exam 1 lecture 7 whole muscle regulation Flashcards
Can a muscle fiber increase the number of sarcomeres in series?
yes. can grow more sarcomeres.
Cell can contract more while each sarcomere doesn’t have to as much. Requires more energy. Doesn’t make it stronger just faster. stays in optimal working zone more.
___ kind of training leads to:
Increased oxidative capacity though increased mitochondrial numbers
Increased capillaries around the tissue to supply blood
Conversion of fast glycolytic fibers to fast oxidative fibers
aerobic
___ training will lead to
Increased glycolytic capacity through increased storage of glycogen
Increased fiber diameter (satellite cells triggered to form more myofibrils in parallel)
anaerobic (without oxygen)
Also, evidence suggests that resistance training strengthens muscles by increasing the number of ___ in motor unit recruitment
synchronization
what cells are used to increase muscle fiber diameter and how?
satellite cells form more myofibrils in parallel in response to anaerobic training
satellite cells make more nuclei
Hypertrophy is mediated by satellite cells, which can be activated by:
Myogenic pathways
Growth hormone, testosterone, cytokines, IGF
Muscle stress/tension, damage
•satellite cells fuse with muscle fiber increasing the number of ___ within the fiber
nuclei
how do you think increasing the number of nuclei impacts cell size and functionality?
increase transcription- increases translation of parts that make up myofibrils →
gets bigger, more myofibrils, becomes stronger faster
___ is a motor nerve and all the fibers it innervates
motor unit
a single muscle fiber can be innervated by more than one neuron. True or False?
false
one fiber = one neuron
(each neuron can innervate many muscle fibers)
•Muscle fibers within a motor unit contract ___ upon motor neuron firing
synchronously
(at the same time- activated simultaneously)
Describe recruitment for a muscle
the more fibers it stimulates the stronger the response
a muscle can have multiple motor units fire at the same time and creates a bigger response
larger motor units have smaller motor neurons. True or False?
false
larger motor units have larger(thicker) motor neurons and more muscle fibers associated with it.
Larger motor units are also stronger than smaller motor units
The larger the motor neuron, the more difficult it is to reach ___ (not to be confused with the relationship between axon diameter and speed of AP propagation)
threshold
thicker axon = faster signal but also thicker axon = harder to get to threshold. (get it going)
a motor unit is comprised of only one type of ___
muscle fiber
either all slow oxidative or fast oxidative or fast glycolytic
will not have a combo
slow oxidative muscle fibers have ___ motor units and are recruited ___.
smaller
first
fast oxidative muscle fibers have what size motor units and when are the recruited?
intermediate and second
- Slow oxidative–Smaller motor units–Recruited first
- Fast oxidative–Intermediate motor units–Recruited second
- Fast glycolytic –Larger motor units–Usually only recruited during intense exercise
Which muscle fiber type has the largest motor unit and is recruited last only during intense exercise?
Fast glycolytic
- Slow oxidative–Smaller motor units–Recruited first
- Fast oxidative–Intermediate motor units–Recruited second
- Fast glycolytic –Larger motor units–Usually only recruited during intense exercise
three places proprioceptors are found to help to refine movement and protect muscle from injury
muscle spindle
golgi tendon organ
joint receptor
Muscle spindle fibers respond to ___
stretch
the muscle fibers within the muscle spindles are called
intrafusal fibers
the muscle fibers outside the muscle spindle are called
extrafusal fibers
Muscle ___ provide feedback to the brain about muscle length
spindles
(too stretched not stretched)
extrafusal fibers are innervated by what kind of neuron?
alpha motor neuron
intrafusal fibers are innervated by what kind of neuron?
gamma neuron
what are the blue lines
sensory neuron that carries info back to the brain about how stretched or contracted the muscle is
how do the sensory neurons within the muscle spindle work
frequency of impulse determines position of muscle
if muscle stretched sends more action potentials to the brain
if muscle contracted action potentials decrease in frequency
gamma motor unit keeps the sensory fibers contracted during contraction- keeps the fibers aware of what is happening
how can a muscle fiber tell if it a lot contracted or a little contracted
the alpha subunit contract the outside fibers
gamma contracts the fibers within the muscle spindle- keeps the sensitivity high
explain stretch reflex
hit tendon, “stretches the muscle.” Muscle spindle sends message to CNS “ we are stretching, could be too stretched”
reflex- skips the brain, goes into the spinal cord and right back out and inhibits antagonistic muscles which makes them relax and original muscle to contract → kick leg
golgi tendon organs respond to ___ in muscle tension
increases
activation of golgi tendon organs causes ___ signals to the motor neuron
inhibitory
what sense organs are used to prevent over contraction
Golgi tendon organs
example- someone throws something really heavy, you immediately drop it
golgi tendon organs will send a signal to inhibit ___ and activate ___
flexor muscles (original muscle that is being contracted)
extensor muscle (muscle opposite to first muscle
ex. someone throughs something , you immediately drop it
withdrawal and crossed extensor reflex
step on something causes left and pull back of the leg
slow twitch type 1
muscle fiber, motor unit, motor neuron
fast twitch Type IIa
chart
Fast twitch type IIb
chart
compare skeletal to smooth muscle
compare skeletal, smooth and cardiac muscle
