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BIO 150 A&P I > Unit 3: Ch 7 (Bone Tissue) > Flashcards

Unit 3: Ch 7 (Bone Tissue) Flashcards

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Biology 101 flashcards
1
Q
  • genic
A

to create

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2
Q
  • poietic
A

generation of

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3
Q

5 major types of bones & examples of each

A
  • Flat bones
    • Bone appears flat
    • Example: sternum
  • Long bones
    • Primarily in the appendicular skeleton
    • Example: femur
  • Short bones
    • Square, cube shape
    • Example: carpal region
  • Irregular bones
    • Example: calcaneus, vertebrae
  • Sesamoid bones
    • Develop in a tendon; purpose is to relieve stress on a muscle
    • Example: patellar
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4
Q

Components of osseous tissue & bones

A
  • Osseous tissue
    • Cells & matrix
  • Bones
    • Compact bone
    • Spongy bone and bone marrow
    • Cartilage
    • Adipose tissue
    • Nervous tissue
    • Dense connective tissue
    • Blood vessels
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5
Q

Bone cell lineage

A
  • Osteogenic, osteoblasts, and osteocytes belong to one cell lineage
  • Osteoclasts have an independent origin
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6
Q

4 principal bone cells

A
  1. Osteogenic cells
  2. Osteoblasts
  3. Osteocytes
  4. Osteoclasts
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7
Q

Bone development

A
  • Development can occur through ossification or osteogenesis
  • 2 methods in fetus and children
    • Intramembranous ossification
    • Endochondral ossification
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8
Q
A
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9
Q

Bone growth

A
  • Bones grow in two directions
    • Length (interstitial)
      • Result of cartilage growth
      • Multiplication of chondrocytes
      • Deposition of new matrix in the interior
    • Width (appositional)
      • Done at endosteum
      • Deposition of new bone at the surface
      • Primarily a response to environmental factors (ie working out)
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10
Q

Bone marrow

  • Description
  • Types & Description
A
  • Description
    • Soft tissue that occupies the marrow cavity of a long bone, the spaces amid the trabeculae of spongy bone, and the larger central canals
  • Types
    • Red bone marrow
      • Hematopoietic tissue (produces RBC, WBC & platellets)
      • Myeloid tissue
      • In adults, most of the red marrow is replaced by fatty yellow bone marrow
      • Always found in the axial skeleton
    • Yellow bone marrow
      • Post-puberty
      • Adipose tissue
      • No longer produces blood
      • In the event of severe or chronic anemia, it can transform back into red marrow and resume its hematopoietic function
      • Found in the appendicular skeleton (if present)
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11
Q

Bone remodeling

A
  • Bones remodel throughout life by absorbing old bone and depositing new bone
  • Process replaces ~ 10% of the skeletal tissue per year due to environmental needs
    • Repairs microfractures
    • Releases minerals into the blood
    • Reshapes bones in response to use and disuse
  • Notes
    • If a bone is little used, osteoclasts remove matrix and unnecessary mass
    • If a bone is heavily used or stress is consistently applied to a particular region of bone, osteoblasts deposit new osseous tissue and thicken it
    • The orderly remodeling of bone depends on a precise balance between deposition and resorption, between osteoblasts and osteoclasts
      • If one outplaces the other, or both processes occur too rapidly, various bone deformities, developmental abnormalities, and other disorders occur
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12
Q

Calcitonin

  • What does it do
  • How is it accomplished
A
  • Promotes mineralization and lowers blood Ca2+ concentration in children, but has little effect in adults
  • Secreted when the blood calcium concentration rises too high, and it lowers the concentration by:
    • Osteoclast inhibition
    • Osteoblast stimulation
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13
Q

