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Biol 223 > Chapter 6 Bones > Flashcards

Chapter 6 Bones Flashcards

1
Q

What are the main organs of the skeletal system?

A

Bones

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2
Q

Aside from osseus tissue, what are bones composed of?

A
  1. dense irregular connective tissue.
  2. dense regular connective tissue.
  3. bone marrow.
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3
Q

What are the 6 functions of the skeletal system?

A
  1. Protection: being the hardest substance in the body provides a strong shell for important organs such as brain, heart, and lungs.
  2. Mineral storage & acid-base homeostasis: bones store calcium, phosphorus, and magnesium salts (also found in blood) are vital to maintenance of electrolyte and acid-base balance.
  3. Blood cell formation: Bones house red bone marrow that performs hematopoiesis aka blood cell formation.
  4. Fat storage: yellow bone marrow contains adipocytes that contain triglycerides that can be used as fuel.
  5. Movement: Bone serves as attachment sites for skeletal muscles that make movement when they pull on bones.
  6. Support: The skeleton supports the body and provides its structural framework.
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4
Q

How many bones do we have?

A

206

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5
Q

What are the 5 classifications of bones?

A
  1. Long bones: classified by shape, not size. Ex: most of the arm and leg bones, bones of the hands, fingers, feet and toes.
  2. Short bones: classified by shape, not size. Roughly as long as they are wide. Ex: carpals and tarsals.
  3. Flat bones: Thin and broad. Ex: most skull bones, clavicles, ribs, sternum, and bones of pelvis.
  4. Irregular bones: Don’t fit into another shape category. Ex: vertebrae, certain skull bones.
  5. Sesamoid bones: sesame shaped. Specialized bones within tendons that give mechanical advantage. Ex: patella
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6
Q

What is the periosteum?

A

is a membrane composed of dense
irregular collagenous connective tissue that forms a covering, rich with blood vessels and nerves, which surrounds the outer surface of long bones

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7
Q

What are perforating fibers (aka Sharpey’s fibers)?

A

are made of collagen that anchors the periosteum firmly to the underlying bone surface by penetrating deep into the bone matrix.

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8
Q

The shaft of long bone is called? What is the cavity inside the shaft called?

A

Diaphysis. Medullary aka Marrow cavity.

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9
Q

The rounded ends of long bone is called? And what are these covered in?

A

Epiphyses. Covered in hyaline cartilage (articular)

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10
Q

What are the two bone textures?

A
  1. Compact bone: hard, dense outer bone. Resists stresses, linear compression, and twisting forces.
  2. Spongy bone aka cancellous bone: forms a framework of bony struts that resists force from many directions and houses bone marrow.
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11
Q

What is endosteum?

A

The membrane that covers the bony struts of spongy bone and all inner surfaces of bone.

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12
Q

What are epiphyseal lines?

A

are found separating both
proximal and distal epiphyses from the diaphysis. These are the remnants of the epiphyseal plates, or growth plates, which is a line of hyaline cartilage found in the developing bones of children.

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13
Q

What 5 things do short, flat, irregular, and sesamoid bones lack?

A

diaphyses, epiphyses, medullary cavity, epiphyseal lines, or epiphyseal plates.

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14
Q

What are epiphyseal plates?

A

growth plates: a line of hyaline cartilage from which a long bone grows in length in children.

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15
Q

What is the internal structure of short, flat, irregular, and sesamoid bones composition?

A

Its like a sandwich with 2 layers of compact bone with a layer of spongy bone (that contains the marrow) in the middle

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16
Q

what is the spongy layer called in flat bones?

A

diploe, meaning fold.

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17
Q

What are sinuses?

A

Hollow, air-filled spaces, which reduces bone weight. Found in Some flat and irregular bones of the skull.

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18
Q

How are the external structures of all bones similar?

A

They are all covered in periosteum attached by perforating fibers, and well supplied by blood vessels and nerves.

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19
Q

What is red bone marrow composed of?

A

of loose connective tissue that supports islands of blood-forming hematopoietic cells.

