assignment seven

Flat bones are broad and thin.

Mrs. Morgan has an occipital bone fracture. Select the correct classification for this bone.

one in which broken bone fragments are displaced inward

A depressed fracture is _______.

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

A step in what bone forming process is shown in the figure?

Glycogen production (glycogenesis) --- it takes place primarily in muscle and liver cells.

Bones do NOT have a role in ________.

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

Choose the CORRECT pairing.

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

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

C. The external membrane of bone, the perisosteum, includes a fibrous outer layer composed of dense irregular connective tissue.

Dense connective tissue forms part of which labeled part of the adult long bone in the figure?

Flat bones consist of two thin plates of compact bone enclosing a diploë (spongy bone layer).

Flat bones consist of compact bone sandwiched between spongy bone. (FALSE)

blood cell formation --- Red bone marrow found within certain regions of spongy bone is the site of blood cell formation from the differentiation of hematopoietic stem cells.

Hematopoiesis is a term for which of the following physiological processes?

B. Hematopoietic tissue is found in the spaces within the red bone marrow found 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).

In which of the labeled parts of the adult long bone would hematopoietic tissue be located?

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

In which step (A-D) does the formation of compact bone first occur?

fibrocartilage --- forms the soft callus, which appears just a few days after the fracture occurs.

Mrs. Morgan's fracture has not developed a soft callus. Which type of cartilage is her body having trouble forming?

break down bone --- are bone-breaking (bone-resorption) cells.

Osteoclasts ________.

Osteoblasts --- are the bone-forming cells that produce the organic bone matrix, the osteoid. Mature bone is produced once the inorganic matrix forms around the cells and collagen fibers of the organic matrix.

Which bone cells form bone?

Hyaline cartilage

is found on the ends of bones that form movable joints, where it is referred to as articular cartilage.

parietal --- he cranial bones are formed by intramembranous ossification.

The illustrated bone-forming process would be associated with which of the following bones?

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

The indicated blood vessels and nerve are found within a ______.

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

The indicated osteocyte is located within layers of bony matrix termed ______.

False --- the main role of the appendicular skeleton involves locomotion; it also allows us to manipulate our environment. The axial skeleton is mostly involved in supporting other body parts and protecting vital organs.

The main role of the appendicular skeleton is to protect and support vital organs. (true or false)

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

A step in which bone-forming process is shown in the figure?

Endochondral ossification is the formation of bone within hyaline cartilage. Hyaline cartilage "bones" are used as templates for the formation of true bone. Most bones below the base of the skull form by endochondral ossification.

Choose the TRUE statement.

expansion of the cartilage matrix --- (The expansion of the matrix results in the pushing of the epiphysis away from the diaphysis. This leads to the lengthening of the bone by interstitial growth.)

During bone growth, which event is most significant at the surface indicated by the letter A?

Calcification of the cartilage matrix leads to its deterioration and replacement by bone.

During bone growth, which event is most significant at the surface indicated by the letter B?

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).)

During bone growth, which significant event occurs at the surface indicated by the letter C?

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.)

During bone growth, which significant event occurs at the surface indicated by the letter D?

growth hormone --- During infancy and childhood the single most important stimulus for bone growth is growth hormone. It directly stimulates growth of the hyaline cartilage that forms the epiphyseal plates in long bones, causing the bones to lengthen.

During infancy and childhood, the most important stimulus of epiphyseal plate activity is ________.

hypersecretion of parathyroid hormone --- Parathyroid hormone functions to stimulate the activity of osteoclasts in bone tissue

Hypercalcemia can be caused by_________.

the medullary cavity of long bones --- In infants, but not adults, red marrow (hematopoietic tissue) is found in the medullary cavity of long bones.

In adults, hematopoietic tissue is NOT found in ________.

in the medullary cavity of the long bones.

In adults, yellow marrow is located ________

Osteomyelitis --- is the medical term for an infection in a bone; it can occur if an injury exposes the bone to germs.

Mrs. Morgan's fracture is described as having "bone tissue sticking out of the skin." This could make her susceptible to which of the following complications?

shaft of the bone closest to the shoulder joint --- Proximal describes a point of attachment of a limb closest to the trunk; the diaphysis is the shaft of a long bone.

One of Mrs. Morgan's fractures is described as being located on the proximal diaphysis. Which of these phrases best describes the anatomical location of this fracture?

the presence of inorganic hydroxyapatites --- (The exceptional hardness of bone, which allows it to resist compression, is attributed to the presence of mineral salts called hydroxyapatites. The hydroxyapatites, mainly calcium phosphates, form the inorganic matrix of bone.)

The notable hardness of bone is attributed to ________.

also called the Haversian system, is the structural unit of compact bone.

The osteon is ________.

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.)

