Bio 168 Chapter 6 Mastering A&P Bones and Skeletal Tissues

Classify the cells seen at the arrow in image A -osteoclasts -osteocytes -osteoblasts -mesenchymal cells

Osteoblasts Osteoblasts ("bone makers") begin bone formation by secreting the bone matrix.

What is the structural unit of compact bone? -canaliculus -Haversian canal -osteon -osteoid

Osteon The structural unit of compact bone is the osteon, an elongated cylinder oriented parallel to the long axis of the bone.

Which of the following pairs of terms is mismatched? -cranial bones: flat bone -tarsals: short bones -sternum: long bone -femur: long bone

Sternum: long bone The sternum is a flat bone.

What is intramembranous ossification? -the formation of bone from preexisting fibrocartilage models -the formation of bone from preexisting hyaline cartilage models -the formation of bone from preexisting elastic cartilage models -the formation of bone from within fibrous membranes

The formation of bones from within fibrous membranes The formation of bone by ossification centers within fibrous membranes is called intramembranous ossification.

The main role of the axial skeleton is to help us manipulate our environment. -True -False

False It is the appendicular skeleton, along with the skeletal muscles that attach to it, that allows us to manipulate our environment. The axial skeleton is mostly involved in protecting, supporting, or carrying other body parts.

Oateoblasts ________ -secrete osteoid -break down bone -form skeletal cartilage -maintain bone matrix

Secrete osteoid Osteoblasts are the bone-forming cells that produce new bone by secreting the components of the organic matrix, called osteoid, They also play a role in the calcification of osteoid to form the mature bone matrix

Which of the following is the major component of the part of the bone labeled E? -dense connective tissue -adipose tissue -osseous tissue -blood

Adipose tissue Yellow bone marrow within the medullary cavity is composed primarily of adipose tissue (fat).

The figure represents a wedge-shaped section of which structural unit of bone? -trabeculae -an osteon -diploè -central canal

An osteon The circular structural unit found within compact bone is termed the osteon, and consists of a central canal surrounded by layers of bone.

During bone growth, which significant event occurs at the surface indicated by the letter C? -bone resorption -appositional growth -expansion of the articular cartilage -conversion of spongy bone to compact bone

Appositional growth Growth in width involves the adding of layers of lamellar (compact) bone along the bone's outer surface. This process of growth by "layering" is termed appositional growth and is distinct from growth by expansion of the interior matrix (interstitial growth).

Which structure is seen at the arrow? -epiphyseal plate -bone collar -periosteal bud -periosteum

Bone collar A collar of ossified tissue forms around the bone in the early stages of ossification.

During bone growth, which significant event occurs at the surface indicated by the letter D? -interstitial growth -production of compact bone -bone resorption -production of hyaline cartilage

Bone resorption As the bone widens, the matrix at the endosteal surface is resorbed to maintain the proper thickness of the walls surrounding the medullary cavity.

The blood vessels and nerve in the figure are found within which type of space? -central (Haversian) canal -canaliculi -marrow cavity -perforating (Volkmann's) canal

Central (Haversian) canal A central (or Haversian) canal runs lengthwise at the center of each osteon.

What event at letter B leads to elongation of the bone? -chondrocyte hypertrophy and deterioration -formation of compact bone -calcification of the cartilage matrix -conversion of bone into cartilage

Chondrocyte hypertrophy and deterioration Cell division of chondrocytes occurs on the epiphysis facing side. Rather than dividing, here chondrocytes hypertrophy and deteriorate along the diaphyseal surface of the growth plate.

Which of the following are correctly matched? -nondisplaced fracture; the fractured bone ends are misaligned -linear fracture; the break is perpendicular to the bone's long axis -compound fracture; the fractured bone ends penetrate the skin -incomplete fracture; the bone is broken through

Compound fracture; the bone is broken through In a compound (open) fracture, the fractured bone ends penetrate the skin. Such open injuries carry a higher risk of infection.

Which step in the figure contains compact bone? -A -B -C -D

D Osteoblasts in the periosteal layer form compact bone characteristie of the exterior surface of a mature bone.

The arrow in the figure is pointing to which of the following structures? -the epiphyseal plate - a primary ossification center -a secondary ossification center -the articular cartilage

The epiphyseal plate During endochondral ossification, a distinct epiphyseal plate is formed at the boundary between primary and secondary ossification centers.