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20
Q

Where is red marrow found in adults?

A

in the pelvis, proximal femur, humerus, vertebrae, ribs, sternum, clavicles, and scapulae. Also in skull, but degenerates w/age.

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21
Q

What is yellow marrow composed of? What does it store?

A

blood vessels and adipocytes. It stores triglycerides.

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22
Q

Why do children have more red marrow vs. adults who have more yellow marrow?

A

Children need a constant supply of blood because of their rapid growth. By age 5, yellow marrow starts to replace red until adulthood is reached.

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23
Q

What is the composition of osseous tissue?

A

extracellular matrix with a small population of cells scattered throughout.

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24
Q

Concerning the ECM of osseous tissue, what is the composition of the inorganic matrix, and what is its percentage?

A

consists of minerals (calcium salts). It makes up 65% of the total weight of the bone.
* also found in the inorganic matrix is bicarbonate, potassium, magnesium, and sodium*

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25
Q

Concerning the ECM of osseous tissue, what is the composition of the organic matrix, and what is its percent?

A

consists of collagen fibers and the usual ECM components. It makes up 35%

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26
Q

Bone stores what % of calcium ions in the body? What else does it store?

A

85%. It store phosphorus.

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27
Q

Calcium and phosphorus exist as a large molecule called? What is the benefit of this molecule?

A

hydroxyapatite crystals. Its benefit is that its super strong and resistant to compression.

28
Q

What is the organic matrix known as? What does it consist of?

A

Osteoid. It consists of protein fibers, proteoglycans, glycosaminoglycans, glycoproteins, and bone-specific proteins.

29
Q

What is the predominant protein fiber in bone, and what is its function?

A

Collagen fibers. They form cross-links with one another and resist torsion and tensile force. They align with hydroxyapatite crystals to enhance bone’s hardness.

30
Q

What is the function of glycosaminoglycans and proteglycans in the organic matrix? What do the glycoproteins do?

A

They create an osmotic gradient that draws water into the osteoid, which helps the tissue resist compression. Glycoproteins act as cellular glue binging to both hydroxyapatite and bone cells.

31
Q

What is the function of osteoblasts? Where are they found? What do they stem from?

A

They form new bone through bone deposition. They secrete organic matrix to help in the formation of inorganic matrix. They are found in the inner periosteum and endosteum. They stem from osteogenic cells that are triggered by chemical signals.

32
Q

What is the function of osteocytes? Where are they found?

A

They are mostly metabolically inactive, but they secrete chemicals to maintain bone ECM and recruit osteocytes to build bone in areas of tension. Found surrounded by secreted bone matrix in small cavities called lacuna.

33
Q

What is the function of osteoclasts? What are they derived from? Where are they found?

A

They secrete hydrogen ions and enzymes from their ruffled borders that dissolves the inorganic and organic matrix. They absorb the remnants and send it back to the blood stream. They are derived from the fusion of cells in the bone marrow, and found on internal and external surfaces of bone.

34
Q

What is an osteon? What is it composed of?

A

aka Haversian system. It is a subunit of bone. They are composed of:
1. Lamellae: layered ring structures of collagen fibers running in opposite directions of each other to create strength to resist twisting and bending in multiple directions.

  1. Central canal: an endosteum-lined hole found in the center of each osteon where blood vessels and nerves reside to supply the bone.
  2. Lacunae: the small cavities found between lamellae that are filled with extracellular fluid.Osteocytes reside here.
  3. Canaliculi: a network of small passageways, or canals in the bone matrix that connect neighboring lacunae. Cytoplasmic extensions of osteocytes extend through these networks allowing for communication.
35
Q

Osteons are not permanent structures as osteoclasts breakdown and osteoblasts rebuild bone matrix depending on the
needs of the bone or the body. This process leaves behind the following characteristic features in compact bone…

A
  1. interstitial lamellae: remnants of reabsorbed osteons found filling spaces btw circular osteons
  2. Circumferential Lamellae: are the outer and inner layers of lamellae just inside the periosteum and at the boundary with spongy bone. These add strength to the bone.
  3. Perforating canals: or Volkmanns’ canals, originate from the blood vessels in the periosteum and travel in right angles or perpendicular to the central canals of neighboring osteons and serve to connect them with one another.
36
Q

What are trabeculae? What are they made of? How do they get their blood supply?

