Muscle physiology and anatomy Flashcards
Study the physiological and anatomical structure of the major muscle types in the human body
What does a muscle look like?
muscles look like bundles of bundles.
What are fascicles?
These bundles that make up muscles structure
what are fascicles made of?
muscle fibers
what are muscle fibers made of?
muscle cells
what are myofibrils in a muscle cell?
muscle cells have smaller bundles called myofibrils
What is a myofilament?
the myofilaments are smaller tubules of the myofibrils
There are two primary types of myofilaments
actin and myosin
epimysium
wrapped around a muscle. Holds a bunch of fascicles inside of the muscle.
Perimysium
each fascicle is wrapped up in a connective tissue called
endomysium
wraps around muscle fiber and cell
epimysium, perimysium, and endomysium
what are three major connective tissues that makes up the repeated bundles of the muscle structures in skeletal muscles.
fascia
a thick layer of connective tissue that sometimes merges with epimysium, can sometimes be inflamed.
sarcomeres
are the repeated units made up of actin and myosin found at the myofibril. They are the light and dark bands repeatedly wrapped and not wrapped around each other in a repeated pattern on the muscle fibers/muscle cell.
Where does actin attached to at the sarcomeres
actin attaches to the end discs at the ends of these sacromeres. z disks attaches to actin.
during muscle contractions, what changes?
These z disks attached to actin to slide over one another. it brings one z-disks closer to the other z-disk during muscle contraction. So the entire sarcomere shortens. the I band with only actin attached shortens as well. the H zone shortens too. A band does not change.
The H zone
middle of the filament with an m line made up of myosin
I band
where actin is at the end of sacromere
A band
is from one end of the myosin all the way to the other end of myosin that meets up with actin.
what do these myosin and actin do during muscle contraction?
they overlap between the two.
What happens to myosin and actin when we lengthen and pull muscle?
actin and myosin band pulls further apart. slide one another and don’t overlap
what happens to actin and myosin when contracted
they overlap more often repeated pattern
How can muscles stretch beyond its resting point?
we need a muscle that works opposite of the other muscle to stretch.
What is the process that enables actin and myosin to overlap together during muscle contraction?
myosin has golf shaped heads that grabs and pulls actin when actin is getting closer. ATP binds to the myosin head and extend it back to loaded position and grabs and pulls when it sees actin.
What is the physiological process when muscles need to relax?
the actin is wrapped in troponin and tropomyosin
What is tropomyosin?
a long protein that can wind all the way around actin and covers around active sides that myosin bind to disabling myosin from pulling actin.
what is troponin?
a little lock mechanism and locks tropomyosin in one place and can unlock tropomyosin to contract.
What is calcium role in relaxing muscles?
calcium floods into the myofibril, calcium binds to troponin, and this unlocks tropomyosin to move out of the way for myosin to see and bind to actin.
Three major processes for producing ATP that aids in contractions
cellular respiration, glycolysis,
cellular respiration
blood glucose and other things undergo cellular respiration; break down glucose and produce ATP, can happen in mitochondria, oxygen, co2, heat and causes ATP which ATP allows myosin to be reloaded
glycolysis
take glucose snaps in half to produce ATP, these two broken glucoses break down into lactic acid, reusable energy that roams around muscles, a byproduct. Doesn’t need oxygen. Is not energy efficient.
What happens to the unspent ATP that is free roaming?
breaks down into creatine and makes a molecule called creatine phosphates can be converted back into ATP and is stored in the muscles. creatine phosphates are more long term than ATP that is consumed easily and fast.
neuro-muscular junction
neurons send out electrical information where a neuron meets a muscle
How does the neuron meet up with the skeleton muscles for contraction to be stimulated?
At the end of an axon of a neuron split into multiple neuron terminals that can touch a variety of different structures such as a skeleton muscle
presynaptic terminal
the end of the neuron closer to skeleton muscles
synaptic cleft
the space between the presynaptic terminal and the skeleton muscle or the post synaptic membrane
How do we get this electrical information to cause stimulation to contract the fibers of the muscles?
the presynaptic terminal has small membrane bound vesicles compartment filled with neurotransmitters are tiny little messenger
flies down the axon terminals and merge with plasma and dumped in the synaptic cleft on the surface of the post synaptic membrane where receptors receive the electrical signals to transmit across the muscle itself that activates calcium to flood into the muscle fibers
to allow the key and lock mechanism to cause myosin to grab onto
the actin and causes muscle contraction.
