Lecture 2: Histology of the musculoskeletal system (Baekey) Flashcards Preview

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Flashcards in Lecture 2: Histology of the musculoskeletal system (Baekey) Deck (54):
1

Embryonic vs. Fetal periods of growth

embryonic growth = organogenesis, wheras fetal period of growth = growth of existing organs and structures

2

what represents the major component of increase in overall body mass during the fetal growth phase?

growth in the musculoskeletal system

3

ossification/osteogenesis

process of laying down new bone material by osteoblasts

4

when does ossification in long bones begin in humans?

third month of embryonic development

5

when does ossification completely finish in humans?

by 25 yrs

6

epiphysis

end portion of long bone

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diaphysis

middle portion of long bone

8

In which direction does ossification occur in long bones?

moves outward from diaphysis to epiphysis

9

skull growth in female vs. male baboons

Males continue along the SAME growth trajectory as females, but for a longer period of time

10

4 mechanisms of growth

1) cell proliferation
2) protoplasmic synthesis
3) water uptake
4) intercellular matrix deposition (i.e. connective tissue, cartilage, bone)

11

protoplasmic synthesis

new organic matter is created from nutrient supply via biosynthesis

12

What are ABSOLUTE growth scales used for?

to compare growth within a species

13

What are RELATIVE growth scales used for?

to compare growth between species

14

What is scaling?

The relationship b/w overall body size and the relative sizes of various body parts

15

Geometric vs. elastic scaling

In geometric scaling, all of the proportions stay the same (aka isometry). In elastic scaling, some areas grow disproportionately to others (can be positive or negative allometry)

16

Allometry

a mathematical tool for analyzing scaling. The study of the relationship b/w size and shape.

17

positive allometry

when the body part of interest grows faster than whatever it's being compared to (i.e. the rest of the body)

18

negative allometry

when the body part of interest grows slower than whatever it's being compared to (i.e. the rest of the body)

19

growth pattern of the human brain

fetal phase = isometry
early postnatal = negative allometry
late postnatal = little or no growth

20

Major tissue components of the MS system

skeletal muscle, cartilage, bone, connective tissue, associated blood vessels and nerves

21

fetal precursor to skeletal muscle

somite myotomes

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fetal precursor to connective tissue

somite dermatomes

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fetal precursor to axial skeleton

somite sclerotomes

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fetal precursor to appendicular skeleton

lateral plate somatic mesoderm

25

fetal precursor to skull and branchial arch bone + cartilage

head mesenchyme (largely neural crest)

26

fetal precursor to skeletal muscle of head and branchial arches 1-3

somitomeres

27

when do myotome cells become myoblasts?

when they lose the ability to undergo mitosis and begin synthesizing myofibrilar proteins

28

myotube

an elongated multinucleated muscle fibers formed by fused myoblasts. Synthesizes actin and myosin which self-assemble into thick and thin filaments

29

3 main steps of skeletal muscle fiber development

1) mesenchymal cells differentiate into myoblasts.
2) myoblasts fuse to form myotubes. Contractile filaments begin to order peripherally
3) nuclei migrate to periphery and cytoplasm is filled with bundles of contractile filaments in banding pattern

30

3 main layers of muscle

epimysium, perimysium, endomysium

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epimysium

(fascia) the outer capsule of muscle

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perimysium

inward extensions of epimysium that package groups of muscle cells into fascicles and bring nerves, blood vessels, and lymphatics into the muscle

33

endomysium

loos connective tissue that surrounds individual multinucleated muscle fibers; brings in capillaries and the smallest division of nerves

34

metaphysis

transition between the epiphysis and diaphysis

35

physes =

growth plates. located at metaphysis. An immovable cartilaginous joint (synchondrosis) b/w the epiphysis and diaphysis

36

characteristics of zone of resting chondrocytes ***

scattered, non-dividing chondrocytes which may serve to weld the growth plate to the epiphysis

37

characteristics of zone of proliferative chondrocytes ***

-isogenic columns of actively dividing chondrocytes
-site of elongation of the long bone
-more mature chondrocytes located at the diaphyseal end of the columns

38

characteristics of zone of hypertrophied chondrocytes ***

-narrow zone at diaphyseal end of isogenic columns
-chondrocytes with lacunae are large and intercellular matrix is minimal
-weakest site in the growth plate & major site of fractures

39

chars. of zone of calcified cartilage ***

-calcium deposition appears as dk. stained matrix
-tidemark visible as border b/w zone of articular cartilage and zone of calcification

40

osteoblast fx

deposit successive lamellae of bone matrix along margins of trabeculae

41

osteocyte

an osteoblast that has become trapped inside the deposited matrix. persist as mature bone cells

42

fx of canaliculi

capture blood supply from haversian canal to supply osteocytes within an osteon

43

what does tidemark denote?

the border between articular and mineralized (calcified) cartilage

44

diarthroidal joint

a movable joint

45

synarthroidal joint

an immovable joint

46

synovial joint components

components: articulating bone surfaces covered by hyaline cartilage separated by a fluid-filled joint cavity, surrounded by a joint capsule

47

examples of synovial joint

scapulo-humeral; stifle

48

symphysis joint components

articular surfaces covered by hyaline cartilage, separated by a pad of fibrocartilage

49

examples of symphysis joint

intervertebral, pubic symphysis

50

components of synovial joint capsule

synovial membrane (epithelial-like layer of fibroblasts), synovial fold (infolding of synovial membrane into synovial space), and fibrous layer (dense white fibrous connective tissue that contains elastic fibers)

51

perichondral ring

where fibrous layer of synovial joint capsule attaches to bone. An area of transition b/w the articular cartilage and the periosteum of the diaphysis

52

periosteum

membrane that lines the outer surface of all bones

53

what are tendons composed of?

dense white fibrous connective tissue anchored to bone or muscle

54

Sharpey's fibers

collagenous fibers that attach tendons, ligaments, and joint capsules to bone

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