A long bone forms by a process known as ________ ossification.

Answer: endochondral

What can a deficiency of growth hormone during bone formation cause?

A)decreased proliferation of the epiphyseal plate cartilage

B)increased osteoclast activity

C)inadequate calcification of bone

D)decreased osteoclast activity

Answer: A

Answer: A

The structural unit of spongy is called ________.

A)osteons

B)trabeculae

C)lamellar bone

D)osseous lamellae

^{Answer: B}

Layers of bone matrix.

Lamellae

The structure of bone tissue suits the function. Which of the following bone tissues is adapted to support weight and withstand tension stress?

^{A)compact bone}

^{B)trabecular bone}

^{C)spongy bone}

^{D)irregular bone}

^{Answer: A}

Several hormones control the remodeling of bones. Which two respond to changing blood calcium levels?

^{Answer: PTH and calcitonin are the major determinants of whether and when remodeling will occur in response to changing blood calcium.}

For intramembranous ossification to take place, which of the following is necessary?

A)The cartilage matrix begins to deteriorate.

B)A bone collar forms around the cartilage model.

C)An ossification center forms in the fibrous connective tissue.

D)A medullary cavity forms.

Answer: C

Cartilage grows in two ways, appositional and interstitial. What is appositional growth?

A)the lengthening of hyaline cartilage

B)the secretion of new matrix against the external face of existing cartilage

C)growth at the epiphyseal plate

D)along the edges only of existing osteons, making each osteon larger

^{Answer: B}

Area where bone longitudinal growth takes place.

Epiphyseal plate

The canal that runs through the core of each osteon (the Haversian canal) is the site of ________.

A)cartilage and interstitial lamellae

B)yellow marrow and spicules

C)adipose tissue and nerve fibers

D)blood vessels and nerve fibers

^{Answer: D}

Osteogenesis is the process of ________.

^{A)bone destruction to liberate calcium}

^{B)making a cartilage model of the fetal bone}

^{C)making collagen fibers for calcified cartilage}

^{D)bone formation}

^{Answer: D}

The resilience of bone is primarily due to which of the following?

A)amount of mineral salts in the bone

B)amount of mineral salt and protein in the bone

C)presence of osteoblasts in the bone

D)sacrificial bonds in or between collagen molecules

Answer: D

The lining of the marrow cavity.

Endosteum

Bones are constantly undergoing resorption for various reasons. Which of the following cells accomplishes this process?

^A)osteoblast

^B)osteocyte

^{C)stem cell}

^D)osteoclast

^{Answer: D}

The periosteum is secured to the underlying bone by dense connective tissue called ________.

^{A)the struts of bone known as spicules}

^{B)perforating (Sharpey's) fibers}

^{C)a bony matrix with hyaline cartilage}

^{D)Volkmann's canals}

^{Answer: B}

^{Answer: B}

In the epiphyseal plate, cartilage grows ________.

^{A)in a circular fashion}

^{B)by pulling the diaphysis toward the epiphysis}

^{C)by pushing the epiphysis away from the diaphysis}

^{D)from the edges inward}

^{Answer: C}

^{Answer: C}

Wolff's law is concerned with ________.

^{A)the diameter of the bone being dependent on the ratio of osteoblasts to osteoclasts}

^{B)the thickness and shape of a bone being dependent on stresses placed upon it}

^{C)the function of bone being dependent on shape}

^{D)vertical growth of bones being dependent on age}

^{Answer: B}

Small channels that radiate through the matrix of bone.

Canaliculi

List the steps in the repair process of a simple fracture.

Answer: Hematoma formation, fibrocartilaginous callus formation, bony callus formation, and remodeling.

The term diploë refers to the ________.

^{A)double-layered nature of the connective tissue covering the bone}

^{B)two types of marrow found within most bones}

^{C)fact that most bones are formed of two types of bone tissue}

^{D)internal layer of spongy bone in flat bones}

^{Answer: D}

The cell responsible for secreting the matrix of bone is the ________.

A)osteoclast

B)osteocyte

C)chondrocyte

D)osteoblast

Answer: D

The area of long bones where cartilage cells are replaced by bone cells.

Diaphysis

What tissue forms the model for endochondrial ossification?

A)bone

B)fascia

C)membranes

D)cartilage

Answer: D

A fracture in the shaft of a bone would be a break in the ________.

A)metaphysis

B)epiphysis

C)articular cartilage

D)diaphysis

Answer: D

What is found in a Haversian canal?

Answer: Blood vessels and nerve fibers

Sixty-five percent of the mass of bone is a compound called hydroxyapatite.

