Chapter 19 Musculoskeletal System 1 The musculoskeletal system the skeleton provides attraction sites for the muscles whose contraction make the bones move so that we can walk 2 Bones are classified by their shape long short flat or irregular a Functions of bones 1 13 20 1 15 20 i ii iii v i Support the bones of lower limbs support the entire body when we are standing Protection the bones of the skull protects the brain Anchorage 1 How muscles adhere to bone iv Mineral storage all bones have an extracellular substance that contains calcium phosphate 1 Calcium phosphorus etc Blood cell formation the flat bones of the skull ribs sternum etc produce blood cells b Types of bone Spongy Bone has an unorganized appearance that is light but very strong Internal layer 1 2 Honeycombed Trabeculae cross pieces a b Around trabeculae is red bone marrow a specialized tissue that produces all types of blood cells i Where blood cells are created ii Compact Bone highly organized and composed of tubular units called osteons 1 Outer layer 2 Solid smooth 3 Osteons circular ring like layers for blood vessels and nerves c Cells of bones i 5 cells found in bone 1 Osteoblasts invade the region of the bone and begin to lay down spongy bone a Matris synthesizing cell b Responsible for bone growth c Matrix collagen secreting d Can turn into osteocytes 2 Osteoclasts break down the spongy bone creating a cavity a Bone resorbing cell b Come from hematopoietic red blood stem cells that directly work with bone resorption i Bone resorption actively breaking down bone releasing calcium into blood removing dead osteocytes to replace with new matrix 3 Osteocytes a Mature bone cell b Monitors and maintains the mineralized bone matrix c Mature bone cells d Matrix forming e Can act as sensory bone cells during stress mechanical pressure placed on bones 4 Osteoprogenitor cells a Stem cells b Can either become osteoblasts or bone lining cells 5 Bone lining cells d Case study bone fracturing vs osteoporosis i Fractured bones 1 Blood clotting agents rush to the fracture site a Hematoma Fibrocartilage callus forms 2 3 Bony callus forms of spongy bone over fracture site 4 Bone remodeling allows healing of fracture e Case study number 2 ii iii iv i i i i When bone resorption breakdown occurs quicker than bone deposition in remodeling Bone matrix remains normal in structure but bone mass depletes 1 Treat with calcium and vitamin D supplements and hormone estrogen replacement therapy or weight bearing exercise Bones easily break fracture with little pressure Postmenopausal women or people that are inactive including men f In an adult bone is constantly being broken down and built up again called bone remodeling g Raises calcium levels in the blood h When osteoblasts take calcium from blood they can become trapped maturing to osteoclasts 3 The skeleton a Human body have over 200 bones 206 b Axial skeleton midline of the body c Appendicular skeleton consists of the limbs along with the girdles Appendages d Connections of the musculoskeletal system Joints when a bone connects with another bone covered by cartilage 1 Also called articulations 2 They join bones together a Cohesion hold skeleton together b Mobility allow skeleton to move 3 Three types of joints a Fibrous immovable i Fibrous connective tissue holds bones together 1 No joint cavities 2 Sutures of the skull b Cartilaginous connect by hyaline cartilage or fibrocartilage i Cartilage more flexible than bone because the matrix is gel like and contains many collagenous and elastic fibers 1 No blood vessels ii Slightly moveable 1 Fibrocartilage very strong because the matrix contains wide rows of thick collagen fibers and it is able to withstand both tension and pressure a Intervertebral discs composed of fibrocartilage that acts as a padding i Prevents vertebrae from grinding against one another and absorbs shock from movements 2 No joint cavities iii Hyaline cartilage firm and somewhat flexible with a uniform and glassy matrix that contains a lot of collagen fibers 1 Not moveable 2 Cartilage that is holding ribs to the sternum c Synovial i ii Joint cavity with synovial fluid prevents friction Highly moveable 1 Most flexible ii Ligaments bind bone to bone with its dense fibrous connective tissue 1 At a joint two bones may be connected by ligaments that hold the bones together iii Tendons connect muscle to bone at joints 1 Tend to stretch iv Ligaments and tendons are dense collagen connective tissues where as joints are usually made up of multiple things e Case study hasta la vista per arnold i Muscle hypertrophy how muscles grow during strength building 1 Muscle is essentially continuously damaged Fibers fuse to repair damage after exercise a b Rebuilt to grow longer Can be achieved by lifting heavier weights and repeating repititions of exercise movements Takes at least several weeks or months of consistent exercise of increasing weight lifted for muscles to visibly change Factors that lead to improved muscle repair and growth 1 Protein in diet testosterone etc 4 Muscle tissue a Tissue a group of similar cells and their intercellular substance specialized to perform a specific function ii iii iv i ii iii b Allows for movement i Make bones move c 3 types of muscle Cardiac Smooth 1 Heart 1 Attached to bone Skeletal muscle makes up the greatest percentage of muscle tissue in the body It is voluntary because it contraction can be consciously simulated and controlled by the nervous system 1 Walls or hollow organs blood vessels and glands 2 Skeletal muscles move the skeleton 3 Over 630 in the body a Origin immovable bone b Insertion moveable bone 4 Fascicles muscle fibers combined in bundles a Composed of individual muscle fibers i Myofibrils composed of myofilaments striped striations 1 2 Repeating dark and light bands along myofibrils 3 Dark A bands 4 Light I bands ii Myofilaments contain sarcomeres 1 Actin thin filament and myosin thick filament iii Sarcomeres are the smallest functional parts of skeletal muscle 1 Linear segment of functional muscle fibers that allow muscles to contract 2 The contractile unit of muscle fiber a Contains A band and part of I band at each end 3 The muscle cell 4 Extends from one Z disc to another Z disc 5 Muscle contraction a Moves bones b Generally shorten c Thick filament myosin i Head 1 Actin binding site 2 ATP binding site a An energetic compound that helps tissues organs actively perform functions i Glucose can be converted to make ATP in