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Anatomy and Physiology I Unit 4: The Skeletal System Physiology of the Skeletal System
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Skeletal System Bones are made of several tissues Primarily made of collagen and hydroxyapatite - Ca 10 (PO 4 ) 6 (OH) 2 About 206 bones in the human body
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Functions of Skeletal System SUPPORT: Hard framework that supports and anchors the soft organs of the body. PROTECTION: Surrounds organs such as the brain and spinal cord. MOVEMENT: Allows for muscle attachment therefore the bones are used as levers. STORAGE: Minerals and lipids are stored within bone material. BLOOD CELL FORMATION: The bone marrow is responsible for blood cell production.
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Parts of the Skeletal System Axial skeleton –Skull and bones that support it –Includes vertebra and ribs –80 bones Appendicular skeleton –Limbs –126 bones
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Features of a Long Bone: Epiphysis: Ends of the bone. Diaphysis: The shaft of the bone which surrounds the medullary cavity. Articular Cartilage: Cushions the ends of the bones and allows for smooth movement. Epiphyseal Plate: Areas made of cartilage allowing for the growth of the bone.
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Joints Where bone meets bone Ligament – holds bone to bone Types of joints: –Immovable - skull –Ball-and-socket - shoulder –Hinge - knee –Pivot – forearm –Gliding - vertebrae
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Joints Cartilage covers ends of movable bones –Reduces friction Lubricated by fluid from capillaries
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Cartilage
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Bone Structure Periosteum – hard outer covering –Cells for growth and repair Compact bone – hard strong layer –Bone cells, blood vessels, protein with Ca and P Spongy bone – at ends of long bones –Has small open spaces to lighten weight Marrow cavity – hollow in middle of long bones
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Bone Marrow Red marrow – produces blood cells and clotting factors –Found in humerus, femur, sternum, ribs, vertebrae, pelvis –Produces RBC 2 million per second Yellow marrow – stores fat –Found in many bones
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Bone Structure
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Haversian System Structure of compact bone Rings of bone tissue with blood vessels and nerves in the center
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Haversian System
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Bone Development Initial skeleton of cartilage in infants Replaced with bone by osteoblasts More than 300 bones at birth – fuse to 206 Always growing and breaking down –Osteoblasts – form new bone cells –Osteoclasts – break bone cells down –Osteocytes – mature bone cells
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Broken Bones Fracture is a break of the bone Simple or Complex fracture Regrowth of bone: –Spongy bone forms in first few days –Blood vessels regrow and spongy bone hardens –Full healing takes 1-2 months
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Homeostatic Imbalances Rickets Disease of children due to a lack of vitamin D. Calcium is not deposited in bones. Bones become soft. Bowing of the bones, and other deformities occur.
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Homeostatic Imbalances Osteomalacia “Rickets” of adults. Due to a lack of vitamin D. Calcium is not deposited in the bones. Bones become brittle.
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Homeostatic Imbalances Osteoporosis Bone reabsorption is greater than bone deposition. Due to any of the following: Lack of estrogen in women. Lack of exercise to stress the bones. Inadequate intake of calcium and phosphorus. Abnormalities of vitamin D metabolism. Loss of muscle mass.
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Age Related Dysfunctions Arthritis: Osteoarthritis- 90% of pop. By age 40 chronic inflammation of articular cartilage can be normal age-dependent change can also be pathology due to ? Age-related changes decrease blood supply trauma
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Osteoarthritis
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Osteoporosis Decline in Bone Density Bone Resorption > Bone Deposition Increase Risk for Fracture compression fractures of vertebrae hip fractures Role of calcium, vitamin D, estrogen, exercise Calcitonin vs. Parathyroid Hormone
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Osteoporosis
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