APK2100C Chapter 6 Outline
APK2100C Chapter 6 Outline APK 2100C
Popular in Applied Human Anatomy with Laboratory
Popular in Anatomy
verified elite notetaker
verified elite notetaker
verified elite notetaker
verified elite notetaker
verified elite notetaker
verified elite notetaker
This 11 page Class Notes was uploaded by Kate Campbell on Monday September 19, 2016. The Class Notes belongs to APK 2100C at University of Florida taught by Joslyn Ahlgren in Fall 2016. Since its upload, it has received 245 views. For similar materials see Applied Human Anatomy with Laboratory in Anatomy at University of Florida.
Reviews for APK2100C Chapter 6 Outline
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 09/19/16
September 13, 2016 CHAPTER 6: BONES AND SKELETAL TISSUES (P. 123-140) 1. INTRODUCTION A. Skeletal System forms internal framework; composed of: i. Bones ii. Cartilages iii. Joints B. Bones provide: i. support and shape for body ii. attachment sites for muscles iii. storage depot for essential minerals C. Cartilage i. Part of numerous joints ii. Helps support and movement while cushioning bone surfaces that are rubbing each other D. Cartilage and Bone i. Linked developmentally 1. Majority of bones formed in cartilage tissue, then replaces by bone tissue during prenatal and childhood development E. Skeletal System contains clues to personal story i. Bones and skeletal tissues reflect: 1. Age 2. Gender 3. Ethnicity 4. Height 5. Health 6. Nutrition status 2. CARTILAGES A. Location ad Basic Structures i. Cartilage: 1. In external ear 2. In nose 3. Articular Cartilages - cover ends of most bones and movable joints 4. Costal Cartilages - connect ribs to sternum 5. In larynx, including epiglottis (a flap preventing food from going into the larynx and lungs) 6. That keeps the respiratory system’s air tubes open 7. Located between the discs between the vertebrae 8. In the pubic symphysis 9. That form articular discs within particular movable joints ie, the meniscus in the knee ii. Greatly more abundant in the embryo than adult iii. Typical cartilaginous structure in skeleton is : 1. made up of connective tissue cartilage that is avascular and not innervated 2. surrounded by the perichondrium (a layer of dense irregular CT) serving as a girdle to protect the cartilage from expanding outward when pressure is applied; also aids in the growing and repairing of cartilage iv. mainly composed of water, being about 60% to 80% H2O v. extremely resilient, able to spring back to initial shape following compression B. Types of Cartilage i. 3 types: 1. hyaline 2. elastic 3. fibrocartilage ii. all cartilage is CT that contains ch ondrocytes and lots of extracellular matrix (ground substance) iii. each chondrocyte is located in a lacuna- a designated space within the extracellular matrix iv. extracellular matrix composed of fibers and gel like ground substance formed with complex sugar molecules, used to attract and hold water v. Hyaline Cartilage 1. Appearance of frosted glass 2. Most abundant 3. Chondrocytes look spherical 4. Collagen fibril is only fiber 2 a. Forms networks not visible with a light microscope because of how tiny 5. Holds lots of water à tissue is excellent at putting up with compression 6. Delivers support with its flexibility and resilience 7. Composes articular cartilage that covers ends of abutting bones in movable joints 8. Makes up most cartilage in respiratory structures 9. Helps to form embryoni c skeleton 10. Makes the cartilaginous attachments of the ribs to the sternum C. Elastic Cartilage i. Similar to above ii. Contains collagen fibrils plus numerous elastic fibers iii. Better able to handle repeated bending iv. Composes epiglottis (opening of larynx) and the most bendable sections of the external ear D. Fibrocartilage i. Resists both intense tension and compression forces ii. Found in particular ligaments and cartilages which experience these forces iii. Comparatively a middle ground between hyaline cartilage and dense regular C T iv. Collagen fibrils v. Specifically in annulus fibrous section of discs between vertebrae and articular discs of some joint E. Growth of Cartilage i. 2 types of growth: 1. appositional growth à growth from inside out a. chondroblasts in surrounding perichondrium make new cartilage tissue through active secretion of matrix 2. interstitial growth à “growth from within” a. chondrocytes within cartilage separate