Support Protection Movement Mineral storage (Calcium phosphate) Hematopoiesis (red bone marrow) Fat (triglyceride) storage: white/yellow bone marrow White fat

Bone & Cartilage Flashcards by Monica Styrczula

Composition of the Skeletal System:

Bones
Cartilages (always stain blue due to sulfate groups)
Ligaments
Joints

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Functions of Bones:

Support
Protection
Movement
Mineral storage (Calcium phosphate)
Hematopoiesis (red bone marrow)
Fat (triglyceride) storage: white/yellow bone marrow
- White fat

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Structure of a Long Bone:

Epiphysis (rounded end of a long bone)
Diaphysis (central part of a long bone)
Blood nerves and vessels
Bone marrow (red and yellow/white)
Periosteum
- Inner-osteogenic progenitors
- Outer-dense irregular CT
- Endosteum (loose CT)
Articular cartilage
- Always at the ends of long bones

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Spongy (Cancellous) Bone Tissue

and

Compact Bone Tissue

Compact Bone Tissue

External layer of all bones
Composed of osteons
Tightly packed
Tree-trunk structure

Spongy Bone Tissue:

Inner part of any bone
RBC’s and WBC’s

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Bone Composition

Periosteum:

2 layers
- Inner = osteoblasts
- Outer = outer-dense connective CT
Thin membrane that covers many bones except articular surfaces
Function for protection
Function as blood supply and nutrients for bone tissue

Endosteum:

Loose CT lining canals and all inner spaces within the bone
Thin layer
Contains osteoblasts and osteoclasts

Osteon (basic structural units):

Central canal
Nerve and blood vessels
Perforating canal
Lamellae
Lacunae
Canaliculus

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Osteocyte:

Cells of Bone (1)

Form the main bone tissue
Surrounded by the matrix that it secretes
Gap junctions to exchange nutrients
Monitor and maintain the Bone Matrix
- Collagen & ground substance
- Calcium phosphate hydroxyapatite crystals
Sensitive to changes in stress
Produce large amounts of Type 1 Collagen
Can signal osteoblasts to increase bone deposition

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Osteoblast:

Cells of Bone (2)

Bone lining cells
Build matrix
Located at the surface of the bone
Not mitotic
- Active secretion of bone matrix
- Mostly Type 1 Collagen
- Derived from mesenchymal stem cells
- Currently produce bone matrix- haven’t released it yet
- No Lacunae- live on the edge of the cell

BABY OSTEOCLASTS

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Osteoclast:

Cells of Bone (3)

Multinucleated, giant cell
Monocyte lineage
Reabsorbs bone matrix
- H+ ions for acidifying
- Secretory vesicles w/ Matrix metalloproteases that can digest type 1 collagen
Release
- Ca2+ reasborption and other minerals stored in the bone tissues
Stimulated by parathyroid hormone
Blocked by calcitonin

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Relationship of Osteoclasts and Parathyroid Hormone

Stimulates osteoclasts
Facilitates Ca2+ reabsorption from bone tissues

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Chondroclasts

Same morphology as osteoclasts
Found and work in the cartilage
Only located near the degeneration zone
Very large

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Endochondral Ossification:

Long bone formation!!

Comes from hyaline cartilage

Replacement of hyaline cartilage with bony tissue

Development of Cartilage model
Growth of cartilage model
Development of primary ossification center
Development of secondary ossification center in epiphysis
Formation of articular cartilage and epiphyseal plate (growth plate)

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Intramembraneous Ossification:

Formation of compact and spongy bone

From sheets of mesenchymal (undifferentiated) connective tissue

Forms flat bones of the face

No need for the cartilage model

Derived from mesenchymal stem cells

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Parts of a Growing Bone:

Epiphysis

Diaphysis

Metaphysis:

Neck portion of a long bone
Between epiphysis and diaphysis
Contains the growth plate

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Epiphyseal Plate Histology

(Growth Plate)

