Chapter 6 : Skeletal System Flashcards
Skeletal System
Composed of bones, cartilages, and ligaments joined tightly together to form a strong, flexible framework for the body
Skeleton functions
Protection, support, movement, electrolyte balance, acid-base balance, blood formation
Osseous tissue
Connective tissue with a hardened matrix (deposition of calcium phosphate and other minerals), part of the composition of a bone
Classification of bones
Classified based on shape and corresponding function
Four categories for classification of bones
Long bones, short bones, irregular bones, flat bones
General features of bones
Epiphysis, diaphysis, medullary cavity
Epiphysis
Ends of bones, composed of cancellous (spongy) bone
Diaphysis
Shaft of bone, composed of compact bone
Medullary cavity
Contains yellow bone marrow, epiphyiseal plate
Four main types of bone cells
Osteogenic, osteoblasts, osteocytes, osteoclasts (bone is also a composite)
Matrix
Composed of inorganic and organic components
Inorganic component
Hydroxyapatite (composed mainly of CaPO4 salt)
Organic components
Protein and carbohydrate, collagen
Osteogenic (osteoprogenitor) cells
Give rise to osteoblasts, osteocytes
Osteoblasts
Bone-forming cells, found along endosteum and periosteum, secrete osteocalcin
Osteon (haversian system)
Basic structural unit of compact bone
Central (haversian) canal
Surrounded by concentric lamellae (matrix)
Perforating canals
Transverse or diagonal passages into the central canal, originate at nutrient foramen?
Spongy bone
Composed by a network of trabeculae, spaces filled with red marrow, beams arranged to sustain stress
Bone development
Ossification or osteogenesis (formation of bone)
Osteocytes
Former osteoblasts that have been trapped in their lacunae, maintain bony matrix, strain sensors
Osteoclasts
Bone-dissolving cells
Bone development (two methods)
Intramembranous ossification, endochondral ossification
Intramembranous ossification
Produces flat bones of skull and clavicles (starts with osteoid and end with diploe)
Endochondral ossification
Bone develops from a hyaline model
Bone elongation
Involves epiphyseal plates (hyaline cartilage between two transitional zones (metaphysis))
Zones of metaphysis
Reverse cartilage, cell proliferation, cell hypertrophy, calcification, bone deposition (spongy bone)
Interstitial growth
Result from growth of cartilage within the metaphysis, finite process (epiphyseal lane)
Appositional growth
Growth in diameter and thickness (circumferential lamellae)
Mineral deposition
Calcium and phosphate are allowed to reach their solubility product (precipitate in the matrix), ectopic ossification (abnormal calcification of soft tissue)
Mineral resorption
HC1 secreted by osteoclasts, acid phosphatase (absorbs collagen)
Fracture
Break in the bone
Two types of fractures
Stress and pathological
Granulation tissue
Fibrous mass of capillaries and cells
Osteoporosis
Sever loss of bone diversity, osteoclast more active than osteoblasts
Osteosarcoma
Most common and deadly form of bone career, metastasizes quickly
Remodeling
Wolff’s law of bone - the architecture of bone is determined by the mechanical stresses placed up to it, bone adapts to withstand stress
Osteogenesis imperfecta
Brittle bones (defect in collagen deposition
