3. Cartilage & Bone Flashcards
Functions of cartilage
Support and protect soft tissues, provide a gliding surface at articulations or joints, provide a model for the formation of most bones
How does cartilage provide a model for bone formation
Bony precursor or a “rough draft” that later ossifies into bone
Components of cartilage
Surrounded by perichondrium, primary cells are chondroblasts and chondrocytes, fibers are collagen and elastic, ground substance
Dense irregular connective tissue surrounding cartilage that aids in protection and regeneration
Perichondrium
Secrete matrix below perichondrium, become chondrocytes
Chondroblasts
Mature cells that maintain cartilage
Chondrocytes
Fibers in cartilage
Collagen and elastic
Characteristics of ground substance of cartilage
Gel-like made of mostly water; contains sugars that draw in water
Why doesn’t cartilage regenerate or heat well?
Avascular and lacks innervation; nutrients received via diffusion; movement (compression & tension) help nutrients diffuse through ground substance
Types of cartilage
Hyaline, elastic, fibrocartilage
Components and function of Hyaline cartilage
Most common in body; fibers are collagen; bony precursor during embryonic development
Locations of hyaline cartilage
Articular cartilage of joints, respiratory tract, nose, costal cartilage
Components/function of elastic cartilage
Least abundant in body; highly flexible; fibers are elastic and collagen
Locations of elastic cartilage
Ear and epiglottis (behind tongue)
Components/function of fibrocartilage
Fibers are collagen and has less ground substance; dense collagen fibers resist tension and distribute loads and make congruent joints
Location of fibrocartilage
Intervertebral discs, pubic symphysis, menisci (in knees)
Functions of bone
Support and protection of soft tissue, movement, energy metabolism, mineral storage, blood cell formation (hematopoiesis) and energy storage
How does movement in bone occur?
Muscles anchored in two bones shorten, causing movement
What minerals are stored in bone
90% of body’s calcium and phosphate reserves
Where does blood cell formation and energy storage occur
Bone marrow
Bone characteristics
Extracellular matrix (aka osteoid) is solid, consists of collagen fibers, has a mineral component (hydroxyapatite)
Bones are flexible and dynamic organs, bones are vascular and innervated
Provides flexibility and resists tension
Collagen
Provides rigidity against compression
Hydroxyapatite
How are bones dynamic?
Growth and development; heal and regeneration
Types of bone cells
Osteoblasts, osteocytes, and osteoclasts
Function/location of osteoblasts
Function: produce osteoid (bone matrix)
Location: near periosteum and endosteum
Function/location of osteocytes
Function: maintain bone; made from osteoblasts
Location: housed in lacunae
Function of osteoclasts
Destroy bone, derived from fused bone marrow cells, help with remodeling of bone during growth and repair
Types of bone
Compact bone and spongy bone
Another name for compact bone
Dense or cortical
Another name for spongy bone
Trabecular or cancellous
Characteristics of compact bone
Hard, outer surface of bone that is solid with canals for neurovasculature
Characteristics of spongy bone
Lattice with spaces; located within bone
Microstructure of compact bone, specifically the Haversian system/osteo
Haversian canal/central canal, lacunae, lamella, canaliculi, and volkmann’s canal
Microstructure of spongy bone
Does not have osteoid; lamellar with osteocytes in lacunae
Classes of bone
Long bones, short bones, flat bones, irregular bones, and special types of bones
Characteristics and kinds of long bones
Longer than wide
Bones of extremities, hands, and feet
Characteristics and types of short bones
Approximately cube shaped
Carpals and tarsals
Characteristics and types of flat bones
Flat and thin
Neurocranial bones, scapula, sternum
Characteristics and types of irregular bones
Unlike all others
Vertebrae, os coxa, facial bones
Special types of bone (example)
Sesamoid bones found within muscle tendons (e.g., patella)
Long bone features
Diaphysis covered by periosteum on outside, epiphysis covered by articular cartilage, periosteum, endosteum lining the medullary cavity, and epiphyseal line
Shaft of long bone
Diaphysis
Ends of long bone
Epiphysis
Connective tissue covering outside of bone
Periosteum
Connective tissue lining inside of bone (medullary cavity)
Endosteum
Space within shaft of long bone, lined by endosteum and contains bone marrow
Medullary cavity
Connective tissues of long bones
Periosteum and endosteum that both contain osteoblasts and osteoclasts for remodeling bone
Remnant of growth plate in long bone
Epiphyseal line
Characteristics of short, irregular, and flat bones
Layer of spongy bone (diploë) sandwiched by outer layers of compact bone; no medullary cavity
Types of bone growth
Interstitial and appositional
Growth in length, occurring during childhood and adolescence at the growth plate made of cartilage; growth stops when epiphysis and diaphysis meet and growth plate ossifies
Interstitial growth of bone
Growth in diameter(thickness)
Appositional growth of bone
How does appositional growth of bone occur?
Osteoblasts secrete matrix forming outer ring at periosteum; new bone is destroyed by osteoclasts then replaced by osteons; Osteoclasts also remove bone in medullary cavity
Why is bone continuously replaced during life?
Maintain fluid concentrations of calcium and phosphate; respond to mechanical stress
Types of bone remodeling
Bone resorption and bone deposition
Why does bone remodeling occur?
Coordinated to maintain total bone mass
Osteoclasts break down bone tissue
Bone resorption
Osteoblasts lay down new bone
Bone deposition
Renewal rate of compact and spongy bone
Compact bone replaced every 10 yrs
Spongy bone replaced every 3-4 yrs
Clinical condition consisting of deterioration of microscopic architecture of bone, low bone mass
Osteoporosis
Effect of osteoporosis
Resorption greater than deposition (more osteoclasts)
Leads to bone fractures (common in vertebrae and neck of femur and occurs mostly in older people- common with post menopause)
Cylindrical structure making up large portion of compact bone microstructure
Haversian system or osteon
Where does spongy bone form
Trabecullae organize along lines of stress
