Chapter 6 - Bone Tissue

In the diagram, where is the trabeculae?

B

Where in the diagram is the metaphysis?

B

Which labeled structures in the figure are lamellae?

B

Which of the labeled structures in the diagram are circumferential lamellae?

B

Which of following selections lists bone cells in the order from unspecialized stem cell to highly specialized mature bone cell? A) Osteogenic Cells, Osteoclasts, Osteocytes B) Osteogenic Cells, Osteoblasts, Osteocytes C) Osteogenic Cells, Osteocytes, Osteoblasts D) Osteoblasts, Osteogenic Cells, Osteocytes E) None of these choices.

B) Osteogenic Cells, Osteoblasts, Osteocytes

The skeletal system is made of several different tissues. However, the two major tissues are

Bone (osseous tissue) and cartilage

Cartilage

- A poorly vascularized C.T. with a matrix composed of chondroitin sulfate and various fibers. - Fiber types distinguish hyaline cartilage from fibrocartilage or elastic cartilage.

Bone is a

- Dynamic Tissue, it is always remodeling (building up and breaking down). - Highly vascularized C.T. with a hard, mineralized extracellular matrix. It is found in the body in two different arrangements: Compact Bone & Spongy Bone

In the diagram, where is the zone of hypertrophic cartilage?

B

What type of bone cell starts forming the bone matrix?

B

Where in the diagram is articular cartilage located?

B

The skeletal system 6 important functions:

- Provide support by acting as a structural framework and a point of attachment for tendons and ligaments - Protect the internal organs (brain, chest, etc.) - Assist body movements (in conjunction with muscles) - Store and release salts of calcium and phosphorus - Participate in blood cell production (hematopoiesis) - Store triglycerides in adipose cells of yellow marrow

Which labeled structure in the figure is a lacuna?

A

The renewal rate for compact bone tissue is...

4% per year.

In the diagram, this zone contains mostly dead chondrocytes surrounded by a calcified matrix.

A

Where in the diagram is the proximal epiphysis?

A

Which bone cell in the diagram below is an osteogenic cell?

A

Which of the following labeled structures in the diagram is a site of red blood cell production in adult bones?

A

Which of the labeled structures in the diagram are fragments of older osteons that have been partially destroyed during bone rebuilding or growth?

A

Where in the diagram can you find red bone marrow in an adult?

A & B

An archeologist and an anthropologist are studying two skeletons from an ancient tomb that had apparently been looted in an earlier time. Both skeletons are females and both are approximately the same height. However, the anthropologist is absolutely certain that one skeleton is the remains of someone from the privileged class while the other skeleton is the remains of a servant or slave. How could the anthropologist be so sure of the economic status of the individuals based solely on their skeletal remains?

A person who is from the privileged class probably has better nutrition but doesn't have to do as much physical labor (exercise) as a person from the servant or slave class. The anthropologist probably notes a difference in bone density in the two skeletons—especially on parts of bones where muscles attached. The skeleton of the servant probably has more density than the skeleton of the privileged class at those points. It is also possible that the servant suffered from malnutrition during life. If so, her skeleton might show evidence of rickets or osteopenia.

Which of the following selections correctly lists the sequence of events that occur during intramembranous ossification? A) Ossification Center Develops > Calcification > Formation of Trabeculae > Development of New Periosteum. B) Calcification > Ossification Center Develops > Formation of Trabeculae > Development of New Periosteum. C) Ossification Center Develops > Formation of trabeculae > Calcification > Development of New Periosteum. D) Development of New Periosteum > Ossification Center Develops > Calcification > Formation of trabeculae. E) Ossification Center Develops > Calcification > Development of New Periosteum > Formation of Trabeculae.

A) Ossification Center Develops > Calcification > Formation of Trabeculae > Development of New Periosteum.

Which of the following conditions is a cancer affecting osteoblasts? A) Osteogenic Sarcoma B) Rickets C) Osteomalacia D) Osteoarthritis E) Osteopenia

A) Osteogenic Sarcoma

Describe the steps in bone repair.

