Ch. 6 - Bones and Skeletal Tissue

Card Set Information

Author:
KellyM
ID:
201335
Filename:
Ch. 6 - Bones and Skeletal Tissue
Updated:
2013-02-18 22:10:13
Tags:
info
Folders:

Description:
info in chapter and slides
Show Answers:

Home > Flashcards > Print Preview

The flashcards below were created by user KellyM on FreezingBlue Flashcards. What would you like to do?


  1. skeletal cartilage
    • -contains no blood vessels or nerves
    • -surrounded by perichondrium (dense irregular connective tissue)
    • -made of some variety of cartilage tissue molded to fit its body location and function

    *all cartilage contains chondrocytes in lacunae and extracellular matrix*
  2. 3 types of skeletal cartilage
    • 1) hyaline = most abundant; provides support, flexibility, and support
    • -- articular cartilage -- cover end of bones at movable joints
    • -- costal cartilage -- connect ribs to sternum
    • -- respiratory cartilage
    • -- nasal cartilage

    • 2) Elastic cartilage = resembles hyaline but contain more stretchy fibers
    • -- external ear and epiglottis

    • 3) Fibrocartilage = thick collagen fibers; great tensile strength
    • -- menisci of knee; vertebral discs
  3. classification of bones: 2 groups
    • axial skeleton
    • - long axis of body
    • - skull, vertebral column, rib cage

    • appendicular skeleton
    • - bones of upper and lower limbs
    • - girdles attaching limbs to axial skeleton
  4. classification of bones by shape
    • long bones
    • short bones
    • flat bones
    • irregular bones
  5. 7 important bone functions
    • 1) Support - for body and soft organs
    • 2) protection - brain, spinal cord, vital organs
    • 3) movement - levers for muscle action
    • 4) mineral storage - calcium and phosphorus
    • 5) blood cell formation (hematopoiesis) - in red marrow cavities of certain bones
    • 6) triglyceride (fat) storage
    • 7) hormone production
  6. 3 levels of bone structure
    • -gross anatomy
    • -microscopic
    • -chemical

    *because they contain different types of tissue, bones are organs*
  7. bone structure -- gross anatomy
    bone textures are divided into compact and spongy bone

    • -- compact = dense outer layer of bone; smooth and solid
    • -- spongy (trabecular) = main portion of bone; inside; honeycomb network of bone that surrounds the marrow space
  8. structure of short, irregular, and flat bones
    • thin plates of spongy bone covered by compact bone
    • plates sandwiched b/w compact bone
    • not cylindrical - no shaft or epiphyses (end of long bone)
    • bone marrow throughout spongy bone
    • *no marrow cavity*
    • hyaline cartilage covers articular surfaces
  9. structure of typical long bone
    • diaphysis
    • -- tubular shaft forms long axis
    • -- compact bone surrounds medullary cavity

    • epiphysis
    • -- bone ends (head of bone)
    • -- external compact bone; internal spongy bone
    • -- articular cartilage covers articular surface
    • -- b/w is epiphyseal line (growth line)
  10. membranes: periosteum -- bone surface layer
    • white, double-layered membrane
    • covers external surfaces except joints
    • outer fibrous layer is dense irregular connective tissue
    • inner osteogenic layer covering bone (contains primitive stem cells --> osteogenic cells)
    • contains many nerve fibers and blood vessels
    • anchoring points for tendons and ligaments
  11. membranes: endosteum -- lines medullary cavity
    • "within the bone"
    • delicate connective tissue membrane covering internal bone surface
    • contains osteogenic cells (stem cells) that can differentiate into other bone cells
  12. Hematopoietic tissue in bone

    Red marrow
    • found within trabelcular cavities of spongy bone of long bone, and in diploe of flat bones
    • adult long bones have little red marrow located only in the heads of femur and humerus
    • red marrow in diploe is much more active in hematopoiesis
    • yellow marrow can convert to red if necessary
  13. bone markings
    projections, depressions, openings

    • -sites of muscle, ligament, and tendon attachment on external surface
    • -joint surfaces
    • -conduits (holes) for blood vessels and nerves
  14. osteocytes
    • mature bone cells in lacunae (spaces)
    • monitor and maintain bone matrix
    • act as stress or strain sensors and induce osteoblasts (bone builders) and osteoclasts (bone destroyers) to remodel bone
    • spidery in shape
  15. osteoblasts
    • bone-forming cells
    • secrete unmineralized bone matrix called osteoid (mostly collagen)actively mitotic
    • ** matrix-synthesizing cell responsible for bone growth**
  16. osteogenic cells
    • mitotically active stem cells in periosteum and endosteum
    • differentiate into osteoblasts or bone lining cells
    • flattened or squamous cells in growing bones
    • ** stem cell **
  17. Microscopic anatomy of bone:

    cells of bone tissue ---> 5 major cell types
    • 1) osteogenic cells
    • 2) osteoblasts
    • 3) osteoclasts
    • 4) osteocytes
    • 5) bone lining cells

