Chapter 6 & 9 AP I
Ligament
a short band of tough, flexible, fibrous connective tissue that connects two bones or cartilages or holds together a joint
Synovial Fluid
a viscous, clear, or pale yellow fluid consists of hyaluronic acid secreted by synovial cells in the syonvial membrane and interstitial fluid filtered from blood plasma. Reduces friction by lubricating the joint, absorbing shocks, and supplying oxygen and nutrients to and removing carbon dioxide and metabolic wastes from chondrocytes within articular cartilage. Also contains phagocytic cells remove microbes and debris that results from normal wear and tear in the joint.
Osteoperosis
A condition of porous bones affects 10 million people a year in the United States. Bone resorption outpaces bone deposition. In large part due to depletion of calcium from the body Bone mass becomes so depleted that bones fracture, under stress of everyday living. Primarily affects middle aged women and elderly people. Bone Mineral densisty tests are done for diagnosis.
Blood cell production
A connective tissue called red bone marrow which produce red blood cells, white blood cells, and plateslets via hemopoiesis
Endosteum
A thin membrane that lines the medullary activity. Contains a single layer of bone forming cells and a small amount of connective tissue
Fractures
Any breaks in a bone named according to severity, shape, or position of the fracture line.
Growth of bone thickness- Step 4
As an osteon is forming, osteoblasts under the periosteum desposit new circumferential lamellae, further increasing the thickness of the bone. As additional periosteal blood vessels become enclosed and the growth process continues.
Growth of bone in thickness-Step 1
At the bone surface periosteal cells differentiate into osteoblasts, which secrete the collagen fibers and other organic molecules that form bone extracellular matrix. Osteoblasts become surrounded by extracellular matrix and develop into osteocytes. This process forms bone ridges on either side of a periosteal blood vessel.
Osteoblasts
Bone building cellls that synthesize and secrete collagen fibers and other organic components needed to build the extracellular matrix of bone tissue and they initiate calcification.
Intramembranous ossification
Bone forms within mesenchyme in the embryonic skeleton in the general shape of bones which arranged in sheetlike layers that resemble membranes.
Bone blood supply
Bone is richly supplied with blood. Blood vessels are especially abundant in portions of bone containing red bone marrow.
Bone's Role in Calcium Homeostasis
Bone is the body's major calcium reservoir storing 99% of total body calcium. One way to maintain level of calcium in the blood is to control the rates of calcium resorption from bone into blood and of calcium deposition from blood into bone. Parathyroid Hormone (PTH) increases CA2+ secreted by parathyroid glands.
Mineral Homeostasis (Storage and release)- Function of the bone
Bone stores several minerals, especially calcium and phosphorus, which contributes to the strength of the bone. On demand bone releases minerals into the blood to maintain critical mineral balances and to distribute the minerals to other parts of the body.
Compact bone tissue
Contains few spaces and is the strongest form of bone tissue. It is found beneath periosteum of all bones and make up the bulk of the diaphyses of long bines. Provides protection and support and resits the streses produced by weight and movement.
Bone Remodeling Phase-Repair of a bone
Dead portions of the original fragments of broken bone are gradually resorbed by osteoclasts. Compact bone replaces spongy bone around the periphery of a fracture.
Calcitonin (CT)
Decreases blood CA2+ level when it rises above normal via the thyroid gland.
Spongy Bone Tissue
Does not contain osteons. Spongy bone is always located in the interior of a bone, protected by a covering of compact bone
Cartilage blood supply
Does not have good blood supply
Hormones-Factors affecting bone growth and bone remodeling
During childhood insulinlike growth factors (IGFs) stimulate osteoblasts, promote cell division at the epiphyseal plate and in the periosteum, and enhance synthesis of proteins needed to build new bones. IGFs are produced in response to the secretion of human growth hormone (hGH)from anterior lobe of pituitary gland. Thyroid hormones fpromote bone growth by stimulating osteoblasts.
Reactive Phase-Repair of bone
Early inflammatory phase. Blood vessels crossing the fracture line are broken as blood leaks the torn ends of the vessels a mass of blood forms around the site of fracture. Fracture hematoma forms because the circulation of blood stops at the site where the fracture hematoma forms, nearby bone cells die. Swelling and inflammation occurs in response to dead bone cells, producing additional cellular debris. Phagocytes and osteoclasts begin to remove dead of damaged tissue. May last up to several weeks.
Reparative Phase: Fibrocarilaginous formation-Repair of bone
Fibrocartilaginous callus and bony callus form to bridge the gap between the broken ends of the bones. Blood vessels grow into the fracture hematoma and phagocytes begin to clean up dead bone cells. Fibroblasts from the periosteum invade the fracture site and produce collagen fibers. In addition, cells from the periosteum develop into chondroblasts and begin to produce chondroblasts in this region. This leads to development of fibrocartilaginous callus a mass of repair tissue consisting of collagen fibers and cartilage that bridges the broken ends of the bone.
Reduction
For bones to unite properly, the fracture ends must be brought into alignment.
Closed reduction
Fractured ends of a bone are brought into alignment by manual manipulation, and the skin remains intact.
Medullary/marrow activaty
Hollow cylindrical space within the dyaphysis that contains fatty yellow bone marrow and numerous blood vessels
Osteoclasts
Huge cells derived from the fusion of as many as 50 monocytes and are concentrated on the endosteum.