Zone of reserve cartilage

Zone of proliferation

Zone of maturation

Blue-ish staining of cartilage disappears

Zone of hypertrophy

Zone of cartilage degeneration

Osteogenic Zone

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Identify Bone vs. Cartilage

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Identify Herringbone Weave

and

Chondrocytes of Fibrous Cartilage

Composed of Type 1 and Type 2 Collagen Fibers

Fibrous: Type of Cartilage

Pink/red staining along with the bluer stain
- Type I collagen stains eosinophilic
  - Arrow-shaped/fishbone shaped
Abundant amt of Type 1 Collagen
Type 2 Collagen
Resembles dense regular CT
Associated w/ dense CT
Round cells
- Different from fibroblasts
- Distinct cell border and nucleus
No distinguishable perichondrium

Location:

inteveterbral disks
symphysis pubis
certain bone-ligament junctions

Elastic Cartilage:

Type #2

Characterized by long elastic fibers
Contains more elastin fibers than Typen 2 Collagen
Function
- Support and flexibility
Location:
- Ear
- Epiglottis
  *

Hyaline Cartilage:

Type #1

Most common
Found at the growth plate
- Bone elongation
Matrix Composition
- Type 2 Collagen (little fibers)
- Proteoglycan-chondroitin sulfate GAG
- Purple to blue staining
Articular Cartilage
- Ends of bone

Cartilage Cells:

Chondroblasts
- Synthesize matrix
- Mitotic potential
Chondrocytes
- Secrete the matrix
- Round cells
- Prominent nucleus
- Basophillic cytoplasm
- Well developed rER and Golgi
Chondroclasts
- Cartilage reabsorption cells
- Multi-nucleated
- Vaculoes
- Similiar to osteoclasts
- Degeneration zone

Cartilage Structure

Perichondrium

Not all cartilage has it
Lacunae vs. Isogenous group
Territorial vs. Interterritorial

Perichondrium of Cartilage

Surface of Cartilage
Dense irregular connective tissue
Surrounds cartilage of developing bone
Outer layer
- Fibroblasts and collagen
Inner layer
- Chondrogenic- stem cells of chondroblasts

Cartilage Matrix Composition

Territorial Matrix:

Tissue surrounding the chondrocytes
- Cells that produce the matrix
- Thin layer
- Dark; basophillic
- Sulfated proteoglycans
Type 2 Collagen

Interterritorial Matrix:

Lighter, paler staining
Fills spaces between chondrocytes
Type 2 Collagen

Lacunae:

Space;hole
Artifact of fixation
Holds the chondrocytes
Nutrients must diffuse through

Isogenous Group

Cluster of chondrocytes
All formed through division of a single progenitor cell
Found in hyaline cartilage and elastic cartilage

Why does the hyaline cartilage stain metachromatic?

* High sulfate content

Ground Substance Composition

* Chondrotin and chondrotin sulfate * More blue-ish on a stain

T of F: No blood vessels or nerves in cartilage

True

Cartilage Types:

Hyaline: * Type 2 Collagen Elastic: * Type 2 Collagen + Elastic fibers Fibrous: * Type 1 Collagen + Type 2 Collagen

Cartilage Matrix:

Fibers: * Type 2 Collagen Ground Substances: * Sulfated vs. non-sulfated

Bone Structure:

Periosteum (osteogenic) and endosteum Compact vs. Spongy Bone Osteon: * Canals * Lacunae * Canaliculus * Lamellae Bone Marrow: * Red vs. Yellow

Bone Matrix:

Organic Matter: * Osteoid * Type 1 Collagen + Ground Substances Inorganic Matter: * Calcium phosphate (hydroxyapatite crystals)

Skeletal Muscle Fibers and Fibroblasts in Dense Connective Tissue

Skeletal Muscle Fibers: * Dark pink stained tissue * Striated * Peripheral Nuclei Fibroblast Location: * Dense regular connective tissue * Lighter staining * String of Pearls appearance

Osteon

What the bone matrix is made of Basic structural unit Gets released by osteocyte

Lacunae

White circle around Osteocyte

T of F: Osteoblasts are not mitotic

True, Chondroclasts are