skeletal ch. 5

BONE FORMATION: ENDOCHONDRAL OSSIFICATION Metaphysis Epiphyseal plate

Steps 1 - 4 : initiation of ossification in developing bone(ex. taking a hyaline cartilage model and building bone around it) • Steps 5 - 7 : increasing length of developing bone (when you have the bone developed then the rest of the process focus on increasing the length of that developing bone)ex. as a individual grew in size the bone become the appropriate size for that individual

pneunatized bone

air cavities ethoid bone

*Spongy bone

aka cancellous/trabecular bone

*TWO TYPES OF BONE •Compact bone

aka cortical bone

If you have excess of calcium phosphate In the body then you have

available resources to create more bone

bone growth and development

before six week of development the skeleton is hyaline cartilage cartilage cell will be replace by bone cell this ossification

osteoclast is a

big cell with multiple nuclei / have a boarder that release enzyme and eat away at the bone

*BONE MAINTENANCE & REMODELING mineralization

bone will mineralized osteoblast get trap in bone matrix /bone mineralization start and it can't go no where then come osteocytes

If you need calcium phosphate in the body then the bone will be

broken down and the store calcium phosphate will be release in the blood stream for the body to use

What component of the bone matrix gives it its toughness?

calcium phosphate

if building a bone you need to required

calcium phosphate to lay down the bone tissue

until individual become skeletally mature which mean they stop growing the epiphyseal plate will consist of

cartilage .The line is where the one will be add so the bone can get big. Once you become skeletally mature it will no longer be cartilage/it fused up and become bone and individual can't increase in length

we have denser bone in the middle and lighter bone on the ends because

compact bone can handel a lot of force on it without breaking where as light weight will break (spongy bone ) middle bone (disphysis) is where there is a lot of stress on the bone ex. walking putting your body weight on the bone and the middle of the bone is where it likely to break /so you need to have bone that thick and very dense (in the middle of the bone )/while in the ends of the bone you don't need to much bone for preventing it from breaking

blood cell/production

contain red marrow which produce blood cell such as red, white, blood cell and platelets

bone remodeling

coordinated removal and replacement of bone tissue by osteoclasts and osteoblasts( both cells work together)

*calcium level in the blood to high

ex. drinking to much milk or yogurt so we want to do is deposit in the bone stimulus raising blood calcium level we have an imbalance thyroid gland is going to release calcitonin and calcitonin is going to stimulate bone to be deposited around the skeleton stimulate calcium up take in the kidneys ( excreate from kidney)(calcium is dump out of your urine) blind coordination of those two thing bring calcium down to homeostatic level

flat bone

flat and thin ex. neuro cranial bone (brain) partial bone (that sit on the side of the head) occipital bone (back of the head) frontal bone (forehead) rib and scapula/sternum(breast bone)

semamoid bone

form inside tendons ex. patella (pebble like bone) purpose to reduce friction at a joint/none under the big toe

sutural bone

found in flat bone in the skull

FUNCTIONS OF THE SKELETON support

frame work for all soft tissue in the body / if we did have a skeleton we will be a pile of goo on the floor

spongy bone found on the

inside of the bone / are light weight /space are where the bone marrow sit /allowing to exist in the bone so it can have that blood cell production function

type of ossification

intramembranous ossification and endochondral ossification

spongy (concellous/trabecular) bone

is has a lot of spaces( lighter weight) •Arranged in parallel struts(look like a sponge ) •Forms branching plates called trabeculae •Trabeculae form a network(trabeculae network give spongy bone it light weight /spaces inbetween trabecular) •Is why bones are lightweight

cartilage purpose

is to reduce friction of the joint by providing a smooth surface for the movement of two articulating bone that come together or that meeting or joining in that joint

osteocyte

living inside bone matrix/ surround by bone tissue / provide nutrients and keep that tissue alive

bone type long bone

longer than are wide found in the limbs ex. humorous, radius, ulnar ,brachium, antibrachium,fermurs,tipla,fibla,clavicle,metacarpal,phalnges

collagen fiber make the bone not to brittle but

make the bone a little bit more flexible

*CALCIUM HOMEOSTASIS

normal blood stream levels (about 10 mg /100mk) calcium level drop (imbalance) parathyroid will be release and stimulate calcium release from bone /osteoclast will eat away at the bone release those store calcium minerals in the blood stream /kidneys not going to release much calcium/ increase uptake in intestine absorbing calcium from food /calcium level will rise and bring us back to homeostasis

bone are hard and dense but

not completely soild /bone are organized to where there are space between them

BONE MAINTENANCE & REMODELING resting phase

nothing is happening the bone is not remodel

*BONE MAINTENANCE & REMODELING reversal

osteoclast ( reabsorption ) will eat away at the bone take at rest /everything get the smooth out mononuclear cell come through and clean up make it nice

osteoblast eventually become

osteocyte

The functional unit of bone is known as an:

osteon

compact bone found in the

outside of the bone and it serve as protection long bone found in limbs femur /hermous compact bone found on the outside /it what you see without cutting it

The outer covering of bone is known as:

periosteum

minerals storage /homeostasis

process of which you body maintain enteral environment in response to changes in external condition /body must contain normal calcium and foliate level (it regulate calcium)

What is the correct order of events for bone remodeling?

resorption, deposition, osteocyte mineralization

each on of the osteon has

several ring of lamellae

ligament

short bands of tuff fibrous bone connective tissue connect bone to other bones at joint

