CARTILAGE & BONE
Cartilage and Bone
objectives Student must learn :. What is the meaning of cartilage, and their function, location in human body.. To distinguish the 3 types of cartilage. And their cells, perichondrium, matrix with their kind of fibers..
CARTILAGE & BONE Cartilage, bone(framework ) & blood (transport) are examples of specialized connective tissue.cartilage (avascular),bone (vascularized) originate from mesoderm and mesenchyme. Cartilage contains an antiangiogenesis factor that prevents invasion of the tissue by blood vessels
Cartilage functions to: (1) support the body (2) provide a framework (3) provide attachment sites for muscles (4) protect underlying tissues (5) helps provide flexibility (6) form structural models for growing bones As an important aside: the first four listed functions above are all actually functions of bones as well.
Location of cartilage in adults External ear Nose Articular covering the ends of most bones and movable joints Costal connecting ribs to sternum Larynx - voice box
Cartilaginous Joints Bones connected by cartilage Examples Pubic symphysis Intervertebral joints Figure 5.27d e
Cartilage is characterized by three traits: lacunae, chondrocytes, a rigid matrix. The matrix is a firm gel material that contains fibers and other substances. No nerves or vessels
. perichondrium: is essential for the growth and maintenance of cartilage, it is rich in collagen type I fibers and contains numerous fibroblasts. The cells in the inner layer of the perichondrium are chondroblasts. When chondroblasts surround themselves with the intercellular matrix, they become less active and are called chondrocytes.
Hyaline Cartilage Elastic Cartilage There are three basic types of cartilage according to their fiber type (collagen or elastic) and the fiber density Fibrous Cartilage or Fibrocartilage
The function of the hyaline cartilage is to provide slightly flexible support and reduce friction within joints. It also provides structural reinforcement.
Hyaline Cartilage The most abundant type of cartilage. It is found in: the trachea, portions of the larynx, the articular cartilage on bones, epiphyseal plates, and the fetal skeleton. It provides support through flexibility and resilience, and its extracellular matrix has a translucent appearance, with no clearly visible collagen fibers, when viewed in a microscopic section. Most hyaline cartilage is surrounded by a dense connective tissue covering called perichondrium.
CARTILAGE MATRIX The extracellular matrix consists of fibers and an amorphous ground substance Fibers are collagen Type II, elastic and reticular Ground Substance is composed of GAGs(glycosaminoglycans) of the roteoglycans Hyaluronic Acid Chondroitin sulfate ** Keratan sulfate
Elastic cartilage Localization: pinna of the ear, larynx, nasal cartilages, epiglottis. Intercellular matter Fibers: elastic and collagen fibers. Elastic cartilage is not very "strong" by comparison to hyaline cartilage, but it is much more flexible and it also has some elasticity Ground substance: glycosaminoglycans and proteoglycans
Fibrocartilage Fibrocartilage has an extracellular matrix with numerous thick collagen fibers type I collagen in addition to the normal type II. that help resist both tensile(stretching) and compressional(compaction) forces. It can act as a shock absorber. Located in regions of the body where a shock absorber is required such as: the intervertebral discs, the menisci of the knee, and the pubic symphysis. It lacks a perichondrium because stress applied at the surface would quickly destroy this layer. Ground (amorphous) substance: glycosaminoglycan and proteoglycans Intervertebral Discs
summary Cartilage is a specialized connective tissue.it is classified according to the presence of fiber in the matrix. Location of each kind in human body.
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