Calcitriol

  • What is it
  • What does it do
  • How is it accomplished
A
  • Ligand receptor protein
  • Negative feedback loop
  • 3 organ systems make calcitriol
    • Integumentary
    • Digestive
    • Urinary
  • Released when we have low Ca levels
  • Promotes intestinal absorption of Ca2+ and phosphate
    • Stimulates osteoclast activity
    • Promotes resorption & mineralization
    • Reduces urinary excretion
  • Raises blood Ca2+ concentration in 3 ways
    • Absorption by the small intestine
    • Resorption from the skeleton
    • Resorption by the kidneys
  • A symport that originates in the kidney
  • Notes
    • Behaves as a hormone. It is called a vitamin only because it is added to the diet
    • Important for bone resorption and necessary for bone deposition
      • Without it, calcium and phosphate levels in the blood are too low for normal deposition
      • The result is a softness of the bones called rickets in children and osteomalacia in adults
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14
Q

Calcium functions

A
  • Neuron communication
  • Muscle contraction
  • Blood clotting
  • Exocytosis
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15
Q

Calcium homeostasis

  • What is it dependent upon
  • How is it regulated
A
  • Depends on a balance between
    • dietary intake
    • urinary and fecal losses
    • exchanges with the osseous tissue
  • A negative feedback loop that is regulated by 3 hormones
    • Calcitriol
    • Calcitonin
    • Parathyroid (PTH)
  • Linked to phosphate homeostasis
  • Notes
    • Skeleton exchanges about 18% of its calcium with the blood each year
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16
Q

Calcium overview

A
  • Cation with 2+ charge
  • Transportation in the body
    • 45% in ion form
    • 55% bound to plasma proteins
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17
Q

Calculus

A
  • Abnormal calcification
  • Ectopic ossification: bone growing in soft tissues
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18
Q

Compact (Dense) Bone

(aka Cortical Bone)

A
  • Outer shell of dense white osseous tissue
  • Shell encloses the marrow cavity, aka medullary cavity, which contains bone marrow
  • ~75% of skeleton
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19
Q

Composite

A
  • A combination of two basic structural materials
  • Bone is a ceramic and a polymer
    • Ceramic is hydroxyapatite and other minerals.
      • Enables a bone to support the weight of the body without sagging
    • Polymer is collagen
      • Protects a bone from fracture by dissipating shock. The bonds re-form when collagen is relieved of stress
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20
Q

Cortisol

  • What is it
  • What does it do
  • What happens if it is in excess?
A
  • Steroid hormone that inhibits osteoclast activity
  • If secreted in excess can cause osteoporosis/Cushing disease by:
    • stimulating osteoclasts to resorb bone
    • inhibiting growth hormone secretion
    • reducing bone deposition (inhibiting cell division and protein synthesis)
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21
Q

Epiphyseal plate & line

A
  • The epiphyseal plate serves as a growth area, allowing the diaphysis to increase in length until early adulthood
  • When growth stops, the epiphyseal plate is replaced with bone, then becoming the epiphyseal line
  • Both occur within the metaphysis
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22
Q

Endochondral ossification process

  • Description
  • Steps
A
  • Bone formation that begins in cartilage
  • Develops from a preexisting model composed of hyaline cartilage (fetal & adolescence)
  • Steps
    1. Formation of primary ossification center, bony collar, & periosteum
    2. Vascular invasion and formation of primary marrow cavity & secondary ossification center
    3. At birth, enlarged primary marrow cavity & secondary marrow cavity in one epiphysis
    4. Epiphyses fills with spongy bone
    5. Remaining cartilage in the plate is generally consumed and the gap closes
  • Notes
    • Bone development that begins in the fetus and continues into a person’s 20s
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23
Q

Epiphysial plate

A
  • A region of transition from hyaline cartilage to bone
  • Functions as a growth zone where the bones elongate
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24
Q

Epiphysial line

A
  • Ossified epiphysial plate
  • Point of fusion between the epiphysis and the diaphysis
  • Slightly denser spongy bone between the epiphysis and the diaphysis
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25
Q

