Chapter 6 Flashcards
Bone
Organ made up of Tissues (bone, cartilage, dense connective tissue, adipose, and nervous tissue) working together ~ no lymphatic vessels
Skeletal system
entire framework of bones + their cartilages
Functions of skeletal system
• 1. Provides support
• 2. Protects the internal organs (brain, heart, etc.)
• 3. Assists body movements (in conjunction with muscles)
• 4. Mineral homeostasis - stores and releases calcium + phosphorus
• 5. Participates in blood cell production (hemopoiesis)
• 6. Stores triglycerides in adipose cells of yellow marrow
Diaphysis
Shaft
Epiphyses
Both ends of bone made of hyaline cartilage
Metaphyses
Between diaphysis and epiphysis containing a growth plate on each end: hyaline cartilage (children) bone (adults)
Epiphyseal line
Remanent of the growth plate in adults - when the layer of hyaline cartilage “epiphyseal growth plate” is replaced by bone in adults
Articular cartilage
thin layer of hyaline cartilage covering both epiphyses where the bone forms a joint
Periosteum
dense irregular connective tissue surrounding diaphysis (where articular cartilage is absent) ~ Rich blood supply. Attaches to underlying bone via Sharpey’s fibers
Inner Osteogenic layer
stem cells ~ enable bone to grow in thickness, not in length
Outer Fibrous layer
dense irregular connective tissue
Perforating (Sharpey’s) fibres
thick bundles of collagen; extend from periosteum into bone’s extracellular matrix
Medullary (marrow) cavity
hollow space within diaphysis ; containing bone marrow (Yellow = adults / Red = infants) lightens the weight of bone
Endosteum
thin membrane lining the medullary cavity (areolar connective tissue)
Bone contains
abundant extracellular matrix ; surrounds widely separated cells
Extracellular matrix
15% water , 30% collagen , 55% crystallized mineral salts
Resorption
process of breaking down extracellular matrix of bone to release calcium into blood
Remodelling
throughout life ; depositing calcium + phosphorus into matrix of bone
4 cell types
Osteoprogenitor
Osteoblasts
Osteocytes
Osteoclasts
Osteoprogenitor cells
• bone stem cells
• undergo cell division when stimulated
• Cells develop into osteoblasts (gap junctions)
- Formed from: Mesenchyme tissue
- Found in: Inner periosteum, endosteum, canals in bone with blood vessels
Osteoblasts
BUILD BONE
• bone-building cells
• synthesize / secrete collagen fibers, forms bone extracellular matrix, deposits
calcium/phosphorus from food, initiate calcification
• cell secretes extracellular matrix
• Surrounded with matrix, trapped in their own secretions —> become osteocytes
- Formed from: Osteoprogenitor cells (gap junctions)
- Found in: Extracellular matrix, aligned along trabeculae of new bone
Osteocytes
• Mature bone cells
• **Primary cells in bone tissue
• maintains bone tissue/metabolism; nutrient exchange in blood
- Formed from: Osteoprogenitor cells - Found in: Lacunae
Osteoclasts
CARVE OUT BONE
• Large Cell; breaks down extracellular matrix
• Develops from white blood cells
• Remodels + bone Resorption ; calcium release
• Ruffled border — folded plasma membrane; secretes digestive enzymes to underlying extracellular matrix that dissolves, releasing calcium to blood
- Formed from: 5-50 fused Monocytes (WBC) ~ multiple nucleus’s - Found in: Endosteum
Bone tissue types
Compact bone
Spongy bone
Skeleton is made up of 80%
Compact bone
Skeleton is made up of 20%
Spongy bone