What is the weakest part of a developing, adolescent long bone? -the medullary cavity -the epiphyseal plate -the epiphyses -the diaphysis

The epiphyseal plate The epiphyseal plate is a weak point because of the lack of calcification.

What bone-associated structures in panel C are indicated by the arrow? -epiphyseal plate -periosteum -trabeculae -osteon

Trabeculae The honeycomb-like network of spongy bone is constructed of bony plates called trabeculae.

Flat bones consist of a thin plate of spongy bone, called diploë, sandwiched between two layers of compact bone. -True -False

True Flat bones consist of thin plates of spongy bone (diploë) covered by compact bone.

You overhear some anatomy students imagining out loud what their bones would look like if they had compact bone on the inside and spongy bone on the outside, instead of the other way around. You tell them that such imaginary bones would be poorly designed mechanically and would break easily. Which of the following statements does NOT accurately support your claim? -Spongy bone consists of a thin organic matrix that serves to lighten the inside of bone, whereas compact bone consists of a dense inorganic matrix designed to resist stress. -Compact bone consists of osteons, which are made up of concentric lamellae with an alternating pattern of collagen fibers designed to resist torsional stress. -Made up of trabeculae that are only a few cell layers thick, spongy bone is much more fragile than compact bone. -An outer layer of spongy bone would be constantly damaged by the bending and twisting forces applied to the surface of bone.

Spongy bone consists of a thin organic matrix that serves to lighten the inside of bone, whereas compact bone consists of a dense inorganic matrix designed to resist stress. The chemical composition of spongy bone and compact bone is the same; both consist of a matrix that is about one-third organic and two-thirds inorganic. The arrangement of this matrix is what differs between compact and spongy bone.

Your patient is returning for follow-up 6 weeks after sustaining a nondisplaced fracture of his radius. He tells you that his forearm is no longer painful, but he is concerned that he can palpate a "lump" in the bone at the site of the healing fracture. What is your response? -"I'm concerned that your bone is not healing properly. Let's ask the doctor about doing some X-rays." -"The lump means that the fracture was not set properly. I'm concerned that the ends of the fracture aren't properly aligned." -"That lump may be a sign of infection. We need to obtain cultures from the site." -"That bump is a normal part of bone healing at this stage. As your body completes the process, the cells in your bone will gradually remodel it to its previous shape."

"That bump is a normal part of bone healing at this stage. As your body completes the process, the cells in your bone will gradually remodel it to its previous shape." Right! You understand the stages of bone healing, including the formation of callus and ultimate remodeling.

You're talking with Liliana before her release from the hospital. Which of her statements indicates the need for further patient education? -"Will the doctor have my vitamin D levels tested?" -"The only supplement I should need would be calcium, so I will take a calcium supplement every morning." -"At last I have an excuse for taking walks outside in the sun!" -"My parathyroids are really important for maintaining my bones!"

"The only supplement I should need would be calcium, so I will take a calcium supplement every morning." Liliana needs to know that to absorb the calcium from those supplements, she will require vitamin D.

Which of the following statements is true? -By the age of 21, the width of the bones stops changing. -Hormones determine where remodeling occurs within the skeleton. -PTH will increase calcium deposits in the bone matrix. - After the age of 21, most people will not experience longitudinal growth of bones.

-After the age of 21, most people will not experience longitudinal growth of bones. This is correct. Longitudinal bone growth ends when the bone of the epiphysis and diaphysis fuses. This process, called epiphyseal plate closure, happens at about 18 years of age in females and 21 years of age in males.

Which of the following diseases would most likely be associated with a disorder at A? -osteoarthritis -osteosarcoma -achondroplasia -osteomalacia

Achondroplasia This genetic disease can lead to shortening of the long bones due to premature closure of the epiphyseal plate.

Which of the following correctly pairs the structure at C with its primary component? -periosteum; dense irregular connective tissue -periosteum; cuboidal epithelium -endosteum; dense regular connective tissue -endosteum; areolar tissue

Periosteum; dense irregular connective tissue The periosteum is composed of dense irregular connective tissue along with a layer of simple squamous epithelium.