and make new matrix ii. grows fast during prenatal development, childhood, and adoles cence iii. ceases growth in late teen years when skeleton stops iv. thus cartilage does not regenerate well in adulthood 1. typically, cartilage is then repaired with fibrocartilage 2. surviving chondrocytes are able to secrete more extracellular matrix v. *occasionally, crystals of calcium phosphate precipitate in to matrix of the cartilage, which indicates aging in adults; normal stage in child ’s growth of majority of bones vi. ** calcified cartilage is NOT bone 3 3. BONES A. Bones of skeleton are organs because contain multiple differ ent tissues: i. Bone tissue ii. Nervous tissue in nerves iii. Blood tissue in blood vessels iv. Cartilage in articular cartilages v. Epithelial tissue lining blood vessels B. Functions of Bones i. Support 1. Solid framework able to support mass of body ii. Movement 1. Skeletal muscles attac hed to bones by tendons and use bones as levers to move 2. Arrangement of bones and structure of joints dictates movements available 3. Support and movement are mutually dependent iii. Protection 1. Skull encases brain 2. Vertebrae protects spinal cord 3. Ribs protect organs within the thorax iv. Mineral Storage 1. Depot for minerals, especially calcium and phosphate 2. Enter blood stream as ions to be delivered to all parts of the body an a need basis v. Blood Cell Formation and Energy Storage 1. Contain both yellow and red bone marrow 2. Red produces blood cells 3. Yellow is where fat is stored vi. Energy Metabolism 1. Osteoblasts (bone -producing cells) release hormone called osteocalcin that plays role in blood sugar regulation and energy metabolism 2. Osteocalcin stimulates pancreatic output of insulin 3. Also influences fats cells to store less fat and secrete hormone that raises insulin sensitivity of cells C. Bone Tissue i. Has both organic and inorganic parts ii. Organic: 1. Cells 4 2. Fibers 3. Ground substance iii. Inorganic: 1. Mineral salts (make bones hard) iv. Tissue fluid sill pre sent but MUCH LESSS WATER v. Extracellular Matrix 1. Organic components - 35% of tissue weight 2. These, especially collagen (abundant), aid the flexibility an tensile strength enabling bone to put up with stretching and twisting 3. Inorganic - 65% 4. Mineral salts = hydroxyapatites 5. Primarily calcium phosphate 6. Small crystals in and around collagen fibrils in matrix 7. This is how bones preserves for millions of years 8. Bone is stronger than concrete in compression and = in tensile strength 9. Not brittle (if correct compositio n) vi. Cells 1. Three types in bone tissue that either make or help maintain it: a. Osteogenic cells i. Stem cells that change into osteoblasts b. Osteoblasts i. Actively make organic components of bone matrix (osteoid) 1. Ground substance 2. Collagen fibers c. Osteocytes i. Created aft er osteoid is filled within a week with inorganic salts that crystalize and they are completely covered with bone matrix and osteoblasts no longer producing new osteoid ii. Maintains bone tissue health 2. Osteoclasts are responsible for the resorption of bone a. Derived from lineage of lymphocytes b. Multinucleated c. Decompose bone by releasing hydrochloric acid, which eats away the mineral part of the matrix, and lysosomal enzymes that eat the organic parts 3. Creating/destroying is normal process, keeping strength and act appropriately to new stresses 5 4. GROSS ANATOMY OF BON ES A. Classification of Bones’ i. Shape indicates function and formation 1. Long bones a. Longer than width b. Contains shaft and 2 clear ends c. Make up most limb bones d. Classified due to elongation not physical size 2. Short Bones a. Cube-shaped b. Wrist and ankle c. Sesamoid bones (sesame seed shaped) are specialized short bones that are created within a tendon ie. kneecap i. Multiple different sizes and amount depending on the person ii. Some help alter the direction of the tendon’s pull iii. Others minimize friction and change pressure in tendons to lessen ripping or abrasion 3. Flat ones a. Thin, curved, flat b. Most cranial bones, ribs, sternum, and scapula 4. Irregular Bones a. Varying shapes that simply do not fit into any of the other categories B. Compact and Spongy Bone i. Normal eye perceives dense outer layer known as compact bone as smooth and solid ii. Spongy bone is internal (trabecular bone is alt. name), appearing as honeycomb of tiny “needle-like” pieces known as trabeculae 1. Open spaces between the trabeculae house red or yellow bone marrow C. Structure of Typical Long Bone i. Almost all the long bones have matching overall structure D. Diaphysis and Epiphyses i. Tubular diaphysis (shaft) creates the log axis of long bone ii. Epiphyses = ends of the bone 1. Joint surfa ce of each coated by articular cartilage (hyaline) iii. Epiphyseal line runs between the diaphysis and epiphyses 1. Created from epiphyseal plate (growth plate; hyaline cartilage) E. Blood Vessels 6 i. Bones are vascularized ii. 3%-11% of blood within body is in skeleton iii. main vessels aiding diaphysis: 1. nutrient artery a. goes inward to for marrow and spongy bone b. then goes outward for compact bone 2. nutrient vein 3. together run through a hole in wall ; referred to as the nutrient foramen F. Medullary Cavity i. Middle of diaphysis has no bone tissue = medullary cavity/ marrow cavity ii. Adult’s cavity contains yellow bone marrow G. Membranes i. CT membrane periosteum covers the whole exterior of all bones excluding the very ends of the epiphyses ii. Has 2 sublayers: 1. Superficial layer of dense irregular CT a. Resists tension during bending 2. Deep osteogenic layer a. Osteoblasts i. Make circumferential lamellae, the layers of bone tissue that encompass the perimeter of bone b. Osteoclasts c. Cannot be distinguished from fibroblasts of this layer iii. Numerous nerves and blood ves sels iv. Perforating collagen fiber bundles secure periosteum to the bone underneath 1. Thick collagen bundles running from periosteum to bone matrix v. Gives insertion points for tendons and ligaments for bone attachment vi. Endosteum covers internal bone features 1. Thinner 2. Cover spongy bone’s trabeculae 3. Lines osteons’ middle canals 4. osteogenic H. Structures of Short, Irregular, and Flat Bones i. Similar composition as long bones ii. Periosteum iii. Endosteum iv. No diaphysis 7 v. No epiphyses vi. Contain marrow but not marrow cavities vii. Dipole = internal spongy bone in flat bones I. Bone Design and Stress i. Bending stretches on one side and compresses on other ii. Both compression and tension are most intense at external surfaces 1. Thus strong compact bone exists here 2. Internally the forces are cancelled out so spongy bone is okay 3. No stress takes place at center medullary cavity, so the lack of bone tissue is okay iii. spongy bone’s trabeculae appear to align perfectly to the stress lines in an organized fashion of small struts iv. Bone markings: 1. Projections where mu scles or ligaments attach 2. Joint surfaces 3. Openings and depressions 5. MICRONSCOPIC STRUCTU RE OF BONE A. Compact Bone i. Looks solid ii. Has pathways for nerves and blood vessels iii. Osteons (Haversian system): 1. Run parallel to long axis 2. Serve as weight bearing pillars 3. Group of concentric tube 4. Each individual tube is a lamella= layer of bone matrix with collagen fibers and mineral crystals who run in the same direction; adjacent lamella e’s fibers always run perpendicular a. Designed to deal with torsion and stress b. Prevent cracks in bone from spreading deeper 5. Each osteon has central canal (Haversian canal) a. Lined with endosteum - an osteogenic layer b. Has own blood vessels to supply osteon cells nutrients c. Own nerve fibers d. Lamellae are added to inner surface of osteons, decreasing the central canal’s diameter 6. Perforating canals (Volkmann’s) 8 a. connect nerves a nd bloods vessels supplies from periosteum to central canal and marrow cavity 7. Osteocytes a. found in lacunae b. spider like bodies c. their legs are incased in tubes called canaliculi which connect the lacunae to each other and the closest capillaries d. legs touch each other and form gap junctions to supply nutrients to entire osteon iv. Interstitial lamellae 1. incomplete lamellae 2. remains of old osteons 3. lay between osteons v. Circumferential lamellae 1. Found in internal and external surfaces 2. Each covers entire circumference of diaphysis 3. Same functions as osteons but on a magnified scale 4. Resist torsion of the whole long bone B. Spongy Bone i. Less complex ii. Every trabecula has multiple layers of osteocytes and lamellae but not large enough to have own osteons or vessels iii. Nutrients received through connections by the canaliculi, giving access to capillaries in the surrounding endosteum 6. BONE DEVELOPMENT AND GROWTH