Factors affecting bone homeostasis

A
  • Vitamins
    • A
    • B12
    • C
    • D
    • K
  • Anabolic steroids
    • Accelerate the transition of hyaline cartilage into compact bone
  • Rate of bone growth during puberty & adolescence
    • Estrogen: Higher in females, results in quicker conversion of the epiphyseal plate into epiphyseal line
    • Testosterone
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26
Q

Examples of flat bone

A
  • Most of the cranial bones
  • Sternum
  • Scapula
  • Ribs
  • Hip
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27
Q

Growth hormone

A
  • Stimulates bone elongation and cartilage proliferation at the epiphysial plate
    • Increases urinary excretion of Ca2+
    • Increases intestinal Ca2+ absorption
28
Q

hemo -

A

blood

29
Q

Insulin

A
  • Stimulates bone formation
  • Significant bone loss occurs in untreated diabetes mellitus
30
Q

Intramembranous ossification process

  • Description
  • Stages
A
  • Bone formation that begins in a membrane
  • Produces the flat bones of the skull, most of the clavicle, and part of the mandible
  • Stages
    1. Deposition of osteoid tissue into embryonic mesenchyme
    2. Calcification of osteoid tissue and entrapment of osteocytes
    3. Honeycomb of spongy bone with developing periosteum
    4. Filling of space to form compact bone at surfaces, leaving spongy bone in the middle
31
Q

Examples of irregular bones

A
  • Vertebrae
  • Some skull bones
32
Q

List the zones of metaphysis

A
  1. Zone of reserve cartilage
  2. Zone of cell proliferation
  3. Zone of cell hypertrophy
  4. Zone of calcification
  5. Zone of bone deposition
33
Q

Long bones

  • Primary long bones
  • Principal features
A
  • Most important bones in movement
  • Include
    • Humerus
    • Ulna/radius
    • Femur
    • Tibia/fibula
    • Metacarpals/metatarsals
    • Phalanges
  • Principal features
    • Diaphysis (shaft): provides leverage
    • Epiphysis (expanded head at each end): provides added surface area for the attachment of tendons and ligaments
34
Q

Metaphysis

A
  • The neck portion of a long bone between the epiphysis and the diaphysis
  • Contains the growth plate, the part of the bone that grows during childhood, and as it grows it ossifies near the diaphysis and the epiphyses
35
Q

Mineral deposition (mineralization)

A
  • Hardening process of osseous tissue
  • A crystallization process in which calcium, phosphate, and other ions are taken from the blood plasma and deposited in bone tissue, mainly as crystals of hydroxyapatite
36
Q

Mineral resorption

A
  • Process of dissolving bone
  • Releases minerals into the blood
  • Resorption is carried out by osteoclasts
37
Q

Organ systems important for calcium

A
  • Integumentary
  • Digestive
  • Urinary
38
Q

Osseous tissue

A
  • Connective tissue in which the matrix is hardened by the deposition of calcium phosphate and other minerals
39
Q

Osteoblasts

A
  • Bone-forming cell that arises from an osteogenic cell, deposits bone matrix, and eventually becomes an osteocyte
40
Q

Osteoclasts

  • Description
  • Components
A
  • Macrophage of the bone surface that dissolves the matrix and returns minerals to the ECF
  • Comes from a blood stem cell lineage different than the osteoblast
  • Components
    • Multinucleated
    • Several lysosomes
    • Ruffled border
41
Q

Describe osteocyte & osteoclast development

A
42
Q

Osteocytes

A
  • Mature bone cell that is formed when an osteoblast becomes surrounded by its own matrix and trapped in lacuna
43
Q

Osteogenesis

A

Bone-building activity

44
Q

Osteogenic Cells

A
  • Stem cells that develop from embryonic mesenchyme
  • Give rise to most other bone cell types
  • Occur in the endosteum and inner layer of the peristeum
45
Q

Osteon (aka Haversian system)

A
  • The basic structural unit of compact bone
  • Consists of a central canal and its lamellae
46
Q

Parathyroid hormone (PTH)