FUNCTIONS OF THE SKELETON protect

skull protect the brain/rib cage protect the heart and lungs/pelvic gurdual protect the abdominal organs

irregular bone

strange /irregular shape ex. vertebra (lumbar/thoracic cervical hip bone/cranial face/shenoid bone /hyoid bone

If osteoclast activity exceeds osteoblast activity, how will the mass of the bone be affected?

the bone would have an decreased mineral content and, as a result, it would also be weaker.

calcification

the deposition of calcium ions into the bone

osteoblast cell constantly secreting osteoid and they eventually they get

trap come surround osteoid that materialized and become osteocytes

articular cartilage

two bone meet /function is to cushion two bones that are meeting and prevent friction between the bone

short bone

wider than they are tall box like appears/interior fill with spongy bone ex. carpals bone/tarsal

mature bone The matrix of bone

•Calcium phosphate •Calcium phosphate eventually converts to hydroxyapatite crystals •Collagen fibers

Functions

•Change bone shape and adapt to environment(ex. if you don't exercise and you decide to lift weight that 400 pounds your bone will break/ but if you build up and exercise and lift weights for months /your bone will have the time to change the amount of bone that are lay down and change shape ) •Replace old/damaged bone ( over the course of your life bone come damage can occur during movement force on that bone can cause bone to form cracks need to be replace with fresh new bone/ osteoclast will come and remove old bone and osteoblast will lay down new bone where that old bone was ) •Release mineral stores (if you need to increase the minerals amount in the blood stream bone modeling will allow you to release those store minerals and when you have enough resources to replace the bone the osteoblast will come and add that bone back )

FUNCTIONAL DIFFERENCE BETWEEN BONE TYPES (spongy or compact/long bone in your limbs)

•Epiphysis (ends of the long bones) •Contains bone marrow where some of these bone marrow exists (pocket of marrow/made up of spongy bone /cover and protect by compact bone on the outside ) •Diaphysis (shaft of the long bones/made up of compact bone ) •The medullary cavity of the diaphysis contains bone marrow •Metaphysis •The widened portion of the diaphysis where bone is added during growth (ex. the particular location is where bone will be add if you were a child so you can increase in length) •Epiphyseal plate(the lining separating the diaphysis and epiphysis /consists of cartilage with skeletal mature ) •The line separating the diaphysis and epiphysis •Consists of cartilage until skeletally mature

*FACTORS AFFECTING BONE REMODELING & GROWTH (in order for bone remodeling to occur you have to have a certain amount of chemicals in your body /need for bone remolding if not bone will be brittle)

•Essential nutrients - ex. Calcium, Phosphorous, Magnesium, Sodium •Vitamins - ex. Vitamin A, Vitamin C, Vitamin D *•Hormones - ex. Parathyroid, calcitonin, sex hormones (store mineralized /matrix deposited osteoblast)

Osteogenic Connective Tissue Layers •Endosteum

•Lines medullary cavity (bone marrow cavity) •One cell thick(thin compare to periosteum) -this lining are able to regenerate bone

*COMPACT (CORTICAL) BONE

•Made up of osteons(several sheets of bone /long tubes of bone /run in the length of the bone compact bone is denser because it has fewer spaces /denser •Basic functional unit of bone Consists of: •Central canal (allow blood supply or nerve supply into the bone which is how bone maintain nutrients and keep tissue alive ) *•Canaliculi (is osteocytes are connected together by the projection of the cytoplasm of their cell membrane connect osteocytes together as one network which allow communication between all the cells so they can transport nutrients along the full length of the bone ) •Osteocytes (live inside osteon / it maintain lamellae and bone tissue) •Lamellae (thin sheet of the bone)

Bone linings

•Periosteum (outer/outside of the bone ) •Endosteum (inner/inside of the bone)

FUNCTIONS OF THE SKELETON

•Support •Protection •Movement •Blood Cell Production •Mineral Storage/ Homeostasis

STRUCTURE OF BONE Bones (Osseous Tissue)

•Supporting connective tissue •Specialized cells •Solid matrix

BONE MAINTENANCE & REMODELING matrix deposition

(bone is deposited )osteoblast come and secrete bone matrix

FUNCTIONS OF THE SKELETON movement

(bone provide attachment point for skeletal muscle that use bone as leverage to move the body muscle execrate force on the body to move joint)

osteoblast

(one nucleus) •bone building machines /secrete osteoid ( precurse to bone matrix gel like substance) •add bone to the body ( required calcium phosphate )

Osteogenic Connective(Osteo=bone/genic=create) Tissue Layers •Periosteum/ Lines outside of bone Functions:

- Protects - Attaches to fascia(provide surface for muscles) - Attachment site for circulatory & nervous supply(hold arteries in place) -this lining are able to regenerate bone

Bone cells contribute only

2 %of the bone mass

THE SKELETAL SYSTEM Made up of:

Bones (aka Osseous Tissue) (also cartilage ,ligament , bone marrow but mostly bone)

The matrix of bone is compose of

Calcium phosphate and Collagen fibers

Connective Tissues:

Cartilages(dense connective tissue)(ear, nose ,thorat,joint,rib,cage) Ligaments Other (for skeletal stabilization) Bones are dynamic organs that consist of several tissue types(contently changing)

intramembranous ossification

Involved in the development of clavicle, mandible, skull, and face

Endochondral ossification

Involved in the development of limbs, vertebrae, and hips