Skeletal System Chp. 5

Recall that connective tissue consists of a matrix with cells suspended w/in it--the type of matrix & cells determine type of tissue. 1.Bones - hard elements of skeleton. 2.Ligaments - dense, fibrous connective tissue that serves to bind bone-to-bone. 3.Cartilage - collagen & elastin fibers suspended in gel-like matrix [ground substance]. Skeletal System Composed of 3 Types of Connective Tissue

5 Functions of Bones 1.Support 2.Movement 3.Protection 4.Formation of blood cells 5.Mineral storage

1. Bone: hard inorganic matrix of calcium salts a.Compact Bone: Dense - extracellular deposits of calcium phosphate matrix w/ living cells Osteocytes- living mature bone cells that maintain structure of bone forms shafts & covers ends of long bones filled with yellow marrow Yellow marrow = Primarily fat for energy reserves Contains blood vessels & nerves Skeletal System cont.

b. Spongy Bone: porous bone found inside enlarged knobby ends of bones [knob = epiphysis] Internal latticework makes bones lighter & stronger Trabeculae = latticework of bones made of calcium minerals + living cells red marrow - found in spaces of trabeculae w/in long bones of upper arms & legs Stem cells w/in red marrow produce RBC’s Skeletal System cont.

Osteons [Haversian Systems] Cylindrical Structures (see text Fig 5.1) Osteons - as compact bone develops & hardens (ossifies) the osteocytes are trapped in hollow chambers within cylindrical osteons in such a way as to maintain contact with other osteocytes yet provide them a strong matrix to support them. Blood vessels traveling through the central Haversian canal feed the osteocytes via cell-to-cell diffusion. Waste products Diffuse away from cells, back to blood vessels.

Periosteum Tough Connective Tissue covering bones Contains bone forming Osteoblast cells

Structure of Bone Human Biology Figure 5.1 * * * * Make note of these

Cartilage - fibers of cartilage & elastin in gel-like matrix Function: support Types: Fibrocartilage - between vertebral disks, in knee joint Hyaline - embryonic “model” for bones, covers ends of mature bones found in joints. Elastic cartilage - outer ear, part of epiglottis Ligaments- attach bone to bone Cartilage and Ligaments

Prenatal: cartilage model Fetus: some conversion to bone Childhood: primary & secondary ossification sites formed Adolescence: cartilage growth plate elongates Bone Development [see Fig. 5.2 from text]

Bone Development ( cont.) Figure 5.2

Changes in: (1) shape, (2) size, (3) strength Dependent on diet, exercise, age Bone cells regulated by hormones Parathyroid hormone (PTH): removes calcium from bone Calcitonin: adds calcium to bone Repair: hematoma and callus formation Mature Bone Remodeling and Repair

Skeletal System: Frontal View Figure 5.5 Blue = Axial Skeleton [skull, vertebral column, ribs, Sternum] Black = Appendicular Skleton [pectoral girdle, pelvic girdle, limbs]

Axial Skeleton: The Skull [ Just make note of the number of bones in the skull ] Figure 5.6

Axial Skeleton: Vertebral Column Figure areas of Axial skeleton: cervical, thoracic, lumbar, scarum, coccyx

Vertebral column Regions: cervical, thoracic, lumbar, sacral, coccygeal Intervertebral disks: cushion vertebrae; assist in movement, flexibility Ribs Twelve pairs Bottom two pair floating Sternum: Breastbone Three bones fused Axial Skeleton: Vertebral Column ( cont.)

Pectoral girdle: shoulder Clavicle, scapulas Pelvic girdles: hip Coxal bones, sacrum, pubis, ilium, ischium Limbs Arms: humerus, radius, ulna, wrist and hand bones Legs: femur, tibia, fibula, ankle and foot bones Appendicular Skeleton

Classified by degree of movement Fibrous joint: immovable (e.g., fontanels) Cartilagenous joint: slightly movable, cartilage connection (e.g., backbone) Synovial joint: freely movable (e.g., knee) Joints (Articulations)

Synovial Joints Figure 5.12A

Joint capsule: synovial membrane + hyaline cartilage Synovial membrane secretes synovial fluid as lubricant Hyaline cartilage cushions Synovial Joints ( cont.)

Sprains: stretched or torn ligaments Bursitis and tendinitis: inflammation of bursae or tendons Arthritis: inflammation of joints Diseases and Disorders of the Skeletal System