Chapter 6: Bone Tissue

Question 1

describe the six main functions of the skeletal system.

Answer 1

he skeletal system functions in support, protection, movement, mineral homeostasis, blood cell production, and triglyceride storage

Question 2

describe the structure and functions of each part of a long bone.

Answer 2

Parts of a typical long bone are the diaphysis (shaft), proximal and distal epiphyses (ends), metaphyses, articular cartilage, periosteum, medullary (marrow) cavity, and endosteum.

Bone tissue consists of widely separated cells surrounded by large amounts of extracellular matrix.

Long bones are supplied by periosteal, nutrient, metaphyseal, and epiphyseal arteries; veins accompany the arteries.

Question 3

explain why bone tissue is classified as a connective tissue.

Answer 3

Matrix w osteoblasts

Question 4

describe the cellular composition of bone tissue and the functions of each type of cell.

Answer 4

The four principal types of cells in bone tissue are osteoprogenitor cells/osteogenic, derived mesenchyme, inner portion of periosteum, endosteum and cnalas of blood vessells (give rise to –>),

osteoblasts (bone-building cells) matrix synthesis, initiates calcification (give rise to –>),

osteocytes (maintain daily activity of bone) mature bones, and metabolism -exchange of nutreints

osteoclasts (bone-destroying cells) endosteum - regulate blood calcium

Question 5

compare the structural and functional differences between compact and spongy bone tissue.

Answer 5

Compact Bone -

Compact bone tissue consists of osteons (haversian systems) with little space between them.Compact bone tissue lies over spongy bone tissue in the epiphyses and makes up most of the bone tissue of the diaphysis. Functionally, compact bone tissue is the strongest form of bone andprotects, supports, and resists stress

Spongy Bone

Spongy bone tissue does not contain osteons. It consists of trabeculae surrounding many red bone marrow–filled spacesSpongy bone tissue forms most of the structure of short, flat, and irregular bones, and the interior of the epiphyses in long bones. Functionally, spongy bone tissue trabeculae offer resistance along lines of stress, support and protect red bone marrow, and make bones lighter for easier movement

Question 6

describe the blood and nerve supply of bone.

Question 7

describe the steps of intramembranous and endochondral ossification.

Answer 7

Bone development begins during the sixth or seventh week of embryonic development.

The two types of ossification, intramembranous and endochondral, involve the replacement of a preexisting connective tissue with bone.

Intramembranous ossification refers to bone formation directly within mesenchyme arranged in sheet like layers that resemble membranes.

Endochondral ossification refers to bone formation within hyaline cartilage that develops from mesenchyme. The primary ossification center of a long bone is in the diaphysis. Cartilage degenerates, leaving cavities that merge to form the medullary cavity. Osteoblasts lay down bone. Next, ossification occurs in the epiphyses, where bone replaces cartilage, except for the epiphyseal (growth) plate

Question 8

explain how bone grows in length and thickness.

Answer 8

The epiphyseal plate consists of four zones: zone of resting cartilage, zone of proliferating cartilage, zone of hypertrophic cartilage, and zone of calcified cartilage. Because of the cell division in the epiphyseal (growth) plate, the diaphysis of a bone increases in length

Bone grows in thickness or diameter due to the addition of new bone tissue by periosteal osteoblasts around the outer surface of the bone (appositional growth)

Question 9

describe the process involved in bone remodeling.

Answer 9

Osteoclast attaches tightly to bone surface forming leakproof seal, releases protein digesting lysosomal enzyme and acid into sealed pocket enzyme digests collagen fibers acid dissolves bone, osteoclasts carve out tunnel, degraded proteins and matrix minerals (Ca and P) enter osteoclast by endocytosis in vesicles and then exocytosis on the other side, minerals in interstitial fluid diffuse into nearby blood capillaries, once area has been reabsorbed osteoclasts depart, osteoblasts rebuild

Question 10

describe the importance and regulation of calcium in the body.

Answer 10

Bone is the major reservoir for calcium in the body

Parathyroid hormone (PTH) secreted by the parathyroid glands increases blood Ca2+ level. Calcitonin (CT) from the thyroid gland has the potential to decrease blood Ca2+ level. Vitamin D enhances absorption of calcium and phosphate and thus raises the blood levels of these substances