After the break in the bone occurs, blood vessels in that area are damaged and blood surrounds the fracture. The blood solidifies to form a clot, which reduces bleeding. White blood cells migrate into the area to remove bacteria and damaged cells. Osteoclasts migrate in to remove dead bone matrix. Secondly, fibroblasts migrate into the fracture to form a plate of cartilage to prevent further movement and damage at the fracture site. Thirdly, osteoblasts invade to replace the cartilage with bone matrix in the form of spongy bone. Lastly, the bone matrix will be remodeled as compact bone replaces spongy bone.

This is a layer of hyaline cartilage that reduces friction between bones involved in a joint.

Articular cartilage

In the diagram, where is the epiphyseal vein?

B

In the diagram, where is the haversian canal?

C

In the diagram, where is the osteon?

C

In which region of the diagram would you find the medullary cavity?

C

Which bone cell in the diagram below is a mature bone cell that helps maintain bone tissue?

C

Which labeled structures in the figure are canaliculi?

C

Which of the following labeled structures in the diagram are concentric lamellae?

C

Which of the following two minerals are need in large quantities when bones are growing? A) Calcium and Chlorine B) Magnesium and Sulfur C) Calcium and Phosphorous D) Manganese and Sulfur E) Potassium and Phosphorous

C) Calcium and Phosphorous

During adulthood, which of the following does NOT significantly contribute to bone remodeling and growth? A) Parathyroid Hormones B) Vitamin D C) Epinephrine D) Sex Steroids E) Human Growth Hormone

C) Epinephrine

Which of the following conditions is observed in adults when new bone formed during bone remodeling fails to calcify? A) Osteogenic Sarcoma B) Osteoporosis C) Osteomalacia D) Osteoarthritis E) Osteopenia

C) Osteomalacia

An increase in bone growth is promoted by which hormones?

Calcitonin and Calcitriol

These are extensions of the lacunae and are filled with extracellular fluid.

Canaliculi

Like other surrounds widely separated cells.

Connective Tissues

In the diagram, where is the zone of resting cartilage?

D

Where in the diagram is the distal epiphysis?

D

Where in the figure is the periosteum located?

D

Which bone cell in the diagram below is an osteoclast?

D

Which illustration and radiograph in the figure shows an impacted fracture where one end of the fractured bone is forcefully driven into the interior of the other end?

D

Which labeled structure in the figure is an osteoclast?

D

Which of the labeled structures in the diagram is formed as the result of cartilage being replaced by bone after the cessation of bone growth?

D

Which of the following structures contain osteocytes? A) Haversian canals B) Volkmann's canals C) Concentric lamellae D) Lacunae E) Canaliculi

D) Lacunae

Which of the following conditions results when the articular cartilages in a joint degenerate to the point where the bony ends of articulating bones touch? A) Osteogenic Sarcoma B) Rickets C) Osteomalacia D) Osteoarthritis E) Osteopenia

D) Osteoarthritis

Which of the following correctly lists the order of the four zones of cartilage found within the growth plate starting at the epiphysis and extending to the diaphysis? A) Calcified Cartilage, Resting Cartilage, Proliferating Cartilage, Hypertrophic Cartilage B) Resting Cartilage, Proliferating Cartilage, Calcified Cartilage, Hypertrophic Cartilage C) Proliferating Cartilage, Resting Cartilage, Hypertrophic Cartilage, Calcified Cartilage D) Resting Cartilage, Proliferating Cartilage, Hypertrophic Cartilage, Calcified Cartilage E) Hypertrophic Cartilage, Calcified Cartilage, Proliferating Cartilage, Resting Cartilage

D) Resting Cartilage, Proliferating Cartilage, Hypertrophic Cartilage, Calcified Cartilage

This is the shaft of a long bone.

Diaphysis

Briefly describe the steps in bone deposition.

During bone deposition, osteogenic cells develop into osteoblasts. The osteoblasts secrete collagen fibers and other organic substances to begin formation of matrix. Within the spaces between fibers, calcification occurs to form a solid matrix that eventually surrounds the osteoblast and some extracellular fluid. The osteoblast in its new lacuna is isolated and becomes an osteocyte. The osteocyte continues to secrete matrix but at a lower level.

Briefly describe the steps in bone resorption.

