Skeletal Muscle Aging Disease

Question 1

Larger muscles more or less fatiguable?

Answer 1

More fatiguable

Question 2

smaller slow muscles more or less fatiguable?

Answer 2

less fatiguable

Question 3

Muscle fibres are static?

Answer 3

lots of muscle fibre malleability

Question 4

what is NOT a goals of intervention for muscle wasting?

Answer 4

don’t want to increase muscle fatigue

Question 5

Myostatin if knocked out?

Answer 5

increased muscle mass gain

Question 6

Myostatin role physiologically?

Answer 6

negative regulator

Question 7

loss of innervation or tone leads to

Answer 7

muscle atrophy

Question 8

Cancer Cachexia affect how much long, pancreatic, GI patients?

Answer 8

80%

Question 9

What is ICU wasting called?

Answer 9

Critical Illness Myopathy

Question 10

Sarcopenia definition

Answer 10

age-associated loss of skeletal muscle mass and function

Question 11

sarcopenia dx needs 3 things:

Answer 11

<2SD

Question 12

What age does performance decline despite exercise regime?

Answer 12

~50yr old

Question 13

slow or fast twitch muscles affected first?

Answer 13

fast twitch first

Question 14

weakness definition

Answer 14

inability to generate an initial force appropriate circumstances

Question 15

Age related motor unit remodelling happens how?

Answer 15

denervation of type 2 motor units, die or reinnervation with type 1 motor units but smaller mass

Question 16

up to how much % muscle in ageing?

Answer 16

30%

Question 17

what replaces muscle in sarcopenia?

Answer 17

connective tissue
fat
noncontractile

Question 18

muscle wasting acute process?

Answer 18

contraction slows before onset of severe muscle wasting

Question 19

how does Ca2+ play a role in sarcopenia?

Answer 19

sarcoplasmic reticulum impaired release or reuptake of Ca2+

Question 20

most susceptible motor units are?

Answer 20

Type IIb fast twitch

Question 21

what 3 things happens to post-synaptic component in ageing?

Answer 21

wider end plates
longer nerve terminals
fewer side branches

Question 22

how to axons look in aged tissue?

Answer 22

smaller and aberrant axons, dysmyelination

Question 23

what hormone can affect sarcopenia?

Answer 23

IGF-1

Question 24

what affects muscle regen capacity?

Answer 24

satellite cells

Question 25

what happens to CT with ageing?

Answer 25

stiffer CT | more fibronectin

Question 26

how to conserve muscle strength for preventions/reversal?

Answer 26

strength training

Question 27

exercise prescription for elderly? 4 things

Answer 27

strength aerobic exercise flexibility balance

Question 28

why not just give people growth hormone as they age?

Answer 28

compromises efficiency of muscle regen d/t daily wear and tear. It's not sustainable

Question 29

focus on treatment for sarcopenia?

Answer 29

function, not just mass

Question 30

Duchenne's onset?

Answer 30

age 2-6

Question 31

Duchenne's symptoms?

Answer 31

generalized weakness | large calves

Question 32

Duchenne's inheritance?

Answer 32

X-linked recessive

Question 33

why calves bigger in Duchenne's?

Answer 33

breaking down of muscle but repairing is occuring and can keep up until eventual failure

Question 34

Duchenne's life expectancy?

Answer 34

20years unless ventilated and corticosteroids

Question 35

What is Gower's Sign in Duchenne's?

Answer 35

unable to stand up without help of hands on their thighs to help

Question 36

which muscles more affected in Duchenne's?

Answer 36

lower limb and torso, not as much upper limb

Question 37

Why occulomotor muscles spared in Duchenne's? 3 possible reasons

Answer 37

1. smalller muscle 2. lower mechanical stress 3. more sarcolemmal expression of compensatory protein

Question 38

Duchenne's deficiency in?

Answer 38

dystrophin

Question 39

Duchenne's mutation on which gene?

Answer 39

Xp21

Question 40

dystrophin important how in muscle?

Answer 40

combines with glycoprotein for: 1. structural, stabilization during eccentric 2. receiver or transducer of signals

Question 41

What is Becker's muscular dystrophy?

Answer 41

less severe than Duchenne's starts later: adolescence/adulthood can make some dystrophin

Question 42

what is dystrophin like in Becker's muscular dystrophy?

Answer 42

smaller amounts | abnormal, smaller molecules

Question 43

DMD is what kind of deletion of gene?

Answer 43

frame shift

Question 44

Becker's muscular dystrophy gene is affected how?

Answer 44

reading frame preserved, can still make some dystrophin

Question 45

how does dystrophin stabilize sarcolemma?

Answer 45

form costameres that make mechanical links

Question 46

without costameres what happens to sarcomeres?

Answer 46

tearing of muscles, build up of Ca2+ in ECM, fibrosis and degen

Question 47

dystrophic muscles susceptible to stretch-induced injury? 3 reasons

Answer 47

Yes due to: 1. muscle fibre branching 2. hypercontraction: necrosis 3. leaky dye uptake studies

Question 48

contraction-induced muscle injury cycle?

Answer 48

``` healthy contraction damage loss of Ca2+ homeostasis muscle degen muscle regen ```

Question 49

current Rx for Duchenne's?

Answer 49

Corticosteroids

Question 50

New Duchenne's drug targets?

Answer 50

Heat Shock Protein Hsp72