A
  • Indirectly activates osteoclasts, which resorb bone and raise blood Ca2+ concentration
    • Inhibits urinary Ca2+ excretion
    • Promotes calcitriol synthesis
  • PTH raises Ca level by 4 mechanisms:
    1. Binds to receptors on the osteoblasts
    2. Promotes calcium reabsorption by the kidneys
    3. Promotes the final step of calcitriol synthesis
    4. Inhibits collagen synthesis by osteoblasts, thus inhibiting bone deposition
47
Q

Perforating canals

A

Join central canals of an osteon

48
Q

Periosteum

A
  • Sheath that covers a bone
  • Tough, outer fibrous layer of collagen and an inner osteogenic layer of bone-forming cells
49
Q

Phosphate homeostasis

  • Description
  • Regulated by
A
  • Required for bone strength, DNA, RNA, ATP & phospholipids
  • Able to act as a buffer
  • Anion
  • _​_Regulated by
    • Calcitriol: Calcitriol raises the phosphate level by promoting its absorption from the diet by the small intestine
    • PTH: Parathyroid hormone lowers the blood phosphate level by promoting its urinary excretion
50
Q

Examples of short bones

A
  • Wrist
  • Ankle
51
Q

Skeleton functions/roles

A
  • Support
  • Protection: Protect critical organs
  • Movement: Interrelationships between skeleton & muscles
  • Electrolyte balance
  • Acid-base balance
  • Blood formation: how bone marrow gives rise to RBC, WBC, & platelets
52
Q

Spongy Bone

A
  • Always enclosed by a shell of compact bone
    • Loosely organized form of osseous tissue
    • Few osteons and no central canals
  • Spongelike appearance composed of
    • Spicules
    • Trabecule
    • Red bone marrow
    • Interstitial lamellae
      • Osteocytes
      • Lacunae
      • Canaliculi
  • Skeleton is ~ 25% spongy bone
53
Q

Testosterone

A
  • Stimulates osteoblasts and promotes protein synthesis, thus promoting adolescent growth and epiphysial closure
54
Q

Thyroid hormone

A
  • Essential to bone growth
  • Enhances synthesis and effects of growth hormone
  • Excesses can cause
    • hypercalcemia
    • increased Ca2+ excretion in urine
    • osteoporosis
55
Q

What does vitamin A do?

A
  • Promotes glycosaminoglycan (chondroitin sulfate) synthesis
56
Q

What is vitamin C (ascorbic acid) required for?

A
  • Collagen synthesis
  • Bone growth
  • Fracture repair
57
Q

What is the study of bones called?

A

Osteology

58
Q

Wolff’s Law of Bone

A
  • The architecture of a bone is determined by the mechanical stresses placed upon it, and the bone thereby adapts to withstand them
  • Balance of osteoblast and osteoclast activity
  • An example of the complementarity of form and function, showing that the form of a bone is shaped by its functional experience
  • Example: Tennis players and “racket arm”
59
Q

Zone of bone deposition

A
  • Zone 5
    • Breakdown of lacuna walls, leaving open channels
    • Death of chondrocytes
    • Bone deposition by osteoblasts, forming trabeculae of spongy bone
60
Q

Zone of calcification

A
  • Zone 4
    • Temporary calcification of cartilage matrix between columns of lacunae
61
Q

Zone of cell proliferation

A
  • Zone 2
    • Chondrocytes multiply and line up in rows of small flattened lacunae
62
Q

Zone of hypertrophy

A
  • Zone 3
    • Cessation of mitosis
    • Enlargement of chondrocytes and thinning of lacuna walls
63
Q

Zone of reserve cartilage

A
  • Zone 1
    • Typical histology of resting hyaline cartilage
64
Q

3 main areas of a long bone

A
  • Epiphyses
  • Metaphyses
  • Diaphysis
65
Q

What is the physiological significance of the epiphysial line?

A

Because its presence indicates that the bone has completed in growth

BIO 150 A&P I (25 decks)

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