Muscles 2 and 3 Flashcards
A motor unit consists of
a motor neuron and the muscle fiber it innervates
What are the two ways you can increase the force of a muscle
recruit more motor units or increase the frequency
At the neuromuscular junction once the action potential reaches the synaptic terminal, the synaptic terminal ______, and voltage gated ____ channels are opened. Then, the neurotransmitter _____ is released into the synaptic cleft via _____. Then the transmitter binds to the ______receptors on the postsynaptic membrane. This causes channels to open, allowing ____ to pass through, which depolarizes the cell membrane
depolarizes
calcium
acetylcholine
exocytosis
nicotonic
sodium
watch this
https://www.youtube.com/watch?v=LlgaziPCFU0
do it
watch this starting 5 mins to 9 mins
https://www.youtube.com/watch?v=Ktv-CaOt6UQ
do itttt
which bands get shorter with a contraction and which ones stay the same?
shorter: I band and H zone
same: A band
Eciation contraction coupling consists of: action potential travelling down the _______, _____is released into the sarcoplasm (muscle cell cytoplasm), ____ binds to troponin, leaving the binding sites exposed which allows for _____ to bind to ______, and ____ is required for them to detach from one another
T tubules
calcium
calcium
myosin
actin
ATP
to terminate the muscle contraction, the enzyme known as ______ turns acetylcholine back into ____ and _____, which causes ____ to move back from T tubule back into terminal cisternae, and ____ to return to resting position
acetylcholinesterase
choline and acetate
calcium
myosin
What is the relationship between force/load and velocity of a muscle contraction
inverse: when the load is high, velocity is low. When force is low, velocity is high
For muscle training, you can either do ____ training or ____ training, but you can’t do both.
endurance
strength
What is the difference between isometric contractions and isotinc contractions?
isotronic: the length is changing, but the load is staying relativley the same. think a bicep curl at the gym
isometric: no change in the size (no shortening or lengthening), think of you holding a glass and it fills with water. your muscles are still working, but they are not changing legnth. Instead, the load is increasing
What are te two kinds of isotonic contractions?
concentric: shortening
eccentric: lengthening
What are the pahses of a muscle twitch?
latent, contraction, relaxation
What is wave summation? Incomplete tetanus? Tetnus?
It is when there is a stimulation to contract while the muscle is still contrcting, so more calcium is entering the sarcoplasm while the first contraction is still happening. This causes summation where the next contractions are stronger than the first. The tension will continue to rise with each action potential until it reaches a peak point (which is called incomplete tetanus). Tetanus happens if the stimulus frequency is too high and doesnt give the muscle cell enough relaxation time (relaxation phase dissapears compeltely)
What are the two anerobic ways to produce ATP? what kind of muscles use these methods?
What is the aerobic way to produce ATP? what kind of muscle uses this method?
creatine phosphate getting converted to creatine via direct phosphorylation creates ATP, enough for 10-15 seconds (type 2b)
glycolysis (break down of glucose) also produced ATP, enough for 2 mins(type 2a)
oxidative metabolism (electron transport chain) produces enough AT{ prolonged periods, (type 1, endurance)
When does myogenesis occur?
during embryonic and fetal development
What happens when there is poor nutrition during primary and secondary myogenesis?
What about in the muscle fiber hypertrophy phase?
there is a loss of fibers and muscle mass and this is not reversible
there is a loss of cross sectional area of the muscles cells and this is reversible
What is the role of satellite cells?
they are stem cells in the muscle and can aid in muscle repair but research is still unsure how much they are able to contribute to the regrowth
Why do muscle cells have tons of neucli?
because to form a mature muscle cell, many cells come together to fuse into one cell
Trye or false: an animal is born with all of its muscle cells already grown (if normal)
true
True or false: after birth an animal can regrow some muscle cells if some become damaged
false
what are the two ways muscle can grow?
hypertrophy (increase in the individual size of each cell)
hyperplasia (splitting, divison, increase in number of cells)
increaseing the length of a sarcomere has what affect on force, velocity, and shortening capacity?
force: no change
velocity: increases/doubles
shortening capacity: doubled
hyperplasia (having more sarcromeres in paralell) has what affect on force, velocity, and shortening capacity?
force: doubled
velocity: no change
shortening capacity: no change
hyperplasia, splitting and increasing the number of muscle fibers/cells, happens mostly in ______
fetal development
what is a muscle spasm?
involuntary contractions of muscles, often painful
what is a muscle cramp?
sustained spasms that can last a few seconds to 15 minutes or longer
What is muscle strain? WHat causes it? Where does it often occur?
tearing of he muscle
overexertion or stretching beyond its range
musculotendinous junctions because everything is coming to a common point
there are two kinds of muscle atrophy what are they?
neurogenic and myogenic
what is neurogenic atrophy? what is an example?
when dennervation occurs and protein degredation then occurs, decreasing muscle mass
ex. sweeny in horses is dennervation of the suprascapular nerve which then causes supra and infraspnatous to atrophy
what is myogenic atrophy?
due to malnutrition or weight loss secondary to other diseases, or an excess in corticosteroids like cortisol. results in ONLY the atrophy of type 2 fibers (fast)
muscle necrosis/ rhabdomyolysis is associated with what clinical features?
muscle pain, contracture (shortening and hardneing of muscles), increased respiratory rate, sweating
what causes muscle necrosis?
nutritional: vitamin ´ and selenium deficiency
infectious
immune
metabolic
what is muscular dystrophy?
inherited progressive degernation of skeletal muscle. there is a deficinecy of dystrophin (protein which anchors sarcrolemma to actin of cytoskeleton), so every time the muscle contracts, small rips form in the cell membrane. this allows calcium to come in and bind with a protease and the proteases destroy and break down muscles
