Cartilage Para Medical PDF

 OBJECTIVE  ☺Mention the general characteristics of cartilage.  ☺Describe the structure of each type of cartilage :hyaline ,yellow elastic &white fibrocartilage.  ☺Describe cartilage cells with special reference to their light & ultra structural morphology correlated to their function...

 OBJECTIVE  ☺Mention the general characteristics of cartilage.  ☺Describe the structure of each type of cartilage :hyaline ,yellow elastic &white fibrocartilage.  ☺Describe cartilage cells with special reference to their light & ultra structural morphology correlated to their function.  CARTILAGE  Definition:  It is a specialized type of C.T. in which the matrix is firm and rubbery to bear mechanical stress. Characters of cartilage: 1) Being a type of C.T. 2) ORIGEN from mesenchymal cells (UMCs). 3) The matrix is rubbery (firm) but flexible. 4) It is avascular* nourished by diffusion of O2 & nutrients from the surrounding C.T. or synovial fluid in the joint cavities.* 5) It has no lymph vessels or nerves. Functions of cartilage:  Supports soft tissues with some flexibility.  Tissue attachment  Keeps airway patent.  Shock-absorbing weight bearing.*  Smooth sliding surface permits almost friction-free movement of the joints of the (for easy movement of bones).  Development and growth of bones, before and after birth.  Composition of cartilage:  like other C.T. it is formed of cells, fibers and ground substance: chondroblasts Cell chondrocytes. collagen Fiber elastic fibers abundant, firm Matrix rubbery.  Types of cartilage: There are three types of cartilage based on the amount of ground substance, and type of fibers embedded in it yellow white Hyaline elastic fibrocartilage. ☺Hyaline cartilage has the typical structure of cartilage. 1- Hyaline Cartilage  The most common type. and has the typical structure of cartilage  3-Costal 2-Epiphyseal cartilage. 4-Articular plate of long surface of bone. bone 5-Respiratory Site of passages 1-Fetal hyaline (nose ,larynx, skeleton. cartilage trachea, bronchi).  1- Hyaline Cartilage  Structure:  A) Perichondrium:  1- it is a capsule-like structure in its outer part  2-it surrounds the hyaline cartilage except at the articular surface of joints.  1- Hyaline Cartilage Structure of Perichondrium : It is formed of two layers: 1-Outer fibrous layer:  white fibrous C.T., formed of fibroblasts, which secrete the collagen fibers (Type I)  It is rich in blood vessels & nerves. 2-Inner chondrogenic (cellular):  rich in chondrogenic cells or cells  Resemble to fibroblasts in form and function  Chondrogenic cells ►Origin  from mesenchymal cells. ►shape: spindle-shaped ►nucleus ovoid with one or two nucleoli. ►cytoplasm is sparse, ►E/M A small Golgi apparatus, a few mitochondria, some rough endoplasmic reticulum (RER), and an abundance of free ribosomes. ►FUNCTION differentiate into chondroblasts  Functions of perichondrium: Growing cartilage Inner layer And new cartilage  Nutrition of non-vascular cartilage (by diffusion).  Growth of cartilage by appositional growth.  Provides attachment for muscles.  A-Cartilage cells:  1- Chondroblasts ( immature chondrocytes)  Origin:  1- from chonrogenic cells ☺ Site, located within the Inner chondrogenic or cellular layer , ☺ LM:  oval or spindle in shape, with deep basophilic cytoplasm  Flat oval pale stained nucleus, with prominent nucleolus.  It can divide.  ☺ Functions: 1-Cartilage growth from outside (appositional growth). 2-Formation of cartilage collagen (type II) 3-- change into chondrocytes. EM.of chondroblasts 2-Chondrocytes: ☺They are the mature cartilage cells. Origin:  they develop from chondroblasts. When chondroblasts mature, they secrete enough matrix to be completely surrounded by it and called in lacunae, they are now  called chondrocytes. LM have lightly stained basophilic cytoplasm & small nuclei.  CHONDROCYTES  Functions: 1. Maintain the cartilage matrix, 2- Maturation & multiplication of chondrocytes in center of cartilage accompanied by formation of new matrix result in growth of cartilage from within (interstitial growth).  b) Fibers:  Collagen type II c) Ground substance (Matrix):  It is produced by chondroblasts and chondrocytes.  It is rubbery  2-Yellow Elastic Cartilage  It is yellow in fresh state, Structure:  Covered by perichondrium.  Has the same structure of hyaline cartilage,  but with large number of branching elastic fibers with few collagen fibers (type II). : Ear pinna. Epiglottis External and some laryngeal cartilages Sites auditory canal. Eustachian tube. 3-White Fibro Cartilage Structure:  FIBROCARTILAGE is a combination of dense white collagenous connective tissue and hyaline cartilage  Chondrocytes are often aligned in alternating parallel rows with the thick, coarse bundles of collagen (type I).  The chondrocytes are dispersed among the collagen fibers (type I),  There is also no surrounding perichondrium  Intervertebral disc. Mandibular joint. Sites Sternoclavicular joint Semilunar cartilages of knee joints. Cartilage around the hip (acetabulum) and shoulder (glenoid cavity) joints. Symphysis pubis  Functions:  It is a strong and tough type.