Chapter 5-Skeletal System Flashcards Preview

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Flashcards in Chapter 5-Skeletal System Deck (73)
1

2 types of bone tissue

-compact(dense smooth bone)
-spongy(bone with open spaces within)

2

Components of Skeletal system

-cartilage
-bone
-tendons
-ligaments

3

functions of skeletal system

-protection
-support (rigid structure)
-movement (bones as levers)
-storage (ca, P, fat)
-blood cell protection

4

cartilage consists of

-cells
extracellular matrix

5

cells in cartilage

chondrocytes found in compartments called lacunae

6

extracellular matrix

-collagen/elastic fibers
-ground substance of chondrotin sulfates

7

types of cartilage

hyaline
elastic
fibrocartilage

8

why does cartilage heal slowly?

no arteries, veins or lymphocytes

9

hyaline cartilage

-most common
-made up of chondrocytes, chondrotin sulfate, some collagen

10

location of hyaline cartilage

embryonic skeleton, articular surfaces, respiratory passages, nasal septum, between ribs and sternum

11

elastic cartilage

-flexible
-structure: chondrocytes, chondrotin sulfate, densely packed elastic fibers
-location: auricle, tip and lateral walls of nose, epiglottis

12

fibrocartilage

-very strong
-structure: chondrocytes, chondrotin sulfate, densely packed collagen fibers
-location: intervertebral disc, public symphysis, articular cartilage in knee

13

perichondrium

-fibrous connective tissue
-surrounds cartilage
-provides support and protection; new chondrocytes

14

perichondrium location

hyaline cartilage and elastic cartilage

15

absent form perichondrium

articular surfaces and fibrocartilage

16

layers of perichondrium

-outer: binds cartilage to adjacent tissues; provides support and protection
-inner: for growth and maintenance

17

apposition growth

-starts in perichondrium
-mesenchymal cells at periphery form in inner layer of perichondrium
-mesenchyme move towards matrix to become chondrogenic cells

18

how are chondrocytes formed from apposition growth

-chondrogenic cells aggregate and become chondroblasts
-chondroblasts secrete matrix-force cells apart
-chondroblasts become enclosed in matrix and become chondrocytes

19

interstitial growth

-chondrocytes enclosed in matrix and divide
-as the move apart, matrix forms between them
-growth of cartilage from within

20

osseous tissue

-supportive CT
-contains specialized cells
-solid extracellular matrix
---osteoid (organic portion, protein fibers)
---ground substance (Ca salts)
---water

21

osteoprogenitor

-bone cell
-mesenchymal cells
-predecessor to osteroblasts
-play role in initial growth and fracture repair

22

osteoblasts

-derived from osteogenic cells
-secrete osteoid
-common in growing bone
-predecessor to osteocytes
-more osteoblasts=stronger bone

23

osteocytes

-mature cells
-exist within bone matrix
-maintain Ca and PO4 homeostasis
-found in spaces called lacunae

24

osteoclasts

-involved in osteolysis (bone break down)
-increase osteoclast activity=weaker bone
-very large
-formed from fusion of many white blood stem cells

25

bone matrix is composed of...

Inorganic material
-65%
-brittle salts
--mostly hydroxyapatite
Osteoid
-orgaic
-35%
-flexible fibers (collagen, glycoproteins, proteoglycans

26

2 types of bone

compact bone
-arranged in osteons
spongy bone
-arranged in trabeculae

27

compact bone osteocytes communicate how?

osteocytes
-osteocytes communicate through canaliculi that radiate outward and connect one cell to the next cell

28

osteons

a unit of compact bone
-concentric lamellae of matrix surrounding acentral canal
-contains blood vessels and nerves

29

how are osteons connected to each other

perforating canals

30

3 types of lamellae

-concentric
interstitial
circumferential

31

concentric lamellae

-layers of bone surrounding the central canal
-make up osteons

32

interstitial lamellae

-found between osteons
-represents older osteons partially removed during tissue remodeling

33

circumferential lamellae

surround the compact bone
-directly produced from periosteum

34

spongy bone contains

trabeculae
-osteocytes in lacunae
-canaliculi
-matrix

35

spongy bone does not contain

-osteons
-central canal

36

trabeculae

-latticework of thin plates of bone oriented along lines of stress
-spaces are filled with red marrow where blood cells develop
-found in ends of long bones and inside flat bones
-lightens the bones, allows for movement

37

periosteum

-encloses bone
-absent at site of attachment of muscles, tendons and ligaments; surfaces covered by articular cartilage

38

layers of periosteum

outer fibrous: gives rise to collage
Inner: for growth or new cells and maintenance

39

endosteum

-1 cell layer
-covers surfaces of spongy bone and medullary cavity

40

cell types of endosteum

osteogenic
osteoblasts
osteoclasts

41

anatomy of a long bone

diaphysis: shaft
epiphysis: one end of long bone
metaphysis: growth plate region
articular cartilage: over joint surface; acts as friction and shock absorber
medullary cavity: marrow cavity

42

2 types of bone marrow

-yellow marrow
-red marrow

43

yellow marrow

-areolar and adipose CT
-in medullary cavity of long bones
-energy storage
-absent in infants

