ACBS 400A

proteoglycans

necessary for cell proliferation, mineral deposition, and remodeling

glycoproteins

necessary for mineral regulation; covalently bound to carbs

epiphysis

end part of a long bone, initially growing separately from shaft

diaphysis

shaft or central part of long bone; mostly compact bone

metaphysis

where epiphysis joins diaphysis

epiphyseal/growth plate

hyaline cartilage plate in metaphysis at each end of a long bone; shrinks/closes as animal grows

medullary space

hollow part of bone that contains bone marrow

trabecular/cancellous/spongy bone

Hierarchical, spongy, or porous material composed of hard and soft tissue elements; found at epiphysis and metaphysis of long bone.

Encloses many large spaces in honeycomb appearance (matrix).

In long bones, ribs, skull, vertebrae.

compact/cortical bone

Hard, dense outer layer/shell of all bones.

Primary component of long bones to provide strong structural support.

periosteum

dense outer layer of bone that contains vascular connective tissue enveloping bones except at surfaces of joint

endosteum

membrane lining inner surface of bony wall and bone marrow

osteoblasts

mononuclear cells that form new bone; originate from mesenchymal cells in bone marrow

ossification

formation of new bonepr

primary ossification

formation of 1-cell thick layer covering surfaces undergoing remodeling

osteoclasts

large multinucleated cells at bone surface and actively resorb bone

osteocytes

Inactive and entrapped osteoblasts within bone matrix.

Revert back when matrix is dissolved.

Long cytoplasmic projections that connect w/ other osteocytes, osteoblasts, and ECF

osteoprogenitor

germ cell that turns into other cells in bone

ground substance

Rich in mineralized calcium phosphate (hydroxyapatite).

Fills compact bone

osteon

cylindrical structures composed of concentric layers of bone tissue (lamellae) that surround a central canal

haversion/central canal

minute tubes that form network in bone and contain blood vessels that run parallel to length of bone

volkmann/perforating canals

Channels that contain smaller blood vessels that run perpendicular to haversian canals.

Connect haversian canals to periosteum and medullary cavity

lacunae

small areas of holes in bone matrix where osteocytes reside

canaliculi

tunnels that form a labyrinth of connections between neighboring osteocytes → where cytoplasmic projections go

trabeculae

Thin columns and plates of bone that create spongy structure along stress lines.

Provide flexibility and improves resistance to fracturing.

(blank) has high level of metabolic activity.

Trabecular bone

red bone marrow

Contains hematopoietic tissue that creates blood cells

yellow bone marrow

Contains mostly adipose (fat) tissue.

Primarily in long bones

bone composition - minerals

calcium, phosphorous, magnesium, sodium, potassium, chloride, fluoride

bone composition - salts

citrate, hydroxyl, carbonate anions

type 1 collagen

Main form found in bone.

Synthesized in osteoblasts

tropocollagen

braided collagen fibrils that have improved strength and rigidity

microfibril

5 tropocollagens joined together

collagen matrix

microfibrils laid end-to-end in staggered formation in same direction

hydroxyproline

Neutral heterocyclic protein amino acid found in bone and gelatin.

Diagnostic indication of bone destruction.

Hydroxylysine

Amino acid unique to collagen-like peptides.

Stabilizes fibrils, creates banding pattern

osteocalcin

Protein in EC matrix of bone and in serum of circulating blood.

Produced by osteoblasts in presence of vitamin K

intramembranous ossification

Bone formation within primitive connective tissue.

In skull as animal grows

endochondral ossification

pre-existing cartilage is turned into bone

ectopic bone formation

pathologic process in which connective tissues that aren’t usually turned into bone are ossified

mesenchyme

Tissue characterized by primordial cell types surrounded by large amount of EC matrix (loose connective tissue).

In areas meant to become flat bones.

woven bone

Early bone where collagen fibrils remain randomly interwoven.

Weak and flexible, high turnover rate.

Replaced later w/ stronger bone.

osteoid

Unmineralized, organic portion of bone matrix that forms prior to maturation of bone tissue.

Beginning stage of formation.

Found in woven and lamellar bone.

centers of ossification

Within hyaline cartilage and distinguished by enlargement of chondrocytes

epiphyseal ossification

won’t replace cartilage

diaphyseal ossification

allow growth in length

zone of proliferation

Grow bone lengthwise.

