MST Week 2 (sports Injury)

Question 1

Define neuromuscular

Answer 1

Affecting or characteristic of both neural and muscular tissue

Question 2

What are the signs of myasthenia gravis

Answer 2

Complaints of muscle weakness in an otherwise healthy and strong patient

Ptosis (droopy upper eyelid)

Cannot prolong muscle contraction

Symptoms progressing

Question 3

What is myasthenia gravis

Answer 3

Disorder of neuromuscular transmission

Production of autoantibodies directed against the nicotinic AChR

Prevalence of about 1 in 10-20,000

Women affected about twice as often as men

Peak onset in women 2-3 decades, peak in men 5-6 decades

Question 4

Key properties of synapses

Answer 4

Unidirectional

Irreversible delay

Chemical

Question 5

How does an action potential in the motor neurone lead to contraction of the muscle fibre

Answer 5

1) action potential in motor neurone arrives at axon terminal
2) terminal membrane depolarises, volatge gated calcium channels open
3) calcium mediated exocytosis of acetylcholine (ACh) into extracellular space
4) interaction of ACh with nicotinic acetylcholine receptor
5) influx of sodium ions and efflux of potassium ions from muscle cell via nAChRs, generation of receptor potentials
6) if RGPs are sufficient to pass thereshold an action potential is generated
7) action potential propagates through muscle, which leads to release of calcium ions from sarcoplasmic reticulum leading to contraction of muscle

Question 6

How does action potential lead to end plate potential

Answer 6

Open Ca2+ ion channel 
Ca2+ entry 
Exocytosis of ACh
ACh binds to nicotinic receptor 
Conformational change 
Na+ influx and K+ efflux 
Depolarisation 

End plate potential

Question 7

How does an end plate potential lead to a contraction

Answer 7

Propagated action potential

Spreads in muscle

Contraction

Question 8

How is myasthenia gravis treated

Answer 8

Increase the ACh levels at the neuromuscular junction.

Question 9

What clinical use does neuromuscular blockade serve

Answer 9

Surgery

Prevents muscle contractions

Maintain muscle relaxation / paralysis without deep general anaesthesia

Cosmetic surgery

Question 10

What does the patient experience during neuromuscular blockade

Answer 10

Slow methodical paralysis in skeletal muscle

Extrinsic muscles of eye first, then the small muscles of the face and hands followed by muscles of pharynx, respiratory muscles last

Individuals still experience pain

Question 11

How can we block neuromuscular transmission

Answer 11

1) prevent synthesis (block Ch uptake)
2) prevent release (exocytosis)
3) block receptor activation (nicotinic receptor antagonists)
4) increase reuptake / inactivation

Question 12

Clinical uses of Botox

Answer 12

Cervical dystonia - neuromuscular movement disorder involving the head and neck

Blepharospasm - involuntary contraction of the eye muscles

Severe primary axillary hyperhidrosis (excessive sweating)

Question 13

What are the 2 classes of neuromuscular blockers

Answer 13

1) non-depolarising: nACh-R antagonists

2) depolarising nACh-R agonists

Question 14

Features of non-depolarising blockers

Answer 14

• Occupy without stimulating post-synaptic nACh receptors
• additive effect of similar drugs
• block is competitive
• onset of action 3-5 min, duration typically 30+ min
• block not preceded by stimulation

Question 15

Features of non-depolarising blockers

Answer 15

• during block, high freq stimulation causes tetanus with duration only slightly longer than a twitch
• block antagonised by agents that depolaris muscle membrane
• block antagonised by drugs that increase ACh release
• block reversed by anticholinesterases

Question 16

How do depolarising blockers work

Answer 16

Persistent activation of nACh-R causes inactivation of voltage - gated Na+ channels ie can no longer open in response to brief depolarisation

Rapid onset of action (<1min), very short duration

Question 17

Features of depolarising blockers

Answer 17

• Block preceded by muscle twitches
• during block tension of tetanus is depressed but does not fade
• AChEs do not reverse block
• block summaries with other depolarising drugs
• drugs with weak curare like action antagonise block

Question 18

What are direct / contact acute injuries

Answer 18

Caused by an external blow or force

Question 19

What is an indirect / non contact acute injury

Answer 19

The actual injury can occur some distance from the impact site
Eg FOOSH can result in shoulder dislocation

The injury doesn’t result from physical contact with an object or person but from internal forces built up by the actions of the performer

Question 20

What is an overuse injury

Answer 20

Exercise applies stress to the body. Your body adapts by thickening and strengthening the various tissues involved hence muscles get stronger, firmer, and sometimes larger
However if exercise is applied in a way that adaptation doesn’t occur the overload can cause microscopic injuries leading to inflammation

Question 21

What are overuse injuries caused by

Answer 21

Training errors, improper techniques, excessive training, inadequate rest, muscle weakness

Question 22

Ligament sprain grading

Answer 22

Grade 1: microscopic tearing, minimal swelling, no joint instability, full / partial weight bearing

Grade 2: partial tearing, moderate / severe swelling, mild / moderate joint instability and unable to weight bear

Grade 3: complete rupture, severe swelling, moderate / severe joint instability, unable to weight bear

Question 23

To help recovery you shoudl avoid HARM

Answer 23

Heat- can increase blood flow whic may increase swelling
Alcohol- can increase bleeding and swelling to injured area
Running - or other forms of exercise
Massage- can cause more swelling or bleeding

Question 24

Define nutrition

Answer 24

The provision of nourishment to cells, tissues, organs, systems and the body as a whole

How food influences our body function and health

Includes dietary guidelines, food composition, and the roles that various nutrients have in maintaining health

Question 25

Define sports nutrition

Answer 25

How food and nutrients influence athletic performance in different sports- use of ergogenic aids

Question 26

Define exercise nutrition

Answer 26

How nutrition modifies the physiological and metabolic responses to exercise in a variety of populations

Question 27

What is sub-maximal exercise

Answer 27

Can be sustained for durations of between 30 and 180 min before fatigue

Because the rate of muscle ATP re-synthesis required is relatively low carbohydrate, and fat can both contribute to ATP re-synthesis ie there is a metabolic fuel integration

Question 28

Carbohydrate ingestion during exercise

Answer 28

CHO ingestion immediately before and during exercise delayed the onset of fatigue by sparing muscle glycogen stores during exercise

Question 29

How much carbohydrates should be ingested

Answer 29

Ingestion of 5-6% CHO solutions in serial feedings every 15-20 mins could be used without impairing emptying from the stomach

A 5-6% CHO solution will also ensure fluid balance is maintained, particularly important when exercising in the heat

Question 30

Why should carbohydrate intake during recovery be increased

Answer 30

It accelerates skeletal muscle and liver glycogen depletion and improves the capacity for repeated exercise

Question 31

How much CHO post exercise?

Answer 31

1.2g/kg body mass / hour for the first 6 hours post exercise (ie 84g per hour for a 70kg person)

Question 32

What is groin strain

Answer 32

When someone pulls / tears one of the proximal attachments of an adductor / flexor

Question 33

Which serious circulatory problems are most likely to affect the lower limb

Answer 33

Arterial insufficiency

Venous insufficiency

Lymphoedema