    *all, except for osteoclasts originate from mesenchymal cells*
  18. osteoclasts
    • giant, multinucleate cells for bone resorption
    • break down bone -- bone destroyers*
  19. bone lining cells
    • flat cells on bone surfaces believed to help maintain matrix
    • on external bone surface called periosteal cells
    • lining internal surfaces called endosteal cells
  20. microscopic anatomy in bone:

    compact bone
    • also called lamellar bone
    • osteon (Haversian system)
    • -- structural unit of compact bone (base unit)
    • -- elongated cylinder parallel to long axis of bone
    • -- hollow tubes of bone matrix called lamellae

    • canals and canaliculi
    • -- central (haversian) canal runs through core of osteon
    • -- perforating (Volkmann's) canals lie at right angles to long axis of bone
    • -- contains blood vessels and nerve fibers
    • -- spider shaped osteocytes occupy lacunae at junctions of lamellae
    • -- canaliculi = hairlike canals that connect lacunae to each other and central canal
  21. microscopic anatomy of bone:

    spongy bone
    appears poorly organized

    • trabeculae
    • -- align along lines of stress to help resist stress
    • -- no osteons
    • -- contain irregularly arranged lamellae and osteocytes interconnected by canaliculi
    • -- capillaries in endosteum supply nutrients
  22. bone
    • half as strong as steel in resisting compression
    • as strong as steel in resisting tension
    • last long after death due to mineral composition (high content of calcium phosphate)
  23. bone development:

    ossification (osteogenesis)
    • process of bone tissue formation
    • formation of bony skeleton -- begins in 2nd month of fetal development
    • postnatal bone growth -- lasts until early adulthood
    • bone remodeling and repair -- lifelong, always
  24. 2 types of ossification
    • 1) endochondral ossification
    • - bone forms by replacing hyaline cartilage
    • - bones called cartilage bones
    • - forms most of skeleton, except for clavicles
    • - begins in late 2nd month fetal development
    • - requires breakdown of hyaline cartilage prior to ossification

    • 2) intramembranous ossification
    • - bone develops from fibrous membrane
    • - bones called membrane bones
    • - forms flat bones... ex: clavicles, cranial bones
  25. endochondral ossification --- summary
    Begins at primary ossification center in center of shaft:

    • 1) bone collar forms around diaphysis of cartilage model
    • 2) central cartilage in diaphysis calcifies, then develops cavities
    • 3) periosteal bud invades cavities --> formation of spongy bone
    • 4) diaphysis elongates and medullary cavity forms
    • 5) epiphysis ossify
  26. Postnatal bone growth
    • 1) interstitial (longitudinal) growth
    • -- increase in length of long bones

    • 2) appositional growth
    • -- increase in bone thickness
  27. Interstitial growth: growth in length of long bones
    • requires presence of epiphyseal cartilage
    • epiphyseal plate maintains constant thickness --- rate of cartilage growth on one side balanced by bone replacement on other
    • result in 5 zones within cartilage: resting, proliferation, hypertrophic, calcification, ossification
    • near the end of adolescence chondroblasts divide less often
    • epiphyseal plate thins then is replaced by bone
  28. Interstitial growth: growth in length of long bones

    5 zones within cartilage
    • 1) Resting (quiescent) zone
    • -- cartilage on epiphyseal side of epiphyseal plate
    • -- relatively inactive
    • -- most superficial layer

    • 2) Proliferation (growth) zone
    • -- cartilage of diaphysis side of epiphyseal plate
    • -- rapidly divide pushing epiphysis away from diaphysis ---> lengthening

    • 3) Hypertrophic zone
    • -- older chondrocytes closer to diaphysis and their lacunae enlarge and erode --> interconnecting spaces

    • 4) Calcification zone
    • -- surrounding cartilage matrix calcifies, chondrocytes die and deteriorate

    • 5) Ossification zone
    • -- chondrocyte deterioration leaves long spicules of calcified cartilage which are eroded by osteoclasts
    • -- covered with new bone by osteoblasts
    • -- ultimately replaced with spongy bone
  29. epiphyseal plate closure
    • bone lengthening ceases --> requires presence of cartilage
    • bone of epiphysis and diaphysis fuses
    • females -- about 18 years
    • males -- about 21 years
    • * can thicken, but cannot get longer **
  30. Appositional growth: growth in width
    • allows lengthening bone to widen
    • occurs throughout life
    • osteoblasts beneath periosteum secrete bone matrix on external bone
    • osteoclasts remove bone on endosteal surface
    • *** usually more building up than breaking down ---> thicker, stronger bone but not too heavy
  31. Hormonal Regulation of bone growth

