Skeletal system

Question 1

made of

Answer 1

bone, ligaments, cartilage, tendons

Question 2

long bones

Answer 2

typically in appendicular in extremities
- mostly compact, spongy at ends
Ex. femur, tibia, humerus

Question 3

short bones

Answer 3

cube shaped
- mostly spongy, compact at surface

Question 4

flat bone

Answer 4

thin
ex. sternum, cranial, scapula

Question 5

irregular bones

Answer 5

vary in relative amts of compact/spongy
ex. vertebrae, facial

Question 6

cartialage

Answer 6

tough, flexible tissue that lines joints and gives structure to nose, ears, larynx, etc

Question 7

bone

Answer 7

ct reinforced w/ Ca and bone w bone cells

Question 8

bone marrow

Answer 8

spongy substance in center of bone
- contains stem cells for WBC and RBC

Question 9

periosteum

Answer 9

membrane of blood vessels and neurons that surround bones, deliver blood, provide feeling

Question 10

functions of skeletal system

Answer 10

1. structural support
2. enable movement
3. protect vital organs
4. help maintain proper a/b balance
5. regulate mineral homeostasis
6. site of blood cell formation

Question 11

bone composition

Answer 11

60% inorganic material
25% organic material
5% water

Question 12

osteoprogenitor cells

Answer 12

stem cells
- retain capacity to dif into osteoblasts
- in haversian canals, endosteum, periosteum, and marrow
- regulate influx/efflux of minerals at ecm

Question 13

osteoblasts

Answer 13

• bone forming
• surface of bone
• produce and secret bone matrix
• become osteocytes or remain quiescent and line cells

Question 14

osteocytes

Answer 14

reside in lacuna canicular system
- produce bone matrix proteins - osteocalcin
- mechanosensation - orchestrators of remolding
- control P levels w/ FGF23

Question 15

osteoclasts

Answer 15

bone reabsorbing

Question 16

reabsorption depends on

Answer 16

osteoclast secretion of H+, phosphatase, and cathepsin K enzymes
- H+ dissolves mineral component, PTH stims activity, calcitonin inhibits

Question 17

organic matter of bones

Answer 17

secreted by osteoblasts
- mainly type 1 collagen
- growth factors
- give bone form and provide resistance to tensile forces

Question 18

bone remoldeling

Answer 18

old, damaged bone removed by clasts and replaced w new bone by blasts

Question 19

phases of bone remodeling

Answer 19

1. initiation at specific site, requires recruitment of clasts
2. resorption and simultaneous recruitment of osteoprogenitor
3. osteoblast differentiation and osteoid synthesis
4. mineralization of osteoid, completion

Question 20

parathyroid hormone

Answer 20

maintain Ca homeostasis, trigger bone resorption to incr blood Ca

Question 21

Calcitonin

Answer 21

preent resorption, decre blood Ca

Question 22

insulin-like-GF1

Answer 22

most abundant, stims cell proliferation and survival of blasts, stims clast differentiation, maintain bone mass and skeletal homeostasis

Question 23

estrogen

Answer 23

regulate bone metabolism, limit formation of clasts, incr lifespan of blasts, decr remodeling and resorption

Question 24

androgens

Answer 24

beneficial effects for formation, incr thickness and strength by decr resorption

Question 25

compact bone tissue

Answer 25

external layer of all bone - shaft of long bones - concentric ring organization - perforating canals contain arteries and nerves

Question 26

osteon

Answer 26

functional compact bone unit - central canal w/ surrounding lamellae, lacunae, osteocytes, and caniculi

Question 27

spongy bone tissue

Answer 27

irregular lattice of thin plates of bone tissue (trabeculae) - in hips, ribs, sternum, vertebrae, and ends of long bone

Question 28

bone homeostasis

Answer 28

depends on balance between blasts and clasts - blood continuously tades of Ca w bone

Question 29

healthy bone growth needs

Answer 29

1. adequate minerals (Ca, P, Mg) 2. adequate vitamins (A, C, D) 3. adequate hormones (GH, insulin, IGF, thyroid, calcitonin, PTH, sex hormones) 4. weight-bearing exercise

Question 30

exercise and bone

Answer 30

mechanical stress increases Ca disposition leading to stronger bones

Question 31

bone thinning apparent

Answer 31

women over 30, men over 60 = loss of organic matrix leads to bones becoming brittle