Bone and Cartilage

Question 1

What is the major type of collagen that composes cartilage?

Answer 1

Type II collagen

Question 2

What is an isogenous aggregate?

Answer 2

A group of 4-7 chondrocytes, separated by septa

Question 3

What is the most abundant collagen in CT proper?

Answer 3

Type I collagen

Question 4

What constitutes appositional growth of collagen?

Answer 4

chondroblasts in the perichondrium differentiate into chondrocytes, and add to existing cartilage

Question 5

What constitutes interstitial growth of collagen?

Answer 5

Proliferation and hypertrophy of existing chondrocytes

Question 6

Inflammatory factors and MMPs play what role in the cartilagenous matrix?

Answer 6

Matrix remodeling

Question 7

What is perichondrium?

Answer 7

A sheath of dense irregular CT that is vascular and contains chondroblasts

Question 8

Where in the body would you find hyaline cartilage?

Answer 8

respiratory passages (larynx, trachea), articular surfaces of bones, and transiently as a skeletal model and at epiphyseal growth plates

Question 9

What distinguishes hyaline cartilage from other types?

Answer 9

Its glossy appearance due to the high level (75-80%) of ECM that is water weight

Question 10

Where in the body would you find elastic cartilage?

Answer 10

The auricle of the ear, eustachian tubes, epiglottis and larynx

Question 11

What distinguishes elastic cartilage from other types?

Answer 11

The high level of chondrocytes, as well as the dark-staining elastic fibers found in the matrix

Question 12

Where in the body would you find fibrocartilage?

Answer 12

The intervertebral discs, meniscus of some joints, pubic symphysis, as well as areas of cartilage that have sustained recurrent damage and repair

Question 13

What distinguishes fibrocartilage from other types?

Answer 13

The presence of Type I collagen fibers, as well as the lack of perichondrium

Question 14

What is perichondritis?

Answer 14

inflammation of perichondrium; often resulting in pus buildup between chondrocytes and perichondrium which can destroy cartilage

Question 15

What is familial osteochondritis dissecans?

Answer 15

A proteoglycan loss of function mutation causing disorganized and weak cartilage

Question 16

What do Haversian canals contain?

Answer 16

nerves, blood vessels, and lymphatics

Question 17

What are osteons?

Answer 17

lamellae of bone surrounding Haversian canals

Question 18

What structure joins adjacent Haversian canals?

Answer 18

Volkmann’s canals

Question 19

What is the role of osteoclasts and osteoblasts in bone remodeling?

Answer 19

Osteoclasts degrade old osteons, and osteoblasts generate new osteons

Question 20

What is the overriding factor in regulation of bone mass?

Answer 20

calcium mobilization

Question 21

What is the pathology of osteoporosis?

Answer 21

Osteoclast activity outpaces osteoblast activity

Question 22

What clinical situations are associated with osteoporosis?

Answer 22

Aging, decreased estrogen in PM women, inactivity, and inability to absorb Ca2+

Question 23

What is Osteopetrosis?

Answer 23

Decreased bone resorption due to defective osteoclasts

Question 24

What are the clinical results of osteopetrosis?

Answer 24

Reduced marrow cavity, decreased blood formation, leading to anemia and infection

Question 25

What is endochondral ossification?

Answer 25

The replacement of a cartilage model with bone

Question 26

What is intramembranous ossification?

Answer 26

The replacement of loose CT with bone

Question 27

What types of bones develop primarily through intramembranous ossification?

Answer 27

flat bones, the skull, and the mandible

Question 28

What type of ossification is responsible for the initiation of bone growth at the diaphysis of the bone collar?

Answer 28

intramembranous ossification

Question 29

What type of ossification is responsible for a growth in diameter of long bones?

Answer 29

intramembranous ossification

Question 30

What is the effect of calcitonin on osteoclasts?

Answer 30

Decrease activity

Question 31

What organ secretes calcitonin?

