Mastering A & P Bone tissue, histology and muscle tissue

Osteoblasts

know as the bown builders, serve to secrete the organic matrix of bone and assist in the formation of the inorganic matrix

hydroxyapatite crystals

made from calcium and phosphorus salts. they give bone its strength and ability to resist compression

Which type of cell is responsible for bone deposition?

osteoblasts

If primary bone were not replaced by secondary bone,

bone would be less resistant to tensile and compressive forces

During testing of a young girl, a doctor found an elevated level of estrogen caused by a tumor. He informed the parents to expect

-the young girl to show significant growth in a very short period but her overall height to be less than average. --The female sex hormone estrogen plays a role in bone growth. Like testosterone, estrogen increases the rate of longitudinal bone growth and inhibits osteoclasts. When the estrogen level increases during the teenage years, a "growth spurt" begins in females. Like testosterone, estrogen also accelerates closure of the epiphyseal plate, although it has a much more potent effect on epiphyseal plate closure than does testosterone. Excessive estrogen secretion will significantly increase longitudinal bone growth, but it will also cause premature closure of the epiphyseal plates. Her height will increase in the short term, but her adult height might be less than average.

Which of the following events does NOT happen during endochondral ossification? 1) Osteoclasts form a medullary cavity. 2) Secondary ossification centers develop. 3) Mesenchymal cells differentiate into osteoblasts. 4) Osteoblasts replace the calcified cartilage with early spongy bone.

3) mesenchymal cells differentiate into osteoblasts during intramembranous ossification

Which of the following happens closest to the diaphysis of a bone that is growing in length? 1) Chondrocytes divide. 2) Chondrocytes die. 3) Chondrocytes enlarge and mature. 4) Calcified cartilage is replaced with bone.

Calcified cartlidge is replaced with bone

Which of the following gives bone its strength and ability to withstand compression and protect?

Hydroxyapatite crystals

Which of the following is not one of the effects of growth hormone on bones? 1) stimulation of osteoblasts in the periosteum 2) increase in the activity of osteogenic cells 3) increase in the activity of osteoclast 4) increase in the rate of mitosis of chondrocytes in the epiphyseal plate

Increase in the activity of osteoclasts

Flat bones such as the bones of the skull form via __________.

Intramembranous ossification

What happens during intramembranous ossification?

Mesenchymal cells differentiate into first osteogenic cells and then into osteoblasts

Bone cells that are found in the endosteum and periosteum and build new bone matrix are called __________.

Osteoblasts

The type of bone that has fully formed lamellae with regularly arranged collagen bundles and a higher percentage of inorganic matrix is classified as __________.

Secondary bone

Predict the effect of growth hormone deficiency during childhood.

Short stature

How would bone growth be affected in children suffering from malnutrition?

They would experience a decrease in mitosis in the hyaline cartilage at the epiphyseal plate, slowing the longitudinal growth of long bones

How does excess growth hormone allows the bone to continue to grow after the epiphyseal plate has closed?

excess growth hormone will continue to stimulate appositional growth even after the epiphyseal plate has closed ---Although only long bones undergo longitudinal growth from the epiphyseal plate, all bones grow in width. This growth occurs through a process known as appositional growth, during which osteoblasts between the periosteum and the bone surface lay down new bone. Growth hormone promotes appositional growth, so if secreted in excess, the bones will grow in width, even if they can no longer grow in length.

Dr. Riehm shows you an unlabeled tissue slide and says the tissue is very resistant to stretching, tearing, and compression. He then asks you what you can conclude about the structure of the extracellular matrix (ECM)

the ECM has abundant collagen fibers in a gel like ground substance