[B] (Pt 1) Human Musculoskeletal Anatomy: SKELETAL TISSUES Flashcards

1
Q

Germ Layers (x3)

A

Early embryonic pluripotent stem cells arranged in germ layers (cells will become all tissues body)

i.e. endoderm (inner), mesoderm, ectoderm (outer)

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2
Q

Connective Tissue

A
  • Connects + supports organs/ other tissues
  • Cells embedded in matrix w collagen fibres + elastic tissue
  • Develops from mesoderm

e.g. cartilage/ bone

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3
Q

Cartilage

A

Hard, flexible connective tissue in respiratory airways + end of bones + anterior end ribs + nose + outer ear

1) Hyaline Cartilage
2) White Fibrous Cartilage (fibrocartilage)
3) Yellow Elastic Cartilage

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4
Q

Chondrocytes

A

Cells in cartilage:

  • Secrete an extra-cellular matrix made of transparent protein chondroitin (may contain fibres collagen/ elastic material)
  • In spaces in matrix (lacunae)
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5
Q

Properties Cartilage

A
  • Rigid: hold open tube e.g. trachea/ Eustachian tube
  • Flexible: allows ribcage movement
  • Returns original shape after bending: role load bearing joints e.g. hips/ knees

(No blood vessels: nutrient acquisition/ gas exchange rely diffusion - diffusion slow so healing slow)
(No nerves)

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6
Q

Hyaline Cartilage

A

Weakest
Role: Prevents friction at joints

  • High proportion collagen (in extra-cellular matrix)
  • “Glassy”
  • Surrounded fibrous coat connective tissue (perichondrium)
  • If damaged replaced fibrocartilage scar tissue
  • Ossifies in foetus (becomes bone) + in adults is articular cartilage at ends of bones
    e. g. joining ribs w sternum/ nose/ larynx/ trachea/ bronchi
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7
Q

White Fibrous Cartilage (fibrocartilage)

A

Strongest
Role: Load bearing in intervertebral discs

  • Collagen organised in dense fibres (higher tensile strength) + in direction of stress
  • Makes intervertebral discs + ligaments
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8
Q

Yellow Elastic Cartilage

A

Intermediate Strength
Role: Maintains shape at epiglottis

  • Chondrocytes surrounded collagen (in matrix) + network elastin fibres
    (makes it elastic but maintains shape)
    e.g. ear pinna/ epiglottis
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9
Q

Bone: Functions (x4)

A
  • Structural support skeleton
  • Movement (bones attachment sites for muscles)
  • Physical protection organs e.g. brain
  • Mineral regulation: storage (e.g. Ca/P), trapping harmful mineral (e.g. lead), regulation calcium content
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10
Q

Bone: Types (x2)

A

1) Spongy/ Cancellous Bone

2) Compact Bone

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11
Q

Spongy/ Cancellous Bone

A

Found end of long bones + in vertebrae

Light + porous and has network of spaces containing bone marrow (flexible tissue where RBCs made)

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12
Q

Compact Bone

A

Strong and rigid + surrounds most bones - gives white/shiny appearance (75% bone body)

Haversian + Volkmann canals run through bone so blood vessels can penetrate

OSTEOBLASTS: Continuously build it up
OSTEOCLASTS: Continuously degrade it

–> cells held in matrix secreted osteoblasts (30% organic collagen fibres to resist fracture + 70% inorganic hydroxy-apatite (mineral rich Ca and P) v hard and resists compression)

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13
Q

Haversian System/ Osteon

A
  • Structural and functional unit of compact bone
  • Separated by interstitial bone
  • Formed concentric lamellae (rings made hydroxy-apatite secreted by osteoblasts in lacunae) around central Haversian canal

Periosteum > interstitial bone > lamellae > Haversian Canal > marrow cavity

(+ lacunae + Volkmann canals + Canaliculi)

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14
Q

Haversian Canal

A
  • Centre of Haversian System

- Contains an arteriole, a venule, lymph vessels and nerve fibres

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15
Q

Volkmann Canal

A

[Haversian System]

Perforating canal that connects Haversian canals with each other and with the periosteum (carries blood vessels)

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16
Q

Canaliculi

A

[Haversian System]
Microscopic channels that radiate out of lacunae (containing osteoblasts) into bone matrix

–> forms 3D network between osteoblasts to supply nutrients via blood vessels + remove waste (also some exchange by diffusion through bone matrix)

17
Q

Bone Formation: Cartilage Bones

A

e.g. limb bones/ vertebrae/ ribs

OSSIFICATION of hyaline cartilage in embryo:
(begins ends/ middle long limb bones)

  • Cartilage cells flatten + Ca deposited around them
  • Osteoblasts secrete layers bone matrix around cartilage while osteoclasts break down cartilage
  • Blood vessels invade

