Bones, Developmental Genetics, and Hox Genes

Question 1

trabecular

Answer 1

spongy and porus material at proximal and distal ends of long bones

Question 2

cortical

Answer 2

hard solid osseous tissue in cortex of bone

Question 3

periosteum

Answer 3

layer of connective tissue, filtered by blood vessels and nutrient arteries

Question 4

sharpey’s fibers

Answer 4

connect periosteum tissue to penerate bones all around

Question 5

endosteum

Answer 5

inner surface of bony wall between bone and bone marrow

Question 6

nutrient artery and foreman

Answer 6

artery enters through foreman to connect/provide nutrient for bone

Question 7

osteon

Answer 7

cylindrical vascular tunnels that make up cortical bone

Question 8

haversian canal

Answer 8

blood vessels and nerve fibers that for a narrow series of tubes

Question 9

Volkman’s canals

Answer 9

transmit blood vessels from periosterum into bone to communicate with haversian canals

Question 10

sonic hedgehog

Answer 10

produces SHH protein which aids in instructing morphology

Question 11

zone of polarizing activity (ZPA)

Answer 11

where sonic hedgehog is produced

Question 12

rhombomeres

Answer 12

compartments in hine of brain that express different patterns of HOX genes

Question 13

lacunae

Answer 13

small spindle spaces that contain ostecyte left behind by osteoblasts in process of remodeling

Question 14

physis

Answer 14

principle of growth and change in nature

Question 15

homeosis

Answer 15

transformation of one structure of the body into the homologous structure of another body segment

Question 16

stylopod

Answer 16

humerus and femur bones

Question 17

zeugopod

Answer 17

ulna, radius, fibula, and tibula bones

Question 18

autopod

Answer 18

wrist, fingers, ankles, and toes bones

Question 19

apical ectodermal ridge

Answer 19

signaler for the positional info produced in the progress zone

Question 20

chondroblast

Answer 20

cell that play an important role in forming cartilage, located in perichondrium

Question 21

distinguish primary and secondary osteons

Answer 21

while osteons are where cortical bone remodeling occurs, primary osteons generates during appositional bone growth and secondary osteons generate during internal bone remodeling (AKA Haversian systems)

Question 22

role of calcitonin and parathyroid hormone in calcium metabolism

Answer 22

calcium homeostasis occurs constantly to regulate levels of calcium in bones;
calcitonin makes calcium salt deposit in bone to increase blood calcium levels while parathyroid hormon degrades bonematrix w/ help of osteoclasts to decrease blood calcium levels

Question 23

distguish the “taxonomy of objects” from their “mechanisms of origin”

Question 24

distinguish trabecular and cortical bone mechanical properties and structure

Answer 24

trabaecular bone is honeycomb-like network with a large remodeling area and high turnover rate in interior part of bone (relatively porous, spongy)
cortical bone is dense and low-porosity with less active tissue, makes up 80% of skeleton

Question 25

briefly desribe how trabeculae form- what maintains them?

Answer 25

removal of mineralized bone by osteoclasts followed by formation of bone matrix through osteoblasts that become mineralized

Question 26

what is the signficance of cortical versus trabecular bone in the human femoral neck?

Answer 26

spongy bone in the femoral neck in humans allows for pressure to occur and helps us determine bipedalism when looking at the ofssil record, cortical bone gives the bone strength

Question 27

what is the “tennis player problem” in the “wolffian developmental paradigm”?

Answer 27

Tennis players have stronger humerus on serving hand which makes many believe that Wolff’s law reigns true and that bone structure is maintain when there is a repeated mechnical stress on said bone, in reality Wolff’s law is not so accurate because bone structure is determined both mechnically and genomically

Question 28

distinguish transcription factors from signaling molecules

Answer 28

transcription factors: proteins that bind to regulatory regions of genes and influence their transcription
signaling molecules: transmit info between cells

Question 29

briefly describe the history of the HOX complexes in mammals

Answer 29

two duplication events in early veretebrate evolution resulted in 4 clusters seen in mammals and birds

Question 30

what is signficance of HOXc6 in vertebrate columns

Answer 30

position of hoxc6 determines position of limb neck/forelimb is

Question 31

BMPs and FGFs roles

Answer 31

BMPs: bone morphogenetic proteins; help in formatting and maintaining various organs including bone, cartilage, muscle, kidney, and blood vessels

FGFs: fibroblast growth factors; signal through FGF receptors to regulate cellular proliferation, survival, migration, and differentiation

Question 32

growth zone

Answer 32

1st zone of bone growth, cartilage cells undergo mitosis

Question 33

calcification zone

Answer 33

3rd zone of bone growth, matrix becomes calcified, cartilage cells die, and matrix begins to deteriorate

Question 34

hypertrophic zone

Answer 34

2nd zone of bone growth, older cartilage cells enlarge

Question 35

ossification zone

Answer 35

4th zone of bone growth, new bon formation occurs