BIO 212...

Question 1

Growth Hormone

Answer 1

stimulates liver to produce somatomedin, which causes cartilage proliferation at epiphyseal plate and resulting bone elongation

Question 2

Thyroid Horomone

Answer 2

stimulates bone growth by stimulating metabolic rate of osteoblasts

Question 3

Calcitonin released by the thyroid hormone

Answer 3

promotes calcium deposition in bone (stimulates osteoblasts), and inhibits osteoclast activity

stimulates osteoblasts in response to increased blood calcium levels

Decrease calcium uptake from intestines and reabsorption from urine.

Question 4

Parathyroid Hormone (PTH)

Answer 4

Works with calcitriol (vitamin D). Stimulates osteoclasts in response to decreased blood calcium levels (bone resorption). Increase calcium uptake in intestines (vitamin D), and increases calcium reabsorption from urine.

Question 5

What causes bone formation rate greater than cartilage growth, initiates the closing of the growth plate.

Stimulates osteoblasts.

Stimulates both cartilage growth and bone formation, but calcification is stimulated more causing the epiphyseal plate to close –> forms epiphyseal line.

Answer 5

Estrogen and testosterone

Question 6

Glucocorticoids

Answer 6

increase bone loss and, in children, impair growth when levels are high

Question 7

Serotonin

Answer 7

inhibits osteoprogenitor cells from differentiating into osteoblasts at high levels

Question 8

1. Ossification centers form within thickened regions of the mesenchyme beginning at the 8th week of development.
2. Thickened cells in the mesenchyme divide, and the committed cells that are formed then differentiate into osteoprogenitor cells. Some of these become osteoblasts and begin to secrete osteoid.
3. Osteoid undergoes calcification. Entrapped osteoblasts become osteocytes.
4. Woven bone (immature) forms and then mesenchyme that surrounds woven bone begins to thicken and eventually organizes to form the periosteum.
5. Lamellar bone replaces woven bone as compact bone and spongy bone form

Answer 8

Intramembranous Ossification

bone growth within membrane – mesenchyme

Question 9

Woven bone becomes_______?

Answer 9

Lamellar bone

Question 10

Intramembranous ossification produces what type of bones?

Answer 10

Flat bones

Question 11

Produces long bones

Answer 11

Endochondral ossification

bones form within cartilage

Question 12

1) Fetal hyaline cartilage model develops
2) Cartilage calcifies and a periosteal bone collar forms. As the cartilage calcifies, blood vessels grow toward the cartilage and start to penetrate the perichondrium around the shaft.
3) The primary ossification center forms in the diaphysis.
4) Secondary ossification centers form in the epiphysis
5) bone replaces almost all cartilage except the articular cartilage and epiphyseal cartilage
6) lengthwise growth continues until the epiphyseal plates ossify and form epiphyseal lines

Answer 12

Endochondral ossification - produces most of the bones in the skeleton

Question 13

Zone 1

Answer 13

Zone of resting cartilage

• nearest the epiphysis. Resembles mature and healthy hyaline cartilage. Secures the epiphysis to the epiphyseal plate.

Question 14

Zone 2 – bone growth in length mostly occurs here

Answer 14

Zone of proliferating cartilage

-chondrocytes undergo rapid mitotic division, enlarge slightly, and become aligned into longitudinal columns of flattened lacunae. Parallel to diaphysis.

Question 15

Zone 3

Answer 15

Zone of hypertrophic cartilage

-chondrocytes cease dividing and begin to hypertrophy (enlarge in size)

Question 16

Zone 4

Answer 16

Zone of calcified cartilage

-minerals are deposited in the matrix between the columns of lacunae; destroys the chondrocytes

Question 17

Zone 5

Answer 17

Zone of ossification (deposition)

-Walls break down between lacunae. Chondrocytes die. Spaces invaded by capillaries and osteoprogenitor cells from the medullary cavity. New matrix of bone is deposited on top of the remaining calcified cartilage matrix.

Question 18

Where does bone remodeling occur?

Bone remodeling does not occur at the same rate everywhere in the skeleton

Answer 18

periosteum and endosteum

Question 19

Bone remodeling is dependent upon…

Answer 19

the coordinated activities of osteoblasts, osteoclasts, and osteocytes. Activity of these cells are influenced by hormones and stress

Question 20

Bone remodeling also occurs in response to…

Answer 20

mechanical stress occurs in the form of weight-bearing movement and exercise, and it is required for normal bone remodeling.
Osteoblasts increase synthesis of osteoid, and this is followed by deposition of mineral salts. Bone strength increases over a period of time in response to mechanical stress. Results from skeletal muscle contraction and gravitational forces.

