CH 5, Osseous Tissue & Skeletal Structure, Mastering A & P

What type of bone has thin, roughly parallel surfaces of compact bone, resembles a spongy bone sandwich, is strong but relatively light, and forms the roof of the skull, the sternum, the ribs, and scapulae?

Flat bones

What term is used to describe a shallow depression in bone?

Fossa

one side of the bone shaft is broken, and the other is bent

Greenstick fracture

In the classification of bones by shape, which type of bone is hollow, or contains numerous air pockets?

Pneumatized bone

A painful and destructive bone infection generally caused by bacteria is __________.

Osteomyelitis

Inadequate ossification is called __________.

Osteopenia

Which bone structure isolates and protects the bone from surrounding tissues, provides a route and a place of attachment for circulatory and nervous supply, actively participates in bone growth and repair, and attaches the bone to the connective tissue network of the deep fascia?

Periosteum

During the process of endochondral ossification, a major step occurs when the centers of the epiphyses begin to calcify. Capillaries and osteoblasts migrate into these areas, creating sites called __________.

Secondary ossification centers

Which of the following accurately states a difference between compact bone and spongy bone?

Spongy bone is arranged into trabeculae.

skeletal system

- Many bones of the skeleton can change the magnitude and direction of the forces generated by skeletal muscles. - Calcium is the most abundant mineral in the human body; 98 percent of the calcium in the body is deposited in the bones of the skeleton. - Individual bones or groups of bones provide a framework for the attachment of soft tissues and organs.

Factors that regulate bone growth

- Normal bone growth requires a constant dietary source of calcium and phosphate salts, as well as other ions such as magnesium, citrate, carbonate, and sodium. - Hormones regulate the pattern of growth by changing the rates of osteoblast and osteoclast activity. - Vitamins A and C are essential for normal bone growth and remodeling.

hormonal regulation of bone growth

- Parathyroid hormone stimulates osteoclast and osteoblast activity, increases the rate of calcium absorption from the small intestine, and decreases calcium loss in the urine. - The sex hormones, estrogen and testosterone, cause osteoblasts to produce bone faster than the rate of epiphyseal cartilage expansion; eventually, the epiphyseal cartilages narrow and ossify. - Growth hormone and thyroxine both stimulate bone growth and maintain proper epiphyseal cartilage activity until puberty.

Periosteum

- it actively participates in bone growth and repair - it is continuous with the joint capsule that encloses the joint - it consists of an intercellular layer consisting of osteoprogenitor cells

Bones are attached to

- muscular system - urinary system - cardiovascular system

endochondral ossification order

1. As the cartilage enlarges, chondrocytes near the center of the shaft increase greatly in size, the matrix is reduced to a series of small struts that soon begin to calcify, and the enlarged chondrocytes die and disintegrate, leaving cavities within the cartilage. 2. Blood vessels grow around the edges of the cartilage, and the cells of the perichondrium convert to osteoblasts. The shaft of the cartilage then becomes ensheathed in a superficial layer of bone. 3. Capillaries and osteoblasts penetrate the cartilage and invade the central region; osteoblasts begin producing spongy bone at the primary center of ossification; bone formation then spreads along the shaft toward both ends of the cartilaginous model. 4. Remodeling occurs as growth continues, and osteoclasts erode the central portion, creating a medullary cavity. The bone of the shaft becomes thicker, and the cartilage near each epiphysis is replaced by shafts of bone. 5. Capillaries and osteoblasts migrate into the epiphysis, creating secondary ossification centers. 6. Epiphyses are filled with spongy bone. Articular cartilage remains exposed to the joint cavity; over time it will be reduced to a thin superficial layer. At each metaphysis, an epiphyseal cartilage separates the epiphysis from the diaphysis.

steps of appositional bone growth

1. Bone formation at the surface of the bone produces ridges that parallel a blood vessel. 2. The ridges enlarge and create a deep pocket 3. The ridges meet and fuse, trapping the vessels inside the bone. 4. Bone deposition proceeds inward toward the vessel, beginning the creation of a typical osteon. 5. Additional circumferential lamellae are deposited and the bone continues to increase in diameter. 6. Osteon is complete with new central canal around the blood vessel. Second blood vessel becomes enclosed.

