7-1 The Skeletal System

7-2 Bone Tissue Tissues/organs of the skeletal system Histology of osseous tissue Bone development Physiology of osseous tissue Bone disorders

7-3 Bone as a Tissue Connective tissue with a _____________ ________________ (_________________) Bones  bone tissue, marrow, blood, cartilage and _____________________ Continually ________________________ Functions of the skeletal system –_____________________________________, electrolyte balances, acid-base balance and blood formation

7-4 Shapes of Bones ________ bones – levers acted upon by muscles Short bones – glide across one another in multiple directions _________ bones – protect soft organs Irregular

7-5 General Features of Bones _________ (___________) = cylinder of compact bone –marrow cavity (____________ cavity) lined with ______________ (osteogenic cells and reticular connective tissue) –________________  collagenous fiber and osteogenic cells Enlarged ends (_________________) –spongy bone covered by compact bone –enlarged to strengthen joint and attach ligaments Joint surface covered with articular cartilage Epiphyseal plate (_______________)

7-6 Match the Columns Long bone Irregular bone Flat bone Short bone As long as it is wide; with flat articular surfaces Longer in one direction Even, parallel surface separated by spongy bone Unusual processes

7-7 Structure of a Flat Bone Surfaces composed of _______________ Middle layer is _________________ and bone marrow Skull fracture may leave inner layer of compact bone unharmed

7-8 Cells of Osseous Tissue ______________ cells in endosteum, periosteum or central canals give rise to new _____________ Osteoblasts _______________________________ Trapped osteoblasts become ________________ –cells in lacunae connected by gap junctions inside ________________________________

7-9 Matrix of Osseous Tissue Organic matter (___________ of mass) –collagen, glycosaminoglycans, proteoglycans and glycoproteins Inorganic matter –85% ___________________________ –10% ___________________________ –other minerals (fluoride, potassium, magnesium) Combination  strength and resilience –minerals resist ______________________; collagen resists ________________ –bone adapts by varying proportions

7-10 Compact Bone _______________ = basic structural unit –cylinders formed from layers (__________) of matrix around central canal (______________________) –osteocytes connected by processes in canaliculi ______________________ –vascular canals perpendicular to central canals

7-11 Spongy Bone Spongelike appearance formed by plates of bone called ____________________ –spaces filled with _______________________ __________ - few osteons or central canals Provides strength with little weight –trabeculae develop along bone’s lines of stress

7-12 Bone Marrow In _____________________ (long bone) and among trabeculae (_________________________) –in vertebrae, ribs, sternum, pelvic girdle and proximal heads of femur and humerus in adults Red marrow like thick blood –_________________________ (produces blood cells) ________________________ –fat long bones (medullary cavity)

7-13 Intramembranous Ossification Osteoblasts on trabeculae lay down osteoid tissue (uncalcified bone) _____________________________________ Osteoclasts create ____________________ _________________ form compact bone at surface Surface mesenchyme produces periosteum

7-14 _____________ Ossification Bone develops from ______________________________ –perichondrium and ____________________________ Most bones develop this process Form _______________________ centers and marrow cavity in shaft of model

7-15 Secondary ossification centers  ______________ Cartilage  __________________ and __________ (growth) plates –Bone length increases during childhood and adolescence –by early twenties, growth plates are gone and primary and secondary marrow cavities united Endochondrial Ossification

7-16 The Metaphysis –Zones of ___________________ –hyaline cartilage of ___________________ –chondrocytes multiply form columns of flat lacunae of _______________ = cell enlargement of calcification –mineralization of matrix of ____________________ –chondrocytes die and columns fill with osteoblasts –osteons formed and spongy bone is created

7-17 Medullary cavity Diaphysis Metaphysis Periosteum Red marrow Epiphyseal line Spongy bone Articular cartilage

7-18 Bone Growth and Remodeling Bones increase in length –growth of ____________________________ –________________line is left behind when cartilage gone Bones increase in width = appositional growth Bones remodeled throughout life –______________ = architecture of bone determined by mechanical stresses action of osteoblasts and osteoclasts –greater density and mass of bone in athletes/ manual worker is adaptation to stress

7-19 Dwarfism ___________________ –long bones stop growing in childhood ______________________ –spontaneous mutation during DNA replication –failure of ____________ ____________________ ____________________ –lack of growth hormone –normal proportions with short stature

7-20 Mineral Deposition ______________ is crystallization process –osteoblasts produce collagen fibers –minerals cover fibers and harden matrix ions (__________________________) are deposited along the fibers Abnormal calcification (______________) –may occur in lungs, brain, eyes, muscles, tendons or arteries (arteriosclerosis)

