Bone & Cartilage Flashcards
Composition of the Skeletal System:
- Bones
- Cartilages (always stain blue due to sulfate groups)
- Ligaments
- Joints
Functions of Bones:
- Support
- Protection
- Movement
- Mineral storage (Calcium phosphate)
- Hematopoiesis (red bone marrow)
- Fat (triglyceride) storage: white/yellow bone marrow
- White fat
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
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
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
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
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
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
Relationship of Osteoclasts and Parathyroid Hormone
- Stimulates osteoclasts
- Facilitates Ca2+ reabsorption from bone tissues
Chondroclasts
- Same morphology as osteoclasts
- Found and work in the cartilage
- Only located near the degeneration zone
- Very large
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)
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
Parts of a Growing Bone:
Epiphysis
Diaphysis
Metaphysis:
- Neck portion of a long bone
- Between epiphysis and diaphysis
- Contains the growth plate
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
Identify Bone vs. Cartilage
Identify Herringbone Weave
and
Chondrocytes of Fibrous Cartilage
Composed of Type 1 and Type 2 Collagen Fibers
3
Fibrous: Type of Cartilage
- Pink/red staining along with the bluer stain
- Type I collagen stains eosinophilic
- Arrow-shaped/fishbone shaped
- Type I collagen stains eosinophilic
- 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
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
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