The structure indicated by the arrow is composed primarily of what material?

Osteon --- The circular structural unit found within compact bone is termed the osteon

The structures in the figure collectively form a structural unit termed a(n) ______.

trebeculae - The honeycomb-like network of spongy bone is constructed of bony plates.

What bone-associated structure in panel C is indicated by the arrow?

mechanical stress and hormones --- (Remodeling goes on continuously in the skeleton, regulated by genetic factors and two control loops that serve different "masters." One is a negative feedback hormonal loop that maintains Ca2+ homeostasis in the blood. The other involves responses to mechanical and gravitational forces acting on the skeleton.)

What controls bone remodeling?

Calcification of the cartilage matrix --- leads to the breakdown of the matrix. Subsequently, periosteal vessels and bone-forming cells (osteoblasts) migrate into the cavities within the cartilage model to form the primary ossification center depicted in the figure.

What event precedes the step in the bone-forming process shown in the figure?

closure of the epiphyseal plate --- (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 (becoming an epiphyseal line), the bone has reached its maximum length. )

What indicates that a long bone has reached its adult length?

is the formation of bone from hyaline cartilage models. The hyaline cartilage must be broken down and replaced with the bone tissue.

What is endochondral ossification?

the organic part of the matrix of bone - is the organic part of the (extracellular) bone matrix and includes ground substance, composed of proteoglycans and glycoproteins, and collagen fibers.

What is osteoid?

bone remodeling --- 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.

What is the final stage in the healing of a bone fracture?

osteon --- an elongated cylinder oriented parallel to the long axis of the bone.

What is the structural unit of compact bone?

Sesamoid bone ---- The patella, kneecap, is a sesamoid bone, a special type of short bone that forms in tendons. It functions to alter the direction of pull of the tendon.

What type of bone is the patella?

Interstitial growth ---- occurs when chondrocytes divide and form new matrix, thereby expanding the cartilage tissue from within. (Note: the word inter means between, and stitial means space; these are common roots for anatomical terms.)

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

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 description of bone cells is INCORRECT?

osteocalcin --- Bones produce osteocalcin, a hormone which not only helps regulate bone formation, but also protects against obesity, glucose intolerance, and diabetes mellitus.

Which hormone is produced in bone and regulates bone formation, but also protects against diabetes mellitus?

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

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

vertebrae, humerus, femur --- All bones except the clavicle and those of the cranium are formed by an endochondral mechanism.

Which of the following bones are formed by the illustrated process?

Yes, calcitonin is currently thought to decrease plasma calcium levels in children and pregnant women.

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

n a compound (open) fracture the fractured bone ends penetrate the skin. Such open injuries carry a higher risk of infection.

Which of the following is CORRECTLY matched?

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

Which of the following is UNLIKELY to affect bone remodeling?

trochanter --- All of the other choices listed are categorized as depressions or openings.

Which of the following is a bone projection?

phosphate --- Bone is a reservoir for calcium and phosphate.

Which of the following is stored in bones?

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

Which of the following is the major component of the part of the bone labeled E?

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.)

Which of the following refers to a bone disorder found most often in the aged and resulting in the bones becoming porous and light?

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 of the following substances is NOT a component of the osteoid material secreted by the cells indicated by the arrow in panel A?

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

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?)

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

Which of the labeled parts of the bone is composed primarily of compact bone?

A. The articular cartilage at the ends of long bones

Which of the labeled parts of the bone is composed primarily of hyaline cartilage?

Hyaline cartilage

Which type of cartilage covers and protects the ends of bones at freely moveable joints?

where long bone lengthening occurs --- (Long bones elongate from growth at the epiphyseal plate, a layer of hyaline cartilage between the epiphyses and diaphysis of long bones.)

he epiphyseal plate is ________.

canaliculi --- Cytoplasmic extensions of osteocytes form contacts within hairlike canals, termed canaliculi, within the lamellae. Сanaliculi allow for communication and exchange of materials between osteocytes.

Osteocytes are connected to each other through which structure?

Yes, parathyroid hormone promotes the formation of calcitriol.

PTH promotes the formation of which hormone?

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

The above figure depicts which of the following bone-forming processes?

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

The arrow in the figure is pointing to which of the following structures?

The ribs

The axial skeleton includes the ________.

Mesenchymal cells ---are stem cells that differentiate into the matrix-forming cells of the various connective tissues, including the osteoblasts that form bone.

The cells indicated by the arrow at the center of panel A arise from the differentiation of which precursor stem cell?

hematoma formation, fibrocartilaginous 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. Use the pneumonic HFBR (His Femur Better Repair!) to help you remember the order. H = hematoma, F = fibrocartilaginous callus, B = bony callus, R = remodeling.

The correct order (from start to finish) of fracture repair is ________.