AHE: BLOCK 2: MSK SYSTEM: INTRO & HISTOLOGY

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Questions and Answers

What is the primary function of the fibrous outer layer of the periosteum?

To provide structural support for tendons and ligaments (correct)

To store fat and hematopoietic cells

To house osteocytes and other bone cells

To facilitate nutrient absorption by bone tissue

Which type of bone cell is responsible for the maintenance and regulation of bone matrix?

Osteoblasts

Osteocytes (correct)

Chondrocytes

Osteoclasts

What is the primary function of cartilage in the skeletal system?

To produce red blood cells in the marrow spaces

To absorb shock and reduce friction in joints (correct)

To facilitate bone mineralization

To connect muscles to bones

During the bone remodeling process, which of the following activities is primarily carried out by osteoclasts?

Resorption of old or damaged bone Signup and view all the answers

What role does osteoid play in bone formation?

It is the unmineralized organic component of bone matrix Signup and view all the answers

What function do osteogenic cells serve in the periosteum?

They create and differentiate into bone cells. Signup and view all the answers

Which statement best describes osteoblasts?

They become osteocytes when surrounded by matrix. Signup and view all the answers

What role do osteocytes play in bone maintenance?

They act as a signaling mechanism for osteoblasts and osteoclasts. Signup and view all the answers

Which of the following statements about the periosteum is accurate?

It supplies nutrients to the underlying bone via diffusion. Signup and view all the answers

Which cell type is primarily responsible for the synthesis of new bone material?

Osteoblast Signup and view all the answers

Which cells are known as bone lining cells?

Flat cells where bone remodeling is inactive. Signup and view all the answers

What is the primary function of osteoclasts?

To resorb bone and break down the matrix. Signup and view all the answers

What is one of the main functions of cartilage in the body?

It provides flexibility and a low-friction surface for joints. Signup and view all the answers

Which process is mainly facilitated by osteoclasts in the body?

Bone remodeling and resorption Signup and view all the answers

What is the osteoid primarily composed of?

Organic components including collagen. Signup and view all the answers

What is the primary role of osteoid in bone tissue?

To create a framework for mineralization. Signup and view all the answers

How do osteocytes communicate with other bone cells?

Via protoplasmic projections. Signup and view all the answers

What structure does the endosteum line?

The medullary cavity. Signup and view all the answers

Study Notes

Compact Bone - Microscopic Anatomy

Osteons (Haversian systems): The basic structural unit of compact bone.
- Central canal: Contains blood vessels and nerves to nourish the bone.
- Concentric lamellae: Layers of bone matrix surrounding the central canal, giving the osteon its characteristic appearance.
- Lacunae: Spaces between the lamellae that house osteocytes.
  - Canaliculi: Tiny channels that connect lacunae and allow for communication between osteocytes via cellular extensions.
- Perforating (Volkmann's) canals: Connect central canals, providing a pathway for blood vessels and nerves to travel throughout the bone.
- Circumferential lamellae: Located adjacent to the periosteum and endosteum, these lamellae help to strengthen the overall bone structure.
Interstitial lamellae: Fill in the gaps left over from remodeled osteons, representing remnants of previous bone structures.

Trabecular Bone

Located deep to compact bone, within the marrow cavity.
Named for the needle-like projections called trabeculae, which make up the spongy structure.
Lamellae are not arranged around central canals like in compact bone.
Nutrients diffuse through canaliculi connected to capillaries in the endosteum, which surrounds the trabeculae.

Osteoid

Related tissue to bone.

Periosteum

Double-layered connective tissue membrane covering the outer surface of the bone.
- Fibrous outer layer: Dense irregular connective tissue, anchoring tendons and ligaments to the bone.
- Osteogenic inner layer: Contains osteogenic cells that create new bone cells.
  - Sharpey's fibers: Connect the periosteum to the bone.

Endosteum

Internal connective tissue membrane lining the medullary cavity of the bone.

Bone Cells

Osteogenic (osteoprogenitor) cells: Mitotically active stem cells located within the periosteum and endosteum.
- They differentiate into osteoblasts and bone lining cells.
Osteoblasts: Bone-building cells located on bone surfaces.
- Synthesize and secrete osteoid (unmineralized organic matrix of bone).
- Become osteocytes when surrounded by the matrix they create.
Osteocytes: Mature bone cells responsible for bone maintenance.
- React to strain or stress through deformation, loading, and weightlessness.
- Stimulate osteoblasts and osteoclasts.
- Located within lacunae.
- Connect and communicate with other osteocytes, osteoblasts, and bone lining cells through protoplasmic projections.
Bone lining cells: Flat cells on bone surfaces where remodeling is not occurring.
- Help maintain bone matrix.
- Called periosteal cells on the external bone surface and endosteal cells on the internal surface.
Osteoclasts (osteophages): Bone-resorbing cells responsible for bone breakdown (osteolysis).
- Large, motile, multinucleated cells that originate from bone marrow through fusion of monocytes.
- Enzymes secreted by osteoclasts break down bone matrix.

Cartilage

Tough, durable form of supporting connective tissue essential for mechanical and protective roles in the body.

Functions of Cartilage:

Provides flexibility.
Provides smooth, low-friction, gliding surfaces on articular surfaces (joints).

Components of Cartilage:

Gelatinous extracellular matrix (ECM) with abundant fibers.
Chondrocytes: Cartilage cells found within the ECM in spaces called lacunae.
Perichondrium: Dense connective tissue covering that supplies cartilage with nutrients through diffusion.

Characteristics of Cartilage:

Avascular: Cartilage lacks blood vessels and relies on diffusion for nutrient delivery.
Lacks nerves: Cartilage is insensitive to pain.

Cartilage Types:

Hyaline cartilage: Most common type, providing movement and support.
- Sparse chondrocytes and collagen fibers.
- Juvenile: Forms scaffolding for developing bone, allowing for longitudinal bone growth.
- Adults: Found at the ends of bones in many joints, in the respiratory tract, and connecting ribs to the sternum.
Elastic cartilage: Provides flexibility and stretching abilities.
- Contains more elastin fibers than hyaline cartilage.
- Found in the ear and epiglottis of the upper respiratory tract.

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Description

Test your knowledge on the microscopic structure of compact bone with this quiz. You'll explore terms like osteons, lacunae, and canaliculi, uncovering the intricate details of bone anatomy and physiology. Perfect for students studying biology or medicine!