Exam 1 - Chapter 6

Front 1

What are the functions of the skeletal system?

Back 1

Support, storage of minerals and lipidss, blood cell production, protection, leverage

Front 2

What is the bony matrix made of

Back 2

- 2/3 is inorganic calcium phosphate, which provides rigidity, can bear weight, and resist compression. Calcium phosphate reacts with calcium hydroxide to form crystals of hydroxyapatite which incorporates other calcium salts and ions.

- 1/3 is made of collagen (protein fibers) which is a strong organic material that is flexible but doesn't stretch

Front 3

What percentage of bone mass is made up of bone cells

Back 3

~2%

Front 4

What is the life cycle of bone cells?

Back 4

Osteoprogenitor to osteoblasts to osteocytes

Osteoclasts break down bone (collapse)

Front 5

Where do osteoprogenitors cells originate from, where are they currently located, and what do they do?

Back 5

- mesenchymal stem cells that divide to produce osteoblasts

- located in endosteum

- assist in fracture repair

Front 6

What are osteoblasts and what do they secrete?

Back 6

- Immature bone cells that secrete matrix compounds through osteogenesis

- osteoid is the matrix compound that is produced by not yet calcified to form bone

- osteoblasts surrounded by bone become osteocytes

Front 7

What are osteocytes, where are they located, and what are their functions?

Back 7

- mature bone cells that live in the lacuna between the layers (lamelle) of matrix

- connect by cytoplasmic extensions through canaliculi in lamellae

- functions are to maintain protein/mineral content of matrix and help repair damaged bone

Front 8

Where do osteoclasts come from and what do they do?

Back 8

- giant multinucleate cells derived from stem cells that produce macrophages

- Secrete acids and protein digesting enzymes to dissolve the bone matrix and released stored minerals (osetolysis) like calcium is if not enough is taken in through diet

Front 9

What's the difference between an osteoblast and an osteoclast?

Back 9

Osteoblasts=build

- bone responds to stress by building the bone

- blasts work with exercise

Osteoclasts=collapse

- will break down the bone and use nutrients elsewhere if you don't need strong bone/don't provide the right nutrients

Front 10

How much bone mass do you lose for every decade past 30?

Back 10

~10% of muscle and bone mass

Front 11

What is osteopenia?

Back 11

Begins at 30+ when the osteoblasts show down but the osteoclasts don't; normal function exists

Front 12

What is osteoporosis?

Back 12

When bone loss causes functionality loss

Front 13

What can you do to decrease bone loss as you get older?

Back 13

Exercise and eat right

Front 14

What is an osteon?

Back 14

Concentric lamellae surrounding blood vessels in central haversion canal

Front 15

Haversian canal

Back 15

Blood vessel along length of the bone in the central canal

Front 16

Canals of volkman

Back 16

Blood vessel that perforates between osteons across the bone toward the medullary cavity

Front 17

Spongy bone

Back 17

-Allows for branching of the bone

-does not have osteon's

-matrix forms an open network of trebeculae

-no blood vessels but red marrow

Front 18

How does the femur shift weight?

Back 18

The femur transfers weight from the hip joint to the knee joint by causing tension on the lateral side of the shaft and compression on the medial side

Front 19

Why is spongy and compact bone arranged this way in longbones

Back 19

-Spongy bone takes the force and spreads it out, like at the top and bottom of the femur

-compact phone directs the force and directs it towards the spongy bone

Front 20

Periosteum

Back 20

- lining on the outside of longbones

- Made up of an fibrous outer layer and inner cellular layer

- collagen fibers of the periosteum connect with collage fibers and bone and with fibers of joint capsules, attached tendence, in legament

Front 21

Functions of the periosteum

Back 21

- Isolate the bone from surrounding tissues

- Provide a route for circulatory and nervous supply

- Participate and bone growth and repair

Front 22

Endosteum

Back 22

- Lines the marrow cavity, incomplete

- contains osteoblasts, osteoprogenitor cells

-is active in bone growth and repair

Front 23

Long bones

Back 23

- long and thin

- contain diaphysis, epiphysis, and metaphysis

Front 24

Flat bones

Back 24

- Thin with parallel surfaces

- resembles a sandwich of spongy bone between 2 layers of compact bone

Front 25

Sutural bones

Back 25

Small irregular bones found between the flact bones of the skull

Front 26

Irregular bones

Back 26

Have complex shapes

Front 27

Short bones

Back 27

Small and thick, often cube shaped with smooth articulating surfaces

Front 28

Sesmoid bones

Back 28

Small and flat, develop inside tendons where there is friction (knees, hands, feet)

Front 29

Diaphysis

Back 29

Shaft of long bones; compact bone marrow cavity

Front 30

Epiphysis

Back 30

Articulation with other bones; mostly spongy bone covered with compact bone

Front 31

Metaphysis (epiphyseal line/disk)

Back 31

Where diaphyais and epiphysis meet

Front 32

How old are humans when they start growing bones and when do they stop?

