Skeletal System 2 Flashcards
What is ossification (osteogenesis)?
The process of bone tissue formation
What are the two methods of bone formation?
Intramembranous & endochondral ossification
What happens in Intramembranous ossification?
Bone forms within the mesenchyme (embryonic connective tissue) which are arranged in sheets of membranes, and form most cranial bones of the skull
What happens in endochondral ossification?
Bones from within a hyaline cartilage model derived from the mesenchyme and forms most bones
What two factors are necessary for bone growth?
New bone formation & bone remodelling
What is appositional growth?
Bone growth in diameter
What is interstitial growth?
Bone growth in length
What two things happen during interstitial growth?
Growth of epiphyseal plates, and the replacement of cartilage with bone
What are the 4 zones of epiphyseal plates
Nearest to epiphysis, zone of resting, proliferating hypertrophic and calcified cartilage
What is the function of the resting zone?
Contain resting chondocytes that anchor the growth plates to the bone
What is the function of the proliferating zone?
Contain larger chondrocytes that continuously divide to produce new chondrocytes and secrete extra cellular matrix
What is the function of the hypertrophic zone?
Contains columns of large maturing chondrocytes
What is the function of the calcified zone?
Contain dead chondrocytes replaced by bone matrix, and broken up osteoclasts and becomes part of the new diaphysis
What is the epiphyseal line ?
Bony structure of faded cartilage layer which signify the fusing of growth plates.
What causes bone thickening?
Increase in weight & muscular activity
What happens during appositional growth?
Osteoblasts deposit bone in periosteum, while osteoclasts remove bone matrix from the endosteum to enlarge the medullary cavity & prevent high bone weight
What are the two actions involved in bone remodeling?
Bone resorption & bone deposition
What two factors control bone remodeling?
Hormones & mechanical stress
Describe what happens during low levels of blood calcium?
Low blood calcium levels instigate PT cells to increase the generation of AMP which activates more PTH and stimulates osteoclasts to resorb bone to release Ca+2 & kidneys to retain calcium.
What is the function of Calcitonin?
Produced by thyroid gland to decrease Ca+2 in blood
What is the function of leptin?
Formed by adipose tissue inhibit osteoblasts
What factors affect bone growth?
Hormones such as sex, thyroid and GH, Minerals, Vitamins, Adequate diet, & Exercise
What are the four phases of bone fracture?
Reactive, reparative fibrocartilaginous callus phase, reparative bony callus phase & remodeling
What happens during the reactive phase of fracture?
Fracture ruptures blood vessels causing blood clot or fracture hematoma formation
What happens during the reparative fibrocartilaginous callus phase?
Blood vessels form across fracture & collagen chondroblasts form the fibrocartilaginous callus (soft) across the ends of the bone
What happens during the reparative bony callus phase?
Osteoprogenitor cells develop into osteoblasts and form spongy bone trabeculae which connects bone fragments. the the cartilage is calcified into bone
What happens during the remodeling phase?
Old bone fracture portions are destroyed by osteoclasts, and replaced by compact bone across the edges of the fracture causing side thickening
What is another name for joints?
Articulations
Joints are a point of contact between what structures?
Bones, bones & cartilage and bones & teeth
How are joints classified?
Their structure & function
What are the 3 Structures?
Fibrous, cartilaginous, & synovial
What are the three functions?
Immovable synarthroses, slightly moveable amphiarthroses and freely moveable diarthroses
What are Fibrous joints?
Synarthroses - little to immovable
What are the 3 types of Fibrous joints?
Sutures, Syndesmoses & Interosseous membranes
What are Sutures?
Thin layers of connective tissue which join skull bones together & immovable
What are Syndesmoses?
Irregular dense connective tissue arranged in bundles or ligaments that connect longer distance joints such as distal tibiofibular ligament - slightly moveable
What are interosseous membranes?
Large sheets of connective tissue that span across neighboring long bones
What are cartilaginous joints?
Connected by hyaline or fibrocartilage and little - immovable
What are the two types of cartilaginous joints
Synchondroses & symphyses
What is a Synchondroses joint?
Joints connected by hyaline cartilage such as the epiphyseal growth plates that connect the epiphysis & diaphysis - immovable
What is the symphyses joint?
Joints connected by fibrocartilage, such as pubic symphysis which are slightly moveable
What are synovial joints?
Joints which are freely moveable & exhibit a joint capsule & synovial cavity
What are the 6 types of synovial joints?
Plane, hinge, pivot condyloid, saddle & ball-socket joint
What is a plane joint?
Two flat bones that glide past each other such as Intercarpal joints
What is a hinge joint?
Angular opening and closing of bones such as elbow
What is a pivot joint?
Rotary joints that allow rotary movement in its own longitudinal axis - radioulnar joints
What is a condyloid joint?
Two cuplike or oval projections that rest on each other such as metacarpophalangeal joints
What is a saddle joint?
Surfaces that are concave and convex such as Carpometacarpal
What is a Ball-socket joint?
Ball fits into socket such as shoulder joint
What is the basic structure of synovial joints?
Surrounded by joint capsule that contain an outer fibrous and inner synovial membrane
Describe the outer fibrous membrane?
Made of dense connective tissue, collagen which enables flexibility & tensile strength and contain ligaments which join synovial joints
Describe the inner synovial membrane?
Made areolar connective tissue, elastic fiber, fat pads and secretes synovial fluid in a synovial cavity between the synovial membrane
What are the functions of synovial fluid?
Reduce friction, lubricate, absorb shock, nourish with blood and nutrients, and enables exist wastes from chondrocytes
What are ligaments?
Connect bones to bones
What are Tendons?
Connect bone & muscle
What is the menisci?
Crest-shaped discs, between the articular bone and fibrous membrane of synovial joints
What are the functions of menisci?
Provide shock absorption, better fit between bone joints, distribute synovial lubricant, and prevent stress, wear and tear.
