muskuloskeletal

Question 1

what is cartilage?

Answer 1

a hard but flexible compressible and elastic tissue found usually at joins and between bones

Question 2

what is cartilage made up of?

Answer 2

chondrocytes embedded in a matrix

Question 3

what is the fluid space that the chondrocytes lie in called?

Answer 3

lacuna

Question 4

does cartilage contain blood vessels?

Answer 4

no

Question 5

how does cartilage receive a blood supply?

Answer 5

perichondrium, the membrane that covers cartilage

Question 6

how do nutrients and oxygen reach the chondrocytes?

Answer 6

by diffusion through the matrix - this makes cartilage slow healing

Question 7

what are the three types of cartilage?

Answer 7

1. Yellow elastic
2. Hyaline
3. White fibrous

Question 8

what are the features of yellow elastic cartilage?

Answer 8

• contains most chondrocytes so most flexible
• found in ear

Question 9

what are the features of Hyaline cartilage?

Answer 9

• 2nd most flexible
• found in nose and end of ribs to expand for breathing

Question 10

why is hyaline cartilage found at the end of long bones?

Answer 10

to prevent bones from rubbing together, so bones can glide over each other smoothly

Question 11

what are the features of white fibrous cartilage?

Answer 11

• fewest chondrocytes, so least flexible
• greatest tensile strength due to collagen protein
• found in knee and vertebrae in spine
• acts as a shock absorber

Question 12

what is compact bone?

Answer 12

found on outside of bones
- hard, outer layer that gives bone smooth, white appearance.

Question 13

what is the composition of organic vs inorganic compounds in bone?

Answer 13

organic - 30%
inorganic - 70%

Question 14

what are organic and inorganic compounds in bone made up of?

Answer 14

organic - collagen
inorganic - hydroxyapatite

Question 15

function of organic compounds in bone?

Answer 15

resists fractures in bone

Question 16

function of inorganic compounds in bone?

Answer 16

resists compression of bone

Question 17

what is compact bone made up of?

Answer 17

units called haversian systems

Question 18

what are osteocytes?

Answer 18

bone cells

Question 19

what are osteoblasts?

Answer 19

they secrete matrix and build bone

Question 20

what are osteoclasts?

Answer 20

break down the inorganic matrix and remodel bone

Question 21

what is rickets?

Answer 21

a disease of children caused by defective calcification of bone as a result of a vitamin D deficiency or lack of calcium in the diet

Question 22

why is vitamin D important?

Answer 22

required for the absorption of calcium from the gut

Question 23

where can vitamin d be found?

Answer 23

• foods such as butter, eggs or fish liver oil
• synthesised by action of UV on a precursor in the skin

Question 24

what is osteomalacia?

Answer 24

affects adults whose bones have stopped growing, when the bones become soft

Question 25

why did rickets and osteomalacia mostly disappear in the western world?

Answer 25

due to foods like margarine and cereal being fortified with vitamin D

Question 26

why is rickets more common in children with darker skin?

Answer 26

as they need more sunlight to manufacture vitamin D in their skin

Question 27

what is osteoporosis?

Answer 27

occurs when the struts become thin, causing them to become fragile and break easily, following a minor bump or fall

Question 28

what are the struts in bone?

Answer 28

the mesh-like structure within bones

Question 29

why is the risk of fracture increased with osteoporosis?

Answer 29

because the density of the bone is lower

Question 30

what are the risk factors associated with osteoporosis?

Answer 30

- low body weight (due to less bone tissue) - smoking (slows down osteoblast activity) - too much alcohol (affects osteoclasts) - menopause (oestrogen controls calcium metabolism)

Question 31

what is osteogenesis imperfecta (brittle bone disease) ?

Answer 31

an inherited condition that causes abnormalities in the genes that control the production of collagen, leading to bones structurally weaker than normal

Question 32

how many people in the UK have osteogenesis imperfecta?

Answer 32

1 in 15,000

Question 33

what are some issues that people with osteogenesis imperfecta struggle from?

