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RUSVM Microscopic Anatomy And Embryology > Musculoskeletal System > Flashcards

Musculoskeletal System Flashcards

1
Q

What are the muscle cells? What do they originate from?

A
  • myocytes (muscle cells) + myofibers (muscle fibers)
  • mesoderm (from myoblasts)
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2
Q

What is sarcoplasm? Sarcolemma? Sarcoplasmic reticulum?

A
  • sarcoplasm: cytoplasm of muscle cells that contains glycogen + myoglobin
  • sarcolemma: plasma membrane of muscle cell
  • sarcoplasmic reticulum: highly specialized smooth endoplasmic reticulum of a muscle cell (regulates calcium flow)
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3
Q

What are the classifications of muscle tissue?

A
  • cross-striated (skeletal + cardiac)
  • smooth
  • myoepithelial cells (basket cells)
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4
Q

Label each muscle type

A
  • skeletal
  • cardiac
  • smooth
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5
Q

What are features of skeletal muscle?

A
  • make up 50% of body weight
  • skeletal myocytes contain multiple, peripherally located nuclei
  • striations are seen in myocytes when cut longitudinally
  • voluntary + fast contraction
  • most insert on bones of the skeleton
  • voluntary sphincters in the GI tract and urinary system, muscles of esophagus +tongue
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6
Q

Describe skeletal muscle development

A
  • mesenchymal cells (myoblasts) align and fuse together forming multinucleated tubes aka MYOTUBES
  • myotubes differentiate forming functional MYOFILAMENTS and the nuclei are displaced against the plasma membrane
  • some do not differentiate and remain as mesenchymal stem cells called SATELLITE CELLS that function in muscle repair
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7
Q

How is skeletal muscle organized?

A
  • epimysium (fascia): dense irregular CT
  • fascicles, surrounded by permysium
  • myofibers/myocyte, surrounded by endomysium
  • myofibrils
  • myofilaments
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8
Q

Label the indicated features of the muscle

A
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9
Q

Myofibrils are the ___________ elements of skeletal muscle, composed of repeating sections of myofilaments known as thick _______ and thin ________, that create light and dark banding

A
  • contractile
  • myosin
  • actin
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10
Q

Tropomyosin are ______________ , actin + myosin are ______________

A
  • regulatory protein of myofilaments
  • contractile proteins
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11
Q

Skeletal muscle striation is due to the presence of 2 kinds of myofilaments: _____________ + _____________

The _____________ is a protein disc that bisects each ________

A
  • A band: dark
  • I band: pale
  • Z-line, I-band
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12
Q

A ____________ is the contractile or functional unit of myocytes, which includes all elements from Z-line to Z-line.

At full contraction, z-lines (discs) will be:

A
  • sarcomere
  • drawn closer to each other
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13
Q

The _____________ is dark and corresponds to the area where thick and thin filaments overlap. It is mostly composed of ________.

The _____________ is pale and is composed of only _________.

A
  • A-band, myosin filaments
  • I-band, actin filaments
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14
Q

What is motion mediated by? How does muscle contraction occur?

A
  • motion is mediated by muscle cells and based on conversion of chemical energy (ATP) into mechanical energy
  • during muscle contraction actin filaments slide over myosin filaments, shortening the I-band
  • actin + myosin are held in position in the myofibrils by other proteins (desmin, tropomyosin, and troponin)
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15
Q

What is the sliding filament mechanism?

A
  • sarcomere shortens > myofilament length is constant > I-band shortens > thin (actin) filaments slide past thick (myosin) filaments
  • results in contraction of muscle cell
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16
Q

What are the steps of muscle contraction?

A
  • binding of calcium to troponin C (TnC)
  • conformational change in tropomyosin,exposing the myosin-binding site on actin
  • myosin head binds to actin; ATP > ADP moving myosin head
  • bound thin filaments slide over thick filaments
  • shortening of muscle fiber
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17
Q

Label the structures

A
  • 1: myofibrils
  • 2: sarcoplasmic reticulum (stores + releases Ca)
  • 3: terminal cisterna (expanded ends of SR)
  • A: transverse T-tubule
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18
Q

___________________ are deep invaginations of sarcolemma (plasma membrane) of skeletal and cardiac muscle cells. What do they allow to occur?

A
  • T-tubules (transverse tubule)
  • allow depolarization of the membrane to quickly spread to terror of the cell allowing release of calcium sarcoplasmic reticulum
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19
Q

What is the sarcoplasmic reticulum?