Osteoid-producing osteoblasts must rely on this organelle to produce primary structures leading to the formation of collagen and calcium-binding proteins. -Ribosomes -Mitochondria -Peroxisomes -Centrioles

Ribosomes

Which of the following statements is true? -Spongy bone is well adapted to accept stress in many directions, which makes it good for shock absorption. -Osteoclasts are important in removing calcium from the blood stream. -The red marrow in the medullary cavity produces our red blood cells. -Bone would be more brittle with more collagen in the matrix.

Spongy bone is well adapted to accept stress in many directions, which makes it good for shock absorption The trabeculae in spongy bone align precisely along lines of stress and help the bone resist stress.

Which of the following statements regarding the skeleton is INCORRECT? -The axial skeleton supports and protects internal organs. -The appendicular skeleton includes the shoulder girdles. -The axial skeleton includes the bones of the limbs. -The appendicular skeleton allows us to move around.

The axial skeleton includes the bones of the limbs The bones of the limbs makeup the appendicular skeleton.

Which of the following best describes the process shown in the figure? -bone remodeling in response to changes in mechanical stress -bone repair at a site of fracture -the formation of bone in a preexisting cartilage model -the formation of bone in a membrane

The formation of bone in a membrane The figure illustrates the formation of new bones within a fibrous membrane ("'intramembranous") during embryonic development.

Which of the following statements is true regarding the future actions of the vessels in the medullary cavity and the vessels in the epiphyses of the bone? -They will eventually degrade and die, leaving the bone with little or no blood supply. -They will grow and encourage bone formation until all articular cartilage is ossified. -They will grow and encourage bone formation until the epiphyseal plate eventually ossifies. -They will grow to a certain size and then maintain all of the cartilage seen in the figure.

They will grow and encourage bone formation until epiphyseal plate eventually ossifies The loss of the epiphyseal plate will seal the epiphysis and diaphysis and eventually end the lengthening of the bone.

In long bone formation, from what embryonic structure does the articular hyaline cartilage on the end of an adult long bone arise? -from the osteoblasts in the primary ossification center -from superficial tissues surrounding the bone as it develops -from the periosteum -from the original hyaline cartilage bone model of the embryo

from the original hyaline cartilage bone model of the embryo The hyaline cartilage on the ends of adult long bones is a remaining layer of cartilage that existed as part of the original embryonic cartilage model.

Apply what you have learned about skeletal tissue and select the factors that would increase bone density and help prevent osteoporosis. -Aquatic exercise -Walking -Estrogen replacement therapy for post-menopausal women - A high-protein diet -A diet rich in vitamin D and calcium -Calcitonin administration -Medications such as bisphosphonates, which inhibit osteoclasts

-Aquatic exercise -Walking -Estrogen replacement therapy for post-menopausal women -A diet rich in vitamin D and calcium -Calcitonin administration -Medications such as bisphosphonates, which inhibit osteoclasts There are many lifestyle and pharmaceutical interventions that can build stronger bones and decrease the loss of bone density that occurs with aging. Early intervention and making healthy choices early in life can decrease the risk of osteoporosis.

What is the role of osteoclasts in the endosteum during long bone growth? -They produce the yellow marrow found in medullary cavities. --They proportionally increase the size of the medullary cavity as the bone grows to prevent the weight of the growing skeleton from becoming too heavy. -They add to the bone's density and strength by increasing the diameter of the shaft. -They produce the red marrow found in spongy bone tissue.

-They proportionally increase the size of the medullary cavity as the bone grows to prevent the weight of the growing skeleton from becoming too heavy. The osteoclasts in the endosteum break down bone tissue in the medullary cavity while osteoblasts in the periosteum add more bone matrix to the outer surface of the bone. This allows the bone to increase in width while remaining hollow and lightweight.

The correct order (from start to finish) of fracture repair is _______ -Hematoma formation, hard callus formation, bone remodeling, and fibrocartilaginous callus formation -bone remodeling, hematoma formation, soft callus formation, and hard callus formation -Bony callus formation, hematoma formation, fibrocartilaginous callus formation, and bone remodeling -hematoma formation, soft callus formation, bony callus formation, and bone remodeling

-hematoma formation, soft callus formation, bony callus formation, and bone remodeling From start to finish, a fracture is repaired by (1) formation of a hematoma, (2) formation of a fibrocartilaginous callus, (3) formation of a bony callus, and (4) bone remodeling

Which event has to precede all others during endochondral ossification? -Bone trabeculae appear in the epiphyses. -An epiphyseal plate is formed. -A cartilage model of the bone is formed. -A nutrient artery invades the diaphysis.

