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64 Cards in this Set

  • Front
  • Back
condition of porous bones due in large part to depletion of calcium
disorder in which bones fail to calcify
rickets and osteomalacia
degeneration of articular cartilage such that the bony ends touch; the resulting friction of bone against bone worsens the condition.
Usually associated with the elderly
bone cancer that primarily affects osteoblasts and occurs most often in teenagers during their growth spurt; the most common sites are the metaphysis if the thigh bone (femur), the shin bone (tibia), and the arm bone (humerous).
Metastese occur most often in lungs; treatment consists of mutidrug chemotherapy and removel of the malignant growth or apmutation of the limb
osteogenic sarcoma
an infection of the bone characterized by high fever, sweating chills, pain and nausia, pus formation, edema, and warmth over the affected bone and rigid overlying muscles.
reduced bone mass due to a decrease in the rate of bone synthesis to a level too low to compensate for normal bone resorption; any decrease in bone mass below normal.
Ex: osteoperosis
- shaft or long part.
- ends of the bone.
- where the shaft joins epiphyses. This is where new bone is laid down to lengthen bone at the epiphyseal plate which becomes the epiphyseal line when bone stops lengthening.
- covers the bones at joints to reduce friction. Repair of damage is limited because it lacks a perichondrium.
Articular cartilage
- tough membrane around the outside of bone. It contains cells that make bone increase in diameter. - serves in repair and nutrition of bone.
- space inside of the diaphysis and contains fatty yellow marrow.
Medullary (marrow) cavity
- thin membrane lining the marrow cavity and contains cells that break down and build up bone.
-is composed primarily of calcium salts that provide the hardness to the bone. Is also composed of collagen fibers which make it less brittle. Like reinforcing rods in concrete, they provide tensile strength.
- unspecialized stem cells that can divide to make bone forming cells (osteoblasts).
Osteogenic cells
-the bone-forming cells - secrete matrix.
-former bone-building cells that are trapped in the matrix. They are supplied with blood and continue to survive.
-serve to break down bone (resorption). Are important in maintenance and repair of bone.
- forms the external layers of all bones. it is relatively strong. -release a lipid-rich, water-repellent secretion.
Compact bone
- the individual, somewhat circular, units that make up bone.
- run longitudinally and contain blood & lymph vessels, as well as nerves.
Central (Haversian) canals
- rings of hard calcified matrix.
Concentric lamellae
- small spaces that contain osteocytes.
- small canals that carry nutrients and wastes between the osteocytes and central canal, and from one osteocyte to another osteocyte.
- carries blood and lymph vessels, and nerves into bone transversely.
Perforating (Volkman’s) canal
- areas between osteons.
Interstitial lamellae
occurs in epiphyses of long bones, lines their medullary cavities, and makes up most of the other bones.
1. Consists of a latticework of more or less cylindrical trabeculae.
2. Spaces in between these can contain red bone marrow. 3. Trabeculae do not contain osteons but have lacunae and canaliculi that get blood from surrounding cavities.
Spongy bone
enter diaphysis through perforating (Volkmann’s) canals and service the periosteum and outer compact bone.
Periosteal arteries and veins, as well as nerves,
pass into the medullary cavity of the diaphysis through the nutrient foramen and service internal areas up to the epiphyseal plates.114
Nutrient artery & vein
service red bone marrow and bone tissue of their respective regions.
Metaphyseal and epiphyseal arteries and veins
- is the process by which bone forms.
Ossification (osteogenesis)
- mesenchymal cells--> osteogenic cells--> osteoblasts--> osteocytes. **Occurs in the mandible and flat bones of the skull. Mesenchymal cells in fibrous C.T membranes differentiate into osteogenic cells, which become osteoblasts. This happens first at the center of ossification. Osteoblasts secrete matrix and become surrounded by matrix so that they are now called osteocytes. Calcium salts are deposited in the matrix so that it hardens. Bone matrix is formed into spongy bone. The mesenchymal cells surrounding bone become periosteum and superficial layers of bone are replaced by compact bone.
Intramembranous ossification (bone forms on or in loose fibrous C.T. membranes)
- (bone forms inside of hyaline cartilage) mesenchymal cells -->chondroblasts--> chondrocytes, which die and are replaced by osteoblasts--> osteocytes. ***At the site where the bone forms, mesenchymal cells differentiate into chondroblasts which produce cartilage. A perichrondrium (membrane) forms around the developing cartilage. Chondroblasts become chondrocytes. As the cartilage model grows chondrocytes die which alters the pH and triggers calcification. Small cavities begin to form the marrow cavity. A primary ossification center begins to form from the outside inward at the mid-region (diaphysis)) of the bone when a nutrient artery penetrates and stimulates osteogenic cells to become osteoblasts. Osteoblasts produce compact bone on the outside and spongy bone on the inside. Osteoclasts break down spongy bone to form the marrow cavity. Blood vessels penetrate epiphyses to form secondary ossification centers. Bone formation here is similar to primary but no cavity is formed and ossification proceeds from the inside outward. Cartilage remains on the outside to form the articular cartilage and remains between diaphysis and epiphysis to form the epiphyseal plate
Endochondral ossification
Explain the role of Vitamin C in regulating bone growth
- needed for synthesis of collagen and for differentiation of osteoblasts into osteocytes.