Back 32

From 6 weeks (in utero) until about age 25

Front 33

Osteogenesis

Back 33

Bone formation

Front 34

Ossification

Back 34

The process of replacing other tissue with bone

Front 35

Calcification

Back 35

The process of depositing calcium salts during ossification

Front 36

Endochondral ossification

Back 36

Ossifies bones that originate as hyaline cartilage and has 6 steps

Front 37

Interstitial growth

Back 37

Increases length

Front 38

Appositional growth

Back 38

Increases width

Front 39

6 steps to endochondral ossification

Back 39

1. Chondrocytes enlarge in hylaine cartilage then die, leaving cavities in cartilage

2. Blood vessels grow around cartilage, and osteoblasts produce a layer of bone around the shaft which will grow to become compact bone

3. Spongy bone turns to compact through remodeling

4. Remodeling creates a marrow cavity and bone forms at epiphyseal disk

5. Capillaries and osteoblasts create second ossification center in the epiphysis

6. Epiphysis fills with spongy bone

Front 40

Intramembraneous ossification

Back 40

Occurs in the dermis and produces dermal bones like mandible and clavicle; has three steps

Front 41

Steps of intramembraneous ossification

Back 41

1. Mesenchymal cells aggregate; differentiate into osteoblasts, begin ossification, develop spicules (projections)

2. Blood vessels grow into area to supply osteoblasts and spicules trap them inside bone

3. Spongy bone develops and is remodeled into osteons, periosteum, or marrow cavities

Front 42

Remodeling

Back 42

The adult skeleton maintains itself and replaces mineral reserves common is oath reserved, it recycles and renews the bone matrix, involves osteocytes, osteoblasts, and osteoclasts

Front 43

What minerals are needed to build bone

Back 43

Calcium and phosphate salts, small amounts of Magnesium, fluoride, iron, and manganese

Front 44

Where is calcitrol made and what does it do?

Back 44

It's made in the kidneys and it helps absorb calcium and phosphorus from the digestive tract; synthesis requires vitamin D3

Front 45

What do vitamins C, A, K, and B12 do?

Back 45

C - required for collagen synthesis; stimulates osteoblast differentiation

A - stimulates osteoblast activity

K and B12 - help synthesize bone proteins

Front 46

Where is growth hormone made and what does it do?

Back 46

Made in pituitary gland, stimulates bone growth

Front 47

Where is thyroxine made and what does it do?

Back 47

Made in the thyroid gland and stimulates bone growth

Front 48

Where are sex hormones made and what do they do?

Back 48

Made in ovaries (estrogens) or testes (androgens) and stimulate osteoblasts

Front 49

Where is parathyroid hormone made and what does it do?

Back 49

Made in parathyroid glands, regulate calcium and phosphate levels

Front 50

Where is calcitonin made and what does it do?

Back 50

Made in thyroid glands, regulates calcium and phosphate levels

Front 51

What is the most abundant mineral in the body

Back 51

Calcium makes up ~99% of bone

Front 52

Calcium functions/regulations

Back 52

- Vital to membranes, neurons, muscle cells (especially heart muscle)

- homeostasis maintained by calcitonin and parathyroid hormone

Front 53

What cells release/add calcium?

Back 53

Osteoclasts release calcium and osteoblasts add it

Front 54

Where is calcium absorbed and excreted?

Back 54

Digestive tract is where is is absorbed and kidneys excrete it

Front 55

How does parathyroid hormone (PTH) increase calcium levels?

Back 55

Stimulates osteoclasts, increases intestinal absorption of calcium, decreases calcium excretion at kidneys

Front 56

How does calcitonin lower levels of calcium?

Back 56

Inhibits osteoblast activity, increases calcium excretion at kidneys

Front 57

Fractures

Back 57

Cracks or breaks in bones caused by physical stress

Front 58

What are the 4 steps to fracture repair?

Back 58

1: bleeding produces clot (fracture hematoma) and establishes a fibrous network while bone cells die in that area

2: cells of endosteum and periosteum divide and migrate into fracture zone where calluses stabilize the break

3: osteoblasts replace central cartilage of external callus with spongy bone

4: osteoblasts/clasts remodel fracture for up to a year reducing bone calluses

Front 59

Epiphyseal line

Back 59

When long bone stops growing after puberty, epiphyseal cartilage disappears and is visible on x-rays as epiphyseal line