During bone resorption, an osteoclast attaches tightly to the endosteum or periosteum of the bone and forms a leak proof seal at the edges. Then it releases protein- digesting lysosomal enzymes and several amino acids into the sealed pocket. The enzymes digest collagen fibers and other organic substances while the acids dissolve the bone materials. Working together several osteoclasts carve out a small tunnel in the old bone. The degraded bone proteins and extracellular matrix minerals enter an osteoclast by endocytosis, cross the cell in vesicles, and undergo exocytosis on the side opposite the ruffled border. Now in the interstitial fluid, the products of bone resorption diffuse into nearby blood capillaries. Once a small area of bone has been resorbed, osteoclasts depart and osteoblasts move in to rebuild bone in that area.

What structure in the diagram is the only place on a long bone NOT covered by the periosteum?

E

Where in the diagram is the endosteum located?

E

Which illustration and radiograph in the figure shows a Pott's fracture?

E

Which labeled structure in the figure is an osteocyte?

E

Which of the labeled structures in the diagram are perforating (Sharpey's) fibers?

E

In the diagram, which of the following vessels directly serve the periosteum?

E & F

Calcium is involved in all of the following important bodily functions EXCEPT A) Blood Clotting. B) Nervous System Communication. C) Muscle Contraction. D) Acting as a cofactor in some enzymatic reactions. E) Being the primary cation that regulates osmotic balance in cells.

E) Being the primary cation that regulates osmotic balance in cells.

Which of the following is NOT a major function of the skeletal system? A) Support B) Locomotion C) Hemopoiesis D) Energy storage E) Carcinogenesis

E) Carcinogenesis

Which of the following statements about bone remodeling is FALSE? A) It occurs throughout your lifetime. B) It involves bone resorption. C) It involves bone deposition. D) It occurs at different rates at different locations. E) It occurs at a faster rate in compact bone than spongy bone.

E) It occurs at a faster rate in compact bone than spongy bone.

Which of the following substances are stored in the structure of adult bones for use by other tissues in the body? A) Calcium B) Phosphorous C) Triglycerides D) Iron E) More than one of these substances is stored in bone.

E) More than one of these substances is stored in bone.

Which of the following conditions is characterized by reduced bone mass due to a decreased rate of bone synthesis to a level too low to compensate for normal bone resorption? A) Osteogenic Sarcoma B) Osteomyelitis C) Osteophytes D) Osteoarthritis E) Osteopenia

E) Osteopenia

This is a layer of hyaline cartilage that allows the diaphysis to grow in length.

Epiphyseal Plate

This is the region of a long bone that articulates with other bones.

Epiphysis

In the diagram, where is the Volkmann's canal?

F

Which illustration and radiograph in the figure shows a Colles' fracture?

F

Which of the labeled structures in the diagram consists of thick bundles of collagen fibers that extend into the extracellular bone matrix?

F

Where in the figure is spongy bone located?

G

Which of the following labeled structures in the diagram stores triglycerides in adult bones?

G

Which of the labeled structures in the diagram are composed of trabeculae, which are bony structures that lack osteons?

G

This type of fracture is considered a partial fracture and is only seen children.

Greenstick

In the diagram, where is the nutrient artery?

H

Patient X has a tumor of the parathyroid glands that causes a hypersecretion of PTH from these glands. Predict the effect this hypersecretion would have on the skeletal system and on the secretion of calcitonin from the thyroid gland.

High levels of PTH would cause high levels of osteoclast activity, thus removing calcium from bones. Bones would become weak and soft. Excess phosphate would be lost from the kidneys. High levels of calcium ions in blood may disrupt nerve and muscle function. Calcitonin levels would probably be high, trying to restore homeostasis by increasing deposition of calcium into bone.

Bone mass reduction is promoted by which hormone?

Parathyroid Hormone

Describe the signs and symptoms of osteoporosis and describe the risk factors for developing osteoporosis.

In osteoporosis, bone resorption outpaces bone deposition so that bone mass is depleted, sometimes to the point of spontaneous fracture. Pain and height loss may occur as vertebrae shrink. Postmenopausal women are especially at risk due to dramatically reduced estrogen levels after menopause. Family history may play a role, as does ethnicity (white and Asian women have a higher rate of disease), inactivity, cigarette smoking, excessive alcohol consumption, and a diet low in calcium and vitamin D.

Compact Bone

Is good at providing protection and support. It forms the diaphysis of long bones, and the external layer of all bones.

