Topic 6 Flashcards
Skeletal system
System made up of a number of organs, mostly bones
What tissues are found in bones
Osseous tissue, cartilage, dense CT, epithelium, adipose tissue, and nervous tissue
Functions of bone and skeletal system
Support Protection Assistance in movement Mineral homeostasis Blood cell production Triglyceride storage
Types of bones in the body
Long bones (90) Short bones (28) Flat bones (36) Sesamoid bones (4) Irregular bones (48) Total 206
Epiphyis
Structure of the bone: proximal and distal ends of the bone
Diaphysis
Structure of the bone: shaft or body of the bone
Medullary cavity
Structure of the bone: a hollow, cylindrical space within diaphysis filled with yellow bone marrow in adults
Articulât cartilage
Structure of the bone: thin layer of hyaline cartilage overlaying the epiphysis (joint surface)
Metaphysis
Structure of the bone: region between epiphysis and diaphysis, in growing bones, contains epiphyseal (growth) plate
Periosteum
Structure of the bone: CT sheath around surface of bone (except for area of articular cartilage)
Endosteum
Structure of the bone: thin membrane that lines the internal bone surface
Compact bone tissue
Hard external layer of all bones
Arranged into repeating structural units called esteons
Resists the stresses produced by weight and movement
Spongy bone tissue
Arranged in a lattice of thin columns called trabeculae
Spaces between the trabeculae make bones lighter and contain red bone marrow
Hemopoiesis (blood cell production) occurs in red bone marrow
T or F bone tissue is CT
True
CT=
Cells + ECM
Osteoprogenitor cell
Bone cell: unspecialized bone stem cell which can divide
Osteoblasts
Bone cell: “build bone” cause bone deposition
Osteoclasts
Bone cell: “carve out bone” cause bone resorption
Osteocytes
Bone cell: maintains daily activities of bone
Bone ECM
Consist of
15% water
30% collagen fibers
55% crystallized mineral salts (calcium phosphate)
Calcification
Mineral salts are deposited and crystallized in the framework formed by the collagen fibers of the ECM
Blood and nerve supply
Bone is supplied with blood, nerves accompany some of the blood vessels that supply bones, and are sensitive to tearing and tension
Ossification or osteogenesis (bone formation)
1) formation of bone in an embryo
2) growth of bones until adulthood
3) remodelling of bone
4) repair of fractures
Intramembranous ossification
Pattern of bone formation: growth occurs inside CT. Flat bones of the skull, most of the facial bones and clavicle
Endochondral ossification
Pattern of bone formation: growth occurs within a hyaline cartilage model. Hyaline cartilage cells differentiate from mesenchyme tissue. The rest of the bones in the body
How many steps in intramembranous ossification
4
How many steps in endochondral ossification
6
Bone metabolism depends on
Minerals
Vitamins
Hormones
Bone metabolism minerals
Calcium and phosphorus
Estrogen and testosterone
cause a dramatic effect on bone growth
cause a sudden “growth spurt” during the teenage years
Shut down growth at epiphyseal plates
Growth factors
stimulate osteoblasts, promote cell division at the epiphyseal plate,
and enhance protein synthesis
Thyroid hormones
calcitonin stimulates osteoblasts which promotes bone growth
T3 and T4
Parathyroid hormone
stimulates osteoclasts which increases blood calcium levels
also stimulates formation of calcitriol (the active form of vitamin D),
which promotes absorption of calcium from foods in the GI tract
Insulin
promotes bone growth by increasing the synthesis of bone proteins
Calcium in the body
Bone is the body’s major calcium reservoir
Your heart, muscles, nerves need calcium
Repair of bone steps
1) formation of fracture hematoma
2) fibrocartilaginous callus formation
3) bony callus formation
4) bone remodeling
Formation of fracture hematoma
Blood leaks from the torn ends of blood vessels, a clotted mass of blood forms around the site of the fracture
Fibrocartilaginous callus formation
Fibroblasts invade the fracture site and produce collagen fibres bridging the broken ends of the bone
Bony callus formation
Osteoblasts begin to produce spongy bone trabeculae joining portions of the original bone fragments
Bone remodeling
Compact bone replaces spongy bone
Bones of the axial skeleton
Cranial bones Facial bones Vertebrae Sternum Ribs
Vitamin A
stimulates activity of osteoblasts
Vitamin C
is needed for synthesis of collagen
Vitamin D
helps build bone by increasing the absorption of calcium from foods in the gastrointestinal tract into the blood
Vitamin K and B12
needed for synthesis of bone proteins
