Cartillage /\ Bone

Functions and Types of Cartilage

• Cartilage provides flexibility and support in various structures, allowing for a range of motion.
• Elastic cartilage, found in the pinna of the ear and epiglottis, is pliable due to its composition of type II collagen and elastic fibers.
• Hyaline cartilage functions as a smooth surface for joint movement and supports respiratory structures.

Composition of Bone

• Bone is composed of a mineralized matrix, primarily made of hydroxyapatite, with organic components including collagen fibers (primarily type I) and non-collagenous proteins.
• The epiphyses are primarily made of spongy bone, containing red bone marrow for hematopoiesis, surrounded by a thin layer of compact bone.
• The diaphysis of long bones consists mainly of compact bone, providing structural integrity and strength.

Bone Healing and Formation

• Bone healing involves a series of organized events, starting with hematoma formation and leading to callus formation and hardening into bone.
• Types of bone formation include intramembranous ossification (found in flat bones like the skull) and endochondral ossification, where cartilage is replaced by bone.
• Secondary ossification centers form in the epiphyses of long bones.

Specific Bone Structures and Cells

• Compact bone is dense and organized into osteons, featuring central canals that house blood vessels.
• Osteoblasts are responsible for producing bone matrix, while osteoclasts are involved in bone resorption.
• The periosteum serves as a protective outer layer, providing points for muscle and ligament attachment, and contains osteoprogenitor cells for bone repair.

Hormones and Nutrient Supply

• When serum calcium is low, parathyroid hormone (PTH) is released, stimulating osteoblasts to produce osteoclast-stimulating factor for bone resorption, increasing blood calcium levels.
• Cartilage receives nutrients through diffusion, as it lacks a direct blood supply.

Characteristics of Bone Tissue

• Cancellous (spongy) bone is highly vascularized and metabolically active, allowing for efficient nutrient exchange.
• The endosteum lines the inner surface of bones, playing a role in bone growth and repair.

Miscellaneous

• Structural features of cartilage include its avascular nature, making effective nutrient distribution vital for maintenance.
• Hyaline cartilage does not function in structural support as prominently as elastic cartilage does in certain areas.