BIO 201 UNIT 2 Bone Growth

endochondral ossification, secondary ossification, metaphysis, growth and remodel

What is the first step of endochondral ossification

forms in cartilage model

(Cartilage model) mesenchyme develops to —-

hyaline cartilage covered by fibrous perichondrium

(Cartilage model) perichondrium produces —-

chondrocytes

(Cartilage model) chondrocytes reduce matrix by —-

multiplying, swelling and forming columns

(Cartilage model) When matrix is reduced it will —-

calcify, killing chondrocytes by cutting of nutrient supply

(Cartilage model) once chondrocytes are dead perichondrium will —-

produce osteoblasts to build bone collar/shell around cartilage model

(Cartilage model) once bone collar built next step is

blood vessels fill in cavity with blood, stem cells, and fibroblasts

when cartilage model is complete this builds the —-

primary ossification center in the diaphysis.

What is the second step of endochondral ossification

primary marrow cavity

(Primary marrow cavity) fibroblasts turn into —-

osteoblasts (build bone) on outside

how do osteoblasts build bone in primary marrow cavity

line cavity and deposit osteoid tissue to calcify into bone framework of trabeculae. Wave of carilage dead moving to each end of bone

(Primary marrow cavity) stem cells turn into —-

osteoclasts (cleanup cells) on inside

how do osteoclasts build bone in primary marrow cavity

enlarge to dissolve calcified cartilage remnants

what is the third step of endochondral ossification

perichondrum becomes periosteum

what is perichondrium for

perichondrium covers cartilage

what is periosteum for

periosteum covers bone

What is the fourth step of endochondral ossification

metaphysis

What is the metaphysis transition

cartilage turns to bone

when endochondral ossification complete it builds the

secondary ossification site for time of birth

where does secondary ossification center form

epiphysis (ends of bone)

key points when secondary ossification complete

hyaline/articulate cartilage stays on join surface, builds epiphyseal plate/line

what is the metaphysis

transitional area in developing long bones between head and diaphysis

what does the metaphysis add

length via interstitial growth

how many zone in metaphysis

5 zones at various stages of mineralization

how does the metaphysis go away

shrinks with age

what are the steps of ossification in the metaphysis

proliferation, hypertrophy, calcification, bone deposition to grow/remodel

what is the metaphysis reserve zone

layer of resting cartilage

what is the metaphysis cell proliferation zone

chondrocytes multiply to form columns of flat lacunae

what is the metaphysis cell hypertrophy zone

chondrocytes enlarge

what is the metaphysis calcification zone

mineralization of matrix between columns of lacunae

what is the metapysis bone deposition zone

chondrocytes die leaving channels to fill with blood and osteoblasts, build central canel (osteon)

what is interstitial growth

growth of length at epiphyseal plate

What is oppositional growth

growth in width via osteoblasts and osteoclasts

what happens if appositional growth is irregular?

bone deformities occur

what is mineral deposition

mineralization via crystalization to remove ions from blood plasma and deposit into bone tissue

what are the steps of mineralization

osteoblasts build collagen fibers and fibers become encrusted with minerals

what is ewhat is the metaphysis

abnormal calcification

where can ectopic ossification occur?

lungs, brain, muscles, tendons

what is mineral resorption

dissolve bone to release minerals into blood

how does mineral resorption occur

osteoclasts clean up bone minerals with hydrochloric acid and clean up collage with acid phosphatase

What is calcitriol

calcium increase in blood

what produces calcitriol

vitamin D from UV radiation

how does UV radiation build calcitirol

UV radiation makes keratinocytes convert cholesterol derivative to cholecalciferol

what organ converts calcidiol

liver

what organ converts calcidiol to calcitriol

kidney

how does calcitrol increase calcium from intestines?

stimulate intestine to absorb calcium, phosphate, magnesium

how does calcitrol increase calcium from bones?

increase osteoclast activity

What is calcitonin

calcium increase in bone

how to remember calcitonin

Cal (calcium) + in (in bone) = for growing kids

what secretes calcitonin

c cels from thyroid gland

when are c cells secreted

when blood calcium too high

how does calcitonin increase calcium from bones?

reduce osteoclast activity, increase osteoblast activity

What is the parathyroid hormone

parathyroid gland release when calcium in blood too low

parathyroid hormone stimulates

osteoclast multiplication and activity

parathyroid hormone promotes

calcium resorption and calcitriol synthesis in kidney

parathyroid hormone inhibits

osteoblasts from collagen synthesis and bone deposition

What is the first step of a fracture healing?

hematoma formation (blood clot) for severed blood vessel in periosteum and bone

What is the second step of a fracture healing?

fibrocartilaginous callus formation for capillaries growth in hematoma. Collagen and fibrocartilage deposit to reconnect bone

when does the second step of fracture healing occur?

within day

What is the third step of a fracture healing?

Bony callus osteoblasts build new trabeculae for spongy bone to start endochondral ossification process

when does the third step of fracture healing occur?

within a week

What is the fourth step of a fracture healing?

bone remodels itself and compact bone laid from mechanical stress

when does the fourth step of fracture healing occur?

with a week to months after