Bone Tissue Overview

Study Notes

Bone Tissue

Bone is a connective tissue composed of cells embedded in an extracellular matrix.
The matrix is primarily made of collagen fibers and calcium phosphate crystals (hydroxyapatite), giving bone its hardness and strength.
Bone cells include osteoblasts (bone-forming cells), osteocytes (mature bone cells), and osteoclasts (bone-resorbing cells).
Bone tissue is classified into two main types: compact bone and spongy bone.
Compact bone is dense and forms the outer layer of bones, providing strength and protection.
Spongy bone is less dense and has a porous structure, making it lighter and allowing for the passage of blood vessels and marrow.
Bone is a dynamic tissue, constantly being remodeled throughout life by the actions of osteoblasts and osteoclasts.
This remodeling allows for repair of fractures and adaptation to stress.
Bone tissue plays a crucial role in calcium homeostasis, storing and releasing calcium into the bloodstream as needed.

Cartilage Tissue

Cartilage is a specialized connective tissue that is avascular (lacks blood vessels) and has a firm, flexible consistency.
It is composed of cells called chondrocytes embedded in an extracellular matrix.
The matrix is primarily composed of collagen and proteoglycans (large molecules containing protein and sugar), giving cartilage its resilience.
Cartilage is also a low-friction surface.
Cartilage is classified into three types: hyaline cartilage, elastic cartilage, and fibrocartilage.
Hyaline cartilage is the most common type, found in the articular surfaces of joints, the nose, trachea, and end of ribs. It provides support and a smooth surface for low friction movement.
Elastic cartilage is more flexible and has a higher concentration of elastin fibers, found in the external ear and epiglottis. This cartilage maintains shape and flexibility.
Fibrocartilage is more durable and has a high concentration of collagen fibers, found in intervertebral discs and menisci of the knee. It withstands high tension and pressure.
Cartilage growth is limited or absent in adults.

Differences between Bone and Cartilage

Bone is vascular, cartilage is avascular.
Bone is hard and strong, cartilage is firm and flexible.
Bone is a highly dynamic tissue, cartilage growth is limited in adults.
Bone is a crucial site for calcium storage, cartilage does not store calcium.
Bone serves as a structural support, cartilage primarily provides flexibility and support.
Bone repairs more readily than cartilage.
Bone is stronger and more resistant to compression and fracture, while cartilage offers considerable resilience to repeated impact or compression.

Key Functions of Bone

Support and protection of the body
Movement (serving as levers for muscles)
Hematopoiesis (blood cell formation in the bone marrow)
Mineral storage (calcium and phosphate)
Calcium homeostasis

Key Functions of Cartilage

Support and flexibility in joints and other locations
Cushioning within joints and between vertebrae
Smooth movement at joints
Maintenance of shape in some structures (e.g., ears)

Description

This quiz covers essential aspects of bone tissue, including its composition, types, and cellular functions. It explores the roles of osteoblasts, osteocytes, and osteoclasts in maintaining bone structure and health. Additionally, it discusses the dynamic nature of bone and its importance in calcium homeostasis.