A. Osteogenesis and Ossification (the process of bone tissue formation) i. Osteogenesis starts in the embryo and carries on until the skeleton stops growing in adulthood, then slows down ii. Membranous bones develop from mesenchymal membrane by intramembranous ossification iii. Endochondral bones (c artilage replacement bones) are made from hyaline cartilage through endochondral ossification B. Intramembranous Ossification i. Not ever modelled into cartilage; goes straight from mesenchyme to bone ii. Skull bones (excluding some at the base) and the clavicles are the only ones form by this process 9 C. Endochondral Ossification i. The rest of bones are formed in this fashion ii. Initially molded in hyaline cartilage iii. Gradually bone tissue replaces iv. Completed once skeleton has finished growing v. Bones increase in both length an d width vi. Epiphyseal plates cause the bones to grow longer for about 20 years give or take D. Anatomy of Epiphyseal Plate i. Organized to grow really quickly and efficiently ii. Resting (quiescent) zone - area near cartilage where cells are inactive and tiny iii. Proliferation zone- chondroblasts near top of zone rapidly divide, which pushes the epiphysis from the diaphysis à bone lengthens iv. Hypertonic zone- old chondroblasts get bigger and indicate for matrix to calcify v. Calcification zone- matrix calcifies and kills chondr ocytes vi. Ossification zone- were spicules are made bony on the diaphysis side by being covered with bone tissue by osteoblast after some erosion by osteoclasts vii. Cartilage is replaced with bone tissue on diaphysis side at roughly the same rate it grows, so the plate stays about the same size the entire time the bone is lengthening E. Postnatal Growth of Endochondral Bones i. Closure of the epiphyseal plates: epiphyses and diaphysis fuses, so bones stop getting longer 1. Happens between 15 -23 yr. 2. Females typically close earlier ii. Bones also widen while lengthening 1. Osteoblasts in osteogenic layer of periosteum add bone tissue in circumferential lamella to external part of diaphysis while osteoclasts eat away at the inner diaphysis wall a. So bones don’t get too heavy as they widen b. Example of appositional growth: the growth of bone by adding bone tissue to surface iii. Regulated by hormones iv. These steps have been specific to large long bones v. Short bones come from only one ossification center vi. Irregular bones come from multiple specific ossification centers vii. Small long bones form from a main ossification with a smaller secondary helping ossification center F. Bone Remodeling 10 i. Lots of bone matrix and osteocytes are always being removed and replaced ii. The architecture of bones is consistently c hanging on a small scale iii. Bone remodeling- in adults, bone deposited and taken away mainly at the endosteal surface 1. Spongy bone completely replaces within 3 -4 years 2. In compact bone, takes place at endosteum lining in central canals of osteon and takes clos er to 10 years to be replaced 3. Coordinated by neighboring osteoblasts and osteoclasts 4. Total mass remains same in healthy individuals once the skeleton has ceases growing 5. Not uniform; some bones or parts are more heavily remodeled than others iv. Bone resorption 1. Osteoclasts break down bone tissue 2. Membrane creates tight seal on bone then releases hydrochloric acid (minerals in matrix not a fan, dissolve) 3. The dissolved calcium and phosphate from matrix go into tissue fluid and blood 4. Lysosomal enzymes also secreted and they digest organic substance of matrix 5. Phagocytosis used to coll ect collagen and deceased osteocytes v. Bone deposition 1. Osteoblast put organic osteoid on bone 2. Calcium salts are crystalize d in osteoid 3. Osteoblast become osteocytes once encompassed by bone matrix vi. Osteoblasts 1. come from mese nchyme 2. in adults, from mesenchyme resembling stem cells in periosteum, endosteum, and connective tissues of close bone marrow vii. Osteoclasts 1. Form in bone marrow 2. Come from hematopoi etic stem cells (immature blood cells) 3. Stem cells often fuse t ogether when forming each osteoclast à multinuclear viii. Continuous Remodeled Reasons: 1. Keeps specific concentrations of calcium and phosphate in body fluids 2. Response to mechanical st ress endured a. More stressà thicker bones b. Less stressà weaker bones 11
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'