chp 6: skeletal system

lacunae

cavities in extracellular matrix within cartilages that enclose chondrocytes

hyaline cartilage

most abundant cartilage that provides support and only has fine collagen fibers

articular cartilage

type of hyaline cartilage that covers ends of most bones at movable joints

costal cartilage

type of hyaline cartilage that connects the ribs to sternum

respiratory cartilage

type of hyaline cartilage that forms the skeleton of the larynx

nasal cartilage

type of hyaline cartilage that forms the nose tip

elastic cartilage

made of more stretchy elastic fibers found in external ear and epiglottis

fibrocartilage

parallel rows of chondrocytes alternating with thick collagen fibers found in menisci and vertebral discs

perichondrium

layer of dense irregular connective tissue around cartilage

function of perichondrium

resists outward expansion when cartilage compressed and nourishes cartilage cells

appositional growth

cartilage forming cells secrete new matrix against existing cartilage tissue

interstitial growth

lacunae-bound chondrocytes divide and secrete new matrix within cartilage

differences between cartilage and bone

cartilage is avascular, flexible, and can grow interstitially

similarities between cartilage and bone

surrounded by perichondrium/periosteum, chondrocytes/osteocytes in lacunae, made by chondroblasts/osteoblasts

what is the general structure of bones?

outer compact bone layer, inner spongy bone layer, mesh needle like pieces of bone called trabeculae, and spaces filled with bone marrow

diaphysis

shaft of long bone that has a collar of compact bone that surrounds central medullary cavity and thin spongy bone layer

epiphyses

bone ends that have outer shell of compact bone and interior spongy bone

periosteum

double layered membrane that covers external surface of bones

endosteum

covers internal bone surfaces and trabeculae

hematopoietic tissue

red bone marrow found only in flat bones of skull, sternum, ribs, and heads of femur and humerus

types of bone markings

projections, surfaces that form joints, depressions and openings for vascularization

osteogenic cells

mitotically active stem cells in periosteum and endosteum that differentiate to osteoblasts when stimulated

osteoblasts

bone forming cells that secrete bone matrix

osteocytes

mature bone cells that occupy lacunae

bone lining cells

flat cells on bone surfaces where remodeling is not occurring

osteoclasts

multinucleate cells at sites of resorption that have a ruffled border

osteon

structural unit of compact bone that is made of groups of hollow tubes of bone matrix

lamella

each tube of an osteon

central/Harvesian canal

runs through the core of each osteon and contains blood vessels and nerve fibers

canaliculi

super thin canals that radiate from lacunae and connect them to each other and to the central canal

how do nutrients reach osteocytes of spongy bone?

through canaliculi from capillaries in the endosteum

what is the chemical composition of bone?

soft organic substances resist tension and hard inorganic substances (mineral salts) resist compression

endochondral ossification

bone develops by replacing hyaline cartilage

where is bone usually deposited and removed?

bone is usually deposited and removed at the endosteal surface

how are fractures classified?

position of bone ends, completeness, and whether bone ends penetrate skin

the four fontanelles

squamos, mastoid, anterior, posterior

transverse fracture

fracture along long axis of bone

comminuted fracture

several breaks resulting in many small pieces between two segments

greenstick fracture

partial fracture in which one side of bone is broken

diploe

layer of spongy bone between layers of compact bone found in flat bones