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
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*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 5.7
5 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
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