Compendium Review 6

Skeletal System

*Bones

development

growth

repair

remodeling

*Joints

skeletal movement

mobility

lubrication

*Muscle

structure

cell structure

contraction

muscular disorders

homeostasis

*Functions of Skeleton

-supports the body

-protects soft body parts

-produces blood cells

-stores minerals and fat

-allows flexible body movement

*Anatomy of a Long Bone

-the shaft is called a diaphysis

-medullary cavity is contained in the diaphysis whose walls are composed of compact bone

-epiphysis is the expanded region at the end of the bone

-epiphyses are coated with a thin layer of hyaline cartilage, which is called articular cartilage due to it occurs at a joint

-spongy bone has an unorgaized appearence

-red bond marrow fills the spaces of a spongy bone

*Cartilage

-is not as strong as bone

-more flexible

-chondrocytes cells lie within lacunae that are irregularly grouped

*types of cartilage

*Hyaline

-firm

-somewhat flexible

*Fibrocartilage

-stronger than Hyaline

-can withstand pressure and tension

*Elastic

-more flexible than hyaline

-found in ear flaps

*Bones

Bones growth, remodel, and repair need involvment of a couple different cells

*Osteoblasts

-bone firming cells

-secrete organic matrix

-promote deposition of calcuim salts into the matrix

*Osteocytes

-mature blood cells

-derived from osteoblasts

-maintainbone structure

*Osteoclasts

-bone-absorbing cells

-break done bone

-assist in depositing calcuim and phosphate in the blood

*Bone development and Growth

-ossification

-formation of bone

-intramembranous ossification

-bone develop between sheets of fibrous connective tissue

-endochondral ossification

-bone replaces the cartilaginous models of the bone

-hormones affect bone growth

*Bone remodeling

-normally keeps bones strong

-bones can respond to stress

*Bone Repair

-required after it breaks or fractures

*It takes 4 stages to heal a fracture:

-Hematoma, blood escapes from ruptured blood vessels and forms a hematoma in the space between the broken bones within 6-8 hours

-Fibrocartilaginous callus fills the space between the ends of the broken bone for about 3 weeks after tissue repair begins

-Bony callus. Osteoblasts produce trabeculae of spongy bone and convert the fibrocartilage callus to a bony callus that joins the broken bones together and lasts about 3-4 months

-Remodeling. Osteoblasts build new compact bone at the periphery, and ostoclasts absorb the spongy bone, creating a new medullary cavity

*Skull

-formed by the cranium

-fontanels usually close by 16 months old by intramembranous ossification

-sinuses are air spaces lined by mucous membrane

-mastoiditis is a condition that can lead to deafness, is an inflammation of these sinuses

-frontal bone forms the forhead

-parietal bones extend to the sides

-occipital bone curves to form the base of the skull

-foramen megnum through which the spinal cord passes and becomes the brain stem

-sphenoid bone is shaped like a bat with outstreched wings

-ethmoid bone lies in front of the sphenoid

*facial bones

-mandible is the lower jaw

-maxillae are the bones that form the upper jaw

-zygomatic bones are the cheekbone prominence

-nasal bones form the bridge of the nose

*Hyoid bone

-not part of skull

-part of the axail skeleton

-attached to the temporal bones by muscles and ligaments and to the larynx by a membrane

*Synovial Joints

-a joint having a cavity filled with synovial fluid, a lubricant for the joint. Ligaments connect bone to bone and support or strengthen a joint. Fluid-filled sacs called bursae ease friction between bare areas of bone and overlapping muscles, or between skin and tendons.

*Types of muscles

-smooth muscle fibers are spindle-shaped cells

-cardiac muscle forms the heart wall

-intercalated disks contain gap junstions that permit contractions to spread quickly throughtout the heart wall

-skeleton muscle fiberes are tubular, multinucleated, and striated.

*Functions of muscles

-supports the body

-make bones move

-help maintain a constant body temperature

-contraction assists movement in cardiovascular and lymphatic vessels

-help to protect internal organs and stabilize joints

*Muscle Fibers

-sarcolemma, the plasma membrane

-the cytoplasm is the sarcoplasm; and the endoplasmic reticulum is the sarcoplasmic reticulum

-T tubules penetrate into the cell so that theycomes into contact but not fuse

-myofibrils contractile portions of the mucsle fibers

*Myofilaments

-thick filaments are composed of several hundred molecules of the protein myosin

-thin filaments consists of 2 intertwinning strands of protein actin