Atrophy

Question 1

What are some common causes of atrophy

Answer 1

• inactivity
• aging
• malnutrition
• neuro conditions
• chronic conditions
• injury/surgery

Question 2

what are some symptoms of muscle atrophy?

Answer 2

• muscle weakness
• decreased muscle mass
• fatigue
• difficulty moving
• balance issues
• joint pain

Question 3

what are some risk factors for atrophy

Answer 3

• age
• sedentary lifestyle
• chronic disease
• neuro disease
• poor nutrition

Question 4

T or F: with atrophy, both myofiber size and muscle quality is reduced

Answer 4

T

Question 5

what are mechanisms of initiating muscle atrophy

Answer 5

• cortical steroids
• FOXO
• cytokines
• myostatin

Question 6

what are some mechanisms to mitigate muscle atrophy

Answer 6

• anabolic steroids
• growth factors
• exercise stimulus
• follistatin (sequesters myostatin and inhibits it)

Question 7

what are some inflammatory cytokines

Answer 7

IL-6
TNF-a
IL-1

Question 8

what are some cytokine-like inflammatory markers

Answer 8

• HMGB1
• S100
• myostatin

Question 9

what is HMBG1

Answer 9

an immune response modulator

Question 10

what happens if you don’t have a myostatin gene? is this a viable therapy?

Answer 10

• lack of myostatin gene increases muscle mass but altering it to prevent muscle loss does not work well

Question 11

what are 2 ways proteins can be recycled?

Answer 11

proteasome system
autophagy via lysosome

Question 12

explain the ubiquitin system

Answer 12

• attaches to protein to signal
• 4+ tags = target for degradation

Question 13

_________ expedites the wasting of skeletal muscle by selectively targeting and degrading sarcomeric proteins through the ubiquitin-proteasome pathway

Answer 13

MuRF1

Question 14

MuRF1 expedites the wasting of skeletal muscle by selectively targeting and degrading sarcomeric proteins through the ______________ pathway

Answer 14

ubiquitin-proteasome

Question 15

what’s another word for MAFbx

Answer 15

Atrogin

Question 16

___________ directly targets MyoD and elF3-f, hence indicating that this muscle-specific E3 ligase promotes muscle wasting by principally impairing protein synthesis and muscle regeneration

Answer 16

Atrogin/MAFx

*dismantles machinery involved in muscle synthesis

Question 17

what can trigger autophagy?

Answer 17

fasting
exercise
drugs

Question 18

____________- is the natural, conserved degradation of the cell that removes unnecessary or dysfunctional components through a lysosome-dependent regulated mechanism. It allows the orderly degradation and recycling of cellular components

Answer 18

autophagy

Question 19

______ activates calpains

Answer 19

Ca+

Question 20

what do calpains do?

Answer 20

induce enzymatic destruction of cells to break up proteins.