Compact and Spongy Bone Quiz

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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?

In concentric layers around a vascular central canal (Haversian canal). Signup and view all the answers

What is contained in a central (Haversian) canal?

One or more blood vessels (normally a capillary and a venule) that carry blood to and from the osteon. Signup and view all the answers

What is a venule?

A very small vein. Signup and view all the answers

In what direction do central canals generally run to the surface of the bone?

Parallel. Signup and view all the answers

What are perforating canals?

Volkmann's canals. Signup and view all the answers

What forms a spiral pattern within each lamella that adds strength and resiliency to the bone matrix?

Collagen fibers. Signup and view all the answers

Where is compact bone the thickest?

Where stresses are applied from a limited number of directions. Signup and view all the answers

In which direction are osteons in the diaphysis of the long bone oriented in relation to the long axis of the shaft?

Parallel. Signup and view all the answers

What is the structure of spongy bone?

Lamellae are not arranged in osteons. No osteons are present. The matrix forms a meshwork of supporting bundles of fibers called trabeculae. Signup and view all the answers

What is trabeculae?

A meshwork of supporting bundles of fibers in spongy bone that create an open network oriented along stress lines and extensively cross-braced. Signup and view all the answers

Where is spongy bone found?

Where bones are not heavily stressed or where stresses originate from many directions. Signup and view all the answers

What is a function of spongy bone?

Because it is less dense than compact bone, it reduces the weight of the skeleton, making it easier for muscles to move the bones. Signup and view all the answers

What does spongy bone contain instead of capillaries and venules in its matrix?

Red bone marrow. Signup and view all the answers

What is the function of red bone marrow?

It fills spaces between the trabeculae, forms blood cells, supplies nutrients to osteocytes, and removes wastes. Signup and view all the answers

Since trabeculae have no blood vessels, how does it receive nutrients?

They diffuse along canaliculi that open onto the surfaces of trabeculae. Signup and view all the answers

What is yellow bone marrow?

A type of bone marrow that is a form of adipose tissue, important as an energy reserve. Signup and view all the answers

What are the two different kinds of coverings on bones?

Periosteum and endosteum. Signup and view all the answers

What is periosteum?

One of the two different types of bone coverings. A superficial layer of compact bone consisting of a membrane with a fibrous outer layer and a cellular inner layer. Signup and view all the answers

What are the functions of the periosteum?

<ol> <li>Isolates the bone from surrounding tissues. 2. Provides a route for the blood vessels and nerves. 3. Takes part in bone growth and repair.</li> </ol> Signup and view all the answers

How does periosteum attach near joints?

It becomes continuous with connective tissues (joint capsule, tendons, ligaments) that hold the bones in place. Signup and view all the answers

What are perforating fibers?

Collagen fibers of the periosteum. Signup and view all the answers

What is endosteum?

One of the two different types of bone coverings. Lines the medullary cavity and covers the trabeculae of spongy bone. An incomplete cellular layer that is active in bone growth and repair. Signup and view all the answers

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.