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The Musculo skeletal System Support, Protection, Movement and Locomotion. Skeletal Functions. Framework for support Transmits movement Maintains shape Protects internal organs from mechanical injury Contains and protects the red bone marrow, one of the hemopoietic (blood-forming) tissues
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The Musculoskeletal SystemSupport, Protection, Movement and Locomotion
Skeletal Functions • Framework for support • Transmits movement • Maintains shape • Protects internal organs from mechanical injury • Contains and protects the red bone marrow, one of the hemopoietic (blood-forming) tissues • Mineral reservoir - storage site for excess calcium and phosphorus • Storage of fats – yellow marrow
Cytoskeleton • Maintains cell shape • Microfilaments • Intermediate filaments • Microtubules • Protection • Enables motion • Cilia • Pseudopodia • Flagella • Intracellular transport • Cell division
Structural support in plants • Cell walls • Collenchyma and sclerenchyma tissue • Cellulose and lignin
Hydrostatic skeleton • Fluid-filled closed chambers • Internal pressure generated by muscle contraction • e.g. sea anemone and worms
Exoskeleton • Shelled molluscs (CaCO3) • Arthropods (chitin) • Hard segments covering muscles and visceral organs • Muscles are attached to the exoskeleton • Restricts growth and size of insect molting
Endoskeleton • Endoskeleton • Internal, often mineralized, connective tissue • Muscles on the outside • Cartilage – elasmobranchs • Other vertebrates – cartilage replaced by bone as embryo matures and develops
Appendicular and axial skeleton • Axial skeleton (80 bones) • axis of the body • support and protection of main organs • Skull • Sternum • Ribs • Vertebral Column + sacrum and coccyx • Appendicular skeleton (126 bones) • anchors appendages to the axial skeleton • Upper Extremities • Lower Extremities • Pectoral Girdle • Pelvic Girdle
Types of bones • Long bones • Long shaft (diaphysis) • Two joint surfaces (epiphyses) • Mostly compact bone • e.g. femur, tibia, fibula, radius, ulna • Short bones • Cube-shaped, mostly spongy bone • e.g. bones of wrist and ankle, patella • Flat bones • Thin and curved • e.g. skull and sternum • Irregular bones • Irregular and complicated shapes • e.g. spine and hips
Joints or articulations • Meeting of two bones • Types of joints • Immovable • Slightly movable • Freely movable
Bone Tissue • Compact bone • series of Haversian canals • concentric layers of bone cells (osteocytes) • new bone formed by osteocytes • Spongy bone • ends of long bones • less dense • contains red or yellow marrow • Periosteum • outer layer of bone • rich in nerve endings, blood, and lymphatic vessels • inner portion forms new bone or remodels existing bone
Types of bone cells • Osteoblasts • immature bone cells • manufacture hormones and enzymes that aid in bone mineralization • Osteocytes • mature osteoblasts in lacunae (spaces) • form bone, maintain matrix • act for calcium homeostasis • Osteoclasts • responsible for bone reabsorption and shaping • located on bone surfaces
Intramembranous ossification formation of the flat bones of the skull Endochondral ossification formation of long bones Bone formation
Bone remodeling • Resorption of bone (by osteoclasts) followed by replacement of bones (by osteocytes) • Functions to regulate calcium levels, repair damaged bones, and shape and sculpt the skeleton during growth • Rate is regulated by parathyroid hormones (PTH) and Vitamin D
Disorders of the skeletal system • Osteoporosis • Reduced bone density leading to fractures • Rickets and osteomalacia • Softening of bones leading to deformations and fractures • Arthritis • Inflammation of joints • Bone fractures • Scoliosis, kyphosis