Chapter 7

Hyaline

joints, respiratory cartilage

Most abundant skeletal cartilage

hyaline cartilage

Elastic

ear and epiglottis

Fibrocartilage is found in

menisci, pubic symphysis, intervertebral discs

What features make up all cartilages?

cells, matrix, and perichondrium

Cartilage cells

chondroblasts and chondrocytes

Chondroblasts

secrete cartilage matrix

Chondrocytes

maintain cartilage matrix

Cartilage matrix is made of

ground substance and fibers

Perichondrium

layer of DIRCT that surrounds cartilage; resists outward expansion

How does cartilage grow?

appositional and interstitial

Appositional

from outside; width

Interstitial

from within; length

Functions of bone

protection, storage, manufacture, movement, support

Bone protection

encases essential organs

Bone storage

fat in yellow marrow; calcium phosphates (minerals)

Bone manufacture

hematopoeisis (blood cell formation)

Bone movement

anchorage: attachments for muscles to pull on bones

Bone support

bears weight of bone framework

Spongy bone

open, made of trabeculae; privide strength w/o weight

Compact bone

dense bone tissue organize into osteons; provide strength, resist compression

Endosteum

covers canal, trabeculae

Medullary cavity

hollow space in long bone, with yellow marrow

Hematopoeitic tissue

red marrow: medullary cavity and trabeculae

Where is red marrow not replaced by yellow?

head of femur, humerus, pelvis

Nutrient artery

blood supply

Epiphyseal plate

thin layer of cartilage; growth plate

Epiphysis

end of long bone

Periosteum

2 layers: fibrous: DIRCT, protect & strengthen; osteogenic: makes new bone

Diaphysis

middle bone: compact bone, medullary cavity, yellow marrow

Articular cartilage

protect bones at joint

Osteoprogenitor (osteogenic) cells

stem cells divide, differ into osteoblasts; found in peri- and endosteum

Osteoblasts

secrete bone matrix (osteoid)

Osteocytes

mature cells in lacunae; maintain matrix

Osteoclasts

break down bone (resorption)

Bone lining cells

inactive, maintain matrix along edge

Inorganic components of bone

mineral salts: calcium phosphate crystals (hydroxiapatite)

Organic components of bone

osteogenic cells and matrix

Matrix of bone

ground substance, fibers: sacrificial bonds

Formation of flat bones

intramembranous ossification

Formation of long bones

Endochondral ossification

How to bones grow in childhood and adolescence?

interstitial and appositional growth

What hormones control bone growth?

growth, thyroid, and sex hormones

Growth hormone

effects epiphyseal growth plate

Thyroid

modulates GH

Sex hormones

adolescent growth spurt, m/f skeletal fts, close ep. plates

Resorption

osteoclasts attach to affected border, digest groove into bone

Deposition

osteoclasts lay down new bone

2 ways bone remodeling is controlled

hormonal, response to mech stress

Parathyroid hormone

increases calcium ion levels by stimulating osteoclasts

Calcitonin

released if too much Ca, promotes Ca storage

Displaced fracture

notable gap between fragments

Non-displaced fracture

broken ends align

Compound fracture

through the skin

Simple

not through skin

Comminuted fracture

multiple bone fragments

Spiral fracture

winds around bone; from twisting force

Depressed fracture

portion of bone is pushed inward

Compression fracture

bone is crushed; common in vertebrae

Epiphyseal fracture

occurs in ep. region

Greenstick fracture

incomplete: one side breaks the other bends; more common in kids

Broken bone treatment

reduction (return to anatomical position), immobilization

How fast does a bone heal?

6-12 weeks

Step 1 of bone healing

a hematoma forms

Step 2 of bone healing

fibrocartilaginous callus forms: macrophages start clean up, fibroblasts → collagen fibers, chondrocytes → cartilage matrix

Step 3 of bone healing

bony callus forms: osteoblasts make new bone

Step 4 of bone healing

bone remodeling occurs

Osteomalacia

soft bone: osteoid is produced, not calcified correctly

Rickets

osteomalacia in kids; ep. plates can’t calcify & keep growing

Osteoporosis

bone reabsorbed faster than deposited