Perichondrium surrounding cartilage –> periosteum surrounding bone (dense fibrous connective tissue)

18
Q

Bone Formation: Membrane Bones

A

e.g. collarbone (clavicle)/ most skull (cranium)/ facial bones

–> form directly in embryonic connective tissue

19
Q

Bone Diseases (x3)

A

1) Rickets + Osteomalacia
2) Brittle Bone Disease (osteogenesis imperfecta)
3) Osteoporosis

20
Q

Rickets + Osteomalacia

A

Rickets: Childhood disease where Ca not absorbed into growing bones so become soft/ weak/ deformed

Osteomalacia: Milder rickets in adults

Symptoms: Tenderness/ fractures/ bone deformity e.g. bow legs toddlers/ knock knees/ less wide pelvic girth women (difficulty childbirth)

Diagnosis: Blood tests (low Ca)/ x-rays/ bone density scans

Cause: Lack vitamin D/ Ca (sunlight converts inactive to active vitamin D which incorporates Ca into bones)

Prevention: Exposure sunlight + Ca in diet + vit D (fat soluble so found butter/eggs/fish)

Treatment: Vitamin D/Ca supplements/ ultraviolet B light exposure/ surgery for bone deformities

21
Q

Brittle Bone Disease [osteogenesis imperfecta (OI)]

A

Inherited disorder in balance organic vs inorganic components bone - leading increase risk fractures

Symptoms: Fractures/ poor muscle tone/ loose joints

Diagnosis: Test collagen from skin biopsy/ DNA analysis
(Normally collagen has high proportion smallest amino acid glycine but OI replace w bigger amino acids so cannot coil tightly so H-bonds holding triple helix weaker - interaction triple helix w hydroxy-apatite altered so brittle bones)

Cause: Genetic (mutations in type 1 collagen)

Treatment: No cure

  • Drugs (increase bone mass, reduce pain/ fractures)
  • Surgery (metal rods in long bones to walk)
  • Physiotherapy (strengthen muscles, mobility)
22
Q

Osteoporosis

A

Abnormal loss of bone mass + density due Ca leached from bones resulting increased risk fracture

Symptoms: Fractures arm, wrist, hip, vertebrae/ stooped posture/ chronic back pain

Diagnosis: Bone scan measure mineral density in hip

Causes/ Risk Factors:

  • Age (post-menopausal women rapid loss bone density due drop oestrogen/ old men due drop testosterone)
  • Lack Ca in diet
  • Family history
  • Inflammatory conditions e.g. rheumatoid arthritis
  • Medical conditions/ drugs that affect hormone lvls
  • Alcohol/ smoking

Prevention/ Treatment: No cure

  • Diet rich Ca/ vit D
  • Regular load bearing exercises (increase bone density)
  • Drugs (increase Ca uptake in bones)
  • Give up smoking/ less alcohol
  • Prevent falls
23
Q

Types of Muscle (x3)

A
  • Skeletal (striped, striated, voluntary)
  • Non skeletal (unstriped, non striated, smooth, involuntary)
  • Cardiac
24
Q

Skeletal Muscle: Structure of Muscle Tissue

A

(Muscle fibres = long thin cells)

Fascicle = Bundle of muscle fibres
(Surrounded by connective tissue - perimysium)

Muscle = Bundle of fascicles
(Surrounded by connective tissue - epimysium)

25
Q

Ultra-Structure/ Fine Structure

A

Detailed structure of cell seen by electron microscope

e.g. myofibrils in muscle fibres

26
Q

Ultra-Structure of Skeletal Muscle Fibres

A
  • Many nuclei
    (Muscle fibres formed by fusion several cells embryo then grow to final size after birth)

[Coenocytic: if nuclei result mitosis]
[A Syncytium: if nuclei result fusion many cells]

  • Myofibrils
  • Sarcoplasmic Reticulum (endoplasmic reticulum)
  • Sarcoplasm (cytoplasm)
  • Sarcolemma (cell membrane)
  • Mitochondria
27
Q

Striations

A

Transverse stripes in skeletal (+cardiac) muscle formed by myofibrils inside muscle fibres

28
Q

Myofibril

A

Long, thin structure in muscle fibre made largely of proteins actin + myosin

  • Surrounded sarcoplasmic reticulum w mitochondria between
  • Organised in long, thin myofilaments
29
Q

Myofilament

A

Thin filaments = mainly actin
Thick filaments = mainly myosin

  • Interact in myofibrils to produce muscle contraction
  • Organised in repeated units: sarcomeres
30
Q

Sarcomeres

A

Repeating units of myofilaments

Sarcomeres of adjacent myofilaments line up inside muscle fibre:

  • Thick myosin filaments line up: A band
  • Thin actin filaments line up: I band
  • End of sarcomere + attachment site for microfilaments: Z band
  • No actin/myosin overlap: H band