Reparative Phase: Bony callus formation-Repair of bone
In areas closer to well vascularized healthy bone tissue, osteoprogenitor cells develop into osteoblasts, which begin to produce spongy bone trabeculae. The trabeculae join living and dead portions of the original bone fragments. In time, the fibrocartilage is converted to spongy bone, and the callus is then referred to as bony callus. Bony callus lasts about 3 to 4 months.
Bursitis
Inflammation of the fluid filled pads that cushion the joints.
Articulation
Joint
Minerals- Factors affecting Bone growth and bone remodeling
Large amounts of calcium and phosphorus are needed while bones are growing, as are smaller amounts of magnesium, fluoride, and manganese. Also necessary during bone remodeling
Epiphyseal Growth Plate
Layer of hyaline cartilage in the metaphysis that consists of four zones. Zones of resting cartilage,proliferating cartilage, hypertrophic cartilage, calcified cartilage.
Aging and Bone and Tissue
Loss of bone mass because of demineralization and brittleness. Demineralization is the loss of calcium and minerals from bone extracellular matrix. Brittleness results from a decreased rate of protein synthesis. In elderly people collagen fiber synthesis slows due to diminished production of human growth hormone.
Osteocytes
Mature bone cells. The main cells in bone tissue and maintain its daily metabolism, such as the exchange of nutrients and wastes with the blood.
Assistance in movement- Function of the bone
Most skeletal muscles attach to bones; when they contract they pull on bones to produce movement
Growth of bone thickness- Step 3
Osteoblasts in the endosteum deposit bone extracellular matrix, forming new concentric lamellae. The formation of additional concentric lamellae proceeds inward toward the periosteal blood vessel. In this way, the tunnel fills in and a new osteon is created.
Bone Remodeling
Ongoing replacement of old bone tissue by new bone tissue. It involves bone resorption and bone deposition
Ossification/osteogenesis
Process by which bone forms. 1) initial bone formation in embryo or fetus 2)the growth of the bone during infancy 3) the remodeling of the bone 4) the repair of fracture throughout life.
Stress Fracture
Series of microscopic fissures in bone that forms without any evidence of injury to other tissues. Usually in healthy adults from repeated strenous activities like running jumping.
Exercise and Bone Tissue
Research has shown that high-impact intermittent strains more strongly influence bone deposition. Whereas Bedridden people the strength of unstressed bone diminishes because of loss of bone minerals and decreased numbers of collagen fibers.
Bone Deposition
The addition of minerals and collagen fibers to bone by osteoblasts. Results in the formation of bone extracellular matrix. Osteoclast attaches tightly to the bone surface at the endosteum of periosteum and forms a leakproof seal at the edges of its ruffled border.
Synovial Joints
The bones forming the joint have a synovial cavity and are united by the dense irregular connective tissue of an articular capsule, and often by accessory ligaments. Permits considerable movement. Covered by hyaline cartilage called articular cartilage.
Diaphysis
The bones shaft or body, the long cylyndrical main portion of the bone.
Open Reduction
The fractured ends of a bone are brought into alignment by a surgical procedure using internal fixation devices such as screws,plates, pins,rods, and wires.
Epiphyses
The proximal and distal ends of the bone
Metaphyses
The regions between the diaphysis and the epiphyses. In a growing bone it contains an epiphyseal plate a layer of hyaline cartilage that allows the dyaphysis of the bone to grow in length.
Bone Resorption
The removal of collagen fibers and minerals from bone by osteoclasts. Results in the destruction of bone extracellular matrix.
Growth of bone thickness-Step 2
The ridges fold together and fuse, and the groove becomes a tunnel that encloses the blood vessel. The former periosteum now becomes the endosteum that lines the tunnel.
Protection -Function of the bone
The skeleton protects the most important internal irgans from injury.
Support - Function of bone
The skeleton serves as the structural framework for the body by supporting soft tissues and providing attachment pointa for the tendons of most skeletal muscles.
Fibrous Joints
There is no synovial activity, and the bones are held together by dense irregular connective tissue that is rich in collagen fibers. Permit little or no movement. ie. sutures, syndesmoses, interosseous membranes.
Cartilaginous Joints
There is no synovial cavity, and the bones are held together by cartilage. Permit little or no movement connected by hyaline cartilage or fibrocartilage. i.e. Synchondroses, symphyses
Perforating Fibers
Thick bundles of collagen that extend from the periosteum into the bone extracellular matrix
Articular cartilage
Thin layer of hyaline cartilage covering the part of the epiphysis where the bone form a joint with another bone
Periosteum
Tough connective tissue sheath and its associated blood supply that surrounds the bone surface whereever it is not covered by articular cartilage
Osteopeogenitor Cells
Unspecialized bone stem cells derived from mesenchyme, the tissue from which almost all connective tissues are formed.
Vitamins- Factors affecting bone growth and bone remodeling.
Vitamin A stimulates activity of osteoblasts. Vitamin C is needed for synthesis of collagen, the main bone protein. Vitamin D helps build bone by increasing the absorption of calcium from food. Vitamins K and B12 needed for synthesis of bone proteins.
Trygliceride storage
Yellew bone marrow consists mainly of adipose cells, which stores tryglycerides.
Endochondral Ossification
bone forms within hyaline cartilage that develops from the mesenchyme.
Long bone growth during childhood
interstitial growth of cartilage in the epiphyseal side of the epiphyseal plate and replacement of cartilage on the disphyseal side of the epiphyseal plate with bone by endochondral ossification.
