NU PATHO UNIT 5 PRACTICE QUESTIONS
WITH COMPLETE SOLUTIONS
◉ Bone Matrix:
Made of extracellular elements of bone (35% organic, 65%
inorganic). Major organic components are collagen fibers; major
inorganic elements are calcium and phosphate minerals. Water
makes up 5-8%.
Answer: Collagen Fibers- major organic component of bone
matrix. 90% type 1 collagen which is made by osteoblasts
(collagen 1 essential to bone strength). Collagen molecules
combine into threes to form fibrils. These fibrils overlap one
another with a space between called hole zones. Mineral crystals
are deposited into these gaps. After mineral deposition, the fibrils
are linked together and twist to form ropelike fibers (this gives
bone its tensile strength). Collagen is the most abundant
macromolecule in the body (consists of 1/3 of all protein and
provides structure to nearly all tissues).
Proteoglycans- large complexes of numerous polysaccharides
attached to a common protein core. Hyaline cartilage is made of
specific proteoglycans. They strengthen bone by forming
compression-resistant networks between collagen fibrils. Also
control transport and distribution of ions (particularly calcium)
through the bone matrix, playing a role in calcium deposition and
calcification.
Glycoproteins- carbohydrate-protein complexes that control
collagen interactions that lead to fibril formation. Also may play a
role in calcification. Osteocalcin- may play a part in bone
,reabsorption by recruiting osteoclasts. Osteonectin- thought to
bind calcium in bones. Laminin- stabilizes basement membrane is
bones and is most effective in neuron and axon growth. Bone
albumin- identical to serum albumin; transports essential
elements to and from bone cells and maintains osmotic pressure
of bone fluid. a- Glycoprotein affinity for calcium 40x that of
albumin and thought to play an important role in the calcification
of growing bone and may facilitate bone resorption by activating
osteoclasts.
◉ Bone minerals/mineralization
Answer: Mineralization is the final step in bone formation, after
collagen synthesis and fiber formation. 2 stages: (1) formation of
initial mineral deposit (initiation), and (2) proliferation of
additional mineral crystals (growth). Majority of mineral content
in the body is an analog of naturally occurring hydroxyapatite
(HSP). Calcium and phosphate undergo chemical changes to
render a final product of insoluble HAP.
◉ Types of Bone Tissue-
Answer: Compact bone (cortical bone) and spongy bone
(cancellous bone). Compact bone makes up 85% of the skeleton.
The major difference between the two types is the organization of
elements. Compact bone is highly organized, solid, and strong. The
basic structural unit in compact bone is the Haversian system. In
the center is the Haversian canal which contains one or two blood
vessels and nerve fibers. The blood vessels in the canal
communicate with those on the surface and marrow cavity to
transport nutrients and wastes. Spongy bone is less complex and
lacks haversian canals. In spongy bone the lamellae are not
, arranged in concentric layers but in plates or bars termed
trabeculae that branch and unite with one another to form an
irregular meshwork.
◉ Characteristics of Bone
Answer: All bones are covered with a double-layered connective
tissue called the periosteum. 206 bones.
Axial skeleton- 80 bones that make up the skull, vertebral column,
and thorax.
Appendicular skeleton- 126 bones that make up the upper and
lower extremities, the shoulder girdle, and pelvic girdle.
Long bone- longer than they are wide. The diaphysis (narrow
tubular midportion) can tolerate bending forces and contains
yellow marrow, which assists red marrow in hematopoiesis only
during times of stress. The epiphysis (broad end) allows weight
bearing to be distributed over a large area and contains red
marrow. In a child, the epiphysis is separated by the metaphysis
by the epiphyseal (growth) plate. After puberty, the epiphyseal
plate calcifies and the two merge.
Flat bones- ribs, scapulae. Contain two plates of compact bone
separated by a layer of spongy bone. Short bones- wrist, ankle.
Often cuboidal in shape. Spongy bone covered by a thin layer of
compact bone.
Irregular bones- vertebrae, mandible, or other facial bones.
