Unit 3 Study Guide I Lecture 1 A Axial Skeleton 80 bones skull vertebrae sternum ribs B Appendicular skeleton 126 bones arms legs shoulder girdle and pelvis C Functions i Support bones hard framework soft tissue anchorage ii Protection vital organs ex skull scapula ribs vertebrae pelvis iii Movement Bones and Joints create a lever system shape determines function iv Manufactures RBS s marrow cavities v Storage minerals 99 calcium 90 phosphorus stored as mineral salts in bone D Classification of Bones metacarpals etc i Long Bones weight baring and movement femur tibia humerus ii Short bones rounded shape shock absorbers carpals and tarsals iii Seasmoid bones short bones enclosed in tendons and other tissues improve mechanical efficiency of muscles patella and bones in hand and feet iv Flat bones protect organs large surface for muscle attachments v good shock absorber s ex ribs sternum skull scapula s Irregular bones function specific to each bone protection and sound transmission vertebrae and inner ear bones E Bone Cells i Osteoblasts bone forming cells mineralize organic matter of matrix i Osteocytes bone cells mature osteoblasts trapped in the matrix they formed 1 cells in lacunae connected by gap junctions inside canaliculi ii Osteoclasts large specialized in endosteum absorb and reabsorb bone secrete lysosomal enzymes and metabolic acids phagocytize bone matrix 1 develop in bone marrow by fusion of 3 50 stem cells 2 Reside in pits that they ate into the bone F Bone Matrix G Bone Properties i Organic material provide tensile strength 1 Fibers mostly collagen Resist bending twisting stretching ii Inorganic materials resist compression forces Include mineral salts primarily Ca and P iii Matrix is hard therefore bone is hard i Combination of organic inorganic materials strong bones ii Remove inorganic salts by soaking in vinegar Leaves only organic materials Bone can be tied to a knot iii Remove organic materials boiling Leaves inorganic materials Brittle bone will crumble iv Bones stronger in compression than tension 1 Organic materials less able to withstand tension compression during support and weight bearing 2 Fracture from tension before compression H Bones Microscopic Structure i Bone matrix 1 Sheets or layers lamellae 2 Lacunae open spaces scattered throughout lamellae 3 Osteocytes in lacunae ii Thin processes pass through openings called Canaliculi in solid lamellae iii Processes joined by gap junctions and nutrients pass by diffusion from one osteocyte to another I Cancellous Spongy Bone more space less material i Function Shock absorber ii Location Short bones Flat bones Irregular bones Ends of long bones iii Composition Lamellae arranged in thin spicules or plates of bone 1 Hard material called Trabeculae where Lacunae is found a Osteocytes in lacunae 2 Bone is a living tissue so it is highly vascularized 3 Trabeculae arranged with many open spaces that contain bone marrow looks like net or lattice a arranged in patterns that reflect the stresses applied to bone b can realign to new stress patterns c requires permanent change and takes time J Cortical or Compact Bone more material with less space i Functions in support 1 Resists bending twisting and compression forces ii Located in long bone shafts and covers cancellous bone iii Composition Many Haversian systems or Osteons 1 Each system has a Haversian or Central Canal 2 Haversian system runs parallel to the length of bone iv Haversian Canal 1 Transportation system that contains blood vessels that supply bone and contains nerves and other CT 2 Lamellae in concentric rings around canal Cylinder of solid tissue v Osteocytes in Lacunae within the lamellae 1 Arrangement is concentric rings of solid material 2 Canaliculi channels extend from lacunae interconnect processes of osteocyte vi Volkmann s external vessels perforating canals connect Haversian system with 1 External to Haversian system at right angle 2 Acts as a transportation system blood vessels in out of K Structure of Long Bones Haversian canal i Shaft or Diaphysis long narrow part of bone ii Center medullary marrow cavity runs the length of diaphysis 1 Lined with endosteum which contains a membrane composed of areolar CT and has both osteoblasts and osteoclasts 2 Thin layer of cancellous bone that contains red marrow early in life This produces Red Blood Cells a Adult red marrow replaced by yellow marrow Fat cells iii Surrounded by cortical bone thickest in middle 1 3 of shaft strength and thinner toward ends of diaphysis iv End of bone Epiphysis 1 Contain cancellous bone covered by thin layer of cortical bone 2 Function Shock Absorption v Articular Cartilage covers articulating surfaces 1 Reduces friction prevents wear and tear 2 Hyaline cartilage vi Periosteum Double layered membrane that covers outer surface except articular cartilage Inner or osteogenic layer Primarily osteoblasts 1 2 Outer layer or fibrous layer Dense irregular CT a Contains Fibers of Sharpey or perforating fibers and is made of collagenous fibers that secure periosteum to bone b Secure ligaments and tendons c On internal side penetrate into bone d On external side Fibers of Sharpey become entwined with fibers of tendons etc e Mechanically very secure attachment to bones L Structure of Short Flat and Irregular bones i Constructed like the epiphysis Interior is cancellous bone called the diploe 1 2 Covered by thin layer of cortical bone ii Excellent shock absorber iii In flat bones and vertebrae there are cavities which contain red bone marrow Produces red blood cells RBCs 1 In children RBCs from marrow of long flat bones and vertebrae M By age 18 22 Long bones Red marrow replaced by yellow marrow and RBC Production shifts to flat bones vertebrae II LECTURE 2 A Ossification Producing hardened bone from fibrous connective tissue membranes and cartilage i Extends from 6th fetal week to 25 years ii Two types 1 Intramembranous ossification within membranes Bone formed by hardening fibrous CT into membranes ex flat bones a Primitive CT cells arrange around blood vessels differentiate into osteoblasts osteoblasts secrete organic bone matrix Osteoid around CT collagen fibers b Minerals deposited into osteoid c Trabecular structure begins to appear d Osteoid now mineralized true hardened bone i Osteoblasts trapped in lacunae mature into osteocytes ii Outside fibrous CT differentiates into double iii layered periosteum Inner layer of periosteum contains osteoblasts form cortical bone around