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Skeletal System. 300 baby bones 206 adult bones >1/2 in hands & feet Humans & giraffes have same # neck bones Longest bone= femur Smallest bone= inner ear (hammer, anvil, stirrup). Functions of Skeletal System. Support Protection Movement Hematopoiesis
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Skeletal System 300 baby bones 206 adult bones >1/2 in hands & feet Humans & giraffes have same # neck bones Longest bone= femur Smallest bone= inner ear (hammer, anvil, stirrup)
Functions of Skeletal System • Support • Protection • Movement • Hematopoiesis • Reservoir for minerals and adipose tissue
Skull – 22 bones Cranium – 8 Facial - 14 Vertebral Column - ___ Inner ear - __ Thorax - 27 ___ bones Upper limb – ___ Shoulder girdle - __ Lower limb – ___ Pelvic girdle – __ ___ bones
Abnormal Spinal Curvatures ___________ ______________________
The Skull 22 bones Nerves and vessels “keystone of cranium” Ethmoid Ethmoid
Fibrous joint Projection that contacts adjacent bone
closes at ___ wks closes at ________mths Infant Skull Fontanel – space between infant skull bones
Sinus: air-filled space Sinus Cavities
Compact Bone canaliculi
OsteonStructural and functional unit of bone • ___________________ Canal • Allows passage of blood vessels, lymphatic vessels, and nerve fibers • ______________ • Concentric rings of collagen fibers around haversion canal • Allows bone to withstand force • Lacunae • Small cavities occupied by ______________ that join lamella • Canaliculi • Hairlike _______ that join lacunae to each other and the central canal • Allow osteocytes to exchange nutrients, wastes, and chemical signals via gap junctions
Bone Classification _____ _____ Scapula Sternum Ribs Skull Arms Legs Phalanges _____ _________ Wrist Ankle Vertebrate Hip Patella
Type of Cells in Bone • Osteo_____ • ______ bone cells • Synthesize and secrete organic components of bone matrix • Initiate calcification • Found in __________________ and ____________________ • Osteocytes • Mature bone cells • Formed when osteoblasts get trapped in matrix • Do not secrete matrix • _________ bone tissue • Osteoclasts • Bone _______________ (digest/break down matrix): part of normal bone growth, development, maintenance and repair • Found in _________________
Bone Matrix • Organic components (1/3) • ___________ fibers • Provide resilience against stretching and twisting • Inorganic components (2/3) • Mg, F, Na • Salts that interact to form ________________ • Calcium phosphate • Calcium hydroxide • Provide hardness and resist compression
Types of Tissue in Bone • Connective • Osseous • Dense fibrous • Adipose • Vascular • Lymphatic • Nervous
Bone Marrow • Red = hematopoietic tissue • Bone cell forming tissue • Everywhere in _____________ • Yellow = fatty tissue • Young to middle age develop in ________ • Does NOT produce blood
Bone Development • Osteogenesis (________________) – bone tissue formation • Embryo: leads to skeleton • Intramembranous ossification • Fibrous membrane replaced with bone • Endochondral ossification • __________ cartilage replaced with bone • Most bones develop this way • More complicated (hyaline cartilage broken down first) • Children: leads to bone growth • Adults: leads to bone remodeling and repair
Intramembranous Ossification • ______________ permit calcification • Some osteoblasts trapped in ossification center (now considered ________________) • Growth is _________ from ossification center • Osteoblasts require oxygen and nutrients, so blood vessels are trapped in bone • Fibrous membranes→spongy bone→compact bone • Outer fibrous membrane becomes _______________
Endochondrial Ossification • Chondrocytes in center of shaft increase in size and calcify • Deprived of nutrients and die • Vessels grow into perichondrium • Inner layer turns to osteoblasts • Perichondrium now periosteum • Thin layer of bone formed around shaft • Bone collar provides support • Calcified cartilage breaks down • Osteoblasts replace with spongy bone • 1° oss. center- bone dev and spreads toward epiphysis
Endochondrial Ossification • 1° oss. center enlarges • Osteoclasts break down spongy bone • Medullary cavity now open • Osteoblasts move to epiphysis
Bone Growth • Length • ________________ossification center • center of ________________ • Thickness • ________________ossification center • center of ________________
Hormonal Effects on Bone Growth • Growth Hormone (GH) • Produced by pituitary gland • Stimulates protein synthesis and cell growth • Thyroxine • Produced by thyroid gland • Stimulates cell metabolism and increases osteoblast activity • Sex Hormones at Puberty • Cause osteoblasts to produce bone faster than epiphyseal cartilage can divide • Growth spurt • Epipyseal plate closure • Estrogens (female) • Cause faster closure of plate than androgens • Androgens (male) • Parathyroid Hormone • ___________ blood calcium level (decreases bone calcium) • Inhibits _______________; Stimulates osteoclast • Calcitonin • “tones down” blood calcium level (increases bone calcium) • Inhibits _____________; stimulates osteoblast
Nutrients and Bone Growth • Calcium and phosphate salts • Hormone ____________ and Vit ___ allow absorption • Vitamins A, C, K, B12
Types of Fractures • ____________- the bone is broken, but the skin is not lacerated • ___________________- skin is pierced by the bone or by a blow that breaks the skin at the time of the fracture • ___________________- fracture on one side of the bone, causing a bend on the other side of the bone. • _____________ – fracture wraps around bound in spiral manner • ___________________ - results in three or more bone fragments. • __________________ - fracture is at right angles to the long axis of the bone • ___________________–occurs in vertebrate • Lisfranc - one or all of the metatarsal bones are displaced from the tarsus
Fractures Bony (Fracture Hematoma)
Skeletal Disorders • Osteomalacia • “__________ _________” • Lacking minerals (ie. Calcium, vit D) • Rickets • Child form of osteomalacia • More detrimental since bones are still growing • Signs: bowed legs; deformities of pelvis, ribs and skull • Osteomyelitis • “bone marrow inflammation” • Caused by pus-forming bacteria that enter via wound or nearby infection • Osteoporosis • Bone degradation occurs faster than bone can be deposited • Decrease in bone mass • _____________ bones • Fractures in the vertebrate and femur are common • Most common postmenopause: rapid decline in estrogen (stimulates osteoblasts and inhibits osteoclasts
Skeletal Disorders • Giantism • __________ hypersecretion of GH • Excessive growth • Acromegaly • __________hypersecretion of GH • Overgrowth of face, feet, hands • Pituitary Dwarfism • Childhood _______________ of GH • Short long bones; max height is 4 ft. • Paget’s Neoplasms • Bone remodeling process disturbed • Bones are abnormal, enlarged, not as dense, brittle, and prone to fracture • Affects older adults