7-21 Mineral Resorption from Bone Bone dissolved (osteoclasts) and minerals released into blood Dental braces reposition teeth and remodel bone –create more pressure on one side of the tooth –stimulates osteoclasts to remove bone –decreased pressure stimulates osteoblasts

7-22 Calcium and Phosphate Phosphate is component of ____________ ____________________________________ – ~750 g in adult skeleton –plasma concentration is ~ 4.0 mg/dL –2 plasma forms: HPO 4 -2 and H 2 PO 4 - Calcium needed in ___________________ ______________________ and exocytosis – ~1100g in adult skeleton –plasma concentration is ~ 10 mg/dL

7-23 Ion Imbalances Changes in phosphate levels = _____________ Changes in calcium can be serious –__________________ - deficiency of blood calcium excitability of nervous system –muscle spasms, tremors or tetany ~6 mg/dL –laryngospasm and suffocation ~4 mg/dL with less calcium, sodium channels open more easily, sodium enters cell and excites neuron –__________________ - excess of blood calcium makes sodium channels less likely to open, depresses nervous system –______________________________________, cardiac arrest ~12 mg/dL Calcium phosphate homeostasis  calcitriol, calcitonin and PTH hormone regulation

7-24 Hormonal Control of Calcium Balance Calcitriol, PTH and calcitonin maintain normal blood calcium concentration.

7-25 __________ (Activated Vitamin D) Produced by –___________________________ convert steroid to cholecalciferol - D3 –liver converts it to calcidiol –kidney converts that to ______________ (vitamin D) Calcitriol ________________ blood calcium concentration –increases _____________________ and absorption from the skeleton –increases ______________________ –promotes urinary reabsorption Abnormal softness (________) in children and (______________) in adults with low vitamin D

7-26 Calcitonin Secreted (_____________) when calcium concentration too high Functions –____________________ activity –increases the number/ activity of ___________________ Important in children, little effect in adults –osteoclasts more active in children –deficiency does not cause disease in adults ________________________________

7-27 Parathyroid Hormone Glands on posterior surface of ____________ Released with __________ Function = ______ calcium blood level –increases in _____________ ____________________ –_______________________ resorption by the kidneys –promotes __________________ synthesis in the kidneys –________________________ ________________________ ________________________

7-28 Other Factors Affecting Bone ______________________ Growth rapid at puberty –hormones stimulate ______________________, chondrocytes and matrix deposition in growth plate –girls grow faster than boys and reach full height earlier (estrogen stronger effect) –males grow for a longer time and taller ______________________ –teenage use of anabolic steroids = premature closure of growth plate and short adult stature

7-29 Spongy bone Osteon Volkman’s canal Periosteum Osteocyte Lamella Canaliculi

7-30 Fractures _________________________ caused by trauma –car accident, fall, athletics ____________________ bone weakened by disease –bone cancer or osteoporosis Fractures classified by structural characteristics –break in the skin (_______________________) –multiple pieces

7-31 Types of Bone Fractures

7-32 Healing of Fractures Normally weeks (__________________) Stages of healing –__________________ - clot forms, osteogenic cells form granulation tissue –__________ - fibroblasts produce fibers and fibrocartilage –_________ - osteoblasts produce a bony collar in 6 weeks –____________ - spongy bone replaced by compact bone in 3 to 4 months

7-33 Treatment ________________________ –fragments align with manipulation/ casted Open reduction –__________________________________________ Traction long-term confinement in bed Electrical stimulation used on fractures –if 2 months necessary for healing ____________________ = prevention and correction of injuries and disorders of the bones, joints and muscles

7-34 _______________ Bones loses mass (__________________);  ______________ –risk of fracture of hip, wrist and vertebral column –complications (pneumonia and blood clotting) Postmenopausal white women at greatest risk –by age 70, average loss is _______ of bone mass –black women rarely suffer symptoms

7-35 Osteoporosis _____________ maintains density in both sexes (inhibits resorption) –________________ produce estrogen in men –rapid loss after ____________, if body fat too low or with disuse during immobilizaton Treatment –HRT slows bone resorption, but increases risk breast cancer, stroke and heart disease –PTH slows bone loss if given daily injection Forteo increases density by 10% in 1 year may promote bone cancer –_____________________________ _____________________________ _____________________________ _____

7-36 Spiral Comminuted Pott’s Colles’ Greenstick Open (compound) displaced

7-37 PTH Osteoporosis Calcitonin Hypocalcemia Achondroplasia Calcitriol Reduces osteoclast activity Dwarfism Vitamin D Excitable nervous system Increases blood calcium Pathological decrease in bone mass