CH 7 Lecture Exam Study Guide

Question 1

What are the inorganic components of the bone matrix?

Answer 1

Calcium phosphate (hydroxyapatite) and Calcium carbonate.

Question 2

What are the functions of the inorganic component of the bone matrix?

Answer 2

To make bone strong and rigid.

Question 3

What are the organic components of the bone matrix?

Answer 3

Cartilage protein fibers (90%) and Ground substance.

Question 4

What are the functions of the organic component of the bone matrix?

Answer 4

Gives bone flexibility.

Question 5

What functions of the skeleton do osteoblasts attribute to?

Answer 5

Support and Protection.

Question 6

What functions of the skeleton do osteoclasts attribute to?

Answer 6

Electrolyte balance and Acid-base balance.

Question 7

What does the outer fibrous layer of the periosteum contain?

Answer 7

Dense irregular CT (cartilage fibers).

Question 8

What does the inner osteogenic layer of the periosteum contain?

Answer 8

Bone forming cells.

Question 9

All bone cells stem from osteogenic cells, except osteoclasts. Osteoclasts come from what stem cell?

Answer 9

Hematopoietic stem cells.

Question 10

Describe canaliculi.

Answer 10

Cytoplasmic channels found in lacunae, that allow communication between osteocytes.

Question 11

Describe perforating/ volkmann’s canal.

Answer 11

Allow blood vessels to enter bone from periosteum. Interconnect and run perpendicular to the central canals.

Question 12

What’s another word for central canal?

Answer 12

Haversian canals.

Question 13

What are resorption bays?

Answer 13

Osteoclasts are seen to be located in shallow depressions called resorption bays. The resorption bays are created by the erosive action of osteoclasts on the underlying bone.

Question 14

What is the ruffle border?

Answer 14

A wave-like cell membrane surface on one side of the osteoclast cell. Seen as an extensive area of cell surface where secretion of enzymes as well as uptake of matrix components takes place.

Question 15

What is the function of the ruffled border?

Answer 15

The function of the ruffled border is to increase the surface area for bone resorption by increasing the number of contact points between the osteoclast cell and bone in the resorption pits.

Question 16

Describe the process by which osteoclasts dissolve organic bone matrix.

Answer 16

Osteoclasts secrete proteolytic enzymes that digests collagen and other proteins .

Question 17

Describe the process by which osteoclasts dissolve inorganic bone matrix.

Answer 17

Osteoclasts secrete hydrogen, Cl follows due to electrical attraction, which makes hydrochloric acid (HCl) which is a strong acid that dissolves minerals.

Question 18

Describe the process in order of Endochondral Ossification.

Answer 18

Mesenchyme ~> differentiate into chondrocytes ~> produce cartilage ~> chondrocytes undergo apoptosis ~> osteoclasts arrive and dissolve calcified cartilage ~> osteogenic cells give rise to osteoblasts, which deposit bone. (cartilage remains in epiphysis until growth stops, leaving spongy bone and the epiphyseal line)

Question 19

For endochondral ossification, recognize the events of each zone of the metaphysis in order from furthest from medullary cavity to closest.

Answer 19

Zone of reserve cartilage
Zone of cell proliferation
Zone of hypertrophy
Zone of calcification
Zone of Bone deposition

Question 20

Describe the zone of reserve cartilage.

Answer 20

Resting hyaline cartilage.

Question 21

Describe the zone of cell proliferation.

Answer 21

Multiplying chondrocytes.

Question 22

Describe the zone of hypertrophy.

Answer 22

cell division stops, chondrocytes enlarge, and lacuna walls get thinner.

Question 23

Describe the zone of calcification.

Answer 23

Temporary calcification of cartilage matrix between columns of lacunae.

Question 24

Describe the zone of bone deposition.

Answer 24

Chondrocytes die, osteoclasts break down lacuna walls, osteoblasts deposit spongy bone, and later compacts bone at the perimeter.

Question 25

What is hyperplasia?

Answer 25

Growth of tissue by cell division (most common).

Question 26

What is hypertrophy?

Answer 26

(larger word) Growth of tissue by cellular enlargement.

Question 27

Define appositional growth.

Answer 27

Increase in bone diameter.

Question 28

Describe how the osteoblasts and osteoclasts play a role in appositional growth.