A cartilage model of the bone is formed This event precedes all others in endochondral ossification, the process by which a bone develops by replacing existing hyaline cartilage.

What would be the physical sign that a bone cannot continue longitudinal growth? -the presence of osteons -the presence of osteoblasts -an epiphyseal line -the presence of hyaline cartilage on the ends of the bone

An epiphyseal line The epiphyseal plate is a zone of hyaline cartilage between the epiphysis and diaphysis of a long bone. When the cartilage is replaced with bone and the plate closes, the bone has reached its maximum length. This ossified remnant of the "growth plate" is called the epiphyseal line.

In which of the labeled parts of the adult long bone would hematopoietic tissue be located? -A -B -C -D -E

B Hematopoietic tissue is found in the red bone marrow within certain body locations consisting of spongy bone. Examples include the diploe of flat bones and the proximal epiphyses of the femur and humerus (pictured).

Which epiphyseal plate zone contains dying and deteriorating chondrocytes? -proliferation zone -hypertrophic zone -ossification zone -calcification zone

Calcification zone The calcification zone is where chondrocytes die while the surrounding matrix calcifies, becoming hardened.

Which hormone is NOT matched with its correct function? -PTH; indirectly stimulates osteoclast activity -calcitonin; increases blood calcium levels -osteocalcin; helps regulate glucose metabolism -growth hormone; lengthens long bones

Calcitonin; increases blood calcium levels Calcitonin is produced in the thyroid gland; it plays a minor role in regulating Ca?+ homeostasis by decreasing blood calcium levels.

Which of the following substances is NOT a component of the osteoid material secreted by the cells indicated by the arrow in panel A? -glycoprotein -collagen -calcium -proteoglycan

Calcium Calcium is an inorganic component of the bone matrix and is deposited from the interstitial fluids. The organic osteoid secreted by bone-forming cells is composed of proteoglycans, glycoproteins, and collagen.

Which description of skeletal cartilage is INCORRECT? -Fibrocartilages are able to withstand both pressure and stretch. -Costal cartilages reinforce airways and support the external nose. -Elastic cartilages are able to tolerate repeated bending. -Articular cartilages cover the ends of most bones at moveable joints.

Costal cartilages reinforce airways and support the external nose Respiratory cartilages form the skeleton of the larynx (voice box) and reinforce other respiratory passageways. Costal cartilages connect the ribs to the sternum

Which of the labeled parts of the bone is composed primarily of compact bone? -A -B -C -D -E

D The shaft of an adult long bone is composed of compact bone.

Which bone-forming process is shown in the figure? -endochondral ossification -intramembranous ossification -bone remodeling -bone fracture repair

Endochondral ossification The figure illustrates a step in the embryonic formation of a bone from a cartilage model.

What is the first stage in the healing of a bone fracture? -bone remodeling -formation of a fibrocartilaginous callus -formation of a hematoma -formation of a bony callus

Formation of a hematoma This is the first stage in the healing of a bone fracture. In order, here are the stages of bone fracture healing: (1) formation of a hematoma, (2) formation of a fibrocartilaginous callus, (3) formation of a bony callus, and (4) bone remodeling

Which bone would be formed by the process of intramembranous ossification? -frontal bone of the forehead -femur of the thigh -vertebra of the spine -mandible of the lower jaw

Frontal bone of the forehead The frontal bone is a flat bone that, like other cranial bones, forms from within a membrane.

Which of the following is UNLIKELY to affect bone remodeling? -glucagon -parathyroid hormone -low blood Ca2+ concentration -mechanical stress

Glucagon Glucagon's main action is to increase blood glucose levels by triggering the breakdown of giycogen in the liver; it does not affect bone remodeling

During infancy and childhood, the most important stimulus of epiphyseal plate activity is _________ -growth hormone -thyroid hormones -estrogen -testosterone

Growth hormone

What material makes up most of the structure at A? -dense irregular connective tissue -hyaline cartilage -elastic cartilage -fibrocartilage

Hyaline cartilage The articular cartilage at the ends of long bones is formed from hyaline cartilage.