acetylcholine
neurotransmitter at the presynaptic terminal and the post synaptic membrane
sarcolemma
the surface of the muscle fiber like the plasma membrane of the muscle
sarcoplasm
inside of the plasma membrane of the muscle fiber
sarcoplasmic reticulum
weblike structure wrapped around the myofibril (housing the actin and myosin that slides passed each other). This sarcoplasmic reticulum is a modified endoplasmic reticulum where it stores calcium so when the muscle fiber gets stimulated, sarcoplasmic reticulum drops the calcium it stores into the myofibril.
What happens when muscle relaxes at the chemical level when calcium is present and what is the role of the sarcoplasmic reticulum in this process of relaxing muscle?
the calcium is pumped back into the sarcoplasmic reticulum
How can the electrical signals quickly get inside the muscle fibers and into the myofibrils?
T tubes, these transverse tubules allows the signals to go deep into the myofibrils away from the sarcolemma.
how to measure muscle contraction?
unit- muscle twitch. smallest unite of muscles amount of muscle contraction.
lag phase
the beginning of the phase, no contractions visibly seen. the time it takes for the initial stimulus for the muscle to contract. a couple of milliseconds for the electrical signals to pass from presynaptic terminal to cause acetylcholine to release bind to the receptors of the post synaptic surface membrane, triggers calcium to release.
contraction phase
when calcium is release and binds to troponin to unlock tropomyosin for the myosin heads to load and grab and pull actin for contraction to occur, tension is visibly shown on muscle measurements.
relaxation period
calcium is being pumped out and into the sarcoplasmic reticulum holdings and muscle contraction stops.
all or non-principle
if a muscle is stimulated or hit a threshold to contract that muscle fiber that will contract as it can and when the stimuli stop the muscle will relax. (Light switch flip. ON/OFF)
motor unit
one nerve or neuron that sends info to spread and touch muscle fibers and can contract in one unit.
motor unit recruitment
When we take one motor unit and stimulate just those muscle fibers and if needed, we can recruit more motor units to contract more muscle fibers to make the contraction bigger
How can we generate different strength in a muscle?
motor unit recruitment
wave summation
we send information to muscles and cause it to contract. allow the muscle twitch and before it goes to relaxation period, we can send more muscle twitch behind each other to stack to cause higher tension
myogram
wave muscle contractions graph
tetanus
where we can measure the amount of or like the smoothness of the muscle contraction.
complete tetanus
when a muscle is contracted at its highest point and the tension remains solid
incomplete tetanus
when a muscle contracts while holding something and allow it to relax and it will start to shake
isometric muscle contractions
where we put tension on a muscle without moving the bones attached to the muscles we put tension, plank push up position. ideally don’t change length. push on accelerator on a car on steady speed
isotonic muscle
put tension on muscle and the length of the muscle changes
concentric muscl contractions
we put tension on a muscle, and it overcomes resistance and shortens. the upward phase of a bicep curl when we hold a dumbbell in our hand and put tension in the brachii and overcome the tension and contraction and muscle will shorten
eccentric muscle contractions
we put tension in our muscle but allow the muscle to lengthen. start top of our bicep curl the finished position and slowly extend our muscle and allow the dumbbell to lower
muscle hypertrophy process
muscle increases in size after it has been contracting and relaxing for period of time
What happens to muscles that have undergone muscle hypertrophy.
inside of the muscle fibers stays the same, myofibril increases in diameter and amount, more nuclei helps build protein. better coordination, and motor units are effective and fast in being recruited.
muscle atrophy
when you stop working out. in cast, cannot move. the state where a muscle decrease in size. the opposite effect as muscle hypertrophy. increase subcutaneous fats.
slow twitch muscle fibers
genetics dictation. contract slowly. smaller. good blood supply. tons of mitochondria. fatigue resistance. Prolonged activity. produces not much force. like holding our neck. postural muscles. atp break down slow atp. slow twich muscles are good at cycling activities
fast twitch muscle fibers
genetics dictation. respond to nervous stimulation. a little blood supply. fewer mitochondria. seconds of contractions. break down atp fast. single sustained explosive movement. like a jump.
can we train fast or slow twitch muscle fibers?
yes.
muscle fatigue
decrease in the ability for the muscle