TRUE

Inflammation of bony tissue is called ________.

Answer: osteitis

Which hormone increases osteoclast activity to release more calcium ions into the bloodstream?

^A)thyroxine

^B)calcitonin

^{C)parathyroid hormone}

^D)estrogen

^{Answer: C}

What is a disease of the bone in which bone reabsorption outpaces bone deposit, leaving the person with thin and often very fragile bones?

Answer: Osteoporosis

What is found in a Haversian canal?

Answer: Blood vessels and nerve fibers.

Which structure allows the diaphysis of the bone to increase in length until early childhood?

A)epiphyseal line

B)epiphyseal plate

C)lacunae

D)Haversian system

Answer: B

Bone formed is poorly mineralized and soft. Deforms on weight bearing.

Osteomalacia

The cells responsible for the early stages of endochondral ossification.

Chondrocytes

Cartilage has a flexible matrix that can accommodate mitosis of chondrocytes.

TRUE

Which of the following glands or organs produces hormones that tend to decrease blood calcium levels?

^{A)pineal gland}

^{B)parathyroid}

^C)thyroid

^D)spleen

^{Answer: C}

A bone embedded in a tendon is called a(n) ________ bone.

Answer: sesamoid

The growth pattern of bone in which matrix is laid down on the surface.

Appositional growth

The cells responsible for the early stages of endochondral ossification.

Chondrocytes

Which of the following is the single most important stimulus for epiphyseal plate activity during infancy and childhood?

A)growth hormone

B)thyroid hormone

C)parathyroid hormone

D)calcium

Answer: A

Each consecutive bone lamella has collagen fibers that wrap in alternating directions

TRUE

Abnormal bone formation and reabsorption

Paget's disease

The trabeculae of spongy bone are oriented toward lines of stress.

TRUE

Growth of bones is controlled by a symphony of hormones. Which hormone is of greatest importance for bone growth during infancy and childhood?

^A)prolactin

^{B)growth hormone}

^{C)thyroid hormone}

^{D)somatomedins}

^{Answer: B}

A central (Haversian) canal may contain arteries, veins, capillaries, lymph vessels, and ________ fibers.

Answer: nerve

Cranial bones develop ________.

^{A)within osseous membranes}

^{B)within fibrous membranes}

^{C)from a tendon}

^{D)from cartilage models}

^{Answer: B}

^{Answer: B}

An osteon contains osteocytes, lamellae, and a central canal, and is found in compact bone only.

TRUE

What kind of tissue is the forerunner of long bones in the embryo?

A)elastic connective tissue

B)hyaline cartilage

C)dense fibrous connective tissue

D)fibrocartilage

Answer: B

Hematopoiesis refers to the formation of blood cells within the red marrow cavities of certain bones.

TRUE

Blood cell formation is called ________.

Answer: hematopoiesis

What are multinucleated cells that destroy bone called?

Answer: Osteoclasts

Bones are porous and thin but bone composition is normal.

Osteoporosis

The term osteoid refers to the organic part of the matrix of compact bones.

TRUE

Bone fragments into many pieces.

Comminuted

What causes osteoporosis?

^{A)poor posture}

^{B)abnormal PTH receptors}

^{C)heritage such as African or Mediterranean}

^{D)Osteoclasts out-pace osteoblasts due to low hormone production of the ovaries.}

^{Answer: D}

An incomplete fracture or cracking of the bone without actual separation of the parts. Common in children.

Greenstick

What is absolutely required for bone growth or healing from a fracture?

^A)osteocytes

^{B)osteoblasts}

^{C)dietary intake of calcium and vitamin D}

^{D)osteoclasts}

^{Answer: B}

Common sports fracture resulting from a twisting force.

Spiral

Which of the following is not a function of the skeletal system?

A)storage of minerals

B)support

C)communication

D)production of blood cells (hematopoiesis)

Answer: C

Cells that can dissolve the bony

Osteoclasts

Cells that can build bony matrix.

Osteoblasts

The process of bones increasing in width is known as ________.

^{A)closing of the epiphyseal plate}

^{B)concentric growth}

^{C)epiphyseal plate closure}

^{D)appositional growth}

^{Answer: D}

Lengthwise, long bone growth during infancy and youth is exclusively through ________.

^{A)the secretion of bone matrix into the medullary cavity}

^{B)differentiation of osteoclasts into osteocytes}

^{C)interstitial growth of the epiphyseal plates}

^{D)calcification of the matrix of the zone underlying articular cartilage}

^{Answer: C}

Normal bone formation and growth are dependent on the adequate intake of ________.

