Muscle Pt 6 (SM reflexes/hypertrophy/atrophy) Flashcards
What are 3 types of skeletal muscle adaptations?
- Hypertrophy / atrophy
- Increase in ATP synthesizing capacity
- Nueral adaptations
T/F there is a constant remodeling of muscle mass
True
The constant remodeling of muscle mass is controled by protein ___ & ___
protein synthesis & degragation
If you want to increase Muscle mass, protein synthesis must ___ degragation. How can this be done? which method is most common?
synthesis > degragation
1. hypertrophy = increase in diameter of already present muscle fiber = MOST COMMON
2. hyperplasia = increase in # of muscle fibers (via splitting) (u can’t make new muscle fibers via myosatellite cells, that only occurs during development) = unlikly
Satellite cells vs. myosatellite cells
- satellite = can cause regeneration of damaged muscle fiber by donating nuclius
- myosatellite = can create new muscle fibers in developent phase
Hytrophy is a skeletal mass adaptation that ___ muscle mass
increases muscle mass
What is hypertrophy? What is it’s result?
hypertrophy = overload in stimulas
Causes = muscle fibers to expand outward setting off myogenic events that lea to increase in size of sarcomere & # of contraclile proteins
In hypertrophy, # of muscle fibers . . . and # of myofibers within the one muscle fiber . . .
muscle fiber = remain constant
myofibril (myofiber?) within fiber= increases
Expain the 3 myogenic events that lead to hypertrophy . . .
- Increase in size/# of proteins (actin/myosin) = increase # of myofibrillar proteins
- increased # of sarcomeres = increase myofibrils
- increased sarcoplasmic storage (glycgen)
in humans = hypertrophy can’t be caused by an increased # of muscle fibers
In which muscle type does hypertrophy occur fastest?
T1 or T2
Type 2 muscle is more succeptible to hypertrophy
If you want to decrease muscle mass via atrophy = protein ___ must exceed ___
atrophy = mass decrease
protein degragation > synthesis
What is atrophy?
Mechanism to reduce muscle mass that can be triggered by multiple stimulas
Don’t use it = lose it
What are some causes of atrophy (decrease in muscle mass?)
- Dissuse (immobalization, bedrest, unloading = no gravity)
- Food deprivation
- Muscle wasting due to chronic disease (Cachexia)
Muscle mass is naturally effected by age = it ___ muscle mass. How does it do this?
age = decrease muscle mass
muscle mass replacedd with adipocyte tissue
What are 3 myogenic events that lead to atrophy?
- loss of nucleus
- decreased amount of myofibril proteins (actin/myosin)
- decrease in myofiber cross-section area
ALS and Muscular dystrophy are examples of skeletal muscle __
atrophy
1. ALS = nueromuscular disorder = decrease use of muscle fiber
2. Muscular dystrophy = mutation that causes your fibers to easily break (non fixable)
Voluntary skeletal muscle movement starts in the ____ —> sends signal to __/__ motr neurons –> signal sent to muscle = contraction
signal made in primary motor cortex –> upper motor nueron –> lower motor nueron –> muscle fiber = contraction
Involuntary skeletal muscle movement occures via sensory nuerons which return a signal to spinal cord = alter lower motor nueron acticity
True
Involuntary skeletal muscle movement occures at the __ lvl & voluntary movment a the __ lvl
involintary SM = spinal cord level
voluntary = primary cortex level
The sensory recepotrs associated with involantary SM movement can respond to stimulus in 2 ways . . .
1 .stimulus says contraction is needed = spinal cord sends signal to CNS to activate motor nuerons for muscle fibers
2. stimulus senses relaxation is needed = input activates inhibitaory interneurons in the CNS which stop activty in motor neuron –> relaxation
T/F activation/inhibitin of skeletal muscle can ONLY occur via input from brain (CNS / primary cortex)
False
Activation/inhibition can also occur in response to sesory receptors in spinal cord that don’t rely on brain input
What are the 4 components of skeletal muscle reflexes?
- sensory receptors
- integrating center
- efferent neurons
- effectors
Monosynaptic reflex vs polysynaptic reflex
monosynaptic = 1 sensory nueroun directly connecting onto the motor nueron in spinal cord [motor nueron joining with only 1 sensor]
polysynaptic = 1+ sensory nueron can attach to motor nueron (with use of interuerons) [motor nueron joins with 1+ sensores] = excitatory / inhibitory
synapse = connection of sensory nuerons onto somatic motor nueron
What are the primary sensory receptors that cause skeletal muscle reflexes?
Proprioceptors
give info to CNS about position of limbs in space & effort exerted by SM
What are the 3 important parts of proprioceptors?
- Muscle spindle
- Golgi tendon organ
- Joint receptor s
Found in propioceptors
Explain Muscle spindles
function: respond to changes in muscle legnth
stretch receptor
Info carried = send info to CNS about muscle length & their changes
Muscle spindles repsond to ___ due to being __ receptors
respond to muscle length change due to strech receptors
T/F Muscle spindles only activate when they sense a change in muscle length
False = they are tonically active, always on lookout for change = this impacts your resting muscle tone
not 100%%% sure
What effect do muscle spindle cause?
if they sense change in muscle length –> they alter amount of contraction poduced
What is the muscle spindle reflex?
the addition of a load sretches muscle & spindles = creating a reflex contraction
{muscle streched = spindle creates a contraction to offset load displacement)
What 2 parts make up muscle spindles?
- sensory nuerons wrapped around intrafusal muscle fibers
- gamma motor nueron (starts contraction in response to length change)
proprioceptor
What 2 parts make up the golgi tendon organ
- sensory nueron interwoven among collagen fiber
- connective tissue capsule
What stimulus do golsi tendon organs respond to?
changes in muscle tension
What do goli tendon organs do?
sense tension change –> control force within muscle & stability around joints
What is the tendon golgi reflex?
protect the muscle from extra heavey loads by causing muscle to relax and drop load
Are golgi tendons tonically active?
No
What are joint receptors within propioreceptors
found in capsules and ligaments around joints & are activated by mechanical distortion that accompanies change in position of bone
sense change in position of bones
What is reciprocal inhabition
when stimulus of sensory receptors lead to contraction of one muscle and inhibition in the antigonisitic muscle
What are flexion reflexes? Name an example?
flexion reflex = pull limbs away from painful stimuli
Ex. Crossed extensor reflex= a flexion reflex in one line causes extension in the opposite limb (coordination of reflex = maintain balance)