A
  • equivalent to endoplasmic reticulaum but seen in smooth and striated muscle
  • stores and releases calcium ions to initiate contractions
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20
Q

What are the types of skeletal muscle fibers?

A
  • type 1: “red muscle” - SLOW TWITCH
  • type 2: “white muscle” - FAST TWITCH, 2A + 2B
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21
Q

What are features of type 1 skeletal muscle?

A
  • “red muscle”; rich in myoglobin
  • SLOW twitch
  • AEROBIC metabolism: fatigue resistant
    - high fat, low glycogen
    - many mitochondria
    - myoglobin: help transfer oxygen
  • ex: postural muscles of mammals, pectoral muscles of migratory birds
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22
Q

What are features of type 2 skeletal muscle?

A
  • “white muscle”
  • FAST twitch
  • ANAEROBIC metabolism: more prone to fatigue
    - lowfat, high glycogen content
    - few mitochondria
    - less myoglobin
  • type 2A (aka intermediate): mixed oxidative-glycolysis; slow fatigue
  • type 2B: fast-contracting, fast fatigue, glycolytic
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23
Q

What are features of cardiac muscle?

A
  • cardiomyocyte: myocardiocyte: cardiac myocyte
  • single cell with one central nucleus
  • cross striated
  • intercalated discs: gap junctions + desmosomes
  • sarcoplasmic reticulum
  • many mitochondria; up to 20% cell volume: requires lots of O2
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24
Q

What kind of muscle fiber? Label some features

A
  • cardiac muscle
  • intercalated discs: attach cardiac muscle fiber cell to each other providing strength and ability to behave as a functional syncytium
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25
Q

What are intercalated discs composed of?

A
  • 1: transverse element
    • anchor
    • desmosome: fascia adherens or macula adherens
    • serve for strong attachment
  • longitudinal element
    • communication
    • gap junction (nexus) with ion channels
    • propagate electric impulse
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26
Q

Label the two types of cardiomyocytes

A
  • A: contractile cardiac muscle cells: red
  • B: conductile cardiac muscle cells (purkinje fibers): pale pink
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27
Q

What feature is shown here? What are some characteristics?

A
  • purkinje fibers (in heart)
  • modified cardiac muscle cells wit 1 or 2 nuclei,myofibrils are sparse and restricted to periphery of cell
  • arranged in groups, cells are bigger and paler than contractile cardiac muscle cells
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28
Q

What are features of smooth muscle cells?

A
  • spindle shaped (fusiform) cells surrounded by a basal lamina and reticular fibers
  • single centrally located nucleus
  • no striations (no myofibrils, unordered actin + myosin)
  • cytoplasmic dense bodes represent anchos or myofilaments (like Z bodies)
  • desmosomes and gap junctions
  • no T-tubules and sarcoplasmic reticulum poorly developed
  • parasympathetic + sympathetic innervation
  • INVOLUNTARY contraction
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29
Q

What are the 2 kinds of smooth muscle?

A
  • single unit smooth muscle
    - found in visceral organs
    - cells behave like syncytium contracting in network
    - sparse nerve innervation, but cells communicate via multiple gap junctions
  • multi-unit smooth muscle
    - found in iris (ciliary muscles)
    - precise contraction
    - individual innervation of each myocyte
    - lack of gap junctions, function individually
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30
Q

What are functions of smooth muscle cells?

A
  • peristalsis: wave-like contractions (ex: gi tract)
  • vascular dynamics: contraction alters blood flow, important in blood pressure
  • propulsion: urinary badder, uterus
  • secretion: minor role
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31
Q

How are the layers of the tunica muscularis arranged in the walls of luminal organs? What kind of contraction?

A
  • inner circular
  • outer longitudinal
  • non-voluntary
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32
Q

What are the black arrows indicating? What will happen to this cell during contraction?

A
  • dense bodies: equivalent of Z discs of skeletal and cardiac muscle
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33
Q

What are features of myoepithelial cells?

A
  • contractile non-muscle cells
  • ectodermal origin
  • contain actin/myosin
  • similar to smooth muscle
  • can be stimulated by hormone (mammary gland)
  • basket-like shape > BASKET CELLS
  • located: salivary, mammary, lacrimal glands
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34
Q

What are these 2 contractile non-muscle cells and what are they derived from?

A
  • myoepithelial cells/basket cells; ectoderm
    • close clusters of glandular cells
  • myofibroblasts: mesoderm
    • wound contraction
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35
Q

_________ are postitioned between basal lamina and sarcolemma of the muscle cell. They retain _________ and so can accomplish some repair.

