EXSC 223 1st EditionExam # 2 Study Guide Lectures: 1 - 7Note: Don’t forget to learn the material in the Chapter 4 and Chapter 5 lecture power points on Blackboard.Lecture 1 (February 19)Chapter 63 Types of skeletal cartilage:1)Hyaline- Provides support but flexible- Made up of collagen fibers- Most abundant type of cartilage- Located at end of long bones, articulating joints (ex: fingers), trachea, bronchi tubes, larynx, nose- Designed to withstand compression and decrease friction (slick)2)Elastic- Withstands repeated stretching- Made of collagen fibers and elastin fibers- Composes external ear and epiglottis- Elastic cartilage is hyaline with more flexibility3)Fibrocartilage- Compressible with high tensile strength- Where you find fibrocartilage, you do not find hyaline cartilage (except in knee)- Found in vertebral column – allows spine to stretch and compress- Also found in pubic symphysis and menisci in knees (cushion)- Very durable, lots of dense collagen fibersBecause cartilage does not have a blood supply, it does not grow very fast. It receives nutrients via diffusion.How does cartilage grow?1)Appositional growth (outside) – chondroblasts secrete new matrix on external face2)Intersititial growth (within) – lacunae chondrocytes proliferate/secrete matrixa. Chondrocytes are mature chondroblasts surrounded by cartilage. Its job is to repair tissues. *check on thisBones have five vital functions:1)Support – framework for body, supports organs2)Protection – protects brain, spinal cord, and rib cage3)Movement – used as levers for movement, attached to muscles4)Mineral storage – calcium and phosphate5)Blood cell formation – hematopoiesis within marrow cavities (only red marrow)6)Triglyceride (fat) storage – fat stored in bone as a source of energyBones are divided into 2 groups:1)Axial skeleton – long axisa. Skull, vertebral column, rib case2)Appendicular skeleton – upper/lower limbs and girdlesClassification of Bones: By Shape1)Long bones – longer than they are wide (humerus, femur)2)Short bones – cube-shaped bones of the wrist and anklea. Sesamoid bones form within tendons (patella)3)Flat bones – thin, flattened, and a bit curved (sternum, scapulae, ribs, most skull bones)4)Irregular bones – bones with complicated shapes (vertebrae and hip bones)Two types of bone:1)Compact bone – dense, hard, smooth2)Spongy bone – hard, but consists of struts and columns with air spaces called trabeculae; your red bone marrow exists here-Spongy bone is always encased in compact bone.Trabeculae – small needle-like or flat pieces of bone that form the framework of spongy bone.-redistribute mechanical stress.Long bones consist of 1 diaphysis (middle region) and 2 epiphyses (end regions). Short bones only have 1 epiphysis.1) Diaphysis – tubular shaft that forms the axis of long bonesa. Composed of compact bone that surrounds the medullary cavity.2) Epiphyses – expanded ends of long bonesa. Exterior is compact bone and interior is spongy boneb. Located at jointsc. Surface is covered with articular (hyaline) cartilaged. Epiphyseal line separates the diaphysis from the epiphyses. This is seen in adults and is the remnants of the growth plate.Lecture 2 (February 21)1) Periostium – double-layered outer bone membranea. Outer fibrous layer is dense irregular connective tissueb. Inner osteogenic layer composed of osteoblasts and osteoclastsc. Richly supplied with nerve fibers, blood, and lymphatic vessels, which enter the bone via nutrient foraminad. Secured to underlying bone by Sharpey’s fibers2) Endosteum – inner bone membranea. Lines medullary cavityb. Surrounds/covers trabeculaec. Lines central canals inside compact boned. Contains osteoblasts and osteoclastsFour Types of Bone Cells: (fig. 6.4)1) Osteogenic cell – precursor bone cell (stem cell) which produces osteoblasts2) Osteoblast – responsible for bone growth3) Osteocyte – formerly an osteoblast, surrounded by bone in a structure called a lacunaei. Main function is to maintain the bone matrix4) Osteoclast – a specialized macrophage that breaks down bone and is responsible for bone resorptionCompact BoneMade of osteons, the structural unit of compact bone made of concentric layers of mineralized collagen.Lamella – Weight-bearing, column-like matrix tubes composed mainly of collagen fibers. The fibers in a single lamella run in the same direction, but run in different directions in adjacent lamella (fig. 6.6).Central (Haversian) canal – central channel of an osteon containing blood vessels and nervesVolkmann’s canals – channels running at right angles to the central canal and connect the blood and nerve supply of the periosteum to those in the central canals and the medullary cavity.Spongy BoneMade up of trabeculae and found in short, irregular, and flat bones.- Always encased in compact bone- Encased by endosteumHematopoietic tissue is found in red marrow.Where is hematopoietic tissue found in infants vs. adults?a) In infants – medullary cavity of diaphysis and all areas of spongy boneb) In adults – trabeculae of flat bones and head of femur and humerusChemical Composition of Bone: InorganicHydroxyapatites, or mineral salts compose 65% of bone mass.- Include calcium and phosphates- Responsible for making bone hard and resistant to compressionBone DevelopmentOssification = osteogenesis and refers to bone formation by osteoblastsa) Embryo – formation of bony skeletonb) Up to adulthood – bone growthc) Adult – bone remodelingEmbryo Bone FormationMembrane bone is formed by intramembranous ossificationEndochondral bone is formed by endochondral ossification.1) Intramembranous ossification (fig. 6.8) – the process by which flat bones in the embryo are formeda. Ossification center appears in connective tissue membraneb. Bone matrix (osteoid) is secreted by ossification center.c. Woven bone and periosteum formsd. Bone collar of compact bone forms and red marrow appearsLecture 3 (February 24)2) Endochondral Ossificationa. Begins with a hyaline cartilage templateb. Bony collar forms outside cartilage around ossification center.c. Cartilage cells hypertrophy, secrete calcium, and die. This occurs in the center of the cartilage shaft.d. Periosteal bud invades internal cavities and spongy bone forms.e. Medullary cavity forms as ossification continues.f. Secondary ossification centers appear in each epiphysis.g. Ossification of