Skeletal Muscle Ageing and Disease Flashcards Preview

Hugh's Locomotor > Skeletal Muscle Ageing and Disease > Flashcards

Flashcards in Skeletal Muscle Ageing and Disease Deck (30):
1

What are the criteria for diagnosis of sarcopenia?

A gait speed of <1m/s

Appendicular lean/fat ratio of <2SD of the average young adult

1

What type of muscle is more affected by ageing?

Fast twitch

1

What changes occur at the motorneuron level with age?

Increase in the amount of connective tissue

Aberrant, small diameter axons

Dysmyelination

2

What is Gower's sign?

Stepping forwards along the floor into a standing position

4

What are the goals of therapy to attenuate muscle wasting?

Attenuate muscle atropy

Promote muscle strength

5

What is the name of the most severe muscular dystrophy?

Duchenne muscular dystrophy

5

Which muscles are preferentially affected in DMD?

Limb and trunk muscles

6

What happens to neuromuscular plate with age?

Widened end plate

Fewer side branches

Longer nerve terminals

6

What is the best intervention for sarcopenia?

Strength training to converse strength and attenuate wasting

7

When does DMD present?

At 2-6 years old

9

Do muscles usually have only one type of muscle fibre that best suits their function, eg the soleus only has slow twitch fibres

No, muscles generally have a mixture of fibres even if they have specific functions

10

What is the inheritance pattern of Duchenne muscular dystrophy?

X-linked recessive

10

What treatment is currently used for muscular dystrophy?

Glucocorticosteroids

 

11

What are the causes of sarcopenia?

Disuse

Endocrine changes

Chronic diseases

Inflammation

Insulin resistance

Nutrient deficiencies

12

Which protein is deficient in DMD?

Dystrophin

12

What is the difference between DMD and Becker muscular dystrophy in terms of clinical course?

Becker muscular dystrophy has a later onset, and slower progression

14

What replaces muscle lost with ageing?

Fat and connective tissue

16

Describe age related muscle remodelling

Fast twitch fibres become deinnervated

Some are lost

Others are reinnervated by slow twitch motor neurons

 

Overall there is a decrease in mass and proportionate increase in slow twitch fibres

17

How does the lack of dystrophin effect cell physiology?

Increases its susceptibility to injury

- Makes the cell membrane leaky > Ca influx > Hypercontractility and necrosis

18

How do DMD patients eventually die?

Cardiorespiratory failure

19

What is the pathogenesis cycle of the muscular dystrophy?

Increase cellular damage followed repair but eventually the rate of damage overtakes the ability to repair

21

What causes slower contraction and reduced force of contraction of muscles that occurs before loss of muscle mass?

Slowed release and uptake of Ca

22

At what age does muscle strength decline occur more rapidly?

>50 years old

24

Apart from loss of muscle mass, what also occurs in cachexic muscles?

Loss of muscle architecture

25

What is the postulated role of dystrophin protein?

It provides structure support to stabilize the sarcolemma (myocyte cell membrane) during muscle contraction

26

What the average survival time of DMD?

Late twenties

27

What contributes to accelerated muscular atropy in ICU patients?

The inflammatory state

28

What effect does myostatin have on muscle mass?

Causes a decrease in mass

29

Which anabolic hormones decline with ageing?

GH

IGF-1

Testosterone

30

How much muscle must be lost during cachexia for death to occur?

>40%