A

Branching ribs of bone found in spongy bone that are covered in endosteum. They form a protective framework around bone marrow. They do not contain osteons. They are composed of concentric lamellae. They get blood directly from bone marrow.

37
Q

What is the process of bone formation called? When does it begin and finish?

A

Ossification. Begins in the embryonic period and continues until age 7.

38
Q

The 2 types of ossification aka osteogenesis.

A
  1. intramembranous: are built on a model or a starting material made of a membrane of embryonic connective tissue. Many flat bones, bones of the skull, and clavicles form this way.
  2. endochondral: are built on a model of hyaline cartilage.
39
Q

What is primary bone and secondary bone?

A

Primary: aka woven bone, the first bone formed, gets reabsorbed by osteoclasts and replaced by.. secondary bone aka lamellar bone (has more inorganic matrix and strength.

40
Q

What are the steps of intermembranous ossification?

A
  1. Osteoblasts develop in the primary ossification center. Mesenchymal cells differentiate into osteogenic cells then into osteoblasts.
  2. Osteoblasts secrete organic matrix. In a few days time, calcium salts and other components of the inorganic matrix are deposited in a process called calcification.As the bone hardens, osteoblasts get trapped in lacunae and become osteocytes.
  3. Early Spongy Bone is formed as osteoblasts continue laying down new bone and forming trabeculae. Periosteum (by mesenchymal cells) and bone marrow (by vascular tissue) begin to form.
  4. Early compact bone is formed by the calcification of spongy bone.
    * Larger bones have more than one primary ossification center which leads to bones fusing together. Ex: soft spots of infants skull fusing together.
41
Q

All bones in the body below the head (minus the scaps) for by endochondral ossification. What are the steps?

A
  1. Chondroblasts in perichondrium differentiate into osetogenic cells then into osteoblasts. The perichondrium becomes the periosteum.
  2. Bone begins to ossify from outside as:
    a. osteoblasts build the bone collar on the outside of the bone and
    b. internal cartilage begins to calcify and chondrocytes die.
  3. In the primary ossification center, osteoblasts replace the calcified cartilage with early spongy bone, and the secondary ossification centers and medullary cavity develop.
  4. As the medullary cavity enlarges, the remaining cartilage is replaced by bone, and epiphyses finish ossifying.
42
Q

The hyaline cartilage model is composed of chondrocytes, collagen, and ECM, all surrounded by a connective tissue membrane called the… and immature cartilage cells called…

A

perichondrium. chondroblasts.

43
Q

Long bones have …… ossification centers found in their …..?

A

secondary ossification centers found in their epiphyses.

44
Q

What are the 2 locations where hyaline cartilage persists after endochondral ossification?

A
  1. epiphyseal plates (which disappear in adulthood)

2. articular cartilage (joints)

45
Q

What is the name of the process that long bones grow by? It involves the division of what? Where does this happen?

A
  1. Longitudinal growth.
  2. Involves the division of chondrocytes (not osteoblasts or osteocytes).
  3. Happens in epiphyseal plates (on the side of the diaphysis).
46
Q

What are the 5 zones of the epiphyseal plate?

A
  1. Zone of Reserve cartilage: Doesn’t actively divide, but can be called upon if needed.
  2. Zone of proliferation: Actively dividing chonrocytes in lacunae.
  3. Zone of hypertrophy and maturation: chondrocytes enlarge and mature.
  4. Zone of calcification: chondrocytes die and calcify.
  5. Zone of Ossification: calcified cartilage is replaced with bone.
47
Q

The most mitotic activity in the epiphyseal plate occurs in the…

A

zone of proliferation

48
Q

When does the zone of proliferation begin to overtake the ephipyseal plate? When do the plates seal into epiphyseal lines?

