Human Anatomy and Physiology PDF

Human Anatomy and Physiology Eleventh Edition Chapter 6 Bones and Skeletal System Slides have been modified and edited by C. Youngson PowerPoint® Lectures Slides prepared by Karen Dunbar Kareiva, Ivy Tech Comm...

Human Anatomy and Physiology Eleventh Edition Chapter 6 Bones and Skeletal System Slides have been modified and edited by C. Youngson PowerPoint® Lectures Slides prepared by Karen Dunbar Kareiva, Ivy Tech Community College Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved  Pre-lecture questions: 1. What are the different bone cells and what are their functions? 2. What is compact bone? 3. What is spongy bone? 4. What bones make up the axial skeleton? appendicular skeleton? 2 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved  Functions of Bones There are seven important functions of bones: 1. Support  For body and soft organs 2. Protection  Protect brain, spinal cord, and vital organs 3. Movement  Levers for muscle action 4. Mineral and growth factor storage  Calcium and phosphorus, and growth factors reservoir 5. Blood cell formation  Hematopoiesis occurs in red marrow cavities of certain bones 6. Triglyceride (fat) storage  Fat, used for an energy source, is stored in bone cavities Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Classification of Bones 206 named bones in human skeleton Divided into two groups based on location – Axial skeleton  Long axis of body  Skull, vertebral column, rib cage – Appendicular skeleton  Bones of upper and lower limbs  Girdles attaching limbs to axial skeleton Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved The Bones and Cartilages of the Human Skeleton Figure 6.1 The bones and cartilages of the human skeleton. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Classification of Bones Bones are also classified according to one of four shapes: 1. Long bones  Longer than they are wide  Limb bones 2. Short bones  Cube-shaped bones (in wrist and ankle)  Sesamoid bones form within tendons (example: patella) 3. Flat bones  Thin, flat, slightly curved  Sternum, scapulae, ribs, most skull bones 4. Irregular bones  Complicated shapes  Vertebrae and hip bones Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Classification of Bones on the Basis of Shape Figure 6.2 Classification of bones on the basis of shape. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Gross Anatomy: long bones Structure of typical long bone – All long bones have a shaft (diaphysis), bone ends (epiphyses), and membranes  Diaphysis: tubular shaft that forms long axis of bone – Consists of compact bone surrounding central medullary cavity that is filled with yellow marrow in adults  Epiphyses: ends of long bones that consist of compact bone externally and spongy bone internally – Articular cartilage covers articular (joint) surfaces  Between diaphysis and epiphysis is epiphyseal line – Remnant of childhood epiphyseal plate where bone growth occurs Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Gross Anatomy: long bone Structure of long bones – Compact bone: dense outer layer on every bone that appears smooth and solid – Spongy bone: made up of a honeycomb of small, needle-like or flat pieces of bone called trabeculae  Open spaces between trabeculae are filled with red or yellow bone marrow Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Gross Anatomy: long bone  Membranes: two types (periosteum and endosteum) – Periosteum: white, double-layered membrane that covers external surfaces except joints Fibrous layer: outer layer consisting of dense irregular connective tissue consisting of Sharpey’s fibers that secure to bone matrix Osteogenic layer: inner layer abutting bone and contains primitive osteogenic stem cells that gives rise to most bone cells – Endosteum Delicate connective tissue membrane covering internal bone surface Like periosteum, contains osteogenic cells that can differentiate into other bone cells Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Gross Anatomy: flat bone Structure of short, irregular, and flat bones – Consist of thin plates of spongy bone covered by compact bone – Compact bone sandwiched between connective tissue membranes  Periosteum covers outside of compact bone, and endosteum covers inside portion of compact bone – Bone marrow is scattered throughout spongy bone; no defined marrow cavity Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Table 6.2-1 Bone Markings Table 6.2 Bone Markings. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Table 6.2-2 Bone Markings (2 of 2) Table 6.2 Bone Markings. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Microscopic Anatomy of Bone Cells of bone tissue 1. Osteogenic cells 2. Osteoblasts 3. Osteocytes 4. Osteoclasts Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Microscopic Anatomy of Bone 1. Osteogenic cells – Also called osteoprogenitor cells – Mitotically active stem cells in periosteum and endosteum – When stimulated, they differentiate into osteoblasts 2. Osteoblasts – Bone-forming cells that secrete unmineralized bone matrix called osteoid  Osteoid is made up of collagen and calcium-binding proteins  Collagen makes up 90% of bone protein Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Microscopic Anatomy of Bone 3. Osteocytes – Mature bone cells in lacunae that no longer divide – Maintain bone matrix and act as stress or strain sensors 4. Osteoclasts – Derived from same hematopoietic stem cells that become macrophages – Giant, multinucleate cells function in bone resorption (breakdown of bone) – When active, cells are located in depressions called resorption bays – Cells have ruffled borders that serve to increase surface area for enzyme degradation of bone Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved An Osteoclast Figure 6.7 An osteoclast. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Microscopic Anatomy of Compact Bone Osteon (Haversian system) – An osteon is the structural unit of compact bone – Consists of an elongated cylinder that runs parallel to long axis of bone  Acts as tiny weight-bearing pillars – An osteon cylinder consists of several rings of bone matrix called lamellae  Lamellae contain collagen fibers that run in different directions in adjacent rings  Withstands stress and resist twisting Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Microscopic Anatomy of Bone Canals and canaliculi – Central (Haversian) canal runs through core of osteon  Contains blood vessels and nerve fibers – Perforating (Volkmann’s) canals: canals lined with endosteum that occur at right angles to central canal – Lacunae: small cavities that contain osteocytes – Canaliculi: hairlike canals that connect lacunae to each other and to central canal Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Microscopic Anatomy of Compact Bone Figure 6.9 Microscopic anatomy of compact bone. