Skeletal System: Formation Flashcards Preview

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Flashcards in Skeletal System: Formation Deck (16):
1

What is CALCIFICATION?

Deposition of Ca (hardens tissues, but no OSTEOCYTES)

2

What is OSSIFICATION?

BONE formation (with OSTEOCYTES), occurs during fetal development

3

What are the 2 methods of OSSIFICATION?

1) INTRAMEMBRANOUS
2) ENDOCHONDRAL

4

Quick vague overview of INTRAMEMBRANOUS OSSIFICATION (IO)

It begins in fetus, forms FLAT BONES of skull, mandible, and part of the clavical, *starts w/in CT membrane*

5

1st step of IO

Nutrient artery brings MESENCHYMAL CELLS

6

2nd step of IO

MESENCHYMAL CELLS divide and become OSTEOGENIC CELLS, which divide and become OSTEOBLASTS

7

3rd step of IO

OSTEOBLASTS produce BONE MATRIX around COLLAGEN FIBERS, form thin struts of BONE = OSSIFICATION center

8

4th step of IO

OSTEOBLASTS on surface of struts produce more BONE, struts thicken, connect to form TRABECULAE

9

5th step of IO

CELLS specialize, take on new functions
- Trapped bv (blood vessels?), CELLS between TRABECULAE form RED BONE MARROW
- CELLS surrounding BONE form PERIOSTEUM
- OSTEOBLASTS in PERIOSTEUM form outer COMPACT BONE
- OSTEOBLASTS trapped in BONE become OSTEOCYTES

10

Quick vague overview of ENDOCHONDRAL OSSIFICATION (EO)

Begins in fetus, forms all bone except parts of skull, mandible, and clavicle, starts w/ HYALINE cartilage model

11

1st step of EO

Primary ossification center forms in mid-region (use notes to see the process, it's too much to type and I'm lazy)

12

2nd step of EO

MEDULLARY CAVITY forms
- OSTEOCLASTS remove SPONGY BONE in mid region to form MEDULLARY CAVITY
- OSTEOBLASTS remodel SPONGY BONE into OSTEONS = forms thick layer of COMPACT BONE
- OSTEOBLASTS and OSTEOCLASTS form endosteum which lines MEDULLARY CAVITY
- Blood vessels in MEDULLARY CAVITY form RED BONE MARROW = blood formation

13

3rd step of EO

Secondary ossification center forms in ends (around time of birth)
- repeat steps a - h in EPIPHYSIS

14

4th step of EO

Cartilage remaining at BONE ends become ARTICULAR CARTILAGE to reduce friction and rubbing between bones

15

5th step of EO (part a)

Cartilage remaining at EPIPHYSEAL GROWTH PLATE allows bone lengthening
- EPIPHYSEAL PLATE has zones of resting, dividing, hypertrophying, and calcifying cartilage
- At puberty, hormones stimulate BONE to grow faster than cartilage
- in adult, all EPIPHYSEAL CARTILAGE has been replaced by bone so no further lengthening can occur (see chart in notes)

16

5th step of EO (part b)

BONES thicken by appositional growth
- OSTEOCLASTS in ENDOSTEUM remove MATRIX enlarging MEDULLARY CAVITY
- OSTEOBLASTS in PERIOSTEUM add BONE in circumferencial lamellae
- Circumferencial lamellae remodeled into OSTEONS (see notes for pictures)