Week 112 - Trauma Wrist

Question 1

What do tendons link?

Answer 1

muscle to bone

Question 2

What do ligaments join?

Answer 2

Bone to bone

Question 3

What are the components of tendons?

Answer 3

Collagen, 95% type I, 5% minor collagen - type III, V, VI. provides the tensile properties.
Elastin
Proteoglycans - regulate fibril size during growth and development

Question 4

Enthesis

Answer 4

Fibrocartilage is present where the tendon inserts on the bone.

Question 5

Fibrocartilage function?

Answer 5

to dissipate compressive forces to reduce wear and tear

Question 6

Aggrecan

Answer 6

Major proteoglycan of cartilage

Question 7

Three functions of ligaments?

Answer 7

Stabilise joint
Guide joint motion
Provide proprioceptive information
modified to form articular discs for shock absorption
rich in nerve fibers, stretching activates muscle contractions and prevents over stretching
pain fibers, autonomic nerve fibers supply their blood vessels

Question 8

what is enthesopathy and provide an example

Answer 8

disorder involving the attachment of the ligament or tendon to the bone
Tennis elbow - pain at attachment of extensor carpi radialis brevis tendon to lateral epicondyle
golfers elbow -pain at attachment of extensor carpi radialis brevis tendon to medial epicondyle

Question 9

Role of collagen in the tendon?

Answer 9

give the tissue high tensile strength and ability to resist stretching

Question 10

Synovium?

Answer 10

lines a fibrous sheath through which the tendon glides and is lubricated by synovial fluid

Question 11

which glkycoaminoglycan gives synovial fluid it’s lubricating properties?

Answer 11

hyaluronan

Question 12

3 types of muscle cell?

Answer 12

skeletal striated muscle
cardiac striated muscle
smooth muscle

Question 13

neurotransmitters at a neuromuscular junction?

Answer 13

acetylcholine

Question 14

resting potential at a motor nerve terminal?

Answer 14

-70mv

Question 15

which receptor dies the neurotransmitter bind on the post synaptic membrane at a neuromuscular Junction

Answer 15

nicotinic receptors on the motor end plate. this causes the activation of ion channels and influx of sodium ions

Question 16

after an action potential what breaks down the neurotransmitter?

Answer 16

acetylcholinesterase

Question 17

the thick filaments in myofibrils are made from what protein

Answer 17

myosin

Question 18

what three proteins make up the thin filaments in myofibrils?

Answer 18

actin
troponin
tropomyosin

Question 19

in muscle contraction what initiates binding of cross Bridges to actin

Answer 19

calcium binding

Question 20

what are the four steps involved in the cross Bridge cycle in muscle contraction?

Answer 20

1 cross Bridge formation myosin head attaches to an actin myofilament forming a cross bridge
2 the power stroke ADP and phosphate are released and the myosin head pivots and bends, changing to its bent low energy state. as a result it pulls the actin filaments towards the m line
3 cross Bridge detachment after ATP attaches to myosin, the link between myosin and actin weekens and the myosin head detaches
4 cocking of myosin head. as ATP is hydrolyzed to ADP and phosphate the myosin head returns to its pre stroke high energy position

Question 21

what is the role of calcium in muscle contraction

Answer 21

calcium bind to specific sites on troponin, this causes the troponin to change shape and the tropomyosin to be moved away from the myosin Binding site

Question 22

what is isometric contraction?

Answer 22

when a muscle develops tention but does not shorten. This occurs when muscles supports a load in a constant position or when it attempts to move a load that is greater than the tension developed by the muscle. For example lifting an object that is too heavy

Question 23

what is isotonic contraction?

Answer 23

a contraction in which the muscle shortens while the load of the muscle remains constant. for example when a muscle shortens against a load and the load moves.

Question 24

eccentric contraction?

Answer 24

a contraction where the muscle is lengthening while resisting an external load . for example the length of the quadriceps femoris muscle while walking down stairs

Question 25

what is the difference between slow twitch fibres type 1 and fast twitch fibres type 2?

Answer 25

slow twitch fibres contain myosin with lower ATPase activity
fast twitch fibres contain myosin with high ATPase activity
they have different rates at which they can split ATP this determines the cross-bridge cycling rate and shortening velocity

Question 26

what are the three types of skeletal muscle fibre?

Answer 26

slow twitch type 1 low myosin ATP ase activity red fibres due to good blood supply and high myoglobin levels , resistant to fatigue
fast twitch type 2A high myosin ATP ase activity, red fibres, glycogen stores and enzymes for anaerobic glycolysis resistant to fatigue
fast twitch type 2B high myosin ATP as activity what fibres which glycogen stores and enzymes for anaerobic glycolysis rapidly

Question 27

what order of motor units are recruited in an active muscle

Answer 27

first slow oxidative motor units second fast oxidative units third fast glycolytic units

Question 28

what causes peripheral muscle fatigue?

Answer 28

contractions failure - this is where action potentials fail to be conducted along the fibre
lactic acid build-up elevated hydrogen ions affect the muscle proteins
ATP hydrolysis generates please hydrogen ions
inhibition of cross Bridge cycling build up of ADP and phosphate with in muscle fibres