pathophysiology

Question 1

4 functions of bone

Answer 1

structure (give structure and shape to the body), mechanical (sites for muscle attachment), protective (vital organs and bone marrow), metabolic (reserve of calcium and other minerals)

Question 2

2 composers of bone, and relative %

Answer 2

inorganic (65%), organic (35%)

Question 3

what makes up the inorganic section of bone

Answer 3

calcium hydroxyapatite crystals

Question 4

what 4 things does inorganic section of bone store, and relative %

Answer 4

99% calcium, 85% phosphorus, 65% sodium, magnesium

Question 5

what 2 things make up organic section of bone

Answer 5

bone cells, protein matrix, collagen fibres

Question 6

structure of a long bone: sections

Answer 6

epiphysis (head) -> metaphysis -> diaphysis (shaft) -> metaphysis -> epiphysis

Question 7

what does the metaphysis contain

Answer 7

growth plate (cartilage structure allowing linear growth of bone)

Question 8

what type of bone is present in epiphysis centre

Answer 8

spongy bone

Question 9

name of hollow section in diaphysis

Answer 9

medullary cavity

Question 10

function of medullary cavity

Answer 10

storage of red and/or yellow (adipose) bone marrow

Question 11

what type of bone makes up the surface of the long bone

Answer 11

compact bone

Question 12

layers of diaphysis (superficial to deep)

Answer 12

periosteum, cortex, medulla

Question 13

what line separates metaphysis and epiphysis

Answer 13

epiphyseal line

Question 14

what is attached to the bone at the epiphysis, and name of bone this attaches to

Answer 14

articular cartilage, attached to subchondral bone

Question 15

% bone mineralised to be seen on x-ray

Answer 15

50

Question 16

5 anatomical bone types

Answer 16

flat (e.g. skull, ribs - protection), long (e.g. femur, tibia - support), short/cuboid (e.g. carpals, tarsals - movement), irregular (e.g. vertebrae, pelvis - protection), sesamoid (e.g. patella embedded in tendons - protection)

Question 17

2 macroscopic structure types of bone

Answer 17

trabecular/cancellous/spongy (in metaphysis), cortical/compact (in diaphysis)

Question 18

2 microscopic structure types of bone

Answer 18

woven bone (immature), lamellar bone (mature)

Question 19

what anatomical bone type is cortical bone found (and hence skeleton it makes up), and % of entire skeleton they make up

Answer 19

long bones (hence appendicular), making up 80% of entire skeleton

Question 20

% calcified and function of cortical bones

Answer 20

80-90% calcified and low turnover, so mainly structural, mechanical and protective

Question 21

what anatomical bone type is cancellous bone found (and hence skeleton it makes up), and % of entire skeleton they make up

Answer 21

vertebrae and pelvis (hence axial), making up 20% of entire skeleton

Question 22

% calcified and function of cancellous bones

Answer 22

15-25% calcified, high turnover so mainly metabolic (large surface area facilitates this)

Question 23

describe cortical bone microanatomy (superficial to deep)

Answer 23

made up of parallel osteons in lamellar bone (osteons with blood vessels in centre): circumferential lamellae -> concentric lamellae -> interstitial lamellae -> trabecular lamellae (rod/plate like with no osteons)

Question 24

what is the osteocyte mechanosensory cannaliculi network, and what does it form

Answer 24

dendrites from osteocytes, which form signalling network

Question 25

where is woven bone located

Answer 25

woven bone (mechanically weak) in developing skeleton, before replacement by mature bone; also where rapid growth/pathological high bone turnover

Question 26

3 types of bone cell

Answer 26

osteoclasts, osteoblasts, osteocytes

Question 27

function of osteoclasts

Answer 27

multinuclear cells that reabsorb bone

Question 28

function of osteoblasts

Answer 28

produce osteoid to form new bone

Question 29

function of osteocytes

Answer 29

mechanosensory network embedded in mature bone

Question 30

describe bone remodelling cycle

Answer 30

monocyte -> osteoclast precursor -> mature osteoclast (activated by RANKL, reabsorb bone); reversal cells; mesenchymal stem cell -> pre-osteoblast -> mature osteoblast (lay down bone, release RANKL or M-CSF, which acts as a fake ligand, so control activity of osteoclast)