Order of intramembranous ossification (AKA Dermal ossification)

1. Differentiation of osteoblast within the Mesenchyme 2. Formation of bony spicules 3. Entrapment of blood vessels in the bone 4. Formation of spongy bone -occurs in the deeper layers of the dermis Examples of bone: -roofing bones of the skull (the frontal, pariental and occipital bones) and the mandible (lower jaw).

Steps to repair a fracture

1. Immediately after the fracture, extensive bleeding occurs. Over a period of several hours, a large blood clot, or fracture hematoma, develops. 2. And internal callus forms as a network of spongy bone unites the inner edges, and an External callus of cartilage and bone stabilizes the outer edges. 3. The cartilage of the external callus has been replaced by bone and struts of spongy bone now unite the broken ends. Fragments of dead bone and the areas of bone closest to the brake have been removed and replaced. 4. A swelling initially marks the location of the fracture. Over time, this region will be remodeled, and little evidence of the fracture will remain.

function of the skeletal system

1. Support 2. Leverage 3. Protection

bone marking called a ramus is:

And extension of a bone making an angle to the rest of the structure

Immediately after a bone fracture, extensive bleeding occurs. Over a period of several hours, what develops as a result of this bleeding?

A fracture hematoma

found at the ends of bones?

Epiphysis

After the perichondrium is converted to a periosteum, the inner osteogenic layer produces a thin layer of compact bone around the shaft of the cartilage known as __________.

Bone collar

Which diagnostic procedure would be most useful when checking for metastatic bone cancer, fractures, early infections, or certain degenerative bone diseases?

Bone scan

Which anatomical structures of the skeleton are complex, dynamic organs that contain osseous tissue, other connective tissue, smooth muscle, and neural tissue?

Bones

digestive system plays an important role in providing certain minerals needed for bone growth. Which mineral must be constantly provided by the digestive system, because it makes up a large portion of the bone matrix?

Ca+2

What accounts for almost two-thirds the weight of bone?

Calcium phosphate

Which type of lamellae fill in the spaces between the osteons in compact bone?

Interstitial lamellae

Which classification of bones is described as having complex shapes, with varied internal structure?

Irregular bones

Which cell population of mature bone directs both the release of calcium from bone to blood and the deposition of calcium salts in the surrounding matrix?

Osteocytes

Which function of the skeletal system changes the magnitude and direction of the forces generated by skeletal muscles?

Leverage

Which of the following congenital disorders of the skeleton involves excessive cartilage formation at the epiphyseal cartilages, resulting in extremely long and slender limbs?

Marfan's syndrome

What term is used to describe a passageway through the substance of a bone?

Meatus

In the formation of blood and lymphatic supply, which vessels supply blood to the diaphyseal surface of each epiphyseal cartilage, where bone is replacing cartilage?

Metaphyseal vessels

Which type of fracture retains the normal alignment of the bones or fragments?

Nondisplaced fractures

Which cells in bone are considered "bone-forming" because they secrete the organic components of the bone matrix?

Osteoblast

Bone growth occurs when osteoblasts are creating more bone matrix than __________ are removing.

Osteoclasts

congenital disorder of the skeleton called achondroplasia?

Unusual slow growth of epiphyseal cartilage in a child. Affected adults have a short stocky limbs, and abnormal proportions. Most cases result from spontaneous mutation.

Which vitamins are essential for normal bone growth and remodeling?

Vitamin A & C

Which type of bone consists of small, flat, oddly shaped bones that are occasionally found in the suture lines?

Wormian

Bones are largely under the physiological control of the __________ system.

endocrine