    3 major groups
    • 1) Growth hormone
    • most important in stimulating epiphyseal plate activity in infancy and childhood
    • 2) Thyroid hormone
    • modulates activity of growth hormone
    • ensures proper proportions
    • 3) Sex hormone (testosterone and estrogens)
    • promote adolescent growth spurts
    • end growth by inducing epiphyseal plate closure

    ** excesses or deficits of any cause abnormal skeletal growth **
  32. bone homeostasis: bone remodeling
    • consists of both bone deposit and bone resorption
    • occurs at surfaces of both periosteum and endosteum
    • remodeling units: adjacent osteoblasts and osteoclasts
    • recycle 5-7% bone mass each week
    • - spongy bone replaced ~ 3-4yrs
    • - compact bone replaced ~ 10yrs
  33. bone resorption is the function of _____ ?
    osteoclasts

    • they dig depressions or grooves as they break down matrix
    • secrete lysosomal enzymes that digest matrix and protons (H+)
    • acidity converts calcium salts to soluble form

    osteoclasts also phagocytize (eat garbage) then once resoprtion is complete, they undergo apoptosis (eat garbage then die)

    *** Osteoclast activation involves PTH ***
  34. importance of calcium

    functions in ?
    • nerve impulse transmission
    • muscle contraction
    • blood coagulation secretion by glands and nerve cells
    • cell division

    • 1200-1400 g of calcium in body
    • 99% as bone minerals
    • amount in blood tightly regulated
    • intestinal absorption requires Vit D metabolites
    • dietary intake required
  35. Parathyroid hormone (PTH)
    • prduced by parathyroid glands
    • removes calcium from bone regardless of bone integrity
  36. why is calcium homeostasis important?
    minute changes in blood calcium is dangerous and can result in:

    • severe neuromuscular problems
    • -- hyperexcitability (levels too low)
    • -- nonresponsiveness (levels too high)

    • hypercalcemia (too much calcium)
    • -- sustained high blood calcium levels
    • -- deposits of calcium salts in blood vessels, kidneys can interfere w/function
  37. other hormones affecting bone density
    • leptin: hormone released by adipose tissue
    • serotonin: neurotransmitter regulating mood and sleep; most made in gut
  38. Three "either/or" fracture classifications
    • 1) position of bone ends after fracture
    • - nondisplaced = ends retain normal position
    • - displaced = ends out of normal alignment

    • 2) completeness of break
    • - complete = broken all the way through
    • - incomplete = not broken all way through

    • 3) whether skin is penetrated
    • - open (compound) = skin is penetrated
    • - closed (simple) = skin not penetrated
  39. 4 stages of bone repair
    • 1) Hematoma forms
    • - torn blood vessels hemorrhage; clot forms; site swollen, painful, and inflamed
    • 2) Fibrocartilaginous callus forms
    • - capillaries grow into hematoma; fibroblasts secrete collagen fibers to span break and connect broken ends; fibroblasts, cartilage, and osteogenic cells begin bone reconstruction; mass repair tissue called fibrocartilaginous callus
    • 3) Bony callus forms
    • - w/in 1 week new trabeculae appear in fibrocartilaginous callus; callus is converted to bony callus of spongy bone; ~2 month later firm union forms
    • 4) Bone remodeling occurs
    • - begins during bony callus formation; continues for several months; excess material on diaphysis exterior and w/in medullary cavity removed; compact bone laid down to reconstruct shaft walls; final structure resembles original bcuz responds the same to mechanical stressors
  40. 3 homeostatic imbalances of bone
    • osteomalacia
    • - bones poorly mineralized; calcium salts not adequate; soft, weak bones; pain upon bearing weight

    • rickets (osteomalacia of children)
    • - bowed legs and other bone deformities; bones ends enlarged and abnormally long
    • - cause = Vit D deficiency or insufficient dietary calcium

    • osteoporosis
    • - group of diseases; bone resorption outpaces deposits; spongy bone of spine and neck of femur most susceptible


    -
  41. risk factors for osteoporosis
    • petite body form
    • insufficient exercise to stress bones
    • diet poor in calcium and protein
    • smoking
    • hormone-related condition
    • immobility
    • males w/prostate cancer taking androgen suppressing drugs
    • postmenopausal women (30% 60-70yrs; 70% by age 80)

What would you like to do?

Home > Flashcards > Print Preview