___________ also form connective tissue (scars) as part of the repair process

A
  • satellite cells
  • mitotic potential
  • fibroblasts
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36
Q

________ muscle cells lack the ability to regenerate

________ muscle regeneration is limited. In addition to some mitotic activity, new smooth muscle cells may be derived from ______________________ cells

In all muscle types, repair is completed by scar tissue formation and requires _______________

A
  • cardiac
  • smooth, pericapillary mesenchymal
  • intact basal lamina
37
Q

What are features of bone?

A
  • alive and constantly remodeling
  • osteoid: 90% collagen and inorganic (mineral) components
    - hydroxyapatite (Ca10(PO4)6(OH)2)
  • bones are organs; in that they are a major part of the skeletal system
  • lightweight but strong, with internal flexibility because of spongy bone (spicules w/ space between)
38
Q

What are functions of bone?

A
  • protect other organs
  • produce hematopoietic cells
  • store minerals
  • provide structure + support
39
Q

What are the two main layers of bone?

A
  • trabeculae (T)
    • cancellous or spongy bone
    • large surface area; bone marrow
  • cortical (C)
    • aka compact bone, more dense
40
Q

Label the features of this bone

A
  • T: trabecular bone
  • C: cortical bone
  • E: epiphysis
  • D: diaphysis
  • M: metaphysics
  • P: physis = growth plate
  • AC: articulate cartilage
41
Q

What kind of bone is this? What are some features?

A
  • lamellar bone
  • strong mature bone, forms slowly
  • collagen fibers in matrix arranged in parallel layers (lamellae)
  • results in strong mature bone (osteoid)
  • organized into osteons (haversian systems) in mature cortical and trabecular bone
42
Q

What kind of bone is this? What are some features?

A
  • woven bone
  • weak, immature, produced quickly
  • disorganized arrangement of collagen fibers
  • present at sites of rapid bone formation (ex: fracture repair, inflammation, neoplasia)
  • ex: periosteal new bone or reactive bone
  • ** can be re-modeled into lamellar bone
43
Q

__________, the functional unit of lamellar bone is located in circles around the central canal (haversian) and in the interstitial bone between circles of bone.

What are some features?

A
  • osteon
  • in mature bone (lamellar), not woven bone
  • located in cortex, trabeculae of bones
  • volkman’s canals run in bone and connect haversian (central) canals
44
Q

Label the structures of bone

A
  • osteon: circles of lamellar bone around central canal. Small holes with lacunae are osteocytes
  • blood vessels
  • central canal
  • osteocyte within a lacuna
  • canaliculi: thin channels between lacunae
45
Q

What is this?

A
  • osteon
46
Q

Label the features

A
47
Q

What are cellular elements of bone tissue?

A
48
Q

What are features of osteoblasts?

A
  • along bone spicules
  • produce osteoid (organic component of bone material) and initiate mineralization
  • some osteoblasts become surrounded by osteoid and embedded in the bone (become osteocytes)
49
Q

What is this? What are some features/functions?

A
  • osteocytes
  • most abundant cells
  • reside in lacunae surrounded by mineralized matrix (long filipods to increase their cell area)
  • regulate exchange of Ca2+ (and other ions) between bone
  • fluid and ECF under influence of parathyroid hormone
50
Q

What is this? What are some features/functions?

A
  • osteoclasts
  • parathyroid hormone (PTH) stimulates activity
  • bone resorption
  • reside in shallow pits (Howship’s lacunae)
  • acid demineralizes bone and enhances activity of acid hydrolases released from osteoclasts (extracellular digestion)
51
Q

Label the figure

A
  • A: osteoblast
  • B: osteoclast
  • C: osteocyte
  • D: mesenchyme
  • E: bone matrix
  • F: osteoid
  • osteoblasts are rounded, form a single row of cells along trabeculae
  • osteocytes are thinner and located within lacunae embedded in bone
  • osteoclasts are multinucleated cells located along trabeculae and will absorb bone under stimulation of cytokines secreted by osteoblasts or inflammatory cells
52
Q

What are the cellular elements of bone?

A
53
Q

What systemic hormones affect bone?

A
  • parathyroid hormone (PTH): promoted bone resorption
  • 1,25-dihydroxyvitamin D3: required for normal bone growth and mineralization; also stimulates bone resorption
  • glucocorticoids: inhibit formation and stimulate resorption
  • calcitonin: inhibits bone resorption
  • estrogen: inhibits bone resorption
  • insulin, growth hormone, androgens, and thyroid hormones are also included in bone metabolism
54
Q

What are the elements of bone matrix?

