KINS 1223 Unit 3 Test Study Guide Unit 3 Lecture 1 Skeletal System 1 Support Mainly Connective tissue predominantly bone cartilage Functions a Bones hard framework b Soft tissues supports provides anchor 2 Protection Surrounds vital organs a Skull Brain b Ribs Sternum Heart c Vertebrae Spinal cord d Pelvis Reproductive organs 3 Movement single part or total body a Bones Joints system of levers Internally operated by muscles i ii Shape arrangement of bones joint design determine possible movement 4 Manufactures Red Blood Cells majority in marrow cavities 5 Storage a Fat in the internal cavities of bones converted to energy when needed b Minerals i Major storehouse 99 Ca 90 P also K Na S Mg Cu ii Stored as mineral salts released into blood in ionic form when needed Bones Bone is a living tissue Highly vascularized 1 Axial Skeleton 80 bones a Skull Vertebrae Sternum Ribs 2 Appendicular Skeleton 126 bones 64 superior 62 inferior a Arms Legs Shoulder Girdle Pelvis Bone Type 1 By Shape 1 Long femur tibia humerus metacarpals etc a Enlargements at each end b Where weight bearing and movement are important c Structure i Shaft or Diaphysis 1 Long narrow part of bone Thickest in middle 1 3 and thinner towards ends of diaphysis 2 Center Medullary Marrow cavity a Lined w endosteum composed of areolar CT both osteoblasts osteoclasts 3 Thin layer of cancellous bone a Early life contain red marrow produce RBC b Adult red replaced by yellow marrow fat cells ii Epiphyses 1 Bulbous expansions at ends of long bones 2 Cancellous bone covered by thin layer of cortical bone 3 Shock absorption iii Articular cartilage hyaline cartilage 1 Covers articulating surfaces reduce friction prevents wear and tear iv Periosteum 1 Double layered membrane covering outer surface except articular cartilage Inner or osteogenic layer primarily osteoblasts a b Outer or fibrous layer dense irregular CT i Contains Fibers of Sharpey perforating fibers 1 Collagenous fibers 2 Secure periosteum to bone 3 ligaments and tendons Internal side penetrate into bone External side Fibers of Sharpey become entwined w fibers of tendons v Hollow cylinder structure 1 Stronger than solid bone of same cross section 2 IMPORTANT Large forces during movement lighter weight weight bearing 2 Short carpals tarsals a Rounded shape b Shock absorbers c Sesamoid bones type of short bone patella i Enclosed in tendons or other tissue ii Functions to improve mechanical efficiency of muscles 3 Flat ribs scapula skull a Protects vital organs b Large surfaces for muscle attachment c Good shock absorbers 4 Irregular vertebrae small facial bones inner ear a Functions specific to bone i Protection Vertebrae facial bones ii Sound transmission inner ear bones 2 By organization of materials same materials different organization 1 Cancellous or Spongy More space less material a Shock absorber short flat irregular ends of long bones b Lamellae arranged in thin spicules or plates of bone Trabeculae i Trabeculae many open spaces contain bone marrow looks like net or lattice ii Arranged in patterns that reflect stress applied to bone iii Can be permanently realigned to new stress but takes time c Lacunae found within trabecular plates osteocytes in lacunae 2 Cortical Compact Hard More material less space a Functions in support located in long bone shafts i Resists bending twisting compression forces b Covers cancellous bone c Composition i Many Haversian systems or Osteons ii Each system runs parallel to the length of the bone and has a Haversian or Central Canal 1 Haversian canal function a Transportation system b Contain blood vessels that supply bone c Contains nerves and other CT 2 Lamellae in concentric rings around Haversian canal 3 Osteocytes in Lacunae within the lamellae arranged in concentric rings of solid material a Canaliculi channels extend from lacunae iii Volkmann s perforating canals connect Haversian system w external vessels 1 External to Haversian system right angle 2 Transportation system blood vessels in out of Haversian canal Chemical Composition Organic materials called Osteoid Cells 1 Osteoblasts Bone forming cells a Arise from embryonic fibroblasts multiply continuously b Mineralize organic matter of matrix 2 Osteoclasts a Large specialized cells in endosteum b Functions i Destroy or reabsorb bone ii Secrete lysosomal enzymes metabolic acids iii Phagocytize bone matrix c Develop in bone matrix by fusion of 3 50 stem cells 3 Osteocytes Bone cells a Osteocytes are osteoblasts trapped in the matrix they formed Bone Matrix Organic material provides tensile strength mostly collagen Inorganic materials resist compression forces mineral salts Matrix is hard therefore bone is hard Sheets or layers lamellae Lacunae open spaces scattered throughout lamellae Osteocytes in lacunae Thin processes pass through openings Canaliculi in solid lamellae Processes joined by gap junctions pass by diffusion from osteocyte to osteocyte Bone Properties 1 Combination of organic inorganic materials a Remove inorganic salts by soaking in vinegar i Bone can be tied to a knot b Remove organic materials by boiling i Brittle bone will crumble 2 Bones stronger in compression than tension organic materials less able to a Fracture from tension before compression withstand tension RBC Production By age 18 22 Ossification o Long bones red marrow replaced by yellow marrow o RBC production shifts to flat bones vertebrae Producing hardened bone from Fibrous CT membranes Cartilage At fetal 6 weeks Skeleton is either fibrous CT membranes or hyaline cartilage Bone begins to develop
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