Biology II Honors - Compact Bone

What is an Osteon?

the functional unit of bone tissue that is circular in shape

(bricks that make up walls)

How is the Osteon arranged?

both the cells and matrix are arranged in concentric circles

What is the Osteon formally called?

the haversian system

What is the Lamella?

the matrix of bone tissue

What does the Lamella do?

holds individual osteons together and connects adjacent osteons

Where is Interstitial Lamella found?

between osteons

What does Interstitial Lamella function as?

the “mortar” that holds adjacent osteons together

(holds bricks of wall together)

What is Concentric Lamella?

the matrix that holds an individual osteon together

(the clay that holds a brick together)

What is Circumferential Lamella?

the matrix that covers both osteons and Interstitial lamella

What does Circumferential Lamella cover?

outer surface of bone

What is Lamella composed of?

calcium compounds that are inorganic and non-living

What does Lamella act as?

calcium reservoir for muscles and nerves

What does the Lamella provide?

strength in bone

What is an Osteocyte?

a general term for a bone cell

What does an Osteoblast do?

builds new bone tissue, maintains existing bone, and repairs damage to bone

What does an Osteoclast do?

cleans up damaged or non-functional bone tissue, releases enzymes that digest old or damaged bone, and makes room for osteoblasts to build new tissue

What is a Lacuna?

depressions found in concentric and Circumferential Lamella where both Osteoblast and Osteoclast live

What are Haversian Canal’s?

channels located in the center of an osteon

What does the Haversian Canal contain?

blood vessels (arteries and veins)

What does the Haversian Canal do?

it delivers oxygen and nutrients to osteocytes and removes waste

What does the Haversian Canal connect?

the outer and inner surfaces of bones (vertically)

What is the Volkmann’s Canal?

channels that move through concentric and Interstitial lamella

What does the Volkmann’s Canal connect?

adjacent osteons along with the outer and inner surfaces of long bones

What is Spongy Bone?

thin plates of compact bone tissue

What are the spaces in spongy bone filled with?

bone marrow

When bone tissue forms, what forms first?

spongy bone

How does compact bone form?

when spongy bone spaces are filled in with lamella (matrix)

What does compact bone have more of?

lamella

What is Ossification?

the process of forming bone in which cartilage is replaced with bone tissue

What is the embryonic skeleton composed of and what is it converted to?

hyaline cartilage; bone after birth

When does Ossification begin?

6 to 7 weeks and continues until adulthood

What are the two types of Ossification?

Intramembranous and Endochondral

What is Intramembranous Ossification?

simpler and more direct type of bone formation

Where does Intramembranous Ossification form from?

the edges of a bone inward; the center hardens last

Where does Intramembranous Ossification mostly occur?

in the bones of axial skeleton (flat and irregular bones)

What is Endochondral Ossification?

a type of Ossification seen in bones of the appendicular skeleton; how long and short bones ossify

What are cartilage cells replaced by?

osteoblast which produce lamella

Where does the Endochondral ossification process begin?

in the diaphysis (shaft) of the bone

What hardens last in Endochondral Ossification and what does it allow?

the epiphyses; bone to support weight without bending

How does Ossification occur in Endochondral Ossification?

moves from the center outward to the ends of the bones

What occurs in both types of Ossification?

spongy bone forms first and compact bone forms from spongy bone