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Human Anatomy & Physiology 1 > Chapter 6 (Bones and Skeletal Tissue) > Flashcards

Chapter 6 (Bones and Skeletal Tissue) Flashcards

1
Q

Skeletal cartilage

A

made of highly resilient, molded cartilage tissue that consists primarily of water
– Contains no blood vessels or nerves

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2
Q

Perichondrium

A

layer of dense connective tissue surrounding cartilage like a
girdle
– Helps cartilage resist outward expansion
– Contains blood vessels for nutrient delivery to cartilage

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3
Q

Cartilage is made up of

A

chondrocytes, cells encased in small cavities
(lacunae) within jelly-like extracellular matrix

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4
Q

Three types of cartilage:

A

hyaline, elastic, cartilage

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5
Q

Hyaline cartilage

A

 Provides support, flexibility, and resilience
 Most abundant type; contains collagen fibers only
 Articular (joints), costal (ribs), respiratory (larynx), nasal cartilage (nose
tip)

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6
Q

Elastic cartilage

A

 Similar to hyaline cartilage, but contains elastic fibers
 External ear and epiglottis

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7
Q

Fibrocartilage

A

 Thick collagen fibers – has great tensile strength
 Menisci of knee; vertebral discs

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8
Q

Cartilage grows in two ways:

A

appositional and interstitial

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9
Q

Appositional growth

A

 Cartilage-forming cells in perichondrium secrete matrix against
external face of existing cartilage
– New matrix laid down on surface of cartilage

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10
Q

Interstitial growth

A

 Chondrocytes within lacunae divide and secrete new matrix, expanding
cartilage from within
– New matrix made within cartilage

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11
Q

There are seven important functions of bones

A
  1. Support
     For body and soft organs
  2. Protection
     Protect brain, spinal cord, and vital organs
  3. Movement
     Levers for muscle action
  4. Mineral and growth factor storage
     Calcium and phosphorus, and growth factors reservoir
  5. Blood cell formation
     Hematopoiesis occurs in red marrow cavities of certain bones
  6. Triglyceride (fat) storage
     Fat, used for an energy source, is stored in bone cavities
  7. Hormone production
     Osteocalcin secreted by bones helps to regulate insulin secretion,
    glucose levels, and metabolism
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12
Q

206 named bones in human skeleton

A

 Divided into two groups based on location

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13
Q

Axial skeleton

A

 Long axis of body
 Skull, vertebral column, rib cage

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14
Q

Appendicular skeleton

A

 Bones of upper and lower limbs
 Girdles attaching limbs to axial skeleton

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15
Q

Bones are also classified according to one of four shapes:

A
  1. Long bones
     Longer than they are wide
     Limb bones
  2. Short bones
     Cube-shaped bones (in wrist and ankle)
     Sesamoid bones form within tendons (example: patella)
     Vary in size and number in different individuals
  3. Flat bones
     Thin, flat, slightly curved
     Sternum, scapulae, ribs, most skull bones
  4. Irregular bones
     Complicated shapes
     Vertebrae and hip bones
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16
Q

Bones are organs because they contain different types of tissues

A

Bone (osseous) tissue predominates, but a bone also has nervous
tissue, cartilage, fibrous connective tissue, muscle cells, and epithelial
cells in its blood vessels

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17
Q

Three levels of structure

A

– Gross
– Microscopic
– Chemical

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18
Q

Structure of short, irregular, and flat bones

A

– Consist of thin plates of spongy bone (diploe) covered by compact bone
– Compact bone sandwiched between connective tissue membranes
 Periosteum covers outside of compact bone, and endosteum covers
inside portion of compact bone
– Bone marrow is scattered throughout spongy bone; no defined marrow
cavity
– Hyaline cartilage covers area of bone that is part of a movable joint

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19
Q

Structure of typical long bone

A

All long bones have a shaft (diaphysis), bone ends (epiphyses), and
membranes
 Diaphysis: tubular shaft that forms long axis of bone
– Consists of compact bone surrounding central medullary cavity that
is filled with yellow marrow in adults
 Epiphyses: ends of long bones that consist of compact bone
externally and spongy bone internally
– Articular cartilage covers articular (joint) surfaces
 Between diaphysis and epiphysis is epiphyseal line
– Remnant of childhood epiphyseal plate where bone growth occurs

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20
Q

Membranes: two types (periosteum and endosteum)

A

– Periosteum: white, double-layered membrane that covers external
surfaces except joints
» Fibrous layer: outer layer consisting of dense irregular
connective tissue consisting of Sharpey’s fibers that secure to
bone matrix
» Osteogenic layer: inner layer abutting bone and contains
primitive osteogenic stem cells that gives rise to most all bone
cells
» Contains many nerve fibers and blood vessels that continue on
to the shaft through nutrient foramen openings
» Anchoring points for tendons and ligaments

