Intro to SKM structure function and metabolism PART 2 Flashcards
includes everything from slide 20 of the powerpoint onwards
Define Isometric contraction and outline the relationship between force and load here
- muscle does not shorten, remains same length
- force generated by the contraction is equal to load applied
define isotonic contraction
- muscle changes length
what are the 2 types of isotonic contraction
- concentric
- eccentric
define concentric contraction and outline the relationship between force and load here
- muscle shortens as it contracts
- force generated is greater than load applied
define eccentric contraction and outline the relationship between force and load here
- muscle lengthens even though its contracting
- force generated is less than load applied
why are isometric contractions uncomfortable?
because this type of contraction impairs blood flow to the area
Name 4 sources of ATP
- Cytosolic ATP (limited)
- Phosphocreatine (PCr)
- aerobic respiration (oxidative phosphorylation)
- anaerobic respiration (fermentation)
how quickly is cytosolic ATP/ATP in muscles used up?
used up in a few contractions
what does phosphocreatine do that allows for synthesis of ATP
can quickly regenerate ATP from ADP
why do people “creatine load”
because phosphocreatine has limited supply in cells.
what is is glucose stored as in muscle cells
glycogen
Name the process of anaerobic respiration and when is it used?
- Glycolysis + lactate fermentation
- used when O2 supply cannont keep up with demand
Name 2 advantages and 1 disadvantage of glycolysis + lactate fermentation (anaerobic resp)
Advantages:
- Does not require O2, so can be used when O2 supply cannot keep up with demand
- generates ATP faster than aerobic respiration
Disadvantage:
- limited functionality
what is produced in anaerobic respiration and what is this product associated with?
lactate is produced
Associated with, but DOES NOT CAUSE:
- muscle soreness
- fatigue
where does aerobic respiration occur
mitochondria
what does aerobic respiration require to form ATP
O2
what type of nuclei do adult skeletal muscle fibres have?
think “division”
postmitotic nuclei
this means they cannot divide
what cells allow for muscles to regenerate?
Satellite cells
what are Satellite cells?
extracellular muscle stem cells
Myogenesis
outline the 4 steps of myogenesis
- somite cells start to exhibit muscle specific genes
- they become myoblasts
- myoblasts then proliferate, regulated by myogenin
- myoblasts then fuse via action of MRF4 to become muscle fibres
what can satellite cells repair?
muscle damage
what ways can tissue (i.e muscle) grow?
can grow through:
- hyperplasia
- hypertrophy
what is hyperplasia?
cells double their nuclei/DNA and content in the cell cycle, then split but at an increased rate ( AKA increased mitosis )
what is hypertrophy?
when adult muscle cells grow in size
why is cellular hypertrophy limited?
because DNA concentration within a cell with one nucleus will be diluted due to their post-mitotic nature
what is the most common form of muscle growth during development?
hyperplasia
what form of muscle growth does not occur in adulthood?
hyperplasia does not occur in adulthood
outline the role of satellite cells in hypertrophy in 3 steps
- hypertrophy stimulus
- Satellite cell proliferation and differentiation
- fusion of some satellite cells with the muscle fibre
why is cellular hypertrophy limited?
because the DNA concentration within a cell with one nucleus will be diluted due to their post-mitotic nature