Question 21

Wolff’s Law

Answer 21

Bone grows in response to forces or demands placed on it

Question 22

Mechanical stress is detected by____

Answer 22

osteocytes, and communicated to osteoblasts triggering an increased synthesis of osteoid adding bone strength

Question 23

Femoral growth is used to determine______

Answer 23

Age

• epiphyseal plates fuse progressively at set ages
• these ages differ among males and females in specific regions with females typically closing at an earlier age
• Know that we can have multiple epiphyseal plates.
• They can become active and close at different times.
• And there are differences between genders.

Question 24

Steps of Fracture and Bone Repair

1.

Answer 24

1. A fracture hematoma forms from broken vessels and clotted blood (converted to granulation tissue)

Question 25

Bone Fracture and Repair

2.

Answer 25

2. A fibrocartilaginous (soft) callus forms - body’s splint to keep bones lined up. Regenerating blood vessels enter this area.

Question 26

Bone Fracture and Repair

3.

Answer 26

3. A hard bony callus forms
   - osteoprogenitor cells adjacent to fibrocartilaginous callus become osteoblasts and produce trabeculae of primary bone. FC is replaced by this bone
   - primary bone (woven bone) forms. It has spongy bone, but no compact bone.

Question 27

Bone Fracture and Repair

4.

Answer 27

4. The bone is remodeled
   - when you take woven bone and you turn it into mature lamellar bone. Remodel using osteoblasts and osteoclasts in order to reform medullary cavity.

Question 28

Reduction in bone mass significant enough to compromise normal function. A significant percentage of older women, and smaller proportion of men suffer from this.

Result of degradation of arches and trusses of trabecular bone.

Answer 28

OSTEOPOROSIS - decrease in density of bone. Weakens the bone, and more prone to fracture

Question 29

The bones of the skeleton become weaker and thinner, resulting in insufficient ossification. All become slightly _________

Answer 29

Osteopenia

become osteopenic

Question 30

Cranial bones interconnection by dense connective tissue forming “soft spots” - ease for travel through birth canal

Answer 30

Anterior fontanelle and posterior fontanelle

largest - posterior closes 9 months
smallest - anterior closes 15 months
-replaced by cranial sutures

Question 31

Areas of the neuron that is influenced by action potentials in saltatory conduction

Answer 31

neurofibril node (large number of voltage gated Na+ channels and K+ voltage gated channels)

Question 32

The type of conduction that occurs in myelinated regions

Answer 32

saltatory conduction

Question 33

unmyelinated axons have this kind of conduction

Answer 33

continuous conduction

Question 34

The type of summation that occurs when a single presynaptic neuron repeatedly releases neurotransmitter to produce multiple EPSP’s in the postsynaptic neuron at the same location repeatedly within a short period of time

Answer 34

temporal summation

Question 35

Occurs when multiple presynaptic neurons release neurotransmitter at various locations onto the receptive segment, thus generating EPSPs and IPSPs, or both in the postsynaptic neuron.

Answer 35

spatial summation

Question 36

The two types of summation.

Type of signals from temporal

Type of signals from spatial

Answer 36

temporal and spatial

temp - EPSPs

spatial - EPSPs and IPSPs

Question 37

Type of common neurotransmitter that binds to nicotinic receptor or muscarinic receptor

Answer 37

acetylcholine neurotransmitter

Question 38

acetylcholine neurotransmitter is synthesized how and where?

Answer 38

synthesized from acetate and choline and then stored within synaptic vesicles within the synaptic knob of the neuron. Released by exocytosis into the synaptic cleft in response to the arrival of an action potential in the presynaptic neuron

Question 39

Skeleton Functions

Answer 39

Hemopoiesis (blood cell formation), support and protection, movement, storage of minerals and energy reserves

Question 40

Bone building cells beneath the _________ lay down bone to form ridges around a blood vessel

Answer 40

periosteum

Question 41

Once a tunnel of bone is formed around a blood vessel, the bone building cells of the __________ lay down bone in concentric circles that fill in the tunnel.

Answer 41

endosteum

Question 42

Encourages calcium deposition from blood to bone

Answer 42

calcitonin - released by the thyroid

Question 43

Sex differences in the skull…

male skulls are

Answer 43

heavier, larger, longer and thicker than female skulls

Question 44

Male skulls tend to have larger ______ with a more massive _______ process and __________ bone

Answer 44

jaws, mastoid, zygomatic bone

Question 45

Male foreheads tend to be more _______ while female foreheads are more _____

Answer 45

slopped, vertical

Question 46

Sex differences in the pelvis

Female pelvis is ________ and _______

Answer 46

Larger and wider than males

Question 47

Pelvis is used to determine ______ and ______

Answer 47

sex and age

Question 48

Females have a rounder pelvic inlet for

Answer 48

childbirth

Question 49

The angle between the inferior pubic rami is acute ______ in men, but obtuse _______ in women. Accordingly, the angle is called the ______ angle in men, and _____ in women.

Answer 49

70 degrees, 90-100 degrees, subpubic angle v, pubic arch