The area where blood vessels are penetrating the center of the bone used to be occupied by which tissue? -adipose tissue -dense connective tissue -hyaline cartilage -fibrocartilage

Hyaline cartilage In this type of ossification, the bone is first modeled from cartilage and then replaced by bone as blood vessels invade the model.

The structure indicated by the arrow is composed primarily of what tissue? -hyaline cartilage -mesenchyme -dense connective tissue -fibrocartilage

Hyaline cartilage The cartilage models used to form bones are composed of hyaline cartilage. This tissue persists within the epiphyseal plate at the boundary between primary and secondary ossification centers until early adulthood.

Which of the following contributes most directly to the hardness of bones? -articular cartilage -osteoid -hydroxyapatite -periosteum

Hydroxyapatite Hydroxyapatite, or mineral salts such as calcium phosphate, accounts for the most notable characteristic of bone- its exceptional hardness, which allows it to resist compression.

Hypercalcemia can be caused by _______ -insufficient vitamin D levels in the body -hypersecretion of parathyroid hormone -reduced parafollicular cell activity -All of the listed responses are correct.

Hypersecretion of parathyroid hormone Parathyroid hormone functions to stimulate the activity of osteoclasts in bone tissue.

When assessing Liliana's condition relative to her tibia fracture after the open reduction, the nurse will be especially alert for signs of which of these problems? -Bleeding. -Infection. -Inadequate calcium for healing. -Failure of the red bone marrow to create enough erythrocytes.

Infection The laceration caused by the broken end of the bone creates a breach in the protective barrier of the skin, providing an entry point for bacteria and other microorganisms.

When chondrocytes in lacunae divide and form new matrix, it leads to an expansion of the cartilage tissue from within. This process is called ________ -Appositional growth -Interstitial growth -Calcification -Hematopoiesis

Interstitial growth Interstitial growth occurs when chondrocytes divide and form new matrix, thereby expanding the cartilage tissue from within.

Which of the following disorders is only associated with the type of bone shown in the figure? -excessive and random bone deposition (Paget's disease) -weakening of the bones through failure in deposition/absorption balance (osteoporosis) -bowed legs and pelvic deformities (rickets) -lack of formation of certain skull bones and the clavicle (cleidocranial dysostosis)

Lack of formation of certain skull bones and the clavicle (cleidocranial dystosis) This genetic disorder of the processes of intramembranous ossification can result in these bones being deformed or even missing

What is the term for the layers of bony matrix surrounding the vessels and nerve? -lacunae -periosteum -lamellae -endosteum

Lamellae Correct Lamellae are layers of bony matrix synthesized by osteoblasts during bone growth and maintenance.

Which statement regarding the classification of bones is FALSE? -Sesamoid bones form within certain tendons. -The sternum is an example of a flat bone. -Irregular bones include the vertebrae and hip bones. • Long bones include all limb bones except the patella.

Long bones include all limb bones except the patella. This is false; long bones include all limb bones except the patella, tarsals, and carpals.

What controls bone remodeling? -mechanical stress and diet -hormones and diet -the nervous system and hormones -mechanical stress and hormones

Mechanical stress and hormones Remodeling goes on continuously in the skeleton, regulated by genetic factors and two control loops that serve different homeostatic conditions. One is a negative feedback hormonal loop that maintains Ca?+ homeostasis in the blood; the other involves responses to mechanical and gravitational forces acting on the skeleton.

A homeostatic imbalance that activates these bone cells would lead to a loss of bone density. -osteoblasts -osteoclasts -chondroblasts -osteocytes

Osteoclasts Osteoclasts are the bone cells that break down bone. If they were activated more than normal, you should expect to see bone loss.

What type of cell is shown at A? -mesenchymal -osteoblast -osteoclast -osteocyte

Osteocyte Osteocytes, literally "bone cells," are the primary structural and maintenance cells found in bone

Which of the following cells are NOT matched with their appropriate function? -osteoblasts; create new bone matrix -osteocytes; produce new bone cells. -osteoclasts; bone resorption -bone lining cells; maintain bone matrix

Osteocytes; produce new bone cells Osteocytes are mature bone cells that monitor and repair mature bone tissues.