Explain the role of Vitamin A in regulating bone growth
-stimulates activity of osteoblasts.
are produced at puberty and initially produce “growth spurts” of the teenage years Eventually these in both sexes, stop growth at the epiphyseal plate.
Sex steroids (e.g. estrogen and testosterone)
- is an ongoing replacement of old bone by new bone and begins in utero.
- broken ends protrude through the skin. This can lead to infection of bone.
Open (compound) fracture
- bone breaks cleanly but does not protrude through skin.
Closed (simple)
- bone fragments into many pieces.
- one side of the bone is broken and the other side bends.
- broken ends of bone are forced into each other.
Impacted fracture
- a series of microscopic fissures in bone without damage to other tissues.
Stress fracture
Describe how bones Grow in length:
1. The epiphyseal plate is a layer of hyaline cartilage where bone grows in length (interstitial growth)
2. Here the cartilage cells divide near the epiphyseal side of this plate to lay down new cartilage for growth.
3. On the diaphyseal side of the plate cartilage is replaced by bone so that the thickness of the plate stays relatively constant.
4. Between 18-25 years old, the epiphyseal plate closes and totally turns into bone. This leaves the epiphyseal line. A bone fracture at this plate, during youth, can cause it to close prematurely.
Describe how bones Grow in diameter:
1. Bone thickens by appositional growth at the periosteum.
2. Osteoblasts form new osteons by laying down new concentric lamellae around the periosteal blood vessels which become the central canals.
3. Osteoclasts in the endosteum destroy old bone to enlarge the medullary cavity.
Explain the role of calcium and phosphorus in regulating bone growth.
Large amounts of calcium and phosphorus are needed especially when bones are growing.
Explain the role of human growth hormone (hGH) in regulating bone growth.
In childhood, human growth hormone (hGH) stimulates production of insulin-like growth factors (IGF’s) which stimulate cell division in the epiphyseal plate and periosteum.
Describe the processes involved in bone remodeling
A. It is done to strengthen bone, esp. in areas where there is mechanical stress. Also it renews bone before deterioration sets in and helps repair fractures.
B. Osteoclasts release enzymes and acids, which break down bone matrix proteins and dissolve mineral salts.
C. Osteoblasts then move in and lay down new bone matrix where it is needed.
D. Braces used in orthodontics place stress on bone that forms teeth sockets so that it remodels the socket to better align the teeth.
Events in fracture repair:
1. Blood released by injured vessels forms a fracture hematoma (clot). Then blood capillaries grow into clot. Phagocytes and osteoclasts remove damaged tissue to form a procallus.
2. Fibroblasts and chondroblasts produce fibrocartilage to form the fibrocartilaginous callus.
3. Osteoblasts form spongy bone to make a bony (hard) callus.
4. Callus is remodeled by osteoclasts which resorb dead fragments. Spongy bone at the periphery is replaced by compact bone.
Describe the role of bone in calcium homeostasis.
A. Calcium (Ca2+) is needed for various body functions. Bone serves as the major reservoir for Ca2+ so that
exchanges of Ca2+ occurs between bone and the blood.
B. If blood Ca2+ drops too low, this stimulates release of parathyroid hormone (PTH)
C. If blood Ca2+ is too high, this stimulates release of the hormone calcitonin (from the thyroid)
parathyroid hormone (PTH)
1. ↑ the number and activity of osteoclasts which ↑ the rate of bone resorption (break down)which ↑ Ca2+ concentration in the blood.
2. stimulates kidneys to conserve Ca2+ so that it is not lost in the urine.
3. stimulates formation of calcitriol (active form of Vit D) in the kidneys, which causes more Ca2+ to be absorbed from the food in the intestines
4. produced when blood calcium is too low
1. inhibits osteoclast activity (so that less Ca2+ is released into the blood).
2. ↑ Ca2+ uptake by and deposition into the bone.
3. produced when blood calcium is too high
Describe how exercise and mechanical stress affect bone tissue
A. Exercise is good because it places mechanical stress on bone. Bone reacts to this by depositing more Ca2+ and collagen fibers to strengthen stress points.
B. Also this stress ↑ calcitonin production that inhibits bone resorption, thus strengthening bone.
Describe the effects of aging on bone tissue
A. Because of ↓ production of hormones, esp. sex hormones, osteoblast activity ↓, Ca2+ and other minerals concentrations ↓ in bone.
B. Protein synthesis ↓ so that less collagen is deposited in bone so that it looses its tensile strength and becomes more brittle.
Discuss the following function of the skeletal system.

- bone forms a basic framework of the body.
Discuss the following function of the skeletal system

- protects organs from injury (e.g. skull).
Discuss the following function of the skeletal system

Helps in movement
- muscles contract to pull bone and move the body.
Discuss the following function of the skeletal system

Mineral homeostasis
- stores some minerals and releases them into the blood when needed.
Discuss the following function of the skeletal system

Site for energy storage
- yellow bone marrow contains triglyceride energy reserves.
Discuss the following function of the skeletal system

Site for blood cell production (hemopoiesis)
- red bone marrow produces RBC’s, WBC’s, and platelets.
bone resorption (break down) outpaces deposition so that bone mass ↓ and bones become more porous and lighter.
a. Shrinkage of backbone and height loss
b. Hunched back
c. Bone fractures easily
d. Considerable pain
Rickets and osteomalacia
Bones fail to calcify so that they become soft and easily deformed
Rickets and osteomalacia
- bowed legs and bone deformity.
- pain and tenderness in bone and bone fractures from minor traumas.