1.1 -- bones (parts / processes)

Question 1

how does the skeletal system assist with protection in the body ?

Answer 1

• the bone marrow produces blood, including the white blood cells that are part of the immune system
• bones also protect internal organs (heart, lungs, brain) from damage

Question 2

compact bone

Answer 2

forms the outside of bones & most of the diaphysis (“nature of being across” shaft), osteons are close together

Question 3

spongy bone

Answer 3

found inside short, flat, & irregular bones & in the epiphyseas (“nature of being on top” ends) of long bones

Question 4

how does the overall structure of bone provide great strength & flexibility, but keep bone from being too bulky & heavy ?

Answer 4

• bone is stronger than concrete (pound for pound) & stronger than any other natural material
• cells are hollow & have paper-thin walls, giving bone its lightweight structure
• calcium & phosphorus give bone its rigid strength, but ~1/2 of bone mass is soft & alive, allowing bones flexibility to bend
• every bone cell is replaced every 7 years, keeping bone strong

Question 5

what is an x-ray ?

Answer 5

• an invisible type of high energy radiation
• soft tissues are made of smaller atoms & don’t absorb x-ray photons well
• the calicum atoms in bone are larger & absorb x-rays better
• that causes a picture of the bones to show up

Question 6

what are the different types of bone fractures & how are they identified on x-ray ?

Answer 6

communited, transverse, greenstick, depression, oblique, open, compression, closed, spiral

Question 7

comminuted

Answer 7

break in several pieces, splintered/crushed

Question 8

transverse

Answer 8

complete break at right angle to bone axis, often from direct blow

Question 9

greenstick

Answer 9

imcomplete, bone is bent & partially broken, most common form in kids

Question 10

depression fracture

Answer 10

fragment is pushed down, typically due to a blow to the skull

Question 11

oblique fracture

Answer 11

break has curved/sloped pattern, often caused by slanted blow

Question 12

open

Answer 12

bone breaks through skin – greater risk of infection

Question 13

compression

Answer 13

collapse of vertebra, often due to osteoporosis (“holes in bones”) or tumors or to being ejected from an ejection seat

Question 14

spiral

Answer 14

caused by twisting force on bone, such as rotation to leg during skiing

Question 15

closed

Answer 15

bone breaks, but doesn’t puncture skin

Question 16

how can damage to a bone affect other human body systems ?

Answer 16

• fat tissue from the bone marrow can leak into the blood, causing fat embolism syndrome, which can cause lung problems & seizures
• if the skin breaks (open fracture), pathogens can enter the body & cause an infection

Question 17

what is bone remodeling ?

Answer 17

• bone remodeling happens throoughout life & is also called “bone metabolism”
• it’s the process by which bone tissue (ossification)
• it increases after a fracture & is the method by which the bone heals
• remodeling is rapid early in life (100% replacement during first year of life) & then slows (10% yearly for adult)
• an inbalance in the process can lead to bone diseases like osteoporosis

Question 18

how do osteoblasts & osteoclasts assist with bone remodeling & overall bone homeostasis ?

Answer 18

• osteoblasts form new bone tissue, to replace those reabsorbed by osteoclasts – produce the organic part of bone (osteoid), made mostly of collagen protein, that inorganic minerals crystalize around – many of them turn into mature osteocytes
• osteoclasts break down & reabsorb bone tissue – come from monocytes in bone marrow, release minerals (calcium phosphate) & other stored materials (like growth factors)

Question 19

what is the relationship between bone remodeling & blood calcium levels ? how do hormones assist in the maintenance of healthly bone & the release of calcium to be used in other body processes ?

Answer 19

low blood calcium
- glands in the parathyroid release parathyroid (PTH), causing osteoclasts to break down matrix & release calcium ions into blood

high blood calcium
- c cells in the throid release calcitonin & that stimulates storage of calcium in bones