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21
Q

Endosteum

A

» Delicate connective tissue membrane covering internal bone
surface
» Covers trabeculae of spongy bone
» Lines canals that pass through compact bone
» Like periosteum, contains osteogenic cells that can differentiate
into other bone cells

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22
Q

Bone markings

A

– Three types of markings:
 Projection: outward bulge of bone
– May be due to increased stress from muscle pull or is a
modification for joints
 Depression: bowl- or groove-like cut-out that can serve as
passageways for vessels and nerves, or plays a role in joints
 Opening: hole or canal in bone that serves as passageways for blood
vessels and nerves

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23
Q

Cells of bone tissue

A

– Five major cell types, each of which is a specialized form of the same
basic cell type
1. Osteogenic cells
2. Osteoblasts
3. Osteocytes
4. Bone-lining cells
5. Osteoclasts

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24
Q

Osteogenic cells

A

– Also called osteoprogenitor cells
– Mitotically active stem cells in periosteum and endosteum
– When stimulated, they differentiate into osteoblasts or bone-lining cells
– Some remain as osteogenic stem cells
- Stem cell

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25
Q

Osteoblasts

A

– Bone-forming cells that secrete unmineralized bone matrix called osteoid
 Osteoid is made up of collagen and calcium-binding proteins
 Collagen makes up 90% of bone protein
– Osteoblasts are actively mitotic
- Matrix-synthesizing cell responsible for bone growth

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26
Q

Osteocytes

A

– Mature bone cells in lacunae that no longer divide
– Maintain bone matrix and act as stress or strain sensors
 Respond to mechanical stimuli such as increased force on bone or
weightlessness
 Communicate information to osteoblasts and osteoclasts (cells that
destroy bone) so bone remodeling can occur
- Mature bone cell that monitors and maintains the mineralized bone matrix

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27
Q

Bone-lining cells

A

– Flat cells on bone surfaces believed to also help maintain matrix (along
with osteocytes)
– On external bone surface, lining cells are called periosteal cells
– On internal surfaces, they are called endosteal cells

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28
Q

Osteoclasts

A

– Derived from same hematopoietic stem cells that become macrophages
– Giant, multinucleate cells function in bone resorption (breakdown of bone)
– When active, cells are located in depressions called resorption bays
– Cells have ruffled borders that serve to increase surface area for enzyme
degradation of bone
 Also helps seal off area from surrounding matrix
- Bone-reabsorbing cell

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29
Q

Compact bone

A

– Also called lamellar bone
– Consists of:
 Osteon (Haversian system)
 Canals and canaliculi
 Interstitial and circumferential lamellae

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30
Q

Osteon (Haversian system)

A

– An osteon is the structural unit of compact bone
– Consists of an elongated cylinder that runs parallel to long axis of bone
 Acts as tiny weight-bearing pillars
– An osteon cylinder consists of several rings of bone matrix called lamellae
 Lamellae contain collagen fibers that run in different directions in
adjacent rings
 Withstands stress and resist twisting
 Bone salts are found between collagen fibers

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31
Q

Canals and canaliculi

A

– Central (Haversian) canal runs through core of osteon
 Contains blood vessels and nerve fibers
– Perforating (Volkmann’s) canals: canals lined with endosteum that
occur at right angles to central canal
 Connect blood vessels and nerves of periosteum, medullary cavity,
and central cana

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32
Q

Canals

A

Lacunae: small cavities that contain osteocytes
– Canaliculi: hairlike canals that connect lacunae to each other and to
central canal
– Osteoblasts that secrete bone matrix maintain contact with each other and
osteocytes via cell projections with gap junctions
– When matrix hardens and cells are trapped the canaliculi form
 Allow communication between all osteocytes of osteon and permit
nutrients and wastes to be relayed from one cell to anothe

33
Q

Interstitial and circumferential lamellae

A

– Interstitial lamellae
 Lamellae that are not part of osteon
 Some fill gaps between forming osteons; others are remnants of
osteons cut by bone remodeling
– Circumferential lamellae
 Just deep to periosteum, but superficial to endosteum, these layers of
lamellae extend around entire surface of diaphysis
 Help long bone to resist twisting

34
Q

Spongy bone

A

– Appears poorly organized but is actually organized along lines of stress to
help bone resist any stress
– Trabeculae, like cables on a suspension bridge, confer strength to bone
 No osteons are present, but trabeculae do contain irregularly arranged
lamellae and osteocytes interconnected by canaliculi
 Capillaries in endosteum supply nutrients

35
Q

Chemical Composition of Bone

A

 Bone is made up of both organic and inorganic components
– Organic components
 Includes osteogenic cells, osteoblasts, osteocytes, bone-lining cells,
osteoclasts, and osteoid
– Osteoid, which makes up one-third of organic bone matrix, is
secreted by osteoblasts
» Consists of ground substance and collagen fibers, which
contribute to high tensile strength and flexibility of bone

36
Q

Organic components

A

– Resilience of bone is due to sacrificial bonds in or between collagen
molecules that stretch and break to dissipate energy and prevent fractures
– If no additional trauma, bonds re-form

37
Q

Inorganic components

A

– Hydroxyapatites (mineral salts)
 Makeup 65% of bone by mass
 Consist mainly of tiny calcium phosphate crystals in and around
collagen fibers
 Responsible for hardness and resistance to compression
– Bone is half as strong as steel in resisting compression and as strong as
steel in resisting tension
– Lasts long after death because of mineral composition
– Can reveal information about ancient people

38
Q

Ossification (osteogenesis)

A

is the process of bone tissue formation
– Formation of bony skeleton begins in month 2 of development
– Postnatal bone growth occurs until early adulthood
– Bone remodeling and repair are lifelong

39
Q

Endochondral ossification

A

– Bone forms by replacing hyaline cartilage
– Bones are called cartilage (endochondral) bones
– Form most of skeleton
– Forms essentially all bones inferior to base of skull, except clavicles
– Begins late in month 2 of development
– Uses previously formed hyaline cartilage models
– Requires breakdown of hyaline cartilage prior to ossification
– Begins at primary ossification center in center of shaft
 Blood vessels infiltrate perichondrium, converting it to periosteum
 Mesenchymal cells specialize into osteoblasts

40
Q

Intramembranous ossification

A

– Bone develops from fibrous membrane
– Bones are called membrane bones
begins within fibrous connective tissue
membranes formed by mesenchymal cells
– Forms frontal, parietal, occipital, temporal, and clavicle bone

41
Q

Formation of the Bony Skeleton

A

Five main steps in the process of ossification:
1. Bone collar forms around diaphysis of cartilage model
2. Central cartilage in diaphysis calcifies, then develops cavities
3. Periosteal bud invades cavities, leading to formation of spongy bone
 Bud is made up of blood vessels, nerves, red marrow, osteogenic
cells, and osteoclasts
4. Diaphysis elongates, and medullary cavity forms
 Secondary ossification centers appear in epiphyses
5. Epiphyses ossify
 Hyaline cartilage remains only in epiphyseal plates and articular
cartilages

42
Q

Four major steps are involved:

A
  1. Ossification centers are formed when mesenchymal cells cluster and
    become osteoblasts
  2. Osteoid is secreted, then calcified
  3. Woven bone is formed when osteoid is laid down around blood vessels,
    resulting in trabeculae
     Outer layer of woven bone forms periosteum
  4. Lamellar bone replaces woven bone, and red marrow appear
43
Q

Postnatal Bone Growth

A

 Long bones grow lengthwise by interstitial (longitudinal) growth of epiphyseal
plate
 Bones increase thickness through appositional growth
 Bones stop growing during adolescence
– Some facial bones continue to grow slowly through life

44
Q

Growth in Length of Long Bones

A

 Interstitial growth requires presence of epiphyseal cartilage in the epiphyseal
plate
 Epiphyseal plate maintains constant thickness
– Rate of cartilage growth on one side balanced by bone replacement on
other
 Epiphyseal plate consists of five zones:
1. Resting (quiescent) zone
2. Proliferation (growth) zone
3. Hypertrophic zone
4. Calcification zone
5. Ossification (osteogenic) zone

45
Q

Epiphyseal plate consists of five zones:

A
  1. Resting (quiescent) zone
    – Area of cartilage on epiphyseal side of epiphyseal plate that is relatively
    inactive
  2. Proliferation (growth) zone
    – Area of cartilage on diaphysis side of epiphyseal plate that is rapidly
    dividing
    – New cells formed move upward, pushing epiphysis away from diaphysis,
    causing lengthening
  3. Hypertrophic zone
    – Area with older chondrocytes closer to diaphysis
    – Cartilage lacunae enlarge and erode, forming interconnecting spaces
  4. Calcification zone
    – Surrounding cartilage matrix calcifies; chondrocytes die and deteriorate
  5. Ossification zone
    – Chondrocyte deterioration leaves long spicules of calcified cartilage at
    epiphysis-diaphysis junction
    – Spicules are then eroded by osteoclasts and are covered with new bone
    by osteoblasts
    – Ultimately replaced with spongy bone
    – Medullary cavity enlarges as spicules are eroded
46
Q

