A&P1 - Exam 2 - Chapters 6, 7, 8

What are the 6 broad categories of bones

sutural, flat, irregular, long, short, sesamoid

What is the bone classification (by shape) of a bone that is small, flat, and irregularly shaped? Give an example

Sutural bones (or Wormian bones)

Which bone classification (by shape) in known for having complex shapes? Give an example.

Irregular bones; spinal vertebrae and pelvic bones

Which bone classification (by shape) has a boxy appearance? Give an example.

Short bones; carpal and tarsal bones

Which bone class (by shape) is thin with parallel surfaces? Give an example.

Flat bones; bones of skull roof, sternum, ribs, and scapulae

Which bone class (by shape) is characterized by a long and slender appearance? Give an example.

Long bones; humerus, femur

Which bone class (by shape) is characterized by a small, round, and flat appearance? Give an example.

Sesamoid bones; patellae

Differentiate between compact and spongy bone, based on these topics:

• Osteocytes

• Osteons

• Vascularity:

• Makeup of bone matrix

• Weight

• Production of blood cells

Osteocytes: Both contain osteocytes of course!

Osteons: In compact bone, osteons are the basic functional unit; spongy bone contains none.

Vascularity: Compact bones have a central canal and perforating canals that contain blood vessels; spongy bone is avascular

Matrix: compact bone matrix is composed of lamellae while spongy bone matrix is arranged as a network of trabeculae

Weight: Spongy is lighter

Production of blood cells: job of spongy bone marrow!

What is the basic functional unit of compact bone?

Osteons

Spongy bone supports and protects (red/yellow) bone marrow and some spongy bone contains (red/yellow) bone marrow. Give definitions of each of these types of bone marrow.

Supports and protects red bone marrow which fills space between trabeculae (bone matrix) and contains blood vessels that supply nutrients to osteocytes by diffusion.

Some spongy bone contains yellow bone marrow which stores fat

Periosteum

membrane that covers outside of bones

How do spongy bone and compact bone function together?

Spongy bone is able to receive the weight and transfer it to compact bone. Spongy is good for shock absorption while compact is able to actually bear that weight and provide support.

What are the steps of endochondral ossification?

1) Chondrocytes increase in size at primary ossification center in center of shaft; reduced matrix calcifies while condrocytes die

2) Blood vessels grow around cartilage; cells from perichondrium differentiate into osteoblasts; shaft becomes ensheathed in bone

3) Blood vessels enter primary ossification center allong with fibroblasts which differentiate into osteoblasts and begin to produce spongy bone. Both formation spreads from center toward both ends

4) Spongy bone at center remodels and a marrow cavity opens; bone tissue of shaft thickens; and cartilage toward epiphyses is replaced with bone

5) Blood vessels and osteoblasts migrate to epiphyses to create secondary ossification centers

6) Epiphses fill with spongy bone and epiphyseal cartilage separates diaphysis from epiphyses; ossification continues on diaphyseal side while new cartilage is produced on epiphyseal side

7) at puberty, ossificatio becomes faster than rate of cartilage production; epiphyseal closure; epiphyseal line remains after epiphyseal growth ends