Muscle S13

Question 1

exercise physiology

Answer 1

exercise can transform skeletal muscle myofibrils to alter its metabolism

Question 2

altering fiber type oxidative metabolism

Answer 2

• transforming from type II to type I means for efficient at using oxygen and higher endurance level
• upon cessation, metabolic changes are REVERSIBLE

Question 3

marathon runner =

Answer 3

endurance; type I

Question 4

sprint runner =

Answer 4

speed; type IIb

Question 5

remodelling in skeletal muscles involve activation of..

Answer 5

intracellular singling pathways

Question 6

activation of intracellular signalling pathways cause alteration in..

Answer 6

• muscle mass
• contractile properties
• metabolic states (modify myofibrils function lead to changes in muscle performance)

Question 7

Signalling pathway for muscle remodelling

Answer 7

• stress signal (calcium influx)
• receptor receives signal
• activating factors
• change

Question 8

calcium

Answer 8

primarily used as a second messenger for gene expression in myofibre

Question 9

HDAC (histone deacetylases) kinases

Answer 9

activates and phosphorylate HDAC in response to increase in intensity of activity (increase cytosolic Ca2+)

Question 10

phosphorylate of HDAC

Answer 10

create a docking site for chaperone protein 14-3-3 to bind to HDAC

Question 11

binding of chaperone protein to HDAC

Answer 11

induces a conformational change in HDAC causing it to exit from nucleus and promoting MEF2 activation and leading to remodelling

Question 12

HDAC

Answer 12

a class of enzymes that cause histones to wrap the DNA tightly

Question 13

myocyte enhancer factor-2 (MEF2)

Answer 13

a protein/transcription factor that control gene expression and is important regulator of cellular differentiation
-addition of various stimuli enhance DNA binding and promoting muscle transcription

Question 14

calcineurin

Answer 14

a calcium and calmodulin dependent phosphatase
-activated by sustained, low-amplitude calcium waves and is a sensor of contractile activity by sensing calcium fluctuations

Question 15

calcineurin signaling initiated by..

Answer 15

sustained, low-amplitude calcium waves - allowing calcium to bind to calmodulin, activating calcineurin

Question 16

activated calcineurin

Answer 16

dephosphorylates NFAT, resulting in translocation of NFAT from cytoplasm to nucleus where it associated with other transcription factors to activate specific sets of calcium-dependent target genes

Question 17

NFAT activity found higher in .. compared to .. muscles.

Answer 17

slow; fast

Question 18

NFAT activity required for maintenance of ..

Answer 18

slow myosin heavy chain gene expression and potentially in repression of fast myosin heavy chain IIb gene

Question 19

peroxisome-proliferator-activated receptor gamma coactivator-1 (PGC-1)

Answer 19

a transcriptional coactivator that regulates the genes involving in energy metabolism

• considered master of mitochondrial gene expression
• shown to activate mitochondrial biogenesis and oxidative metabolism
• enriched in type I and induced by endurance exercise

Question 20

peroxisome-proliferator-activated (PPAR)

Answer 20

major transcriptional regulator of fat burning in adipose tissue
-increase specifically in type I fibres

Question 21

Exercise induction of PGC1 may … PPAR and induce..

Answer 21

activate; myofiber remodeling

Question 22

in response to increase in workload which causes ATP depletion..

Answer 22

AMPK is activated

Question 23

AMP-activated protein kinase (AMPK)

Answer 23

activates both the uptake and oxidation of glucose and fatty acid
-inhibits synthesis of fatty acids, cholesterol, and triglycerides

Question 24

PI3K/Akt/mTOR

Answer 24

shown to be activated during hypertrophy (of cultured myoblasts in response to IGF-1

Question 25

Phosphorylated Akt inhibits..

Answer 25

forehead box (FOXO) nuclear entry thereby preventing protein degradation (unphosphorylated FOXO induces muscle atrophy)

Question 26

activation of mTOR by Akt..

Answer 26

promotes protein synthesis and increases muscle mass, resulting in HYPERTROPHY

Question 27

obesity

Answer 27

suppression in AMPK activity promoting fat deposition and a shift to fast muscle fiber