Skeletal System

Complete fracture = Bone broken all the way through Incomplete fracture = Not broken all the way through Simple (closed) fracture = A complete fracture that does not penetrate through the surface of skin Compound (open) fracture = A complete fracture that breaks through the surface of the skin

Fracture hematoma = Stage 1 of fracture repair, involves formation of blood clot Fibrocartilaginous callus = Stage 2 of fracture repair, involves formation of soft callus Bony callus = Stage 3 of fracture repair, involves conversion of soft callus to hard callus Bone remodeling = Stage 4 of fracture repair, involves reshaping of bone

Calcitonin = Decrease blood calcium levels by stimulating osteoblast activity and decreasing osteoclast activity Parathyroid Hormone (PTH) = Increase blood calcium levels by stimulating osteoclast activity, decreasing osteoblast activity, increasing calcium absorption from the gut, and causing kidneys to conserve calcium

Hypercalcemia = Blood calcium levels above 11mg/ 100ml blood Hypocalcemia = Blood calcium levels below 9mg/ 100ml blood

Comminuted fracture = A complete fracture with many fracture pieces Greenstick fracture = An incomplete fracture that starts out transverse

Calcitonin = Thyroid gland Parathyroid Hormone (PTH) = Parathyroid glands

Fracture hematoma = Step 1 Fibrocartilaginous callus = Step 2 Bony callus = Step 3 Bone remodeling = Step 4

Decrease blood calcium levels = Calcitonin Increase blood calcium levels = Parathyroid Hormone (PTH)

Stimulating osteoblast activity = Calcitonin Decreasing osteoclast activity = Calcitonin Stimulating osteoclast cell activity = Parathyroid Hormone (PTH) Decreasing osteoblast cell activity = Parathyroid Hormone (PTH)

Normal blood calcium levels = 9-11mg/ 100ml blood

Periosteum = Fibrous, vascular bone covering Medullary cavity = Cavity in diaphysis containing yellow bone marrow Endosteum = Fibrous lining of the medullary cavity Compact bone = The outer external bone tissue that resists compression and bending forces

Osteoprogenitor cells = Stem cells found in periosteum and endosteum that actively divide Osteoblasts = Bone forming cells that release matrix Osteocytes = Mature bone maintenance cells that maintain calcium homeostasis Osteoclasts = Giant multinucleated cells that reabsorb bone matrix

Intramembranous Ossification = Bone develops between membranes Endochondral Ossification = Bone develops within hyaline cartilage Flat bones = Examples of development through intramembranous ossification Hyaline cartilage model = Forms during endochondral ossification in the embryo

Osteoid = Organic portion of matrix, gel-like ground substance Mineral Salt (hydroxyapatites) = Inorganic portion of matrix, responsible for bone hardness Collagen fibers = Type I collagen fibers around which mineral salts are packed Lacunae = Spaces in bone matrix where osteocytes are located

Vitamin A = Needed for bone resorption Vitamin C = Needed for proper collagen synthesis and deposition Vitamin D = Needed for proper gut calcium absorption Physical/Mechanical Stress = Stimulates osteoblast activity

Spongy bone = Irregular bony plates found underneath the compact bone, reduces weight of skeleton Yellow bone marrow = Fat storage in adults Red bone marrow = Where hemopoiesis occurs, found in spongy bone Compact bone = Outer external bone tissue that resists compression and bending forces

Intramembranous Development = Sheet like masses of connective tissue form, osteoblasts form and lay down matrix, spongy bone is produced Endochondral Development = Formation of a hyaline cartilage model, development of periosteum and primary ossification center, appearance of medullary cavity and secondary ossification center

Osteoprogenitor cells = Stem cells that are very actively dividing Osteoblasts = Bone forming cells that are mitotically active Osteocytes = Mature bone maintenance cells involved in maintaining calcium homeostasis Osteoclasts = Giant cells that reabsorb bone matrix and have a ruffled border surface

Osteoid = Type I collagen fibers with gel-like ground substance Mineral Salt (hydroxyapatites) = Tightly packed needle-like calcium phosphate crystals responsible for bone hardness Collagen fibers = Provide flexibility and tensile strength to bone Lacunae = Spaces in bone matrix where osteocytes are located

Nutrition = Affects bone growth through vitamins and minerals Physical/Mechanical Stress = Stimulates osteoblast activity Hormones = Thyroid hormones, sex hormones, and growth hormone all play a role in bone growth Growth Hormone = Stimulates epiphyseal disk growth

Long bones = Greater length than width. Typically have a middle shaft region with two expanded ends. Most but not all bones of the limbs. Short bones = Somewhat cubed shape, nearly equal in length and width. Include wrist and ankle bones. Flat bones = Thin, flattened bones that are usually curved. Includes scapula, ribs, hip bones and most cranial bones. Irregular bones = Complex shapes that do not fit any of the above types. Include vertebrae, some facial bones.

Diaphysis = Shaft region of a bone. Epiphysis = Expanded end regions (plural: epiphyses). Articular cartilage = Layer of hyaline cartilage on the outside of the ends of the epiphyses. Acts to decrease friction and shock absorption. Sutural bones = Develop within joints of the cranium. Vary in number.

Axial skeleton = Bones in the long axis of the body. Includes bones of skull, vertebral column and bony thorax (rib cage). Appendicular skeleton = Bones of the upper and lower limbs as well as the bones that connect them to the axial skeleton (girdles). Sesamoid bones = A type of short bone that develop in tendons. Vary in number. Include patella and bones in tendons of hand and foot. Sutural bones = Develop within joints of the cranium. Vary in number.

Support = Arches of feet, vertebral column, pelvis. Protect = Softer tissues – skull, ribs, pelvis. Act as levers = For movement. Hemopoiesis = Production of blood cells.

Long bones = Humerus, femur. Short bones = Wrist and ankle bones. Flat bones = Scapula, ribs, hip bones and most cranial bones. Irregular bones = Vertebrae, some facial bones.

Diaphysis = The shaft region of a bone. Epiphysis = The expanded end regions (plural: epiphyses) of a bone. Articular cartilage = The layer of hyaline cartilage on the outside of the ends of the epiphyses. Acts to decrease friction and shock absorption. Sutural bones = Bones that develop within joints of the cranium. Vary in number.

Axial skeleton = Includes bones of skull, vertebral column and bony thorax (rib cage). Appendicular skeleton = Includes bones of the upper and lower limbs as well as the bones that connect them to the axial skeleton (girdles). Sesamoid bones = A type of short bone that develop in tendons. Vary in number. Include patella and bones in tendons of hand and foot. Sutural bones = Bones that develop within joints of the cranium. Vary in number.

Support = Involves the arches of feet, vertebral column, pelvis. Protection = Involves protecting softer tissues such as the skull, ribs, pelvis. Leverage = Bones act as levers for movement. Hemopoiesis = Process of blood cell production.

Long bones = Bones that have greater length than width. Typically have a middle shaft region with two expanded ends. Most but not all bones of the limbs. Short bones = Bones that have a somewhat cubed shape, nearly equal in length and width. Include wrist and ankle bones. Flat bones = Thin, flattened bones that are usually curve. Includes scapula, ribs, hip bones and most cranial bones. Irregular bones = Bones that have complex shapes that do not fit any of the above types. Include vertebrae, some facial bones.

Diaphysis = The shaft region of a bone. Epiphysis = The expanded end regions (plural: epiphyses) of a bone. Articular cartilage = A layer of hyaline cartilage on the outside of the ends of the epiphyses. Acts to decrease friction and shock absorption. Sutural bones = Bones that develop within joints of the cranium. Vary in number.