bone inside

hyaline cartilage

surronds outside of bone

metaphysis

where growth of the bone occurs

diaphysis

made of compact bones

marrow cavity

inner middle cavity of bone

endosteum

lower marrow cavity above periosteum

1st type of marrow cavities

red marrow, makes blood and cell formation

2nd type of marrow cavities

yellow marrow, stores adipose tissue (fats)

adipose

stores fat for starvation, helps keep you warm and provide energy

peri

around

periosteum

layer of tissue surronding the bone and has nerves and blood vessels attached to it

endosteum

lines the marrow cavity (inner surface of bone)

end

inside

osteocyte

mature bone cell that cannot divide and is the most numerous bone type

functions of osteocytes

maintain the protein and mineral content of the adjacent matrix (non-living part of bone)

where are osetocytes found

small pockets called lacune

Lacunae are separted from layers of bone matrix called

lamellae

lamellae are connected to each other by small tunnels called

canaliculi

osteoblast

bone building cells

functions of osteoblasts

produce new boney matrix

osteogenesis/ossification

production of new boney matrix

what happens once osteoblasts are surrounded by boney matrix?

they become osteocytes

osteoprogentor

type of stem cell that differentiate into osteoblasts

stem cell

cell that doesnt know its job yet

where are osteoprogentors found?

in the inner lining of the periosteum

endosteum

passageways containing blood vessels

osteoclast

giant cells with more than 50 nucleui

osteoclast function

remove and remodel bone matrix

osteolysis

remove and remodel bone matrix

osteo

bone

lysis

rupture

osteolysis does what

regulates blood mineral levels

1st component of bone matrix

collagen fibers make up 1/3 of bones weight, provides flexibility for the bone

2nd component of bone matrix

calcium phosphate, interacts w/ other minerals and provides strength for the bone and makes up 2/3 of the bone

osteon (flaversion system)

has layers of concentric lamellae around a central canal (Haversion canal)

haversion canal

central canal in an osteon

where are osteocytes found

in lacunae between lamellae

central canal contains what

small blood vessels

what do osteocytes do

make the bone strong along its length

where is spongey bone found

where the bone is not heavily stressed

trabeculae

lamellae form struts and plates that form an open network

trabeculae function

reduces the weight of the skeleton

intramembranous ossification

when osteoclasts devlop bone from a fibrous memebrane

where does intramembranous ossification occur

occurs in the flat bones and the clavicale

step 1 of IO

stem cells cluster and differenticate into osteoblasts at an ossification center

step 2 of IO

osteoblasts secrete bone matrix and then become osteocytes

step 3 of IO

bone matrix accumlates around blood vessels to form trabeculae and the periosteum forms

step 4 of IO

trabeculae thicken to form bone and the vessels become red marrow

endochondral ossification (EO)

is when hyaline cartilage is replaced by bone

step 1 of EO

in diaphysis, chondrocytes enlarge and then die, leaving cavities in cartilage

step 2 of EO

blood vessels grow around the cartilage edge and osteoblasts form to create a superficial layer of bone

step 3 of EO

blood vessels penetrate the central region, osteoblasts enter and spongey bone is produced (primary ossification center) and the spongey bone spreads toward bone ends

step 4 of EO

a marrow cavity is created as cartilage is replaced by bone which allows the bone to grow in length or diameter

step 5 of EO

secondary ossification centers form in the epiphysies

step 6 of EO

epiphysies fill w/ spongey bone

step 7 of EO

the bone continues to grow in length until maturity

intramembranous ossification starts as

a membrane

endochondrial ossification starts as

a cartilage model

hormonal control of calcium

perathyroid hormone and calcitionin

perathyroid hormone is released by

parathyroid glands

parathyroid increase what

blood calcium levels

parathyroids stimulate

osteoclast to release calcium

also effects the release of calcitrol

and increases calcium absorbtion

kidneys

increase the release of calcitriol which causes calcium reabsorption in kidneys

calcitionin

released from thyroid gland, decreases blood calcium levels, decreases osteoclast activity in bones, decreases absorbtion of ca

calcitionin in kidneys

is going to inhibit calcitriol release and ca reabsorbtion