Bone Structure and Function

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Questions and Answers

What is a primary characteristic of bone tissue?

It is predominantly composed of fatty tissue.

It is entirely avascular and static.

It is highly vascular and continuously remodeled. (correct)

It consists only of cells with no matrix.

Which of the following correctly describes compact bone?

It consists of trabeculae and has many open spaces.

It forms the dense exterior layer of the bone. (correct)

It is less dense than spongy bone.

It has a sponge-like structure filled with marrow.

What type of bones are tibia and metacarpals classified as?

Short bones

Irregular bones

Flat bones

Long bones (correct)

Which layer of the periosteum contains osteoprogenitor cells?

Inner cellular layer Signup and view all the answers

What distinguishes irregular bones from other classifications of bones?

Their shape does not conform to long, short, or flat bones. Signup and view all the answers

Which type of joint is typically associated with hyaline cartilage?

Synovial joint Signup and view all the answers

Which of the following is false regarding the outer surface of bones?

They are always covered by periosteum. Signup and view all the answers

What happens to bone when pressure is applied?

Bone is resorbed. Signup and view all the answers

What is the primary component of the periosteum when active bone formation is not occurring?

Fibrous layer Signup and view all the answers

What type of cells are present in the endosteum that can differentiate into osteoblasts?

Endosteal cells Signup and view all the answers

Which part of the bone tissue contains the vascular and nerve supply of the osteon?

Osteonal canal Signup and view all the answers

What distinguishes the collagen fibers in adjacent lamellae of an osteon?

Fibers are laid down in perpendicular directions Signup and view all the answers

What is the primary composition of red bone marrow?

Blood cells in various development stages Signup and view all the answers

What is mature bone commonly referred to as?

Lamellar bone Signup and view all the answers

What is the role of canaliculi in the osteon?

Facilitate the passage of nutrients between osteocytes and blood vessels Signup and view all the answers

What type of bone marrow is primarily found in adults?

Yellow marrow Signup and view all the answers

What characteristic distinguishes mature spongy bone from mature compact bone?

Presence of trabeculae or spicules in spongy bone Signup and view all the answers

Which of the following statements is true about immature bone?

Cells in immature bone are randomly arranged. Signup and view all the answers

What feature identifies Volkmann's canals in lamellar bone?

They connect osteonal canals at right angles. Signup and view all the answers

How does the matrix of immature bone differ from that of mature bone?

It has more ground substance than mature bone. Signup and view all the answers

What is a key feature in the histologic identification of Volkmann’s canals?

They are not surrounded by concentric lamellae. Signup and view all the answers

In terms of collagen fiber arrangement, how is immature bone categorized?

Nonlamellar or woven due to interlacing Signup and view all the answers

Which statement about the rate of formation of bone is accurate?

Immature bone forms at a faster rate than mature bone. Signup and view all the answers

Where is immature bone commonly found in adults?

In alveolar sockets of the oral cavity Signup and view all the answers

Study Notes

General Characters of Bone

Bone is composed of cells, fibers, and ground substances (matrix).
Bone matrix is hard due to calcification with mineral salts.
Bone cells reside in lacunae.
Bone is highly vascular.
Bone is continuously formed and remodeled under hormonal control and mechanical stress.

Bone as an Organ

Bones are the organs of the skeletal system.
Bone tissue is the structural component of bones.
Bones are made up of bone tissue and other connective tissues, including hemopoietic tissue, fat tissue, blood vessels, and nerves.
Hyaline cartilage is present in movable joints (synovial joints).
Bone's skeletal functions rely on bone tissue, ligaments, and articular (hyaline) cartilage.

Classification of Bone Tissue

Compact bone forms the dense outer layer of bones.
Spongy bone forms the interior of bones as a sponge-like meshwork with trabeculae.
Trabeculae are thin, anastomosing spicules of bone tissue.
The spaces within spongy bone are continuous and occupied by marrow and blood vessels.