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Microscopic Anatomy of Spongy Bone Spongy bone – Is organized along lines of stress to help bone resist any stress – Trabeculae confer strength to bone  No osteons are present, but trabeculae do contain irregularly arranged lamellae and osteocytes interconnected by canaliculi  Capillaries in endosteum supply nutrients Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Chemical Composition of Bone Bone is made up of both organic and inorganic components Organic components  Includes osteogenic cells, osteoblasts, osteocytes, osteoclasts, and osteoid – Osteoid, which makes up one-third of organic bone matrix, is secreted by osteoblasts Consists of ground substance and collagen fibers, which contribute to high tensile strength and flexibility of bone Inorganic components – Hydroxyapatites (mineral salts)  Makeup 65% of bone by mass  Consist mainly of tiny calcium phosphate crystals in and around collagen fibers  Responsible for hardness and resistance to compression Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Bone Development Ossification (osteogenesis) is the process of bone tissue formation 1. Embryonic: Formation of bony skeleton begins in month 2 of development 2. Postnatal bone growth occurs until early adulthood 3. Bone remodeling and repair are lifelong Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 1. Embryonic Bone growth Up to about week 8, fibrous membranes and hyaline cartilage of fetal skeleton are replaced with bone tissue Endochondral ossification – Bone forms by replacing hyaline cartilage – Bones are called cartilage (endochondral) bones – Form most of skeleton Intramembranous ossification – Bone develops from fibrous membrane – Bones are called membrane bones Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Embryonic Bone Growth Endochondral ossification – Forms essentially all bones inferior to base of skull, except clavicles – Begins late in month 2 of development – Uses previously formed hyaline cartilage models – Requires breakdown of hyaline cartilage prior to ossification – Begins at primary ossification center in center of shaft  Blood vessels infiltrate perichondrium, converting it to periosteum Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Endochondral Ossification in a Long Bone Figure 6.10 Endochondral ossification in a long bone. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Embryonic Bone Growth Intramembranous ossification: begins within fibrous connective tissue membranes formed by mesenchymal cells – Forms frontal, parietal, occipital, temporal, and clavicle bones Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 2. Postnatal Bone Growth Long bones grow lengthwise by interstitial (longitudinal) growth of epiphyseal plate Bones increase thickness through appositional growth Bones stop growing during adolescence – Some facial bones continue to grow slowly through life Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Growth in Length of a Long Bone Occurs at the Epiphyseal Plate Figure 6.12 Growth in length of a long bone occurs at the epiphyseal plate. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Growth in Width (Thickness) Growing bones widen as they lengthen through appositional growth – Can occur throughout life Bones thicken in response to increased stress from muscle activity or added weight Osteoblasts beneath periosteum secrete bone matrix on external bone Osteoclasts remove bone on endosteal surface Usually more building up than breaking down which leads to thicker, stronger bone that is not too heavy Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Hormonal Regulation of Bone Growth Growth hormone: most important hormone in stimulating epiphyseal plate activity in infancy and childhood Thyroid hormone: modulates activity of growth hormone, ensuring proper proportions Testosterone (males) and estrogens (females) at puberty: promote adolescent growth spurts – End growth by inducing epiphyseal plate closure Excesses or deficits of any hormones cause abnormal skeletal growth Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 3. Control of Remodeling Hormonal controls – Parathyroid hormone (PTH): produced by parathyroid glands in response to low blood calcium levels  Stimulates osteoclasts to resorb bone  Calcium is released into blood, raising levels  PTH secretion stops when homeostatic calcium levels are reached – Calcitonin: produced by parafollicular cells of thyroid gland in response to high levels of blood calcium levels Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Parathyroid Hormone (PTH) Control of Blood Calcium Levels Figure 6.14 Parathyroid hormone (PTH) control of blood calcium levels. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Bone Repair Fractures are breaks – During youth, most fractures result from trauma – In old age, most result from weakness of bone due to bone thinning Three fracture classifications – Position of bone ends after fracture  Nondisplaced: ends retain normal position  Displaced: ends are out of normal alignment – Completeness of break  Complete: broken all the way through  Incomplete: not broken all the way through – Whether skin is penetrated  Open (compound): skin is penetrated  Closed (simple): skin is not penetrated Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Table 6.3-1 Common Types of Fractures (1 of 3) Table 6.3 Common Types of Fractures. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Table 6.3-2 Common Types of Fractures (2 of 3) Table 6.3 Common Types of Fractures. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Table 6.3-3 Common Types of Fractures (3 of 3) Table 6.3 Common Types of Fractures. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Fracture Treatment and Repair Treatment involves reduction, the realignment of broken bone ends – Closed reduction: physician manipulates to correct position – Open reduction: surgical pins or wires secure ends – Immobilization of bone by cast or traction is needed for healing  Time needed for repair depends on break severity, bone broken, and age of patient Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Fracture Treatment and Repair Repair involves four major stages: 1. Hematoma formation 2. Fibrocartilaginous callus formation 3. Bony callus formation 4. Bone remodeling Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Independent Reading Developmental Aspects of Bones pg 194-195 40 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved