Exercise Psy week 9 part 2

winniesmith2's version from 2018-01-09 14:17


Question Answer
Sarcomere structure • Each myofibril is composed of thousands of sarcomeres. • Joined in series and parallel to one another. • Sarcomeres are the functional units of a muscle. • Made up of myofilaments. -actin and myosin myofilaments. -it is what myosin it is that says whether fibre is type 1 or 2
how many myosin molecules per thick filament300.
what are the 2 subunits of myosinS1 – Globular head. S2 – Flexible region and tail. Myosin heavy chain isoforms.
myosin and the speed of contractionspeed of contraction mainly determined by the ATPase. Speed of myosin binding= type 1 or 2
What makes fast-twitch fibres fast?Amount of ATPase activity.
Can we change our fibre type Yes- studies have shown that endurance training increase type 1 and decreases type 2x. and that sprint training decreases type 1 and increase type 2a
What effect does short-term endurance training have on myosin heavy chain gene expressiondecreases type 11x
Capillaries site of gas exchange. Walls are 1 endothelial cell thick. denser capillary network= increased surface area. increased capillary density = improved 02 uptake. Increased capillary numbers by >15%
What does VEGF meanVascular Endothelial growth factor
What stimulates VEGFlow PO2.
What does VEGF stimulate angiogenesis (blood vessel formation)
What happens to VEGF after training VEGF mRNA and VEGF protein increase
What was the effect of 24 week cross-county training on angiogenesisfor each fibre type, amount of capillaries per fibre increased
What is the training effect on capillaries and muscle fibre size muscle fibre size increases . and capillarisation occurs - more capillaries
Mitochindria Recap• Found in cell cytoplasm • Major site of ATP production • Metabolically active cells have many mitochondria
What did a 24 week endurance training program have on mitochandrial numbers. ( Classified fibres according to the number of ‘mitochondrial aggregates’ seen under the microscope) number of mitochondrial aggregates increased. graph bottom of page 9
What is a mitochondrial aggregate mitochondria grouped together inside the muscle cell membrane
Mitochondrial size after 28 week endurance programme36% increase in mitochondrial size
Possible adaption to endurance training change in fibre type composition, increased blood supply, increased mitochondria
muscle fibre types- summary • Endurance trained individuals have a high percentage of Type I fibres • Endurance training promotes a fast-to-slow shift in skeletal muscle fibre types • Major effect of aerobic training is to convert some Type IIx to Type IIa and Type I fibres • Endurance training is a potent stimulus for altered myosin heavy chain (MHC) gene expression
muscle angiogenesis -summary • Exercise training induces angiogenesis (capillaries ↑) • Surface area for diffusion ↑  Improved rate of transfer of oxygen, nutrients and waste products • A major factor is thought to be increased expression of Vascular Endothelial Growth Factor (VEGF)
mitochondria- summary • Endurance training leads to an increase in mitochondrial size and number • Increases in number > increases in size • Fibre type specific

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