(Lesson 4) Chapter 6-Skeletal System Flashcards
Describe the general and microscopic structures of bones. Classify bones according to shape and size. Identify two types of bone formation based on the original tissue. Understand the different types of fractures and describe the steps of healing fractures. Describe some disorders of the skeletal system and point out how some are preventable
Cartilage in the body
Ear, Nose, ribs, joints, larynx, air tubes, between vertebrae, pubic symphisis
Perichondrium
A layer of dense irregular connective tissue that surrounds cartilage.
Three types of cartilage
Hyaline, Elastic, and Fibrocartilage
Hyaline Cartilage
looks like frosted glass. Provides support, flexibility and resilience. Makes up the articular cartilage that covers the end of adjoining bones in movable joints. Also forms attachment from ribs to sternum, most cartilage in respiratory structures, and forms embryonic skeleton.
Elastic Cartilage
More elastic than hyaline cartilage. Can tolerate repeated bending. Epiglottis and outer ear are made of this cartilage.
Fibrocartilage
resists both strong compression and strong tension (pulling) forces. Portion of discs between vertebrae, articular discs of some joints like the menisci of the knee.
Composition of bone
Bone is 65% inorganic and 35% organic.
Compact bone: the external and especially hard part of bones
Compact Bone
External and especially hard part of bones
Spongy bone
less dense than compact bone. Usually found deep to compact bone. AKA Trabecular bone (trabeculae=little beams. Space between beams are filled with marrow.)
Bone marrow
2 types: yellow and red.
Support (bone function)
Hard framework supports the weight of the body. ie leg bones support trunk of the body.
Movement (bone function)
muscles attach to bones by tendons and use bones as levers to move body parts. Humans can walk, lift, etc
Protection
Some bones provide protective casing. ie skull, vertebrae, ribs
Mineral storage
Reservoir for minerals-most importantly calcium and phosphate. minerals are distributed through the blood stream as needed.
Blood cell formation and energy storage
Bones contain red and yellow bone marrow.
Red Bone marrow
makes blood cells
yellow bone marrow
stores fat-no role in blood-cell formation.
Long bones
longer than they are wide. Has shaft and two distinct ends. Limbs, fingers, toes. Size is unimportant
Short bones
roughly cube shaped. occur in write and ankle
Sesamoid bones
special type of short bone that forms within a tendon. Patella. Vary in size and number in different people. Reduce friction/alter direction of pull of tendon.
Flat bones
Thin, flattened, and usually somewhat curved. Most cranial bones, ribs, sternum, scapula.
Irregular bones
various shapes that dont fit in any categories. ie vertebrae and hip bones.
Diaphysis
Shaft of long bone.
Epiphses
bone ends.
Epiphyseal line
Remnant of the epiphyseal plate-a disc of hyaline cartilage that grows during childhood to lengthen the bone.
Osteon/Haversian System
A structural component of compact bone. Long cylindrical structures, parallel to the long axis of the bone. Weight bearing pillars.Contains a group of concentric tubes resembling the rings of a tree trunk.
Lamella
Tubes inside of tubes inside of osteon. Fibers of adjacent lamellae run in opposite directions-optimal for withstanding torsion, twisting, or stresses. Inhibit crack propagation-dispersing forces around lamellar boundaries to prevent crack progression and bone fracture.
Central/Haversian Canal
At the core of each osteon, lined with endosteum. Contains its own blood vessels which supply nutrients to bone cells.
Perforating/Volkmann’s Canal
Lie at right angles to central canals and connect blood/nerve supply to periosteum and marrow cavity.
Osteocytes
Mature bone cells. Spider-shaped. Bodies occupy lacunae and legs occupy canaliculi inside of osteon. Maintains the bone matrix
Lacunae
cavities in the solid bone matrix of osteon, lamellae.
Canaliculi
Run through bone matrix to connect with neighboring lacunae.
Osteoblasts
cells responsible for bone deposition and the precursor to osteocytes
Osteoclasts
cells responsible for bone resorption
- Bone collar formation
Stages of Endochondral Ossicfication
Bone begins as a cartilage model. At week 8 perichondrium surrounding diaphysis is invaded by blood vessels and becomes periosteum. Osteoblasts lay down collar of bone tissue around diaphysis.
- Cartilage Calcifies in the center of the diaphysis
Stages of Endochondral Ossicfication
central area of diaphysis calcifies and disintegrates leaving a cavity in the the diaphysis.
- Periostal bud invades the diaphysis and first bone trabeculae form
Stages of Endochondral Ossicfication
Bud invades diaphysis cavities and destroys remaining cartilage while secreting bone-forming osteoid. Earliest version of spongy bone is formed.
- Secondary ossification centers form in epiphyses
Stages of Endochondral Ossicfication
Cartilage calcifies, degenerates, and is filled with osteoids to begin forming bone.
Elongation of bone
Relies on cell division and growth at the epiphyseal plates of each long bone.
Appositional Growth
Causes bones to widen as the osteoblasts in the periosteum add bone tissue to the external face of the diaphysis.
Organization of Cartilage within epiphyseal plate from bottom to top
ossification, calcification(dead cartilage cells), hypertrophic(old cells enlarge), proliferation, cells undergo mitosis
Intramembranous Ossification
the way flat bones originate in the embryo.
- ossification center appears in fibrous connective tissue
- fibrous membrane ossifies
- periosteum and woven bone formation
- compact bone plate formation
Comminuted
Types of fractures
Bone fragments into three or more pieces. Common in the aged, whose bones are more brittle.
Compression
Types of fractures
Bone is crushed. Common in porous bones-often times after a fall.
Spiral
Types of fractures
Ragged break occurs when excessive twisting forces are applied to a bone. Common in sports fractures.
Epiphyseal
Types of fractures
Epiphysis separates from diphysis along the epiphyseal plate. Tends to occur where cartilage cells are dying and calcification of matrix is occurring.
Depressed
Types of fractures
Broken bone portion is pressed inward. Type of skull fracture.
Greenstick
Types of fractures
Bone breaks incompletely, like a twig. one side of shaft breaks and the other bends. Common in children whose bones are more flexible.
- Hematoma Formation
Stages in healing bone fracture
Fracture is accompanied by hemorrhaging. Blood vessels break, releasing a clot to form hematoma around the break.
- Fibrocartilaginous callus formation
Stages in healing bone fracture
Within a few days new blood vessels form in clot. Bone forming cells invade clot and begin forming soft callus.
- Bony callus formation
Stages in healing bone fracture
Within a week trabeculae of new bone begin to form in bone-spanning width of the callus and growing thicker and stronger-becoming firm about two months after injury.
- Bone Remodeling
Stages in healing bone fracture
Over a period of months the bony callus is remodeled. Excess material is removed, compact bone is laid down to strengthen shaft walls.
Rickets (osteomalacia in a adults)
Soft and weak bones (that dont calcify) in children. Pain is felt when weight is put on bone. Malformations of child’s head and rib cage are common. Leads to bowed legs. Caused by inadequate amount of vitamin D/calcium phosphate. Exposure to sunlight and drinking vitamin D milk can cure it.
Osteoporosis
excessive bone reabsorption
aged and postmenopausal women (there is a relationship between osteoporosis and low estrogen levels). Treated by calcium, vitamin D, increased exercise, and estrogen replacement.