Three “either/or” fracture classifications

A

Three “either/or” fracture classifications
– Position of bone ends after fracture
 Nondisplaced: ends retain normal position
 Displaced: ends are out of normal alignment
– Completeness of break
 Complete: broken all the way through
 Incomplete: not broken all the way through
– Whether skin is penetrated
 Open (compound): skin is penetrated
 Closed (simple): skin is not penetrated

47
Q

Repair involves four major stages

A
  1. Hematoma formation
  2. Fibrocartilaginous callus formation
  3. Bony callus formation
  4. Bone remodeling
48
Q

Hematoma formation

A

– Torn blood vessels hemorrhage, forming mass of clotted blood called a
hematoma
– Site is swollen, painful, and inflamed

49
Q

Fibrocartilaginous callus formation

A

– Capillaries grow into hematoma
– Phagocytic cells clear debris
– Fibroblasts secrete collagen fibers to span break and connect broken
ends
– Fibroblasts, cartilage, and osteogenic cells begin reconstruction of bone
 Create cartilage matrix of repair tissue
 Osteoblasts form spongy bone within matrix
– This mass of repair tissue is called fibrocartilaginous callus

50
Q

Bony callus formation

A

– Within one week, new trabeculae appear in fibrocartilaginous callus
– Callus is converted to bony (hard) callus of spongy bone
– Bony callus formation continues for about 2 months until firm union forms

51
Q

Bone remodeling

A

– Begins during bony callus formation and continues for several months
– Excess material on diaphysis exterior and within medullary cavity is
removed
– Compact bone is laid down to reconstruct shaft walls
– Final structure resembles original structure
 Responds to same mechanical stressors

52
Q

Three major bone diseases:

A

– Osteomalacia and rickets
– Osteoporosis
– Paget’s disease

53
Q

Osteomalacia

A

– Bones are poorly mineralized
– Osteoid is produced, but calcium salts not adequately deposited
– Results in soft, weak bones
– Pain upon bearing weight

54
Q

Rickets (osteomalacia of children)

A

– Results in bowed legs and other bone deformities because bones ends
are enlarged and abnormally long
– Cause: vitamin D deficiency or insufficient dietary calcium

55
Q

Osteoporosis

A

 Osteoporosis is a group of diseases in which bone resorption exceeds
deposit
 Matrix remains normal, but bone mass declines
– Spongy bone of spine and neck of femur most susceptible
 Vertebral and hip fractures common

56
Q

Tuberosity

A

Large rounded projection; may be roughened

57
Q

Crest

A

Narrow ridge of bone; usually prominent

58
Q

Trochanter

A

Very large; blunt, irregularly shaped process (the only examples are on the femur)

59
Q

Line

A

Narrow ridge of bone; less prominent than a crest

60
Q

Tubercle

A

Small rounded projection or process

61
Q

Epicondyle

A

Raised area on or above a condyle

62
Q

Spine

A

Sharp, slender, often pointed projection

63
Q

Process

A

Any bony prominence

64
Q

Head

A

Bony expansion carried on a narrow neck

65
Q

Facet

A

Smooth, nearly flat articular surface

66
Q

Condyle

A

Rounded articular projection

67
Q

Ramus

A

Armlike bar of bone

68
Q

Groove

A

Furrow

69
Q

Fissure

A

Narrow, slitlike opening

70
Q

Foramen

A

Round or oval opening through a bone

71
Q

Notch

A

Indentation at the edge of a structure

72
Q

Meatus

A

Canal-like passageway

73
Q

Sinus

A

Cavity within a bone, filled with air and lined with mucous membrane

74
Q

Fossa

A

Shallow, basinlike depression in a bone, often served as an articular surface

75
Q

Spiral

A

Ragged break occurs when excessive twisting forces are applied to a bone
- common sports fracture

76
Q

Epiphyseal

A

Epiphysis separates from the diaphysis along the epiphyseal plate
Tends to occur where cartilage are dying and calcification of the matrix is occuring

77
Q

Depressed

A

Broken bone portion is pressed inward
- typical of skull fracture

78
Q

Greenstick

A

Bone breaks incompletely, much in the way a green twig breaks. Only one side of the shaft breaks; the other side bends
- common in children, whose bones have relatively more organic matrix and are more flexible than those of adults

79
Q

Paget’s Disease

A

 Excessive and haphazard bone deposit and resorption cause bone to be
made fast and poorly
– Called Pagetic bone
– Very high ratio of spongy to compact bone and reduced mineralization
 Usually occurs in spine, pelvis, femur, and skull
 Rarely occurs before age 40
 Cause unknown: possibly viral
 Treatment includes calcitonin and bisphosphonates

Human Anatomy & Physiology 1 (8 decks)

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