Answer 28

Osteoblasts deposit new bone on inner side of periosteum. Osteoclasts dissolve bone tissue as it widens to increase the marrow cavity (keeps weight of bone from increasing too much).

Question 29

State Wolff’s Law.

Answer 29

The architecture of bone is determined by mechanical stress placed on it. Osteoblasts build trabeculae along lines of greater stress. Bony processes grow larger in response to stress.

Question 30

Explain the importance/functions of calcium in the body.

Answer 30

Calcium is needed for neuron communication, muscle contraction/relaxation, blood clotting, and exocytosis (rapid increase in intracellular calcium directly triggers regulated exocytosis).

Question 31

Calcitonin does what to blood calcium levels?

Answer 31

Lowers blood calcium levels by stimulating osteoblasts and inhibiting osteoclasts. Affects children more, has weak affect in adults.

Question 32

Parathyroid hormone does what to blood calcium levels?

Answer 32

Raises blood calcium level, with a loss of bone mass.

Question 33

Calcitriol does what to blood calcium levels?

Answer 33

Raises blood calcium levels and increases bone density, precursor is Vitamin D. Calcitriol is necessary for bone deposition and bone health.

Question 34

Relate concentration of osteoblasts to calcium blood levels.

Answer 34

Osteoblasts help to synthesize bone and remove calcium from the blood and sequester it in bone. Lowering blood calcium levels.

Question 35

Relate concentration of osteoclasts to calcium blood levels.

Answer 35

Osteoclasts are responsible for resorbing bone matrix and releasing key minerals, including calcium, back into the bloodstream. Raising calcium blood levels.

Question 36

Define hypocalcemia and recognize the given causes.

Answer 36

Calcium deficiency. Can be caused by diarrhea, pregnancy/lactation, and hormonal imbalances.

Question 37

Define hypercalcemia and recognize the given causes.

Answer 37

Excessive calcium levels. Usually a result of overactive parathyroid glands.

Question 38

State how hypocalcemia can affect the muscular and nervous systems.

Answer 38

Causes over-excitability in nervous and muscular systems (muscle spasms, tetany – uncontrolled muscle spasms, tested by Trousseau's – sign of tetany when spasm of the hand and wrist occurs after individual wears a blood pressure cuff).

Question 39

State how hypercalcemia can affect the muscular and nervous systems.

Answer 39

Under-excitability in nervous and muscle systems (muscle weakness, reduced neural reflexes, and non-responsiveness).

Question 40

Define osteomalacia.

Answer 40

Soft bone disease, lack of calcium/mineral deposition .

Question 41

Define osteogenesis imperfecta.

Answer 41

Brittle bone disease, lack of collagen deposition.

Question 42

Define osteoporosis. List the conditions that can result in osteoporosis, especially those related to reduction in estrogen levels.

Answer 42

Severe loss of bone density and mass. It affects spongy bone the most, bones become weak due to loss of matrix and minerals. Highest risk factor for osteoporosis is low estrogen levels, results in higher occurrence of pathological fractures

Question 43

Treatments for open/closed reductions.

Answer 43

Open - surgery, likely to require pins and screws. Closed- no surgery, needs to realign and stabilize.

Question 44

Greenstick fracture. (closed)

Answer 44

Bone is incompletely broken on one side and bent on the other.

Question 45

Non-displaced fracture. (closed)

Answer 45

Bones remain in correct anatomical alignment (need to realign and stabilize).

Question 46

Displaced fracture. (open)

Answer 46

At least one piece is misaligned.

Question 47

Comminuted fracture. (open)

Answer 47

Broken into 3 or more pieces.

Question 48

Describe the events involved in the healing of a bone fracture in order.

Answer 48

Hematoma formation Soft callus formation Hard callus formation Bone remodeling

Question 49

Describe what takes place during hematoma formation.

Answer 49

Hematoma (pool of clotted blood) is converted to granulation (development of new tissue and blood vessels in a wound).

Question 50

Describe what takes place during soft callus formation.

Answer 50

Granulation tissue is replaced as chondrocytes make a soft fibrocartilage callus. (helps join and stabilize the broken pieces)

Question 51

Describe what takes place during hard callus formation.

Answer 51

Osteoblasts deposit a temporary bony collar around the fracture to better unite and stabilize pieces.

Question 52

Describe what takes place during bone remodeling.

Answer 52

Osteoclasts remove small bone fragments. Osteoblasts deposit spongy and compact bone to restore bone structure.