A and P ch 6

T/F: Bone remodeling, especially bone resorption, plays a role in the maintenance of proper levels of calcium in the blood.

true

T/F: A greenstick fracture would only be seen in an elderly person with more fragile bones.

False

T/F: As long bones form in the fetus, the formation of the medullary cavity occurs because of the actions of osteoblast cells.

False

T/F: During the process of bone formation in a fetus, a primary ossification center develops in the epiphysis of a cartilage model of a long bone.

False

T/F: In the activities of secondary ossification centers, the medullary cavity forms later and is much smaller.

False

T/F: Near the diaphysis of a long bone, such as the femur, a large nutrient artery enters the bone through a perforating canal

False

T/F: Osteocytes within lacunae are only found in compact bone and not within the trabeculae of spongy bone.

False

27) Which is the proper sequence of steps in the healing of a fracture (the steps are listed below but are not in the correct sequence of events): 1 osteoblasts form trabeclular bone that joins together the fractured ends of the bone and bony callus replaces fibrocartilage callus 2 bone remodeling occurs and compact bone replaces the spongy bone around the periphery of the fracture site 3 fibroblasts and chondrocytes from the periosteum form the fibrocartilage callus 4 a fracture hematoma forms and bone cells in the region of the fracture die 5 phagocytes and osteoclasts begin to remove the dead cells and damaged tissue around the hematoma a) 4, 5, 1, 2, 3 b) 5, 4, 3, 1, 2 c) 4, 5, 2, 3, 1 d) 3, 1, 2, 4, 5 e) 4, 5, 3, 1, 2

E

T/F: Bone can be classified as a connective tissue because it contains an extracellular matrix that surrounds widely spaced cells.

True

T/F: Bones can only assist in providing movement when they tugged on by the appropriate skeletal muscles.

True

T/F: During a needle biopsy of a person's bone marrow, maybe to test for the presence of cancer , pain is felt when the needle passes through the periosteum because it is richly supplied with nerves.

True

T/F: In a newborn, all bone marrow is red, which means all of the infant's marrow can make blood cells.

True

T/F: Parathyroid hormone (PTH) is able to regulate calcium levels in the blood through a series of steps that provide control through a negative feedback system.

True

Gravity and the pull of muscles against bone are the main mechanical stresses experienced by bone. Stress promotes deposition of mineral salts, collagen, and the strengthening of bone in stressed areas. Which of the following individuals would have a lower rate of bone deposition and would therefore be at greater risk for bone loss through bone resorption? a) a secretary who works at a desk job and does not do any regular weight-bearing exercise b) a college student who plays racket ball and jogs several days per week c) a construction worker who goes up and down ladder carrying tools and building materials all day d) a retired teacher who does all of her own yard work and who hikes with friends and family on the weekends e) none of these individuals are at any significant risk for loss of bone mass

a secretary who works at a desk job and does not do any regular weight-bearing exercise

Which of the following best describes the process of bone resorption in bone remodeling? a) acids and enzymes released by osteoclasts degrade collagen and dissolve away minerals, which diffuse through the interstitial fluid into nearby blood capillaries b) sex hormones stimulates osteoblast activity during growth spurts c) osteoblasts secrete the extracellular matrix of bone d) osteocytes die and no longer maintain the nutrients needed to preserve the extracellular matrix e) the kidneys increase the rate at which calcium is excreted in urine

acids and enzymes released by osteoclasts degrade collagen and dissolve away minerals, which diffuse through the interstitial fluid into nearby blood capillaries

In terms of bone health, why would a physician advise an older patient to do more weight-bearing activity such as walking, jogging, or use of moderate weights? a) it promotes normal bone remodeling b) osteoblasts deposit more minerals salts and collagen fibers as a response to mechanical stress c) being sedentary (not physically active) promotes bone loss through resorption by osteoclasts d) bone formation in stressed bones is stimulated by the tug of muscles (when exercising) e) all of these explain why a physician would give such advice to a patient

all of these

Which of the following is a function of calcium in the body? a) nerve cells require extracellular calcium ions (Ca2+) for proper functioning b) Ca2+ is a cofactor needed for many enzymes to function properly c) Ca2+ is required for the process of blood clotting d) Ca2+ is needed by muscle cells for contraction e) all of these are important roles of calcium in the body

all of these

Which of the following tissues could be found on or within a bone, such as the humerus? a) adipose tissue b) nervous tissue c) cartilage d) osseous tissue e) all of these

all of these

By which process, as an individual grows to adulthood, is the thickness (diameter) of bone increased?

appositional growth

Which two minerals are stored in major quantities in bone tissue?

calcium and phosphorous

When bones increase in thickness (diameter) as an individual grows to adulthood, which tissue or cells of the bone begin this growth process?

cells of the periosteum differentiating into osteoblasts

Long bones adds to its length at the epiphyseal plate. In this region which type of cells proliferate, become calcified, and are eventually replaced with mature bone cells, thereby adding to the bone's length?

chondrocytes

Which is secreted by osteoblasts during bone deposition? a) calcium b) collagen fibers c) hydroxyapatite d) vitamin D e) calcium phosphate

collagen fibers

An elderly woman trips and falls. She puts out her hand to try to stop her fall, and ends up with a fracture of the lower arm. An x-ray shows that at the break, many pieces of bone have a splintered and fragmented appearance. Which type of fracture does this woman have?

comminuted fracture

Which of the following regions of bone would not undergo bone remodeling as frequently as the other regions? a) spongy bone b) compact bone c) bone subjected to new stresses d) damaged bone e) all of these have similar rates of remodeling

compact bone

The process of intramembranous ossification generates bone within a pre-existing template composed of mesenchymal tissue. In contrast, endochondral ossification generates bone within a pre-existing template composed of _____.

hyaline cartilage

Most of the bones of the skull are formed by this process.

intramembranous ossification

Once osteoblasts have surrounded themselves with the extracellular matrix of bone tissue, they remain inside little chambers called __________ where they carry on the metabolic functions that maintain bone tissue. At this point, the cells are called osteocytes.

lacunae

In which region of a long bone, such as the humerus, would you find the epiphyseal plate (growth plate)?

metaphysis

Which is formed from the fusion of as many as 50 monocytes (a type of white blood cell)? a) osteogenic cell b) osteoblast c) osteocyte d) osteoclast

osteoclast

Which represents the correct sequence of development of bone cells? a) osteogenic cells → osteocytes → osteoblasts → osteoclasts b) osteoblasts → osteoclasts → osteogenic cells → osteocytes c) osteoclasts → osteoblasts → osteocytes → osteogenic cells d) osteogenic cells → osteoblasts → osteocytes e) osteogenic cells → osteoblasts → osteocytes → osteoclasts

osteogenic, osteoblasts, osteocytes

Bone tissue stores 99% of the body's calcium. Calcium plays important roles beyond the mineralization of bones. The exchange of calcium between bone and body fluids (especially the blood) is regulated by several hormones. Which of the following is the most important hormone regulating calcium exchange? a) vitamin D (calcitriol) b) calcitonin c) thyroid hormones (T3 and T4) d) human growth hormone (hGH) e) parathyroid hormone (PTH)

parathyroid hormone

Stan is a 35 year old man who is a dedicated long distance runner. He spends hours every week running along neighborhood streets. Recently Stan has had to go to the doctor due to pain in his lower legs that intensifies when he tries to run. There is no swelling or obvious damage, so he is surprised to hear the doctor say he has a fracture of his tibia. Stan is most likely to have which type of fracture?

stress fracture

Compact bone is composed of units called osteons. In contrast, spongy bone is composed of _____.

trabeculae