Formed by chondrocytes that are further from diaphysis

zone of maturation

Grow bone lengthwise.

Formed by chondrocytes that have stopped dividing and have become enlarged.

zone of hypertrophy

Grow bone lengthwise.

Formed by hypertrophy (swelling of cells) and vacuolation of chondrocytes

zone of provisional calcification

Grow bone lengthwise.

Formed by cartilaginous matrix surrounding cells begin to calcify.

hyena disease

Condition where growth plates in hindlimbs closes prematurely compared to frontlimbs.

In heifers secondary to vitamin A toxicosis as calves.

bone remodeling units

small units of bone that undergo remodeling at any given time

bone remodeling steps

1. Activation

2. Resorption

3. Reversal

4. Formation

activation

Converts resting/inactive bone surface into that to be remodeled.

Random event?

resorption

Minerals and bone matrix broken down products absorbed via diffusion or other transport into osteoclasts.

howship’s lacuna

hole created by osteoclasts during resorption

reversal

Needs insulin-like growth factor 2 and transforming growth factor-beta.

Activate cells to revert to osteoblasts (build new bone).

external callus

callus formed from periosteum

forms strong bond

internal callus

callus formed from endosteum

complete fracture

through entire bone

transverse fracture

straight line through bone

oblique fracture

line at an angle through bone

spiral fracture

corkscrew line through bone

comminuted fracture

more than 2 parts

incomplete fracture

not entirely through bone

bowing fracture

bone is bent

greenstick fracture

fracture on convex side

avulsion fracture

bone fragment separates from rest of bone, often attached to ligament or tendon

displacement fracture

ends of fracture not within same area, created a gap

Salter-Harris fracture

injury to growth plate

Salter-Harris type 1

through growth plate

Salter-Harris type 2

through growth plate and metaphysis

Salter-Harris type 3

through growth plate and epiphysis

Salter-Harris type 4

through growth plate, metaphysis, and epiphysis

Salter-Harris type 5

crush injury to growth plate

osteocytic osteolysis

process of Ca2+ resorption from bone

(blank) has to be maintained in very narrow limits

blood Ca2+ concentration

calcitonin

Major Ca2+ regulating hormone.

Acts on osteoclasts to inhibit bone resorption.

chondrocytes

cells responsible for cartilage formation

amorphous gel-like matrix

secreted by chondroblasts and contains collagens, proteoglycans, and non-collagenous proteins

perichondrium

dense fibrous layer around cartilage that secretes hyaline matrix

Outer: protection, mechanical support, attaches cartilage to other structures

Inner: involved in growth and maintenance of cartilage

hyaline cartilage

Bulk of cartilage found in animals

Randomly oriented, but little elastin

Interstitial

Elastic cartilage

Relatively scarce but found in external ear and epiglottis.

Has a ton of elastic fibers embedded in it.

More flexible.

fibrocartilage

Found at site of insertion of many larger ligaments onto bone, intervertebral disks, and symphysis of pubis.

Improve tensile strength.

interstitial growth

Process of growth that occurs thru addition of new cells within existing tissue.

Occurs throughout life.

appositional growth

Process of growth that involves the addition of new cells to surface of the tissue.

Occurs during growth.

type 2 collagen

main collagen form in cartilage

type IX collagen

on surface of type 2

Regulates spatial arrangement of type 2

type X collagen

Found in chondrocytes within growth plates in long bones

Joint (articulation)

junction between any 2 bones

synovial joint

Contained in a capsule

Side to side stability

synovial fluid

Provides lubrication to joint, reducing wear on opposing surfaces.

More compression ability

ligaments

Tough, elastic bands of connective tissue that surround joint to give support and limit movement

Connects bone together

tendons

tough connective tissue on each side of joint and attaches to muscles that control movement of the joint

Connect muscle to bone

bursas

fluid-filled sacs between bones, ligaments, or other nearby structures

Help cushion the friction in a joint

menisci

Special areas of dense fibrocartilage that exist between articulating cartilage surfaces.

Cushions compressive forces

Common in areas bearing weight

pivot joint

freely moveable that allows rotary movement around single axis

hinge joint

allows movement in 1 plane

ball and socket joint

Joint where rounded surface of a bone moves within a depression on another bone

condyloid joint

ex: jaw

plane joint

formed between 2 bones where articular surfaces are flat/near flat

allows bones to slide over each other