^{A)sodium, calcium, and vitamin E}

^{B)calcium, phosphate, and vitamin D}

^{C)potassium, phosphate, and vitamin D}

^{D)vitamin D, phosphate, and chloride}

^{Answer: B}

What is the structural unit of compact bone?

A)lamellar bone

B)the osteon

C)spongy bone

D)osseous matrix

Answer: B

Which of the following is a bone marking name that indicates an armlike bar of bone?

A)fossa

B)foramen

C)meatus

D)ramus

E) epicondyle

Answer: D

The structural unit of spongy is called ________.

A)osteons

B)trabeculae

C)lamellar bone

D)osseous lamellae

Answer: B

Trochanter

Femur

Facet

Vertebrae

The structural unit of compact bone (osteon) resembles the growth rings of a tree trunk.

TRUE

A round or oval hole through a bone that contains blood vessels and/or nerves is called a(n) ________.

Answer: foramen

Ischial spine

Coxal bone

Yellow bone marrow contains a large percentage of ________.

A)fat

B)elastic tissue

C)blood-forming cells

D)Sharpey's fibers

Answer: A

Ramus

Mandible

Foramen

Occipital bone

The periosteum is a tissue that serves only to protect the bone because it is not supplied with nerves or blood vessels.

FALSE

In newborn infants, the medullary cavity and all areas of spongy bone contain yellow bone marrow.

FALSE

Short, irregular, and flat bones have marrow cavities in order to keep the weight of the bones light.

FALSE

Compact bone is replaced more often than spongy bone.

FALSE

Bones are classified by whether they are weight bearing or protective in function.

FALSE

Osteomyelitis is ________.

^{A)due to pus-forming bacteria B)literally known as "soft bones"}

^{C)caused by altered vitamin D metabolism}

^{D)partially due to insufficient dietary calcium}

^{Answer: A}

The hormone that is primarily involved in the control of bone remodeling is the parathyroid hormone.

FALSE

Closure of the epiphyseal plate stops all bone growth.

FALSE

All bones stop growing by the end of adolescence.

FALSE

In newborn infants, the medullary cavity and all areas of spongy bone contain yellow bone marrow.

FALSE

^{Johnny fractured the lower third of his right tibia in a skiing accident. The soft tissues in the area were severely damaged and their surgical removal was necessary. After prolonged immobilization, it was found that Johnny was healing very poorly. The explanation offered by the orthopedic surgeon was that vascularization of the fracture site was still inadequate and good healing was absolutely dependent upon an adequate blood supply. Describe how a long bone receives its blood supply and trace the path of nutrient delivery to the osteocytes.}

^{Answer: Long bones are nourished by nutrient arteries that frequently enter the shaft. Removal of the soft tissues probably reduced the flow of blood to the affected area. The pathway requires transport of nutrients from blood vessels to periosteum to Volkmann's canals to Haversian canals to canaliculi to lacunae.}

Why are the bones of young children much more flexible than those of the elderly?

^{Answer: Bones of children are not completely calcified, with a higher ratio of more flexible organic fibers. Bones in the elderly are more completely calcified, which gives the characteristic of rigidity.}

Bones appear to be lifeless structures. Does bone material renew itself?

^{Answer: Bone only appears lifeless in gross anatomy. Microscopically, bone is full of cells and blood vessels that maintain and renew bone tissue. Approximately 5% to 7% of our bone mass is recycled each week. Up to 0.5 g of calcium may enter or leave the bones each day, depending on the negative feedback hormonal mechanism and gravitational forces.}

Compare the function of the organic materials in the bone matrix with the function of the inorganic materials in the matrix.

^{Answer: The organic matrix contributes to the bone structure and its tensile strength, while the inorganic matrix contributes to hardness and resistance to compression.}

What are the differences between the diaphysis and the epiphyses of long bones?

^{Answer: Diaphyseal bone is composed almost entirely of compact bone (except in irregular and short bones), while the epiphyses are composed almost entirely of spongy bone. The epiphyses are on the ends of the bone; the diaphysis is the "shank" of the bone. The diaphysis in long bones has a large medullary cavity, whereas the epiphyses do not.}

Describe how oxygen is carried from outside a bone to an individual osteocyte.

^{Answer: Blood vessels enter through the periosteum into a perforating canal. The vessel may follow along the axis of the bone through a central canal. Osteocytes have long, almost dendritic-like extensions or arms that reach out through tiny holes called canaliculi. The canaliculi connect one cell to another and to the central canal. Oxygen leaves the blood vessel in the central canal and travels through the canaliculi from cell to cell until it reaches the cell in question.}

How is the beginning of intramembranous ossification different from endochondral ossification?