Answer 31

Thyroid

Question 32

Howship's lacunae are formed by what type of cell?

Answer 32

Osteoclast

Question 33

What type of cell resides IN lacunae, BETWEEN lamellae in bone?

Answer 33

osteocytes

Question 34

What is the main organic component of bone?

Answer 34

Type I collagen

Question 35

What is the main inorganic component of bone?

Answer 35

hydroxyapatite (Ca2+ and PO4-)

Question 36

What is the composition and function of primary (woven) bone?

Answer 36

random collagen fiber orientation; temporary bone to be replaced

Question 37

What is the composition and function of secondary (lamellar) bone?

Answer 37

parallel collagen fibers arranged in layers; to serve as permanent bone (but is continuously remodeled)

Question 38

What is the overriding factor for bone formation/resorption?

Answer 38

calcium mobilization

Question 39

What type of bone occupies that outer walls of bone structures?

Answer 39

compact (corticol) bone

Question 40

What type of bone occupies the interior of bone structures?

Answer 40

spongy (trabecullar/ cancellous) bone

Question 41

What is a Haversian system?

Answer 41

an osteon

Question 42

What differentiates compact bone from spongy bone?

Answer 42

Compact bone has osteons, and therefore requires an internal blood supply; spongy bone is usally thin enough to be nourished from the outside (there are exceptions)

Question 43

What is the function of periosteum?

Answer 43

To cover the outer surfaces of bone, and provide nutrition and osteoprogenitor cells

Question 44

How is the periosteum connected to the bone? What type of fibers compose these structures?

Answer 44

Through Sharpey's fibers; Type I collagen

Question 45

What effect does high serum calcium have on PTH secretion?

Answer 45

Negative feedback; it reduces PTH secretion

Question 46

What substance would you predict to see increased in the bone of a patient with rickets?

Answer 46

Osteoid

Question 47

Osteoporosis can largely be prevented by attaining a high peak bone mass by what age?

Answer 47

30

Question 48

What effect does PTH have on renal PO4 absorption?

Answer 48

Decreased rate of renal PO4 reabsorption

Question 49

A mutation that affects the ability of osteocytes to acidiby the resorption lacuna results in what?

Answer 49

Osteopetrosis

Question 50

What is the effect of PTH on vitamin D activation?

Answer 50

PTH stimulates vitamin D activation

Question 51

What type(s) of tissue replace the hematoma formed in response to a bone fracture?

Answer 51

Hyaline cartilage and loose CT

Question 52

What is the effect of somatotropin on the epiphyseal growth plate?

Answer 52

It upregulates IGF-1, which causes an increase in the mitotic divisions of chondrocytes; it also induces maturation of chondrocytes

Question 53

In what disease of the bone would you most commonly see a decrease in the mineral to osteoid ratio?

Answer 53

Osteomalacia (Rickets)

Question 54

What disease of the bone is most commonly associated with defective osteoclasts?

Answer 54

Osteopetrosis

Question 55

While fibrocartilage cannot undergo appositional growth, it instead undergoes what growth process?

Answer 55

Interstitial growth

Question 56

What structure is formed as the initial step in healing a bone after a fracture?

Answer 56

A hematoma

Question 57

The anterior divisions of the brachial plexus are responsible for innervating what kind of muscles?

Answer 57

Flexors

Question 58

The posterior divisions of the brachial plexus are responsible for innervating what kind of arm muscles?

Answer 58

Extensors

Question 59

Which bone composes the floor of the anatomical snuffbox?

Answer 59

The scaphoid bone

Question 60

Which anatomical structures are contained within the anatomical snuffbox?

Answer 60

The scaphoid bone, the radial artery, and the superficial radial nerve

Question 61

PTH has what effect on alkaline phosphatase activity?

Answer 61

Decrease in activity

Question 62

What is Benign Paroxysmal Positional Vertigo (BPPV)?

Answer 62

Sudden vertigo due to rapid head motion