Chapter 6: Bones and Bone Tissue

Cells that develop into osteoblasts are called:

osteogenic cells.

The structural units of mature compact bone are called:

osteons

The root word _____________ means "growth"

physis

Place the steps of longitudinal bone growth at the epiphyseal plate in the correct order from first to last.

1. Chondrocytes divide in the zone of proliferation. 2. Chondrocytes that reach the next zone enlarge and mature. 3. Chondrocytes die and their matrix calcifies. 4. Calcified cartilage is replaced with bone.

Place the steps of intramembranous ossification in the correct order starting with the earliest.

1. Osteoblasts develop in the primary ossification center from mesenchymal cells. 2. Osteoblasts secrete organic matrix, which calcifies, and trapped osteoblasts become osteocytes. 3. Osteoblasts lay down trabeulae of early spongy bone, and some of the surrounding mesenchyme differentiate into the periosteum. 4. Osteoblasts in the pericardium lay down early compact bone.

Place the steps of endochondral ossification in the correct order from first to last.

1. The chondroblasts in the perichondrium differentiate into osteoblasts. 2. Osteoblasts build the bone collar on the bone's external surface, bone begins to ossify from the outside, internal cartilage begins to calcify and the chondrocytes die. 3. In the primary ossification center, osteoblasts replace the calcified cartilage with early spongy bone. 4. Cartilage replaced by bone; the epiphyses finish ossifying.

____________________ is a loss of bone mass.

Osteoporosis

Place the following steps of bone repair in the correct sequence. 1. The bone callus is remodeled and primary bone is replaced with secondary bone. 2. A hematoma fills the gap between bone fragments. 3. Osteoblasts build a new bone callus. 4. Fibroblasts and chondroblasts infiltrate the hematoma and a soft callus forms.

2, 4, 3, 1

Which of the following hormones is currently thought to decrease plasma calcium levels in pregnant women and children?

Calcitonin.

PTH promotes the formation of which hormone?

Calcitriol Parathyroid hormone promotes the formation of calcitriol.

Why are collagen fibers a critical component of bone?

Collagen fibers help bone resist twisting, pulling, or stretching forces.

What is NOT an effect of growth hormone?

Growth hormone promotes the closure of the epiphyseal plate.

What tissue serves as the model for bones formed during endochondral ossification?

Hyaline cartilage

a comminuted fracture

In a comminuted fracture, the bone is shattered into multiple fragments. It might require surgical repair.

Which of the following is not a major difference between primary and secondary bone?

Primary bone has large amounts of inorganic matrix, while secondary doesn't.

What effects occur to the bones of astronauts who spend a prolonged period in space?

Weight-bearing exercises are minimal due to the weightlessness of space, leading to the decreased amount of compression and tension on bones and decreased osteoblast activity.

The root word ___________ means "immature or precursor"

blast

Bone deposition involves __________.

calcification Bone deposition is the process of building new bone and involves calcification of the bone matrix.

Which hormone works directly in the intestine to increase plasma calcium levels?

calcitriol Parathyroid hormone (PTH) activates Vitamin D into calcitriol in the kidney. Calcitriol then increases absorption of calcium in the intestine.

What accounts for the majority of bone (osseous) tissue matrix?

calcium salts

The major organic component of bone extracellular matrix is __________.

collagen The predominant protein fiber in osteoid is collagen.

The hard, dense bone that forms the outer surface of bones is:

compact bone.

Growth of a long bone occurs at a(n) _____________ plate.

epiphyseal plate

What structure allows the diaphysis of the bone to increase in length?

epiphyseal plate

Thin, broad bones should be classified as:

flat bones

Appositional growth allows bones to __________.

grow in width Appositional growth allows bones to grow in width. In actively growing bones, appositional growth is primarily responsible for thickening the compact bone of the diaphysis.

Blood cells are made in the red bone marrow of bones, a process known as:

hematopoiesis

The patella is classified as a sesamoid bone since it:

is located within tendons.

Calcitonin functions to:

increase bone deposition.

Which of the following is not one of the effects of growth hormone on bones?

increase in the activity of osteoclast Increase in osteoclast activity leads to bone resorption, not growth. It is one of the effects of parathyroid hormone, not growth hormone.

Which of the following would NOT be a way that parathyroid hormone (PTH) could alter plasma calcium levels? (Which one of the following is FALSE?)

increase osteoblasts on bone. This answer is false. PTH would NOT increase osteoblasts. Osteoblasts store calcium on bone, thus lowering plasma calcium levels.

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

intramembranous ossification During intramembranous ossification, embryonic connective tissue called mesenchyme is replaced with bone.

Small cavities that are located between lamellae and contain osteocytes are called __________.

lacunae Lacunae are filled with extracellular fluid and connected by canaliculi.

Bones with a diaphysis and epiphyses are classified as:

long bones

The root word ____________ means "bone"

osteo

A (n) ____________________ is an immature cell involved in bone formation.

osteoblast

The root word ___________ means "around"

peri

The connective tissue that surround compact bone is the _________________.

periosteum

Intramembranous ossification occurs in:

skull bones.