551 Final Exam Study Guide Collagen,
Bone, and Musculoskeletal System
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What is collagen?
The primary structural protein in the extracellular matrix of connective tissues, providing tensile
strength and support.
What is ground substance?
The amorphous, gel-like component of the extracellular matrix that fills spaces between cells
and fibers, facilitating nutrient and waste diffusion.
Main roles of:
• Osteoblast: Bone-forming cell that synthesizes and secretes organic bone matrix
(osteoid).
• Osteoclast: Multinucleated cell that resorbs (breaks down) bone matrix during
remodeling and calcium homeostasis.
• Osteocyte: Mature bone cell embedded in mineralized matrix; maintains bone
tissue and senses mechanical stress.
• Osteoid: Unmineralized organic portion of bone matrix, composed mainly of type
I collagen and ground substance.
What makes up bone?
• Organic (≈35%): Type I collagen fibers + ground substance (proteoglycans,
glycoproteins)
• Inorganic (≈65%): Hydroxyapatite crystals (calcium phosphate) and other mineral
salts
What is osteocalcin?
A noncollagenous protein secreted by osteoblasts that binds calcium and regulates
mineralization.
Different types of collagen & location:
• Type I: Bone, skin, tendon, dentin
• Type II: Hyaline & elastic cartilage
• Type III: Reticular fibers in skin, blood vessels, and bone marrow
• Type IV: Basement membranes
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• Type V: Cell surfaces, hair, placenta
Spongy vs. Compact bone:
• Spongy (cancellous): Porous, low density; filled with marrow; shock absorption
• Compact (cortical): Dense, solid outer layer; provides strength and protection
How many bones in the human body?
206 (adult skeleton)
What is the axial skeleton?
Central “trunk” bones: skull, vertebral column, ribs, and sternum.
What is the appendicular skeleton?
Limb bones plus their girdles: pectoral (shoulder) and pelvic (hip) girdles.
Diaphysis vs. Metaphysis vs. Epiphysis:
• Diaphysis: Shaft of long bone; primary ossification center
• Metaphysis: Flared region between diaphysis and epiphysis; contains growth
plate in children
• Epiphysis: Rounded end of long bone; secondary ossification center; articulates
with adjacent bones
Syndesmosis vs. Synchondrosis:
• Syndesmosis: Fibrous joint with interosseous ligament (e.g., distal tibiofibular
joint)
• Synchondrosis: Cartilaginous joint with hyaline cartilage (e.g., epiphyseal plate)
What is the Haversian System?
Also called an osteon: the functional unit of compact bone, consisting of concentric lamellae
around a central (Haversian) canal that contains blood vessels and nerves.
What composes the Haversian System?
Concentric lamellae, central canal, osteocytes in lacunae, and canaliculi connecting them.
What are Volkmann’s channels?
Bone, and Musculoskeletal System
, lOMoAR cPSD| 30970899
What is collagen?
The primary structural protein in the extracellular matrix of connective tissues, providing tensile
strength and support.
What is ground substance?
The amorphous, gel-like component of the extracellular matrix that fills spaces between cells
and fibers, facilitating nutrient and waste diffusion.
Main roles of:
• Osteoblast: Bone-forming cell that synthesizes and secretes organic bone matrix
(osteoid).
• Osteoclast: Multinucleated cell that resorbs (breaks down) bone matrix during
remodeling and calcium homeostasis.
• Osteocyte: Mature bone cell embedded in mineralized matrix; maintains bone
tissue and senses mechanical stress.
• Osteoid: Unmineralized organic portion of bone matrix, composed mainly of type
I collagen and ground substance.
What makes up bone?
• Organic (≈35%): Type I collagen fibers + ground substance (proteoglycans,
glycoproteins)
• Inorganic (≈65%): Hydroxyapatite crystals (calcium phosphate) and other mineral
salts
What is osteocalcin?
A noncollagenous protein secreted by osteoblasts that binds calcium and regulates
mineralization.
Different types of collagen & location:
• Type I: Bone, skin, tendon, dentin
• Type II: Hyaline & elastic cartilage
• Type III: Reticular fibers in skin, blood vessels, and bone marrow
• Type IV: Basement membranes
, lOMoAR cPSD| 30970899
• Type V: Cell surfaces, hair, placenta
Spongy vs. Compact bone:
• Spongy (cancellous): Porous, low density; filled with marrow; shock absorption
• Compact (cortical): Dense, solid outer layer; provides strength and protection
How many bones in the human body?
206 (adult skeleton)
What is the axial skeleton?
Central “trunk” bones: skull, vertebral column, ribs, and sternum.
What is the appendicular skeleton?
Limb bones plus their girdles: pectoral (shoulder) and pelvic (hip) girdles.
Diaphysis vs. Metaphysis vs. Epiphysis:
• Diaphysis: Shaft of long bone; primary ossification center
• Metaphysis: Flared region between diaphysis and epiphysis; contains growth
plate in children
• Epiphysis: Rounded end of long bone; secondary ossification center; articulates
with adjacent bones
Syndesmosis vs. Synchondrosis:
• Syndesmosis: Fibrous joint with interosseous ligament (e.g., distal tibiofibular
joint)
• Synchondrosis: Cartilaginous joint with hyaline cartilage (e.g., epiphyseal plate)
What is the Haversian System?
Also called an osteon: the functional unit of compact bone, consisting of concentric lamellae
around a central (Haversian) canal that contains blood vessels and nerves.
What composes the Haversian System?
Concentric lamellae, central canal, osteocytes in lacunae, and canaliculi connecting them.
What are Volkmann’s channels?
