Questions and Answers
What is the function of compact bone?
To protect, support, and resist stress.
What is the function of spongy bone?
Provides some support and stores marrow.
What is the basic functional unit of mature compact bone?
Osteon.
How are osteocytes (mature bone cells) arranged in an osteon?
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What is contained in a central (Haversian) canal?
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What is a venule?
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In what direction do central canals generally run to the surface of the bone?
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What are perforating canals?
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What forms a spiral pattern within each lamella that adds strength and resiliency to the bone matrix?
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Where is compact bone the thickest?
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In which direction are osteons in the diaphysis of the long bone oriented in relation to the long axis of the shaft?
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What is the structure of spongy bone?
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What is trabeculae?
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Where is spongy bone found?
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What is a function of spongy bone?
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What does spongy bone contain instead of capillaries and venules in its matrix?
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What is the function of red bone marrow?
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Since trabeculae have no blood vessels, how does it receive nutrients?
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What is yellow bone marrow?
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What are the two different kinds of coverings on bones?
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What is periosteum?
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What are the functions of the periosteum?
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How does periosteum attach near joints?
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What are perforating fibers?
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What is endosteum?
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Study Notes
Compact Bone
- Functions to protect, support, and resist stress in the skeletal system.
- Comprised of osteons, known as Haversian systems, which are the fundamental units of mature compact bone.
- Osteocytes, the mature bone cells, are arranged in concentric layers around a central vascular canal (Haversian canal).
- Each central canal houses one or more blood vessels, typically a capillary and a venule, supplying the osteon with blood.
Spongy Bone
- Provides support and serves as a storage area for bone marrow.
- Contains trabeculae, which are supporting bundles of fibers forming a meshwork, allowing structural support along stress lines.
- Lacks traditional osteon structure; matrix forms a network instead, with lamellae not organized in osteons.
- Found in areas where bones experience light stress or when stresses come from various directions.
Types of Lamellae
- Interstitial lamellae fill spaces between osteons, consisting of remnants of recycled osteons by osteoclasts.
- Circumferential lamellae are located at the outer and inner bone surfaces, crucial during bone growth.
- Collagen fibers within lamellae form a spiral pattern, enhancing strength and flexibility of the bone.
Nutrient Supply
- Spongy bone contains red bone marrow instead of capillaries and venules, serving essential roles in blood cell formation and nutrient supply.
- Nutrients diffuse to osteocytes from marrow through canaliculi that open onto trabecular surfaces.
Bone Coverings
- Two main coverings of bone: periosteum and endosteum.
- Periosteum has a fibrous outer layer and a cellular inner layer, isolating the bone and facilitating blood vessel and nerve pathways.
- Functions of periosteum include growth, repair, and providing attachment for connective tissues around joints.
- Endosteum lines the medullary cavity and covers trabeculae, active in the growth and repair of bone, containing important cell types like osteoblasts and osteoclasts.
Bone Marrow
- Yellow bone marrow is a form of adipose tissue, serving as an energy reserve.
- Red bone marrow occupies spaces between trabeculae, responsible for blood cell production and metabolic support for osteocytes.
Structural Characteristics
- Central canals in compact bone run parallel to the bone surface, while perforating canals (Volkmann's canals) extend perpendicular to supply deeper tissues.
- Compact bone is typically thickest where mechanical stresses are concentrated.
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Description
Test your understanding of compact and spongy bone structures! This quiz covers their functions, types, and cellular organization. Learn about the essential roles they play in the skeletal system and how they support overall body strength.