endochondral ossification

the template is replaced with

bone. REPLACED not converted

what surrounds the outer layer of the epiphyses

articular cartilage, originally part of hyaline cartilage template

how are long bone growth and endochondral growth similar?

at the growth plate there is cartilage and the cartiladge cells hypertrophic, they calcify , they die and you replace it with cartilage.

where is new bone/new cartilage forced

bone= border of the diaphyses and plate cartilage=border of the plate and epiphyses always extending the length of the diaphyses

similarities between endo and intra

both have osteoblasts than form an ossification center that form bone that gets remolded to form compact or spongy bone over time

for normal growth you must have

both hormones, a deficiency in either one will cause you to be short.

the growth or proliferation zone

by the epiphyses. where cartilage cells undergo mitosis. these cells have access to nutrients and can produce new cartilage.

the template

gets larger and larger

girls stop growing sooner than boys

has to do with estergeon.

what other hormone helps the growth hormone

thyroid hormone. permissie, permits other hormones to do their job more effective.

step 2

-cavitation of the hyaline cartilage within the cartilage model -stressed chondrocytes in cartilage with get larger, they will then mineralize the cartilage and that will then cut off all nutrient access to chondrocytes =die. -during this time detriation of the cartilage occurs that makes up the diaphyses.

first step

-formation of bone collar around hyaline cartilage model -the boney collar is formed around the diaphyses and is formed by osteoblasts that laid down osteoid, mineralize it, incase the center region of the template -primary ossification center-has to kill off cartilage first then replace it with bone -boney collar is essential starting place bc it stresses cartilage=killing, provides underlying support for diaphyses to grow & exist in face of decaying cartilages

step 4

-formation of the medullary cavity as ossification continues; appearance of secondary ossification centers in the epiphyses in preparation for stage 5 -the status of bone around a child is born -the medullary cavity is present, bone associated with cavity is converted to compact bone and fusses with boney collar -at ends of diaphyses there is some spongy bone -as diaphyses grows longer the spongy bone gets remolded and you only see it at the very ends -everything in center is compact bone -when child is born the epiphyses are only starting to form bone -cartilage on the outside become articular cartilage and cartilage between the epiphyses and diaphyses that will constitute your growth plate.

what regulates the growth plate and the rate of growth development

-growth hormones-inadequate short, stimulates borsht the cartilage and the bone growth that occurs at the plate. stimulates produce of cells, lengthening of diaphoreses. hormone that doesn't work well unless another hormone is present

step 3

-invasion of internal cavities by the periosteal bud and spongy bone formation -the blood vessels. nerve ending and lymphatic vessels influrtate -blood vessels bring osteoblasts, osteoclasts and hematopietic stem cells -osteoclasts help break down the calcified cartilage= create medullary cavity -osteoblasts will lay down new bone (not compact bone, disorganized bone->spongy bone-> compact bone) -bone laid down in diaphyses will fuse to boney collar eventually

step 5

-ossification of the epiphyses when completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilages -full formed bone, finished AFTER birth -diaphyses has compact bone spongy bones at end next to epiphyseal plate -epiphyses has compact and spongy bone as well and is incase in a layer of articular cartilage.

the process starts at

9 weeks following conecption

the plate is

a region of bone that separates the epiphyses and diaphyses that has not fused. does include hyaline cartilages in various stages. when a person is growing new cartilage is being produce, some is dying and being replaced by bone

secondary ossification centers

cartilage is destroyed by osteoclasts and osteoblasts build the bone.

at childbirth the epiphyses are forming and there is _____ that separates

cartilage that separates the epiphyses from the diaphyses.

the epiphyseal plate

contains hyaline cartilage, separates the epiphyses and the diaphyses and is where long bone growth occurs.

the growth plate can be broken down into

different regions

long bone growth occurs at the

epiphyseal plate

there is cartilage surrounding the

epiphyses

what causes you to be really tall

excess growth hormone NOT thyroid hormone

during long bone growth you are

extending the length of the diaphyses, shaft of bone and pushing the epiphyses further and further apart

the calcification zone

matrix becomes calcified; cartilage cells die, matrix begins deteriorating

the hypertrophic zone

older cartilage cells enlarge.when they become stressed=biggest stress=lack of nutrients hypertrochy, they secrete calcium, calcifies the cartilage with kills the chondrocytes.

in all cases of bone growth

osteoblasts lay down bone osteoclasts remolded bone, they can combine to form compact bone or they can produce spongy bone, depends on signals and cues they receive.

the sex steroids

promote rapid bone growth initially, growth is due to bone formation in the ossification center with causes a rapid lengthening in the diaphyses which is initially early vertical growth. growth in ossification center is faster than proliferating center with the cartilage cells. because of this bone growth will surpass cartilage development and eventually the cartilage will be completely replaced by bone, epiphyseal plate will tuen to line and growth will stop. enhanced by the sex steroids.

what hormone causes the growth of the epiphyseal plate so rapid that the plates seal

sex steroids. after puberty you had rapid growth but as it continued bone growth slowed down. ladies 1-2 years before boys. g

sex steroids vs growth hormone

sex- alter the balance causing more rapid bone growth than cartilage growth growth- will stimulate growth of cartilage cells as well as growth of bone

bone remodel

the bone can still get thicker or thinner after the plates fuse depending on how you use the bone/ your nutrition

the ossification zone is associated with

the diaphyses and in this zone you are forming new bone. bone formation that occurs to replace cartilage

the epiphyseal line

the diaphyses has now fused with the epiphyses and lone bone growth no longer occurs

when a child is born

the epiphyses are far from complete. in the first year the bone develops with a proper diaphyses and epiphyses

the killing of the chondrocytes is a trigger for

the ossification zone to replace the decaying cartilage with bone.

if you have excess growth hormone

the process above doesn't occur. only occurs with normal or inadequate growth hormone.

at #1 you can see hyaline cartilage that serves as

the template. a big difference between the two processes.

when the rate of bone growth in the ossification zone occurs faster than the growth of new cartilage in proliferation zone

these two plates will fuse.