Which description of bone cells is INCORRECT? -Osteoblasts secrete collagen and calcium-binding proteins. -Osteogenic cells can differentiate into osteoclasts. -Osteoclasts secrete digestive enzymes and hydrogen ions. -Bone lining cells are flat cells found on bone surfaces where bone remodeling is not going on.

Osteogenic cells can differentiate into osteoclasts Osteoclasts are derived from the same hematopoietic stem cells that differentiate into macrophages; they are not derived from osteogenic cells.

Which of the following is a characteristic of the bone material at D but NOT of the material at B? -osteocytes -lamellae -osteons -an origin in mesenchyme

Osteons The compact bone at D contains osteons. The spongy bone at B contains trabeculae but no osteons.

Which statement regarding osteons is FALSE? -Osteons are found in all bone tissues -The inorganic matrix of an osteon gives it the ability to resist compression. -Osteons consist of concentric lamellae surrounding a central canal. -Collagen gives osteons the ability to resist twisting forces.

Osteons are found in all bone tissues Osteons are found only in compact bone; they are absent in spongy bone.

Which of the following refers to a bone disorder found most often in the aged and resulting in the bones becoming porous and light? -Paget's disease -rickets -osteomalacia -osteoporosis

Osteoporosis Osteoporosis refers to groups of diseases in which bone resorption outpaces bone deposit. The bones become fragile and easily fractured. The composition of the matrix remains normal, but bone mass declines, and the bones become porous and light. Osteoporosis occurs most often in postmenopausal women.

Old Norse stories tell of a famous Viking named Egil, who lived around 900 AD. His skull was greatly enlarged and misshapen, and the cranial bones were thickened (6 cm, more than 2 inches, thick). He had headaches from the pressure exerted by enlarged vertebrae on his spinal cord. So much blood was diverted to his bones to support their extensive remodeling ,that his fingers and toes always felt cold and his heart was damaged through overexertion. What bone disorder did Egil probably have? -Osteomalacia -Osteoporosis -Paget's disease -Rickets

Paget's disease Paget's disease is characterized by excessive and abnormal bone remodeling. It results in irregular thickening of bone tissue and often affects the skull and spine, causing pain and deformity.

Which of the following pairings is correct? -osteoporosis; increased bone density -rickets; deficiency of vitamin A -osteomalacia; excessive mineralization of the bone -Paget's disease; excessive and haphazard bone deposition and resorption

Paget's disease; excessive and haphazard bone deposition and resorption Paget's disease is associated with excessive and haphazard bone deposition and resorption,

Which of the following is a site for a muscle or ligament attachment? -groove -trochanter -foramen -sinus

Trochanter A trochanter is a type of bone projection; projections often protrude from the bone because of the interaction forced upon them by muscle or ligaments.

The collagen fibers of the osteoid make the overall bone matrix stronger by allowing it to resist bending and twisting forces. -True -False

True The organic matrix, or osteoid, makes up about one-third of the bone matrix. This portion includes the collagen fibers that provide bone with its flexibility and tensile strength, allowing it to resist stretch and twisting.

Bones do NOT have a role in __________. -Blood cell formation -Fat storage -Support -Movement -Waste removal

Waste removal Waste removal is not a role of bone; it takes place primarily in kidneys.

The occurrence of osteoporosis is highest in women between 45-79 years of age. Why do you think this is? -Women in this age group have gone through menopause and have decreased estrogen levels. -Women in this age group do not eat enough calcium. -Older women do not exercise as much as younger women.

Women in this group have gone through menopause and have decreased estrogen levels Osteoporosis is more common in older females due to the effects of menopause on estrogen levels. Post-menopausal women experience decreased levels of estrogen, which results in a loss of bone density and Weaker Bones

You are counseling a patient with osteoporosis about strategies for avoiding fractures. Which of the following comments would NOT be appropriate? -"Adequate protein in your diet will help to keep your bones strong." -"Weight-bearing exercises like walking and strength training for your muscles will help to strengthen your bones." -"Be sure to consistently take any calcium and vitamin D supplements prescribed by your provider." -"You should avoid weight-bearing exercise and strength training because these types of exercise will further weaken your bones."

You should avoid weight-bearing exercise and strength training because these types of exercise will further weaken your bones." Right Remember that Wolff's law states that bone density increases in response to mechanical stress. Appropriate activity is an essential component of the treatment for this condition.