A
  1. Between 12-15 years old when the reate of mitosis slows, but ossification continues.
  2. between 18-21 years old.
49
Q

What is the name of the process of bone growth in width? Which type of bone grows in width?

A

Appositional growth. All bones.

50
Q
  1. Appositional growth does not result in the immediate formation of osteons; instead, new ………………… lamellae are formed.
A

circumferential.

51
Q

True or False? Bones may continue to increase in width even after the epiphyseal plates have closed and the bone is no longer lengthening.

A

True.

52
Q

Which hormone secreted by the anterior pituitary gland, enhances protein synthesis and cell division in nearly all tissues, including bone tissue?

A

Growth hormone

53
Q

One of the main factors that affects bone growth is?

A

Hormones

54
Q

The effects of testosterone on bone growth

A
  1. Causes appositional bone growth in males which makes their bones much thicker and have greater calcium deposits.
  2. Increases the rate of mitosis at epiphyseal plate causing growth spurts.
  3. Accelerates closure of epiphyseal plates.
55
Q

The effects of estrogen on bone growth

A
  1. increases longitudinal bone growth.
  2. Inhibits osteoclasts.
  3. Accelerates closure of epiphyseal plates quicker than males, resulting in women being shorter than men.
56
Q

What is bone remodeling?

A

The process of bone deposition by osteoblasts (in the periosteum and endosteum), and bone resorption by osteoclasts

57
Q

Why does the body remodel bone?

A
  1. to maintain calcium ion homeostasis.
  2. replacement of primary bone with secondary bone.
  3. replacement of brittle bone with new bone.
  4. bone repair.
  5. for adaptation to tension and stress.
58
Q

What is compression? How do bones respond to continuous compression?

A

The act of squeezing or pressing together (like the body’s weight pressing the bones against the ground). Osteoblasts deposit more bone in response to compression.

59
Q

What is Tension, and how do bones respond to it?

What is pressure, and how do bones respond to it?

A
  1. Tension is a stretching force. Stimulates osteoblast stimulated, and deposit bone.
  2. Pressure is continuous downward force. Stimulates resorption by osteoclasts.
60
Q

What are the effects of testosterone and estrogen on bone remodeling?

A

Testosterone: promotes bone deposition
Estrogen: depresses osteoclast activity.

61
Q

As we age, we produce less testosterone and estrogen which diminishes …………. synthesis in bones.

A

protein

62
Q

What dietary factors influence bone remodeling, and how?

A
  1. calcium ion: for bone deposition.
  2. Vitamin D: for calcium ion absorption.
  3. Vitamin C: For collagen synthesis.
  4. Vitamin K
  5. Protein: For osteoblasts to synthesize collagen.
63
Q

When calcium ion levels drop in the blood it is detected by………… which then secrete …………. What is the effect/response?

A
  1. Parathyroid gland cells (is the receptor and the control center)
  2. Parathyroid hormone
  3. PTH triggers osteoclasts to breakdown bone to release calcium ions into the blood., and triggers the small intestine to absorb the ions.
64
Q

When calcium levels increase, what is the receptor/control center? What is the hormone that is released? What does this hormone do?

A
  1. Thyroid gland cells are the receptor and control center.
  2. Calcitonin
  3. Calcetonin pulls calcium ions out of the blood, and deposits them into the bone.
65
Q

When is calcetonin most and least active?

A

Most active in bone growth years. Less active in adult years.

66
Q

What is a simple fracture? What is a compound fracture?

A

Simple: Skin stays closed around fracture.
Compound: when skin is open

67
Q

What are the 4 steps of fracture healing?

A
  1. A hematoma (blood clot) fills in the gaps.
  2. Soft Callus (a mixture of hyaline cartilage and collagenous connective tissue) is formed.
  3. Bone callus (a collar of primary bone formed by osteoblasts) is formed.
  4. Bone callus is remodeled and replaced by secondary bone.

Biol 223 (13 decks)

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