Chapter 12 Flashcards

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1
Q

Bones are

A

Rigid mineralized structure that help perform five major roles in the body

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2
Q

The 5 major roles bones help perform in the body

A

Support
Protection
Movement
Mineral storage
Hematopoiesis

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3
Q

Bones are often called ——
There are —— bones in the humans body

A
  • bones are often called Osseous tissue
  • 80 axial, 126 appendicular (206)
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4
Q

The five shape categories of bones

A

Long bones
Short bones
Flat bones
Irregular bones
Sesamoid bones

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5
Q

Diaphysis

A

Main shaft-like portion, hollow, cylindrical and thick with compact bone

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6
Q

Epiphyses

A

At distal and proximal ends of the bone that provide points of muscle attachments and stability to joints

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7
Q

Articulate cartilage

A

Thin layer of hyaline cartilage

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8
Q

Periosteum

A

Dense, white fibrous membrane that covers bone (except joint surfaces)

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9
Q

Medullary cavity

A

“Marrow cavity”

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10
Q

Endosteum

A

Thin, fibrous membrane that covers the medullary cavity

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11
Q

Compact bone

A

External table: compact bone around the external (distal) cortex
Internal table: compact bone around the internal (proximal) cortex

Diploe: the region between the external and internal tables, which is composed of cancellous bone

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12
Q

Bones differ in?

A

Both size and shape
They also differ in the amount and proportion of two main types of bone:
Cortical (cortex-> outside) - dense and solid bone, primarily around the edge (outer layer) of bone structures
Cancellous - “spongy born”/ “trabecular bone”
- a network of thin branched crossbeams, which provide structural support of bone structures, primarily found in the center

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13
Q

Compact bone constitutes about —— of the total bone mass in adult bones

A
  • compact bone constituents about 80% of total bone mass in adults
  • cylinder-shaped structural units “Haversian systems”
  • Each osteon surround a Central Canal: delivers nutrient and removes wastes from the metabolically active, but imprisoned, bone cells
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14
Q

Structures of the osteon:
Lamellae:

A

Concentric lamellae: cylinder-shaped layers of calcified matrix in the osteon
Interstitial lamellae: layers of calcified matrix between osteons
Circumferential lamellae: lamellae that run along the inner circumference and outer circumference of a bone

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15
Q

Structures of the osteon

A

Lacunae: smalls spaces in bone matrix that contain tissue fluid and bone cells
Canaliculi: ultra-small canals that radiate in all directions from the lacunae and connect them to teach other and to the central canal
Central Canal: “Osteonal canal”/ “Haversian canal” - lined with endosteum and contains blood vessels,, lymphatic vessels and nerves

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16
Q

Bones are held together by and critical for what

A

Bones are held together by ligaments
Critical structures for support, movements and maintaining homeostasis

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17
Q

Bone to bone
Bone to muscle

A

Bone to bone = ligaments (Sprains)
Bone to muscle - tendons (strains)

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18
Q

The three bone cells

A

Osteoblast:
- “Bone-building” cells -> synthesize and secrete an organic matrix called osteoid
- collagen strands in the osteoid serve as a framework for the formation of hydroxyapatite crystals, which mineralizes the bone tissue
Osteoclast:
- “Bone-destroying” / “Bone-reabsorbing” cells
- Giant multinucleate cells which are responsible for the active erosion of bone minerals (hydrochloric acid (HCL) and collagenase)
Osteocyte:
- “mature cells”
- mature no dividing osteoblasts that have become surrounded by matrix and now lie within Lacunae

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19
Q

Cancellous bone consists of?

A

Cancellous bone consists of about 20% of total bone mass
- They contain no osteons but instead consist of crisscrossing bony branches called trabeculae (“trabecular bone”)

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20
Q

Fractal -> cancellous bone

A

They appear random, but they are more complex in orientation

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21
Q

Trabeculae are actually arranged along liens of ——

A

Arranged along lines of stress
- their size and orientation will there differs between individual bones according to the nature and magnitude of the applied load
- the direction of stresses created by the weight of the body

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22
Q

Wolff’s law

A
  • developed from the German Anatomist and surgeon Julius Wolff
  • “bone in a healthy person or animal will adapt to the loads under which it is placed”
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23
Q

Wolff’s law -> loading

A
  • if loading on a particular bone increases, the bone will removal itself over time to become stronger to resist the sort of loading
  • inversely, if the loading on a bone decreases, the bone will become less dense and weaker due to the lack of the stimulus to continued remodeling.
    - osteopenia & osteoporosis
24
Q

Myeloid tissue

A

Type of soft, diffuse connective tissues, often called bone marrow

25
Q

Two types of myeloid tissue

A

Red bone marrow: prominent in children and infants -> responsible for the production of red blood cells (RBCs)
Yellow bone marrow: prominent in older adults -> is a regular of hematopoietic stem cells being replaced with adipocytes

26
Q

Chondrocyte

A
  • product the tough, rubbery ground substance of cartilage
  • found in the lacuna ,similar to osteocytes
27
Q

Perichondrium

A

A connective tissue membrane that surrounds the cartilage mass

28
Q

Hyaline cartilage tissue

A
  • hyalos = glass
  • the most prevalent type of cartilage
  • found in support rings of the respiratory tract and covering the ends of bones
29
Q

Fibrocartilage tissue

A
  • strongest and most durable type of cartilage
  • matrix is rigid and filled with a dense packing of strong white collagen fibers
  • found in intervertebral disks and in the knee joint (menisci)
30
Q