A
  • osteoid (organic component) contains:
    • type i collagen: (~90%)
    • osteonectin: mineralization
    • osteocalcin: vitamin k dependent, mineralization
    • proteoglycans: less abundant than in cartilage
    • growth factors: ex: BMPs, IGFs, TGFs, FGFs
  • hydroxyapatite (inorganic component): needle-like crystals, mineral
55
Q

Describe matrix mineralization

A
  • in bone, osteonectin and osteocalcin absorb to type i collagen and bind Ca2+
  • osteoid is not mineralized immediately (5-10 day delay)
    • failure to mineralized = rickets = osteomalacia = soft bones/fractures
56
Q

What are the two types of bone development?

A
  • intermembranous ossification: increases WIDTH; IN ADULTS
    • bone formed from mesenchymal tissue in periosteum
    • occurs in flat bones of skull and pelvis and on periosteal surfaces throughout life
    • NO CARTILAGE NEEDED
  • endochondral ossification: increases LENGTH; IN YOUNG
    • bone formed from hyaline cartilage precursors in physes
    • most bones develop by this method (appendicular, axial, base of skull)
    • HYALINE CARTILAGE PRECEDES and is scaffold
57
Q

What are the stages of endochondral ossification?

A
58
Q

Label the image

A
  • M: metaphysis
  • arrow: physis
  • E: epiphysis
59
Q

What is this image a example of?

A
  • physis = growth plate
60
Q

What are functions of cartilage?

A
  • semi-rigid support to specific sites (ex: between bones, joints, ligaments, respiratory tree,intervertebral discs)
  • shock absorber in menisci + intervertebral discs
  • protects ends of bones
61
Q

What are the 3 kinds of cartilage?

A
  • hyaline
  • elastic
  • fibrocartilage
62
Q

What is the function of ligaments?

A
  • provide stability of joints, connect BONES to BONES
63
Q

What is the function of tendons?

A
  • strong flexible connections between BONE and MUSCLE
64
Q

What is the function of joints?

A
  • varying degrees of movement and flexibility; lubricated spaces with fluid between bones
65
Q

What does cartilage originate from?

A
  • mesenchymal cells
  • differentiation and maturation is most advanced at the center of growing cartilage, and immature at the periphery aka PERICHONDRIUM
  • at completion, cartilage consists of chondrocytes embedded in extracellular matrix
  • perichondrium contains elongated fusiform cells that resembles fibroblasts, which give rise to chondroblasts
66
Q

What are features of cartilage?

A
  • AVASCULAR
  • semi-rigid form of connnective tissue characterized by absence of blood vessels,lymphatic vessels and nerves(in adults)
    • young animals have blood vessels in growing cartilage
  • supports soft tissues (ear, eyelid, trachea, bronchi)
  • important for longitudinal growth (endochondral ossification)
  • composed of cells (chondrocytes) embedded in amorphous gel-like substance and connective tissue fibers, making it resilient
67
Q

What is this image showing? label the arrows

A
  • cartilage
  • A: chondrocyte
  • B: lacunar space
  • C: matrix in intercellular region
68
Q

What are the steps of chondrogenesis?

A
69
Q

T/F: mature cartilage has a fast cell turnover and replacement of cells

A
  • false; slow
70
Q

What is a cluster of chondrocytes formed through the division of a progenitor cell; found in hyaline, elastic, and fibrocartilage?

A
  • isogenous group
71
Q

Where does primary ossification centers form first?

A
  • epiphyses
72
Q

What is this image of? Label the features

A
  • metaphysis
  • 1: zone of reserve/resting cells
  • 2: zone of proliferation
  • 3: zone of hypertrophic cells
  • B: primary spongiosa: bone that forms on dead mineralized cartilage “scaffold”
73
Q

Label each cartilage type and where it can be found

A
  • A: hyaline
    • joints: articulate cartilage
    • ribs
    • physes
    • nose
  • B: elastic
    • ear
    • epiglottis
    • flexibility needed
  • C: fibrocartilage
    • menisci discs
    • insertions of tendons & ligaments
74
Q

What is cartilage type based on?

A
  • the amount of collagen or elastic fibers present in the extracellular matrix
  • amount of GAGs
75
Q

What is the most abundant cartilage type?

A
  • hyaline
76
Q

What kind of cartilage is shown? Where is it found?

