• Cartilage is a specialized form of connective tissue containing chondrocytes which secrete, and are surrounded by, an extensive intercellular matrix. Chondrocytes occur singly or in isogenous groups, composed of 2-8 cells derived by mitosis from a single chondrocyte. The cells are in the lacunae (cavities) within the matrix. Matrix stains more intensely immediately adjacent to the lacunae and the dark staining zone is called the capsule. The strength and durability of cartilage are properties of the matrix, which is an interlaced network of collagenous and/or elastic fibers in a ground substance, a gel of complex proteoglycans.
• Hyaline cartilage is found lining articular surfaces, and in the nasal septum, tracheal rings, costal cartilages, and the epiphyseal cartilage of growing bone• Elastic cartilage is found in the ear and epiglottis, where it provides a rigid but elastic, framework. Its principal components are elastic fibers but type II collagen is also present. Some elastic fibers may be present in the tracheal cartilage.• Fibrocartilage is found in intervertebral discs, the pubic symphysis, in menisci of joints, and often occurs where tendon and ligament are joined to bones. Its appearance varies with its location. The major and characteristic
Bone Cartilage• Bones grow longer over time • Cartilage forms from initial but they also get thicker. condensation directly from There are mechanism that mesenchyme and then grows by a allow for bones to grow in combination of apositional growth both length and width. • Interstitial growth - Chondroblasts• To make a bone longer just within the existing cartilage divide add bone tissue to the ends. and form small groups of If tissue is added at the end of cells, isogenous groups, which the bone the skeleton could produce matrix to become not move properly. Its like separated from each other by a thin closing both lanes on an partition of matrix. Interstitial growth interstate until the bridge is occurs mainly in immature cartilage. repaired. • Appositional growth - Mesenchymal• Bone tissue must be added cells surrounding the cartilage in below the joint somewhere the deep part of the perichondrium along the length of the bone. (or the chondrogenic layer) This occurs at the epiphyseal differentiate into chondroblasts. plate, or growth plate. Here Appositional growth occurs also in chondrocytes first produce mature cartilage.
• Osteoporosis is when bone density is decreased, normally the process of matrix remodeling keeps bones at the correct density but Osteoporosis slows this down.
• Cancer treatment can destroy bone marrow which is where red blood cells are naturally replaced. Without the bone marrow patients are more susceptible to sickness. Bone marrow transplants replace the bone marrow with healthy normal marrow.
Intramembranous ossification: when cells of an embryotransforms into bone. In early development, the embryo hasthree cell layers: the ectoderm which is on theoutside, mesoderm in the middle, and endoderm on the insideof the embryo. Bones of the skull come directly from themesenchyme cells by intramembranous ossification.Endochondral ossification: this is the gradual replacement ofcartilage by the bone. This process is responsible for formingmost of the skeleton of vertebrates. Osteoblasts arise inregions of cartilage called ossification centers. (9)
1. Inflammation: in a bone fracture, white blood cells move in to the area toclean up debris created by the break. Inflammation triggers the growth newblood cells.2. Soft callus: as the blood cells divide and multiply near the break, the newblood vessels develop to fuel the repair process; the body also createssimply fibrous tissue cartilage around the bone fracture to bridge the gap.3. Hard callus: later on, the body replaces the soft callus with a hard callus,connecting the fragments of the bone more solidly. It creates a bulge at thesite of the fracture.4. Remodeling: the body replaces the old bone with a new bone in acontinual process called remodeling; it makes the bone stronger andcompact and blood circulation in the bone improves.(8)
Bone: the types of bones are divided intolong, short, irregular, flat, sesamoid and sutural bones. Their function isto protect the body from mechanical damage, to providesupport, assist in movement, to store minerals, produce red blood andwhite blood cells, and to be the framework and shape for the body. Thebones are made up of osteoblasts, osteocytes, osteoclasts, and bonelining cells.Cartilage: the types of cartilage are hyaline cartilage, fibrocartilage andelastic cartilage. The main functions is to reduce the friction at thejoints, support tracheal and bronchial tubes, they act as shockabsorbers between the vertebrae, also maintaining the shape andflexibility of ear, nose, along with others. Cartilage is made up ofchondroblasts, chondrocytes, and dense matrix that is composed ofcollagen and elastic fibres. (10)
Main Parts•Haversian Canal•Lucanae•Canaliculi•Osteon•Periosteum•Lamellae•Trabeculae
• Osteoblasts- These are bone forming cells within the bone.• Osteocytes- These are involved in the formation of the bone, maintenance of the matrix, and homeostasis of the calcium.• Osteoclasts- The cells are responsible for bone resorption and remodeling.
• Maintain shape and structure of the bone.• Strengthening the bone and adding tissue.• Remodeling broken bones.• Calcium from bones being used in other parts of body.• Mineral reservoir, contains many minerals that the body can use.
• Is made up of concentric rings of matrix that surround central canals which contain blood vessels.• Embedded in this bone tissue are small cave-like spaces called lacunae, which are connected to each other through small tunnels called canalicula.• The lacunae contain osteocytes cells. As just discussed, osteocytes help maintain healthy bone tissue and are involved in the bone remodeling process that will be outlined later in this lesson.
• Looks like an irregular latticework (or sponge) with lots of spaces throughout.• These spaces are filled with red bone marrow which is the site of hemopoesis or formation of blood cells
• During the aging process, adults face the issue of a changing skeletal framework.• As humans age, the force-generating capacity (strength) of their skeletal muscles is reduced. As a result, many older people experience difficulty in performing their activities of daily living. The loss of force production in older people is primarily to the result of muscle atrophy and alterations in the percentage of contractile tissue within muscle rather than deficits in muscle.
Growth plate In growing children, sprains and fractures strains often result in potentially serious growth plate fractures and physeal fractures. These same sprains and strains in active adults are relatively benign injuries. This article discusses some of the important orthopedic history relative to the physes, relevant anatomy, classification systems, and some details of physeal fractures in specificAn image depicting growth plate fractures can be seen below. areas of the body.
• Growth plate (physeal) fractures. Clinical appearance of the knee of a patient with a minimally displaced Salter- Harris I fracture of the distal femur. Impressive swelling was noted adjacent to the joint, but no evidence of intra- articular swelling was present. The patient was markedly tender to palpation about the distal femoral physis.