Anatomical Classification of Bone

Long bones are longer in one dimension than others, consisting of a shaft and two ends (e.g., tibia, metacarpals).
Short bones are nearly equal in length and diameter (e.g., carpal bones).
Flat bones are thin and plate-like (e.g., bones of the skull vault and sternum).
Irregular bones have a shape that doesn't fit into the other categories (e.g., vertebra, ethmoid bone).

Outer Surface of Bones

Bones are covered by periosteum, a dense fibrous connective tissue sheath containing osteoprogenitor cells.
Periosteum covers bones except where they articulate with other bones (covered by cartilage).
The periosteum of an actively growing bone has:
- An outer fibrous layer resembling other dense connective tissues.
- An inner cellular layer containing osteoprogenitor cells.
In inactive bone formation, the fibrous layer is the main component, and the inner layer is less defined.
Periosteal cells can divide and become osteoblasts under appropriate stimuli.
Collagen fibers in the periosteum are parallel to the surface.
Collagen fibers from ligaments and tendons are continuous with the collagen fibers of the periosteum and extend into the bone's matrix (perforating or Sharpey's fibers).

Bone Cavities

Bone cavities are lined by endosteum, a layer of connective tissue cells containing osteoprogenitor cells.
Endosteum lines both compact bone facing the marrow cavity and the trabeculae of spongy bone within the cavity.
Endosteum is often only one cell layer thick and consists of osteoprogenitor cells that can differentiate into osteoblasts and bone-lining cells.
Endosteal cells are found in bone cavities.

Bone Marrow

Red bone marrow contains blood cells in various developmental stages and a network of reticular cells and fibers supporting developing blood cells and vessels.
In adults, the tissue in the marrow cavity is mostly fat cells (yellow marrow).

Types of Bone Tissue: Mature Bone and Immature Bone

Mature bone is composed of osteons (Haversian systems), which are structural units.
Mature bone is largely composed of cylindrical units called osteons or Haversian systems.
Osteons consist of concentric lamellae of bone matrix surrounding an osteonal (Haversian) canal, which encloses vascular and nerve supply.
Canaliculi containing osteocyte processes are arranged radially in relation to the canal.
Canaliculi opening into the osteonal canal allow for the passage of substances between osteocytes and blood vessels.
Interstitial lamellae are remnants of previous concentric lamellae between osteons.
Mature bone is called lamellar bone due to this organized structure.
The long axis of an osteon is usually parallel to the long axis of the bone.
Collagen fibers in concentric lamellae of an osteon are parallel but arranged in different directions in adjacent lamellae, giving lamellar bone a plywood appearance and great strength.
Circumferential lamellae follow the inner and outer circumference of a long bone's shaft, appearing as growth rings in a tree.
Perforating (Volkmann's) canals are channels in lamellar bone for blood vessels and nerves, traveling perpendicular to the long axis of osteons from the periosteum and endosteum to the Haversian canal. They connect osteonal canals.
Volkmann's canals are not surrounded by concentric lamellae, which is a key feature for their histologic identification.
Mature spongy bone is similar to mature compact bone but organized as trabeculae or spicules. Numerous marrow spaces of various sizes are present between the bone tissue. The bone matrix is lamellated.
Immature Bone:
- Immature bone is initially formed in the developing fetus skeleton.
- Immature bone lacks an organized lamellated appearance.
- It is called nonlamellar bone based on its collagen fiber arrangement.
- It is also known as bundle bone or woven bone because of the interlacing collagen fiber arrangement.
- Immature bone:
  - Contains more cells per unit area than mature bone.
  - Cells are randomly arranged, unlike mature bone where they are typically aligned with lamellae.
  - Has more ground substance than mature bone.
  - Stains more intensely with hematoxylin (matrix) compared to mature bone, which stains more intensely with eosin (matrix).
- Immature bone formation is faster than mature bone formation.
- Mature bone is the primary bone type in adults; immature bone predominates in the fetus.
- Immature bone is common in the alveolar sockets of the adult oral cavity (allowing for orthodontic corrections) and where tendons insert into bones.

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Description

This quiz covers the essential characteristics of bone, including its composition, classification, and role within the skeletal system. It delves into the differences between compact and spongy bone and highlights the structural significance of various bone tissues and cells. Test your knowledge of bone anatomy and physiology!