U2 Lecture 1 Flashcards

1. List and describe the functions of the skeletal system 2. Differentiate between the two divisions of the skeletal system and give examples 3. Describe the classification of bone based on shape, giving examples for each type 4. Describe the anatomy of flat bones and long bones 5. List and describe the functions of the 4 cell types found in bone 6. Discuss modeling and remodeling of bone

1
Q

Functions of the skeletal system

A
  1. Support
  2. Protection from abrasions
  3. Mineral storage
  4. Triglyceride storage
  5. Red and white blood cell formation (hemopoiesis)
  6. Leverage (assistance in movement)
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2
Q

Composition of the skeletal system

A
  • The skeleton is all bones and connective tissues which attach them to each other (cartilage, ligaments, joints etc)
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3
Q

What is unique of each bone?

A

Each bone is an organ containing osseous (connective) tissue, blood vessels, nerves, lymphatic vessels, cartilage, and connective tissue coverings

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4
Q

What is found within bones?

A
  • articular cartilage
  • spongy bone (containing red bone marrow)
  • red bone marrow
  • epiphyseal line
  • compact bone
  • endosteum (lines medullary cavity)
  • nutrient artery
  • medullary cavity (contains yellow bone marrow in adults)
  • periosteum
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5
Q

Divisions of the skeletal system

A

Axial and Appendicular skeleton

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6
Q

Types of bones

A

long (humerus), short (trapezoid, wrist bone), flat (sternum), irregular (vertebra), sesamoid (patella), sutural (skill bones), and pneumatized (ethmoid)

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7
Q

Anatomy of flat bones

A

compact bone and spongy bone (diploe)

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8
Q

Anatomy of sutural bones

A
  • found between suture in the skull, not everyone has them
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9
Q

Anatomy of long bones

A
  • Sections: epiphysis, metaphysis and diaphysis

- Components: spongy bone, compact bone, endosteum, periosteum, medullary cavity and nutrient artery

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10
Q

Importance of the endosteum and the periosteum

A

Important for bone growth and remodeling

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11
Q

Define Periosteum

A
  • Connective tissue membrane covering external surface of bone
  • continuous with tendons, connective tissue of joints
  • attached to bone matrix via perforating fibers
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12
Q

Periosteum layers

A
  1. Outer fibrous layer

2. Inner osteogenic layer

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13
Q

Define endosteum

A
  • Lining inner surfaces of bone including marrow cavity, trabecullae of spongy bone, canals of compact bone
  • Contains osteogenic cells (important for bone growth and remodeling)
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14
Q

Define osteology

A

The study of bone tissue

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15
Q

Main composition of bone

A

Connective tissue

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16
Q

What makes up connective tissue?

A

Extracellular matrix and cells

17
Q

What makes up the extracellular matrix?

A

Ground substance and fibers

18
Q

Define ground substance

A

Organic and inorganic compoents

19
Q

What type of fibers are found in the extracellular matrix?

A

Collagen fibers

20
Q

What are the 4 types of cells found within bones?

A

Osteogenic cells, osteoblasts, osteocytes and osteoclasts

21
Q

Define osteogenic (osteoprogenitor) cells

A

Stem cells that are formed from mesenchyme (embryonic connective tissue)

22
Q

What type of cells do osteogenic cells form?

A

Osteoblasts

  • osteogenic cells go through mitosis to form daughter osteogenic cells and then differentiate into osteoblasts
23
Q

Define osteoblasts

A

Cells that form bone matrix and eventually builds bone

  • They synthesize organic components of matrix and initiate calcification (takes calcium from blood and deposit it within matrix by exocytosis)
  • They are immature cells
24
Q

What type of cells do osteoblasts form?

A

Osteocytes

25
Q

Define osteocytes

A

Mature cell involved in maintaining bone tissue

26
Q

Define osteoclasts

A

Break down bone for bone resorption

  • They release proteolytic enzymes and acids to degrade collagen and release minerals to blood
  • Formed from myeloid stem cells (not osteogenic cells)
27
Q

Define bone modeling

A

Bone is formed by osteoblasts without prior bone resorption

  • happens during growth
  • produces change in bone size and shape
28
Q

Define bone remodeling

A

Occurs when bone is first resorbed by osteoclasts and then formed in the same location by osteoblasts

  • happens throughout life
29
Q

Goal of modeling and remodeling

A

Achieve strength for loading and lightness for mobility

  • deposit bone where it is needed to achieve peak strength (during growth)
  • remove damaged bone where it’s not needed to avoid bulk and maintain strength (during adulthood)
30
Q

Define fatigue damage

A

damage to bone after repeated loading and wear

31
Q

How do cells react to fatigue damage?

A
  1. Osteocytes detect location and magnitude of damage
  2. Osteoclasts remove damage
  3. Osteoblasts replace it with new bone
  4. Restores bone’s material composition, micro- and macro-architecture
32
Q

Steps of bone remodeling

A
  1. Activation: pre-osteoclasts are stimulated and differentiate under the influence of cytokines and growth factors into mature active osteoclasts
  2. Resorption: osteoclasts digest mineral matrix (old bone)
  3. Reversal: end of resorption, recruitment of osteoblasts
  4. Formation: osteoblasts synthesize new bone matrix
  5. Quiescence: osteoblasts become resting bone lining cells on the newly formed bone surface
33
Q

Osteoclast characteristics

A
  1. Sealing zone
  2. Ruffled Border
  3. Functional Secretory Domain