^{Answer: Intramembranous ossification starts in connective tissue from mesenchymal cells that become osteoblasts. These osteoblasts cluster together into an ossification center. Endochondral ossification starts with a hyaline cartilage "template." Mesenchymal cells become osteoblasts and begin forming bone around the cartilage.}

If your doctor notices a marked decrease in calcium ion levels in your blood, what gland might he suspect is not functioning properly and why?

^{Answer: The parathyroid gland normally responds to low calcium ion levels in the blood and releases PTH, which mobilizes osteoclasts to step up bone destruction, releasing more calcium into the bloodstream. Persistent low blood calcium level therefore implies insufficient PTH, suggesting injury or failure of the parathyroid glands}

Explain why swimming is not generally recommended as an exercise to prevent osteoporosis.

^{Answer: Mechanical stress and gravity help to promote skeletal remodeling. Swimming is not considered a weight-bearing exercise. The water, not bones, supports the body's weight while swimming.}

How can a tooth be moved in a bony socket during orthodontic treatment?

^{Answer: Because bone deposition and reabsorption can occur, and because bone responds to mechanical stress (Wolff's law), a tooth can be moved. By applying slight pressure to a tooth, the bone on the forward side will reabsorb, while the bone on the reverse side will be reformed}

If your elderly patient's blood calcium level is normal, does that mean the patient does not have osteoporosis? Explain.

^{Answer: No. The level of calcium in the blood is expected to be normal, even in advanced cases of osteoporosis. The calcium in the bones will be low, but that occurs in order to maintain a normal blood calcium level.}

^{Mrs. Brown was outside on her patio cleaning windows when she fell off her step ladder and fractured her right hip. She had emergency surgery with an open reduction and internal fixation of the right hip. Three days postoperatively, she asks you if she will have trouble going through airport security. What has prompted her concern?}

^{Answer: Open reduction is the correction of the bone alignment through a surgical incision. It may include internal fixation of the fracture with the use of rods, wire, screws, pins, or nails, metal items that may trigger security alarms.}

When does prevention of osteoporosis start?

^{Answer: The prevention of osteoporosis should begin with children. Parents need to provide children with the opportunity to develop as much bone as they have inherited the ability to develop. If people increase their peak bone mass as young adults, they will have additional protection from osteoporotic fractures in the future}

People who live in the north should take supplemental calcium with vitamin D. Explain why.

^{Answer: Vitamin D is manufactured by the skin using sunlight and is needed for absorption of dietary calcium. People who live in the north where the winter months are severe may need supplemental vitamin D because of the decreased amount of sunlight exposure.}

^{A 75-year-old woman and her 9-year-old granddaughter were victims of a train crash. In both cases, trauma to the chest was sustained. X rays of the grandmother revealed several fractured ribs, but her granddaughter had none. Explain these different findings.}

^{Answer: The child had more organic material in her bones, which allows bones to be more flexible, while her grandmother's bones are extensively calcified, with little organic material, and are probably thin due to osteoporosis.}

^{Emily, a 64-year-old formerly obese woman who successfully lost over 100 pounds, was brought to the hospital suffering pain in her legs, and an X-ray revealed that she had a simple fracture in her right femur and a crack in her left tibia. Other tests revealed that her bones were brittle and porous. What might have happened to Emily, and what advice would she have been given by the physician?}

^{Answer: Emily has osteoporosis, a debilitating bone disease that strikes more women than men after age 45-50. The bones become weak and brittle due to osteoclast out pacing of osteoblast in the bone. Emily has been told that she needs to take supplements of Ca, Vitamin D, and do weight baring exercise.}

^{Alice and James adopted a 3-year-old child from a developing country. They noticed that her legs were bowed and there were some deformities in her cranial and pelvic bones. They brought her to a physician for a diagnosis. What was the diagnosis, and what was the treatment for the disorder?}

^{Answer: The child most likely has rickets, a condition caused by poor diet, especially one deficient in vitamin D. The parents were told to increase her intake of calcium and vitamin D and to make sure that she gets some sunshine every day.}

^{While on spring break from college, June fell on the pavement and broke her wrist. At the emergency room, a resident placed a cast on her wrist after manipulating the bones. It seemed to heal within a few months. Now, decades later she has noticed lumps in the area where the break happened and she has been complaining of pain. What could be causing the lumps and the pain?}

^{Answer: June probably has "bone spurs," which are abnormal projections from a bone due to bone overgrowth}