Skeletal System Outline (Chapter 6) AP&P
- Components
- Cartilage
- Bone
- Joints
- Ligaments and Tendons
- Functions
- Support
- Movement
- Protection
- Mineral storage
- Blood cell synthesis - hematopoiesis
- Cartilage
- Hyaline cartilage – most abundant; spherical chondrocytes with thin collagen fibers
- Articular cartilage – covers ends of bones and moveable joints
- Costal cartilage – attach ribs to the sternum
- Respiratory cartilage – forms respiratory passages and larynx
- Nasal cartilage – forms external nose
- Elastic cartilage
- Forms external ear
- Forms epiglottis
- Fibrocartilage – withstands heavy pressure and tensile forces
- Intervertebral disks
- Knees and elbows
- Bone (Cell, tissue, organ)
- Skeleton – Greek for dried up body; composed of 206 bones
- Axial skeleton – 80 bones
- Appendicular skeleton – 126 bones
- Classification of bone
- Long bones
- Diaphysis – shaft
- Epiphysis – ends of bone; contain red marrow
- Medullary cavity – contains yellow marrow
- Epiphyseal plate – found between diaphysis and epiphysis; long bone growth
- Short bones – roughly cuboidal in shape
- Sesamoid bones – form within a tendon e.g. patella
- Flat bones – Thin, flattened, and slightly curved
a. Diploe – spongy bone found between compact bone layers
- Irregular bones – complicated shapes e.g. vertebrae, pelvis
- Bone cells
- Osteoclast – cells which dissolve bone (puts calcium into the blood for muscular contraction, nerve transmission, blood clotting, etc…)
- Osteoblast – cells which build bone by removing calcium and phosphates from the blood in the presence of the enzyme alkaline phosphatase secreted by osteoblasts
- Osteocyte–mature cells found within compact bone (living bone)
- Bone remodeling occurs under the periosteum (White, double layered membrane) which is held to bone by Sharpey’s fibers
- Osseous tissue
- Compact bone (Lamellar bone) – Dense and hard; found on the external surfaces of bones
- Osteon or Haversian System – structural unit of compact bone (cylindrical in shape) which bear weight
- Lamella – each ring of an osteon
- Haversian canal – contains blood vessels and nerve fibers which travel vertically in bone
- Volkmann’s canal – contain blood vessels and nerve fibers which travel horizontally in bone
- Lacuna – spaces found in compact bone occupied by osteocytes
- Canaliculi – lateral canals which connect lacunae which allow osteocytes to diffuse nutrients and wastes into or out of bone tissue through gap junctions
- Spongy bone - contain trabeculae (little beams) which align along lines of stress; and open spaces filled with red or yellow marrow
- Chemical composition
- Hydroxyapatites – mineral salts; mainly calcium phosphates
- Glycoproteins which make up collagen fibers
- Bone markings
- Sites of muscle and ligament attachment
- Tuberosity – large rounded projection
- Crest – narrow prominent ridge
- Trochanter – large, blunt, irregularly shaped process (Only found on the femur)
- Tubercle – small rounded projection or process
- Epicondyle – raised area above a condyle
- Spine – sharp, slender, often pointed projection
- Process – any bony prominence
- Projections that help form joints
- Head – bony expansion carried on a narrow neck
- Condyle – rounded articular projection
- Ramus – armlike bar of bone
- Depressions and openings allowing blood vessels and nerve fibers to pass
- Meatus – canal like passage way
- Sinus – Cavity within bone filled with air and lined with mucous membrane
- Fossa – shallow basinlike depression in bone
- Fissure – narrow, slitlike opening
- Foramen – round or oval opening through a bone
- Hormone Control of Bone Remodeling
- Osteoblast and osteoclast activity is regulated by two hormones; PTH and Calcitonin
- PTH (Parathyroid hormone) is released by parathyroid glands when serum calcium levels are low which increase osteoclast activity.
- Calcitonin is released by the thyroid gland when serum calcium levels are to high which stimulate osteoblast activity
- Homeostatic Imbalance
- Fracture – a break in the bone
- Comminuted – bone broken into 3 or more pieces
- Spiral – ragged break due to twisting forces
- Depressed – broken bone is pressed inward
- Compression – bone is crushed
- Epiphyseal – epiphysis separates from diaphysis
- Greenstick – incomplete break where only one side of bone is fractured; like when you break a branch from a live tree
- Open fracture – bone penetrates through the skin
- Closed fracture – bone does not penetrate skin
- Fracture treatment
- Closed reduction – When a physician pulls on bone to realign bone ends
- Open reduction – When a physician surgically inserts pins or wires to realign bones
- Fracture healing
- Hematoma formation
- Fibrocartilaginous callus formation
- Bony callus formation
- Bone remodeling