Answer 33

lax joins, fragile teeth and bruising

Question 34

why can osteogenesis imperfecta rise in women after menopause?

Answer 34

bone density falls due to low levels of oestrogen

Question 35

what are some treatments of osteogenesis imperfecta?

Answer 35

- drugs to increase mineral density of bone - surgery to place metal rods in long bones

Question 36

what is bone density?

Answer 36

the quality of bone that, when measured, helps to indicate bone strength

Question 37

how are muscles attached to bone?

Answer 37

by tendons

Question 38

why are tendons similar to ligaments?

Answer 38

both are made of collagen with only a small amount of elastin protein

Question 39

what is a fascicle?

Answer 39

larger groups of numerous muscle fibres

Question 40

what is each muscle fibre made from?

Answer 40

myofibrils, which are groups of muscle cells grouped together

Question 41

what is the epimysium?

Answer 41

the protective sheath of connective tissue that encloses the muscle

Question 42

what is the perimysium?

Answer 42

connective tissue that surrounds the fascicle

Question 43

what is each muscle fibre surrounded by?

Answer 43

the endomysium

Question 44

what is the sarcolemma?

Answer 44

the cell membrane of a muscle fibre

Question 45

what is the sarcoplasm?

Answer 45

the cytoplasm of the muscles

Question 46

what are sarcomeres?

Answer 46

contractile proteins arranged in repeating units

Question 47

what are the two main proteins involved in muscle contraction?

Answer 47

actin (thin) and myosin (thick)

Question 48

what regions make up the sarcomere?

Answer 48

- I band - H zone - A band - Z line - M line

Question 49

what does the I band consist of?

Answer 49

only actin filaments

Question 50

what does the H zone consist of?

Answer 50

only myosin filaments

Question 51

how do the I band and H zone appear on an electron micrograph?

Answer 51

appear as lighter bands

Question 52

what does the A band consist of?

Answer 52

the entire length of myosin filaments including overlap with actin. The point of overlap will appear darkest

Question 53

what does the Z line consist of?

Answer 53

a dark, distinct border of a sarcomere and is the attachment site for actin filaments

Question 54

what does the M line consist of?

Answer 54

the M line is a fine line in the centre of the A band and is the attachment site for myosin filaments

Question 55

what do thin filaments consist of?

Answer 55

proteins, actin, tropomyosin and troponin

Question 56

how are the thin filaments structured?

Answer 56

- 2 actin molecules twist around each other to form a helical structure - tropomyosin wraps around the actin - troponin is attached to the tropomyosin along actin fibre

Question 57

what are the myosin molecules composed of?

Answer 57

a head and tail domain

Question 58

what is the structure of the thick filaments?

Answer 58

- the head domain binds to the actin forming cross-links that change position to contract the sarcomere - the tail domain provides an anchor for the rest of the molecule

Question 59

what happens during contractions of the muscle?

Answer 59

- sarcomeres shorten due to inc. overlap of the actin and myosin filaments - Z lines move closer together - H zone and I band become narrower - A band stays the same

Question 60

what theory supports muscle contracts?

Answer 60

sliding-filament theory

Question 61

what is the significance of calcium ions in muscle contraction?

Answer 61

Ca+ binds to troponin to change the shape of the troponin molecule, causing the tropomyosin to change positions

Question 62

where is the calcium ions released from for muscle contraction?

Answer 62

the sarcoplasmic reticulum by nervous impulse

Question 63

what happens when the tropomyosin changes position?

Answer 63

it exposes myosin binding sites on the actin - myosin heads can form cross-bridges with these binding sites on the actin

Question 64

what happens when cross bridges between the myosin binding site and myosin head is formed?

Answer 64

the power stroke - myosin head bends pulling the actin past the myosin

Question 65

what happens at the end of the myosin head?

Answer 65

ATP is hydrolysed into ADP and Pi which is then released, and cross-bridges frms further along the thin filament

Question 66

what causes the cross-bridge to be broken?

Answer 66

when ATP attaches to the myosin head which returns to its original position