44

red marrow

-areolar and myeloid (precursor to red blood cells) tissue
-produces all types of blood cells

45

location of red marrow

-medullary cavities of infants
-spongy bones in adults

46

blood and nerve supply of bone

-periosteal arteries: supply periosteum
-nutrient arteries
--enter through nutrient foramen, supplies compact bone of diaphysis and yellow marrow
-metaphyseal and epipheyseal arteris
--supply red marrow ad bone tissue of epiphysis and metaphyses

47

how does bone growth occur

ossification (replacing CT with bone)

48

2 types of ossification

intramembranous
-mesenchymal cells->spongy bone
endochondral
-hyaline cartilage->spongy bone

49

intramembranous ossification begins when and forms what

about 8 week in embryo
-mainly finished by week 15
Forms:
-cranial flat bones
-facial bones
-dentary bones
-clavicle
-sesmoid bones

50

primary ossification center

-intramembranous oss.
-location where bone growth begins

51

where does bone growth begin plus beginning steps

primary ossification center
-mesenchymal cells arrange around BVs
-bone morphogenic proteins release
-mesenchymal cells divide and become osteoblasts

52

what do osteoblasts do after formation

-secrete osteoid
-become isolated->osteocytes
-produce spicules of bone that interconnect

53

how does spongy bone form during intramembranous ossification

-mesenchymal cells at surface form inner layer of periosteum
-calcified matrix is degraded by osteoclasts to form spongy bone
-end up with spongy bone covered in thin layer of compact bone

54

when does endochondral ossification begin and what forms

-bone relaces cartilage model
-begins at week 7 of embryo
-continues to adulthood
Forms:
-long bones
-most short bones
-non-cranial irregular and flat bones
-middle ear ossicles

55

step 1 of endochondral ossification

-hyaline cartilage forms model of future bone
-cartilage enlarges; chondrocytes near center hypertrophy
--matrix reduced to struts
--chondrocytes deprived of nutrients and die

56

step 2 of E.O.

BV's grow around and penetrate cartilage
-cells differentiate into osteoblasts
-compact bone forms around diaphysis

57

step 3 of E.O.

-spongy bone forms in center of model
--primary ossification center (creates diaphysis)
-nutrient artery in spongy bone forms and penetrates

58

step 4 of E.O.

remodeling of the shaft
-formation of the medullary cavity
-length increases

59

step 5 of E.O

-BV's penetrate ends of model
-secondary ossification centers form at both epiphyses (created here)

60

step 6 of E.O.

-ends with incomplete ossification of epiphysis
-some cartilage remains
--articular cartilage
--epiphyseal plate (growth plate)

61

bone growth: elongation

-occurs at epiphyseal plate
growth in length continues until 2 ossification centers meet
-relative thickness of epiphyseal plat does not change until growth almost complete; then:
--cartilage depleted and epiphyseal plate narrows to epiphyseal line

62

bone growth: appositional

-compact bone deposited beneath periosteum
-bone thickens
-bone remodeling occurs throughout life
--due to osteoclasts and osteoblasts

63

bone remodeling

-ongoing since osteoclasts carve out small tunnels and osteoblasts rebuild osteons
-continual redistribution of bone matrix along lines of mechanical stress
-4% of compact bone, 20% of spongy bone remodeled per year
-distal femur fully remodeled every 4 months

64

fractures: break in a bone (types)

closed (simple): break that does not penetrate skin
open (compound): broken bone penetrates through skin

65

bone repair

-fractures treated by reduction and immobilization

66

stages of bone repair

-fracture hematoma
-fibrocartilage callus
-bony callus
-remodel tissue

67

fracture hematoma formation

-facture hematoma forms within hours of injury
-mass of blood
-swelling and inflammation occur in response to dead bone cells
-phagocytes and osteoclasts eliminate dead cells/broken matrix

68

fibrocartilaginous callus formation

-consists of mass bridging broken ends of bone
-fibroblasts in periosteum produce collagen
-periosteum cells differentiate into chondrocytes
-results in fibrocartilage
-about 3 weeks

69

bony callus formation

-endochondral ossification
-formation of bony callus occurs as fibrocartilaginous callus is converted to spongy bone trabeculae
-bony callus lasts 3-4 months

70

bone remodeling

-remaining dead bone fragments are resorbed, compact bone replaces spongy bone
-well-healed fracture is virtually undetectable
-process can take weeks to months depending on severity

71

factors affecting growth, repair, development

-nutrition=vitamin D
-sunlight (vit D)
-hormones: PTH, calcitonin, GH, thyroid hormone, sex hormones
-physical stress

72

osteoporosis

-abnormal reduction of bone mass
-reasons:
-loss of estrogen at menopause
-deficiency of minerals in youth
-imbalance in activity between osteoblasts and osteoclasts

73

fibrodysplasia ossificans progressiva

-CTP gets ossified when injured
-genetic
-injury results in inappropriate bone formation
-early adulthood: freezing of joints
-early 20s: confined to wheelchair
-starvation and pneumonia result
-no treatment