Bone Tissue Ch. 6 Flashcards
Different Tissues in and on Bone
- Dominated by bone connective tissue
- Contain cartilage on articular surfaces
- Contain nervous tissue and blood connective tissue
- Contain epithelial tissue lining blood vessels
Cartilage
- firm & flexible connective tissue
- resilient tissue that springs back to original shape
- no or few blood vessels/nerves
- matrix contains up to 80% water (yet it is firm)
- comes from chondrocytes
- cell type is chondrocyte
- chondroblasts are found in growing cartilage
Two growths of cartilage are
- appositional growth
- interstitial growth
Appositional growth
- perichodrium (look it up in latin terms) is membrane of fibrous connective tissue that surrounds the external surface of cartilage
- chondroblasts in surrounding perichondrium produce new cartilage
Interstitial growth
- chonodroblasts produce matrix
- chondrocytes (mature chondroblasts) lie in lacunae, divide & secrete new matrix
- Lacuna is a small depression or cavity in bone and/or cartilage that contains a cell
- interstitial growth of cartilage stops when the skeleton stops growing
3 types of Cartilage
- Hyaline Cartilage
- Elastic Cartilage
- Fibrocartilage
Hyaline Cartilage Histology & function
- rich in collagen fibers with glassy appearance
- imperceptible collagen fiber (hyaline=glassy)
- Amorphous but firm matrix
- most abundant cartilage
- supports and reinforces
- resilient, flexible, cushion
- resists repetitive compressive stress
Hyaline Cartilage location
- embryonic/fetal skeleton
- articular cartilage at ends of adjoining bones of moveable joints
- costal cartilage of ribs; attachments of ribs to sternum
- nose
- respiratory tubular structures in neck and thorax including, trachea, bronchi
- in the end of long bones
Fibrocartilage histology & function
- matrix similar but less firm than hyaline cartilage
- not that glassy
- thick collagen fibers predominate
- resists strong compression (pushing pressures) & strong tension (pulling pressures)
- tensile strength & ability to absorb compressive shock
Fibrocartilage locations
- public symphysis (the area in a woman’s body that opens up for birth)
- knew joints
- articular discs of some joints, e.g., menisci in knees
- annulus fibrosis portion of the discs in between vertebrae
Elastic cartilage histology & function
- Similar to hyaline cartilage
- More elastic fibers in matrix than hyaline cartilage
- Contains many elastic fibers in addition to collagen fibers
- Allows great flexibility
- Able to tolerate repeated bending (i.e. ear)
- Maintains shape of structure
Elastic Cartilage location
•External ear pinnae •Epiglottis
Function of Bones
- Support—provides hard framework
- Movement—attachment site for ligaments and muscle tendons; skeletal muscles use bones as levers
- Protection—of underlying organs
- Blood-cell formation—bone contains red marrow
- Fat storage—in yellow marrow in middle of bone
- Mineral storage—reservoir for important minerals e.g., phosphorus and calcium
- Energy metabolism—osteoblasts secrete osteocalcin which stimulates pancreas to produce more insulin and induces fat cells to become more insulin sensitive
Bone Tissue
MAKE SURE TO ADD THE LOCATION AND FUNCTION FROM SLIDE
•Organic components: cells, fibers, and ground substance
•Inorganic components: mineral salts that deposit in bony matrix
•Ground substance calcified with inorganic salts
•Calcified matrix contains many collagen fibers
•Well vascularized
-osteocytes live within lacuna
Composition of bone
- 35%—organic components (especially collagen)
* 65%—inorganic components (hard crystals)
Organic components of Bone Tissue
- Makes up 35% of bone
- Rich in collagen fibers which provide tensile strength and flexibility to resist twisting & pulling
- Tensile strength is the force required to pull something until it breaks
Inorganic components of Bone Tissue
- Makes up 65% of bone
- Inorganic hydroxyapatites, mineral salts e.g., calcium phosphate
- Mineral salt crystals pack tightly in and around the collagen fibrils of the extracellular matrix to give bone its exceptional hardness to resist compression
Bone cells which produce or maintain bone
MAKE INTO SEPERATE FLASH CARDS
•Osteogenic cells—stem cells that differentiate into osteoblasts
•Osteoblasts—actively produce and secrete bone matrix (osteoid) that contains ground matrix & collagen fibrils
•Within a week of osteoid
secretion, inorganic
calcium salts crystallize
within osteoid
•Osteocytes—mature bone cells in lacunae that maintain bone matrix
•Osteoclasts—responsible for bone resorption
Classification of Bone Shapes
- Long bones: longer than wide; a shaft plus two ends; common in extremities
- Short bones: roughly cube-shaped; in wrist and ankle; sesamoid bones are a special type of short bone which are sesame seed shaped and include kneecaps
- Flat bones: thin and flattened, usually curved; includes ribs, sternum, scapula and some cranial bones
- Irregular bones: various shapes, do not fit into other categories; include vertebrae and hip bones
Gross Anatomy of Bones
- Compact bone has dense outer layer of bone
- Spongy bone (also called trabecular bone) has internal three-dimensional network of bone with small needle-like or flat pieces called trabeculae; open spaces in between trabeculae are filled with red bone marrow (mainly hematopoietic cells) and/or yellow bone marrow (mainly adipose cells)