A
  • hyaline cartilage
  • growth plates (physes)
  • articular cartilage covers joint surfaces at costochondral junctions of the ribs, nasal septum, larynx, tracheal rings, and bronchi
  • fetal axial + appendicular skeleton
77
Q

What kind of cartilage is shown? What are some features?

A
  • elastic
  • has a perichondrium, chondroblasts, and chondrocytes in large lacunae
  • contains abundant elastic fibers (stain dark)
  • flexible tissue due to presence of numerous bundles of branching elastic fibers in the matrix
  • found in epiglottis and corniculate/cuneiform processes of the arytenoid cartilage, external auditory canal and ear pinna
78
Q

What type of cartilage is this? What are some features?

A
  • lacks a perichondrium (no regenerative capacity)
  • fibrocartilage contains chondrocytes and lacunae
    • features are intermediate between cartilage and dense fibrous CT
  • contains type i collagen fibers
  • located where support and tensile strength are required:
    • intervertebral discs (annulus fibrosus)
    • menisci
    • insertions of tendons + ligaments
    • mandibular symphysis
    • pubic symphysis
79
Q

What is this image of? What are some features?

A
  • perichondrium
  • outer layer: dense fibrous CT, resembles mature fibroblasts
  • inner layer: cellular, chondrogenic,contains cells with capacity o become chondroblasts
    • present in all hyaline cartilage
    • but not articular surfaces/cartilage
80
Q

What is this image showing?

A
  • cartilage matrix
  • components: collage, elastic fibers, proteoglycans (GAGs)
  • basophilia of cartilage matrix due to high concentration of GAGs
  • matrix near chondrocyte clusters (territorial) is more basophilic than matrix further away (interterritorial)
81
Q

What are GAGs?

A
  • sulfated polysaccharide units (GAGS = glycosaminoglycans)
    • ex: chondroitin sulfate, keratin sulfate, dermatan sulfate, heparan sulfate,and hyaluronan
  • GAGs bound to protein core forming macromolecules called proteoglycans that are responsible for the strong and flexible property of cartilage (shock absorption)
  • within the matrix, GAGs are imbedded at varying proportions of collagen and elastic fibers giving rise to the different types of cartilage
82
Q

What is shown? What are some features?

A
  • tendon
  • ~85% collagen (98% type i)
  • 2% elastin
  • 1-5% proteoglycans
  • parallel bundles of fibers
  • function: attachments, flexibility
  • limited regenerative capacity
    - following injury, lays down type iii collagen (scar tissue) making it less flexible and prone to re-injury
83
Q

What are the kinds of joints?

A
  • fibrous (synarthroses)
  • cartilaginous (amphiarthrosis)
  • synovial (diarthrosis) aka “true joints”
84
Q

What are features of fibrous joints ?

A
  • synarthroses
  • bones or cartilage united by fibrous tissue
  • 3 types:
    • sutures (ex: cranial suture)
    • syndesmosis (ex: tibia-fibula)
    • gomphosis (ex: tooth socket)
85
Q

What are features of cartilaginous joints?

A
  • amphiarthrosis
  • bones or cartilage united by hyaline cartilage (costochondral joints) or fibrocartilage (ex: pelvic and mandibular symphysis)
86
Q

What are features of synovial joints?

A
  • diarthrosis aka true joints
  • unite two bone ends and are covered by articular (hyaline) cartilage and are surrounded by a thick articular capsule
  • joint cavity consists of:
    • capsule composed of fibrous portion
    • well-vascularized synovial membrane lined by 2 cell types
      • type A cell: phagocytic function (remove debris)
      • type B cell: secrete hyaluronic acid and protein complex (mucin) into synovial fluid to help lubricate, protect and give nutrition to joints
87
Q

What are features of articular cartilage? Articular capsule?

A
  • articular cartilage:
  • smooth surface
  • type ii collagen + proteoglycans
  • lacks blood vessels and nerves (poor regenerative capacity)
  • firmly reached to subchondral bone
  • articular capsule:
  • thick sac of connective tissue that covers entire joint and provides additional joint stability
88
Q

What are features of the synovial membrane? Synovial fluid?

A
  • synovial membrane
  • thin membrane with lots of villi
  • superficially lined by a continuous layer of specialized cells (synoviocytes)
  • synovial fluid
  • clear, viscous, colorless or slightly yellow fluid produced by type B synoviocytes (low cellular Ty and protein content)
  • function to reduce friction
  • increases in joint diseases (effusion)
89
Q

What is this? What is labeled A?

A
  • joint synovium
  • synovial epithelium

RUSVM Microscopic Anatomy And Embryology (11 decks)

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