Elastic cartilage joint

A
  • contains few collagen fibers but large number of very fine elastic fibers
  • providing flexibility
  • found in the ear and larynx
31
Q

Articulation:

A
  • a point of contact between the bones “joints”
  • joints may be classified into three major categories by using either structural of functional schemes
32
Q

Structural

A
  • according to the type of connective tissue
    - fibrous
    - cartilaginous
    - synovial
33
Q

Functional

A
  • according to the degree of movement they permit
    • synarthroses
    • amphiarthroses
    • diathroses
34
Q

Fibrous joints (synarthroses)

A
  • held together by fibrous connective tissue (type and amount will vary based on their articulation)
  • joints are immovable
  • the three subtypes: syndesmoses, sutures, gomphoses
35
Q

Amphiarthroses

A
  • joints that are articulated through either hyaline cartilage or fibrocartilage
  • offer limited movement, in certain circumstances
  • the two subtypes: synchondroses, symphyses
36
Q

Diarthroses

A
  • the body’s most mobile, numerous and anatomically complex joints (freely movable joints)
  • the three main groups: uniaxial (hinge and pivot), biaxial (saddle and condyloid), multiracial (ball-and-socket, gliding)
37
Q

Diarthroses -> uniaxial

A
  • synovial joints that permit movement around only one axis and in only one plane
  • hinge joints: those in which the articulating ends of the boned form a hinge-shaped unit (only back and forth movements); flexion and extension
  • Pivot joints: those in which a projection of one bone articulates with a ring or notch or another bone
38
Q

Diarthroses -> biaxial

A
  • synovial joints that permit movement around two perpendicular axes in two perpendicular planes
  • Saddle joint: those in which the articulating ends of the bone resemble reciprocally shaped miniature saddles (allows joints to swing in an arch)
  • condyloid joints: ellipsoidal joints, those in which a condyle fits into an elliptical socket
39
Q

Diathroses -> multiaxial

A
  • synovial joints that permit movements around three or more axes and in three or more planes
  • Ball-in-socket joints: a ball-shaped head of one bones fits into a concave depression on another, thereby allowing the first bone to move in many directions
  • Gliding joints: characterized by relatively flat articulating surfaces that allow limited gliding movements along various axes.
40
Q

Diarthroses seven structures

A

Joint capsule: sleeve-like extension of the periosteum of each articulating bone
Synovial membrane: moist, slippery membrane that lines the inner surface of the joint capsule
Articular cartilage: thin layer of hyaline cartilage covering and cushioning the articular surfaces of bones
Joint cavity: small space between articulating surfaces of the bones of the joint
Menisci (articular disk): pads of fibrocartilage located between the articulating ends of the bones in some Diarthroses
Ligament: strong cords of dense, white fibrous tissue
Bursae: a closed pillow-like structure, which consists of a synovial membrane filled with synovial fluid

41
Q

Ligaments

A

Attach bone to bone in a synovial joint (ACL -> anterior cruciate ligament in the knee)

42
Q

Tendons

A

Attach muscle to bone (Achilles tendon)

43
Q

Both tendons and ligaments are what

A

Composed of tough connective tissue containing collagen (strong, flexible)
- muscles further stabilize joints

44
Q

Osteogenesis

A
  • the forming of new bone
45
Q

Endochondral ossification

A
  • “bone formation in cartilage”
46
Q

Intramembranous ossification

A
  • bones formed within fibrous membrane
    • occurs within the flat bones
47
Q

Bone development in the embryo

A
  • Early fetal development: cartilage model forms (formed by chondroblasts)
  • later fetal development: osteoblasts replace cartilage with bone
  • childhood: primary and secondary ossification sites formed
  • adolescence: elongation at growth plates
48
Q

Hormone regulation

A
  • preadolescence: growth hormone stimulates bone lengthening
  • early adolescence: estrogen and testosterone stimulate bone lengthening
  • late adolescence: estrogen and testosterone cause replacement of cartilage growth plates with bone
49
Q

Intramembranous ossification

A
  • occurs within connective tissue membrane
  • Osteogenic stem cells -> osteoblasts
50
Q

Ossification centers:

A
  • clusters of differentiated osteoblasts
  • secreting matrix material and collagenous fibers
    - bones develop sheets fibrous connective tissue
51
Q

Endochondral ossification

A
  • occurs within cartilage, with bone formation spreading from end to end
    • cartilage develops periosteum
    • bones is deposited by osteoblast, which differentiate from stem cells on the inner surface of the periosteum
  • primary ossification center: develops when blood vessels enter the rapidly changing cartilage model at the midpoint of the diaphysis
  • secondary ossification center: develops in the epiphysis
52
Q

Bone remodeling

A
  • bone is constantly being broken down and reformed
  • as much as 18% of bone is recycled each year
  • this remodeling is regulated by hormones:
    - parathyroid hormone:
    - PTH secretion increases when blood levels of Ca++ fall; stimulates osteoclasts to secrete more bone-dissolving enzymes
    • calcitonin: calcitonin secretion increases when blood levels of Ca++ are high; stimulates osteoblasts to add calcium and phosphate to bone
53
Q

Sprains

A
  • stretched or torn ligaments
  • heal slowly (few cells and poor blood supply)
54
Q

Bursitis and tendinitis

A
  • inflammation of bursae or tendons
55
Q

Arthritis

Osteoporosis

A
  • inflammation of joints
    - osteoarthritis
    - rheumatoid arthritis

Osteoporosis: excessive bone loss

56
Q

Osteoclasts do what

A

They break down

57
Q

Osteoblasts do what

A

Build up