PBL 1

Question 1

What is the periosteum?

Answer 1

a tough connective tissue sheath that surrounds the bone surface wherever it is not covered by articular cartilage

Question 2

what is the function of the periosteum?

Answer 2

protects the bone, assists in fracture repair helps nourish bone tissue, serves as an attachment point for ligaments and tendons

Question 3

what does the medullary cavity contain?

what is the function?

Answer 3

fatty yellow bone marrow and blood vessels

the minimise the weight of the bone

Question 4

what is the endosteum?

Answer 4

a thin membrane that lines the medullary cavity. it contains a single layer of osteoprogenitor cells and a small amounts of connective tissue

Question 5

how are the outer circumferential lamellae connected to the periosteum?

Answer 5

by perforating fibres (Sharpey’s fibres)

Question 6

what are the canals called that blood vessels and nerves from the periosteum penetrate the compact bone with?

Answer 6

transverse perforating canals (Volkmann’s canals)

Question 7

what are the 2 functions of spongy bone?

Answer 7

to reduce the overall weight of the bone so it can move more readily
the trabeculae support ad protect the red bone marrow

Question 8

where does the large nutrient artery pass through the compact bone?

Answer 8

through the nutrient foramen

Question 9

when and how does the nutrient artery divide?

Answer 9

as it enters the medullary cavity

it divides into proximal and distal branches

Question 10

how are the ends of long bones supplied with blood?

Answer 10

metaphysical and epiphyseal arteries

Question 11

describe the veins within the bone?

Answer 11

one or 2 nutrient veins accompany the nutrient artery and exit through the diaphysis
numerous epiphyseal and metaphysical veins exit through the epiphyses and metaphases
many small periosteal veins exit through the periosteum

Question 12

describe how calcitonin can also be stimulated by gastrin?

Answer 12

if we eat high calcium foot then the duodenum senses this and gastrin is released which stimulates the thyroid gland to secrete calcitonin

Question 13

what is bone remodelling?

Answer 13

the ongoing replacement of old bone tissue by new bone tissue. it involves bone resorption and bone deposition

Question 14

what is bone resorption?

Answer 14

the removal of minerals and collagen fibres from the bone by osteoclasts

Question 15

what is bone deposition?

Answer 15

the addition of minerals and collagen fibres to bone by osteoblasts

Question 16

what are the 3 benefits of bone remodelling?

Answer 16

new bone grows thicker and is therefore stronger than old bone

the shape of the bone is altered for proper support based on stress patterns

new bone is more resistant to fracture than old bone

Question 17

describe the process of bone resorption?

Answer 17

osteoclast attach to the bone surface and formed a leakproof seal at the edges of its ruffled borders, it releases lysosomal enzymes and acids which digest collagen fibres and bone minerals. osteoclasts carve out a small tunnel in the old bone. the degraded bone proteins and minerals enter the osteoclast by endocytosis, cross in a vesicle and undergo exocytosis to enter the interstitial fluid.
osteoblasts now move in to rebuild that bone

Question 18

what are the 6 factors that cause variation in bone remodelling?

Answer 18

age (after 30 bone resorption exceeds deposition),
gender (hormones)
protein intake (high protein increases serum insulin-like growth factor 1 levels which promotes oestoblast activity)
smoking (has an adverse effect on bone mineral density)
physical activity (responses to mechanical activity improve the ability of the body to cope)
overtraining (bone remodelling cycle is unable to repair the micro damage as the rate in which it occurs)

Question 19

in bone repair, why do nearby cells die?

Answer 19

as the haematoma stops circulation of blood

Question 20

what are the key features of osteoporosis?

Answer 20

bone resorption outplaces bone deposition. bone mass becomes so depleted that bones fracture under mechanical stresses of everyday living.

Question 21

what are some of the signs of osteoporosis?

Answer 21

frequent fractures
shrinkage of vertebrae
height loss
hunched back
back pain
bone pain

Question 22

what are the 2 reasons in which women suffer from osteoporosis more than men?

Answer 22

women’s bones are less massive than mens

production of oestrogen declines dramatically at menopause whilst production of testosterone in men wanes gradually

Question 23

what are some risk factors for osteoporosis?

Answer 23

gender
family history
European or asian ancestry
thin or small body build
inactive lifestyle
a diet low in calcium or vitamin D
cigarette smoking
alcohol
certain medications

Question 24

what are the 6 types of medications we can give to treat osteoporosis?

Answer 24

bisphosphonates
selective eostrogen receptor modulators
parathyroid hormones treatments
calcium and vitamin D supplements
hormone replacement therapy
testosterone treatment

Question 25

what do bisphosphonates do?

Answer 25

slow the rate that bone is broken down in the body

Question 26

what do selective oestrogen receptor modulators do?

Answer 26

maintain bone density and reduce the risk of fractures

Question 27

what do parathyroid hormone treatments do?

Answer 27

regulate the amount of calcium in the bone

Question 28

what do calcium and vitamin D supplements do?

Answer 28

calcium- regulates amount of calcium in bone

vitamin D- helps the body absorb calcium

Question 29

what is hormone replacement therapy?

Answer 29

given to women going through menopause to help keep bones sting and reduce risk of breakages.

Question 30

when do we give testosterone treatment in osteoporosis?

Answer 30

when the cause is low levels of androgens

Question 31

what is the duty of candour?

Answer 31

being open and honest and tell the patient what has gone wrong, apologise, put things right is possible, follow the organisations procedures and contact the MDU if needed

Question 32

why is it important that the endosteum incomplete?

Answer 32

so osteoclasts and osteoblasts can access the trabeculae and carry out remodelling

Question 33

what is the role of collagen fibres?

Answer 33

strength, structure, flexibility and provides a framework for mineral deposits