Spongy Bone

Is lightweight and provides tissue support. It forms much of the epiphysis and the internal cavity of long bones.

One function of this long bone structure is the storage of energy in the form of triglycerides.

Marrow

This is the region of long bone found between the diaphysis and the epiphysis.

Metaphysis

These are considered bone-building cells.

Osteoblasts

These are considered bone-dissolving cells.

Osteoclast

Osteomalacia is a disease in which inadequate calcification of the bone matrix results in bones becoming "soft" or rubbery to the point that they become very fragile and fracture easily. Hypersecretion of which of the following hormones would produce similar changes in bone?

PTH

During endochondral ossification in a fetus, bones initially develop as a cartilage model surrounded by a connective tissue covering called the...

Perichondrium

This is the fibrous covering on the surface of bone that is involved in thickening of the bone.

Periosteum

Briefly describe the major differences between compact and spongy bone.

Spongy bone is light, which reduces the overall weight of a bone so that it moves more readily when pulled by a skeletal muscle. The trabeculae of spongy bone tissue support and protect the red bone marrow. Compact bone, usually found in the exterior of bone, is heavy and dense and made up of osteons. Its function is to resist breakage and provide support of the body.

Briefly describe what is happening in each step of fracture repair shown in the diagram.

The diagram illustrates repair of a bone fracture. In step one, there is formation of a fracture hematoma. In step two, a fibrocartilaginous callus is formed. In step three, a bony callus is formed. In step four, bone remodeling begins.

Briefly describe what is happening in each of the numbered stages of intramembranous ossification as observed in a child's skull shown in the diagram below.

The diagram is depicting intramembranous ossification in a child's skull. Stage1 involves the development of an ossification center. During stage 2, calcification begins. In stage 3, trabeculae begin to form. Finally, in stage 4, the periosteum develops.

Briefly describe the processes by which bone increases in length and diameter.

The only means by which bone can increase in length (interstitial growth) is by activity at the epiphyseal plate. Until full height is reached, the plate consists of layers of chondrocytes, which generate matrix that is then calcified and replaced by bone matrix secreted by osteoblasts on the diaphyseal side of the plate. Around ages 18-20 the cartilage is replaced completely by bone and no more lengthwise growth can occur. Bone increases in diameter via appositional growth as new bone matrix is laid down by osteoblasts in the periosteum.

Name and describe the major arteries found in bone.

The periosteal arteries accompany nerves that enter the diaphysis through Volkmann's canals and supply the periosteum and outer portion of compact bone. At the center of the diaphysis, the large nutrient artery passes through the nutrient foramen to serve the internal structures of the bone. The metaphyseal arteries enter the metaphysis of a long bone and supply the red bone marrow and bone tissue of the metaphyses. The epiphyseal arteries enter the epiphysis of a long bone and supply the red bone marrow and bone tissue of the epiphyses.

List and briefly describe the six main functions of the skeletal system.

The skeletal system is used for support for the soft tissues of the body and as attachment sites for tendons of most skeletal muscles. The skeletal system also functions in protection for the internal organs. The skeletal system assists in movement working together with the muscle system. Skeletal system aids in mineral (calcium and phosphorus) homeostasis by storing several minerals and releasing them into the bloodstream on demand. Within some bones is red bone marrow that produces blood cells. Bones also contain yellow bone marrow which is a storage site for energy in the form of triglycerides.

About 25% of all stress fractures involve which bone?

Tibia

Briefly, explain how blood calcium level is regulated.

When blood Ca2+ levels drop, PTH is secreted from the parathyroid glands. PTH increases the activity of osteoclasts to increase bone resorption, which ultimately increases Ca2+ in blood. PTH also acts on the kidneys to prevent Ca2+ loss in the urine. PTH also stimulates the production of calcitriol, which acts on the GI tract to increase absorption of Ca2+ from the intestinal lining. When blood Ca2+ level increases, it causes the synthesis and release of calcitonin from the thyroid gland. Calcitonin, inhibits osteoclasts and stimulates osteoblastic activity to increase Ca2+ deposition into bones which promotes bone formation.

Hypersecretion of human growth hormone during childhood results in...

giantism.

The general process by which bones form is called...

ossification.

Osteons in compact bone tissue are aligned...

parallel to the length of the diaphysis.