◉ Remodeling:
WITH COMPLETE SOLUTIONS
◉ Bone Matrix:
Made of extracellular elements of bone (35% organic, 65%
inorganic). Major organic components are collagen fibers; major
inorganic elements are calcium and phosphate minerals. Water
makes up 5-8%.
Answer: Collagen Fibers- major organic component of bone
matrix. 90% type 1 collagen which is made by osteoblasts
(collagen 1 essential to bone strength). Collagen molecules
combine into threes to form fibrils. These fibrils overlap one
another with a space between called hole zones. Mineral crystals
are deposited into these gaps. After mineral deposition, the fibrils
are linked together and twist to form ropelike fibers (this gives
bone its tensile strength). Collagen is the most abundant
macromolecule in the body (consists of 1/3 of all protein and
provides structure to nearly all tissues).
Proteoglycans- large complexes of numerous polysaccharides
attached to a common protein core. Hyaline cartilage is made of
specific proteoglycans. They strengthen bone by forming
compression-resistant networks between collagen fibrils. Also
control transport and distribution of ions (particularly calcium)
through the bone matrix, playing a role in calcium deposition and
calcification.
Glycoproteins- carbohydrate-protein complexes that control
collagen interactions that lead to fibril formation. Also may play a
role in calcification. Osteocalcin- may play a part in bone
,reabsorption by recruiting osteoclasts. Osteonectin- thought to
bind calcium in bones. Laminin- stabilizes basement membrane is
bones and is most effective in neuron and axon growth. Bone
albumin- identical to serum albumin; transports essential
elements to and from bone cells and maintains osmotic pressure
of bone fluid. a- Glycoprotein affinity for calcium 40x that of
albumin and thought to play an important role in the calcification
of growing bone and may facilitate bone resorption by activating
osteoclasts.
◉ Bone minerals/mineralization
Answer: Mineralization is the final step in bone formation, after
collagen synthesis and fiber formation. 2 stages: (1) formation of
initial mineral deposit (initiation), and (2) proliferation of
additional mineral crystals (growth). Majority of mineral content
in the body is an analog of naturally occurring hydroxyapatite
(HSP). Calcium and phosphate undergo chemical changes to
render a final product of insoluble HAP.
◉ Types of Bone Tissue-
Answer: Compact bone (cortical bone) and spongy bone
(cancellous bone). Compact bone makes up 85% of the skeleton.
The major difference between the two types is the organization of
elements. Compact bone is highly organized, solid, and strong. The
basic structural unit in compact bone is the Haversian system. In
the center is the Haversian canal which contains one or two blood
vessels and nerve fibers. The blood vessels in the canal
communicate with those on the surface and marrow cavity to
transport nutrients and wastes. Spongy bone is less complex and
lacks haversian canals. In spongy bone the lamellae are not
, arranged in concentric layers but in plates or bars termed
trabeculae that branch and unite with one another to form an
irregular meshwork.
◉ Characteristics of Bone
Answer: All bones are covered with a double-layered connective
tissue called the periosteum. 206 bones.
Axial skeleton- 80 bones that make up the skull, vertebral column,
and thorax.
Appendicular skeleton- 126 bones that make up the upper and
lower extremities, the shoulder girdle, and pelvic girdle.
Long bone- longer than they are wide. The diaphysis (narrow
tubular midportion) can tolerate bending forces and contains
yellow marrow, which assists red marrow in hematopoiesis only
during times of stress. The epiphysis (broad end) allows weight
bearing to be distributed over a large area and contains red
marrow. In a child, the epiphysis is separated by the metaphysis
by the epiphyseal (growth) plate. After puberty, the epiphyseal
plate calcifies and the two merge.
Flat bones- ribs, scapulae. Contain two plates of compact bone
separated by a layer of spongy bone. Short bones- wrist, ankle.
Often cuboidal in shape. Spongy bone covered by a thin layer of
compact bone.
Irregular bones- vertebrae, mandible, or other facial bones.
◉ Remodeling:
