Muscles Chapter Flashcards
circumduction is
ball and socket
circumduction is found in how many places
2
What motion can your axis and occipital condyles do
gliding
Muscles fibers/cells look like
twizzlers(licorice)
Strings of twizzlers, single one
muscle fiber or muscle cell
bundle muscle fibers/cells are covered by and called
covered by perimysium, bundle called fascicle
my, myo, myology, sarco means
muscle
A bunch of fascicles are wrapped up in the
epimysium
epimysium with many bundles of fascicles are
muscles
what is the extension of the muscle stuck to the bone
tendon
thin skin that covers whole muscle
epimysium
smallest functional unit of muscle
sarcomere
location differences between skeletal, smooth and cardiac muscle.
skeleton,
hallow organs/gi tract/blood vessels,
heart.
skeletal muscle apperance
striations
multinucliated
cardiac muscle appearance
striations, intercalated discs (vertical lines)
smooth muscle appearance
no striations
Involuntary muscles
smooth and cardiac
voluntary muscles
skeletal
functions of muscle tissue
motion, posture, stabilization, thermogenesis
Motion and muscle tissue
external (walking, running, talking and looking) and internal (heartbeat, blood pressure, digestion, elimination) body part movements
Thermogenesis and muscle tissue (creation of heat)
generating heat by normal contractions and by shivering
Muscles are always in a state of
partial contraction
Posture and muscle tissue
slight muscle contraction maintains body posture
Stabilization and musc
stabilize joints- muscles have tone even at rest
When contracting muscles you are always doing what as well
relaxing the opposing force
every single muscle in our body has an…
agonist and antagonist
an antagonist is there
to stabilize the agonist
movement is one of our and how does it have to do with muscle
necessary life functions…
Functional characteristics
Excitability Contractility Extensibility Elasticity Conductivity
Excitability/irritability
the ability to receive and respond to a stimulus (chemical signal molecules)
Contractility
ability of muscle tissue to shorten
Ability to work in muscle.
Excitability or irritability
Extensibility
the ability to be stretched without damage
most muscles are arranged in functionally opposing pairs – as one contracts, the other relaxes, which permits the relaxing muscle to be stretched back
Elasticity
the ability to return to its original shape
Conductivity (impulse transmission)
the ability to conduct excitation over length of muscle
Thin Filaments (Myofibrils – Sarcomeres -Myofilaments)
actin (plus some tropomyosin & troponin)
Thick Filaments (Myofibrils – Sarcomeres -Myofilaments)
Myosin
Elastic filaments (Myofibrils – Sarcomeres -Myofilaments)
titin (connectin) attaches myosin to the Z discs (very high mol. wt.)
Elasticity is only described with what muscles?
Smooth (blood vessels)
The ability of a muscle to return back to its shape
elasticity
Do you measure elasticity
yes
Conductivity relates to
the nervous system and its ability to conduct excitation
miogram
measures the conductivity of a muscle
ability to spread message across muscle fiber
conductivity
sarcomeres are made up of
a lot of protein components
Sarcomeres in visual are
overlapping of actin and myosin overlapping the z lines of a muscle fiber contraction
Tropomyosin is the what in the story
chasity belt
troponin is the what in the story
lock
Key to get into the lock
Calcium and Atp
The functional unit of striated muscle contraction
Sarcomere
The foundation of the muscle cell’s contractile organelle, myofibril
Sarcomere
The myofilaments between two adjacent Z discs
The regular geometric arrangement of the actin and myosin produces the visible banding pattern (striations)
Sarcomere
Rod-like tail with two heads
Tails point to the M line
Myosin
Each head contains ATPase and an actin-binding site; point to the Z line
Myosin
Splitting ATP releases energy which causes the head to “ratchet” and pull on actin fibers
Myosin
Each thick filament contains many myosin units woven together
Myosin
Two G actin strands are arranged into helical strands
Actin
Each G actin has a binding site for myosin
Actin
Two tropomyosin filaments spiral around the actin strands
Actin
Troponin regulatory proteins (“switch molecules”) may bind to actin and tropomyosin & have Ca2+ binding sites
Actin
what has actin binding sites
myosin
what has myosin binding site
actin
Triads
2 terminal cisternae + 1 T tubule
Sarcoplasmic reticulum (SER):
modified smooth ER, stores Ca2+ ions
Terminal cisternae
large flattened sacs of the SER
Transverse (T) tubules
: inward folding of the sarcolemma
where motor neurons communicate with the muscle fibers
The Neuromuscular Junction:
composed of an axon terminal, a synapse and a motor end plate
The Neuromuscular Junction:
the end of the motor neuron’s branches (axon)
axon terminal
the specialized region of the muscle cell plasma membrane adjacent to the axon terminal
motor end plate
Synapse:
point of communication is a small gap
Synaptic cleft
the space between axon terminal & motor end plate
Synaptic vesicles
membrane-enclosed sacs in the axon terminals containing the neurotransmitter
Neurotransmitter:
: the chemical signal molecule that diffuses across the synapse, i.e., acetylcholine, ACh)
Acetylcholine (ACh) receptors:
integral membrane proteins which bind ACh
Binding of the neurotransmitter (ACh) … in excitation
Binding of the neurotransmitter (ACh) causes the ligand-gated Na+ channels to open
Opening of the Na+ channels…. in excitation
Opening of the Na+ channels depolarizes the sarcolemma (cell membrane)
Initial depolarization causes
adjacent voltage-gated Na+ channels to open; Na+ ions flow in, beginning an action potential
Action potential
a large transient depolarization of the membrane potential
transmitted over the entire sarcolemma (and down the T tubules)
Repolarization
the return to polarization due to the closing voltage-gated Na+ channels and the opening of voltage gated K+ channels
when you hear troponin you think
calcium
Where does atp bind to
myosin
Refractory period
the time during membrane repolarization when the muscle fiber cannot respond to a new stimulus (a few milliseconds)
All-or-none response
once an action potential is initiated it results in a complete contraction of the muscle cell
Structure covering all of the muscular fibers
SER
Sarcoplasmic reticulum
What is the job of the SER sarcoplasmic reticulum
to be a storage center for calcium
Where does the calcium come from that is stored in SER
Diet
Parathyroid Horomone breaks down bone for calcium
What happens the minute we have an chemical or electrical signal sent to our sarcomere
we open up these gates that are attached to the SER called T (Transverse) Tubules
SR opens up the T tubules and sends calcium to
troponin for muscle contraction
Crossbridge
myosin/actin getting together
The actual binding of the myosin and actin sites is called
powerstroke
What two things do you need to have myosin and actin to couple
atp and calcium
Whats telling the sarcoplasmic reticulum to release that calcium
the nervous system
Acetylcholine
Is a specific neuromuscular joint that sends a signal to muscle to release calcium
When you see acetylcholine
Muscle contraction
Sarcolema
Membrane of the muscle that is in “contact” with axons of the neuromuscular contractions
The way that any cell in our body conducts impulses
is to change the ionic composition
The way to change the ionic composition and conduct impulses
3Na 2K pump
All acetylcholine doing on the muscle is
opening sodium channels
When we open sodium channels we…
are going against the concentration gradient and sending more 3 sodium out and bringing 2 potassium in
Depolarization
Send sodium out bringing potassium in
Sodium channels open causing
the disruption of whats at rest and that continues to send that impulse or spark all the way down that muscle fiber so it can activate the SER to open and release calcium through the T tubules, attaching to troponin, moving tropomyosin . Then myosin and actin can combine.
At rest inside the cell there is more
potassium
If the cell isnt at rest then we create an action potential that
goes all the way down to those t tubles
What is the neurotransmitter called that sends the message from the nuerons to the muscles?
acetylcholine
acetylcholine has do do with
sending nervous systems mesaage to the muscle side
Where does the neurotransmitter acetylcholine go?
across the synaptic cleft to its receptor on the muscle cell membrane (sarcolemma)
What happens as soon as acetylcholine reaches that recpetor
Opens sodium channels causing to open sodium channels on the muscle side and creates a spark
9 volt batteries are like our
cells
At rest our cells are at
-70 milivolts
Why are our cells at -70 milivolts at rest
because of the concentration of potassium ions on the inside of that cell
we have ionic distribution that is what in our cells at all times
uneven
At rest on the inside of the cell it is what charge
negative
circle K means
at rest K is more in the middle causing it to be negative
acetylcholine causes what?
that switch in K being predominant in a cell to Na being predominant
When we open up sodium channels with acetylcholine what happens
causes sodium to flow rapidly into the cell making the charge from positive to neg
Flipping of the charge in a cell from K- to Na+ is called what
action potential or spark.
Depolarization
The opening of sodium channels,, whole wave going through.
Repolarization
Going back to rest by opening up K channels,sending more K in. Causing the concentration to equalize
Impulse in a cell happens around the
entire membrane
All or none response
Charge goes all the way or not at all
if only a few sodium channels open what happens
you’re not going to produce a strong enough impulse for calcium to diffuse into the cell to attach to troponin so no muscle contraction happens.
The action potential (excitation) travels over
the sarcolemma, including T-tubules
Voltage sensors on the T-tubules cause corresponding SR receptors to
open gated channels and release Ca2+ ions
Excitability is measuring
responded to the nervous system
Excitation and coupling both require?
ATP and Ca+
Thin and thick filaments slide past each other to
shorten each sarcomere and, thus, each myofibril and shorten the muscle
The “on-off switch”: allows myosin
to bind to actin
An action potential causes
the release of Ca2+ ions (from the cisternae of the SR)
Ca2+ combines with troponin, causing a change in
the position of tropomyosin, allowing actin to bind to myosin and be pulled (“slide”)
Ca2+ pumps on the SR remove calcium ions from the sarcoplasm when
the stimulus ends
Cross bridge attachment
Myosin heads bind to actin
The working stroke.
myosin changes shape (pulls actins toward M line); releases ADP + Pi
Cross bridge detachment.
Myosin heads bind to a new ATP; releases actin
“Cocking” of the myosin head
ATP is hydrolyzed (split) to ADP + Pi; this provides potential energy for the next stroke
The “ratchet action” repeats the process
shortening all the sarcomeres and the myofibrils, until Ca2+ ions are removed from the sarcoplasm or the ATP supply is exhausted
The action potential (excitation) travels over
the sarcolemma, including T-tubules
Voltage sensors on the T-tubules cause corresponding SR receptors
to open gated channels and release Ca2+ ions
Ca2+ binds to troponin, causing tropomyosin
to move out of its blocking position
Myosin forms cross bridges to actin, the
power stroke occurs, filaments slide, muscle shortens
Calsequestrin and calmodulin help
regulate Ca2+ levels inside muscle cells
Acetylcholinesterase: an
enzyme that rapidly breaks down acetylcholine is located in the neuromuscular junction
Prevents continuous excitation (generation of more action potentials)
Acetylcholinesterase:
Many drugs and diseases interfere with events in the
neuromuscular junction
Myasthenia gravis
loss of function at ACh receptors (autoimmune disease?)
Curare (poison arrow toxin)
binds irreversibly to and blocks the ACh receptors
One power stroke shortens a muscle about
1%
Normal muscle contraction shortens a muscle by about
35%
cross bridge (ratchet effect) cycle repeats
continue repeating power strokes, continue pulling
increasing overlap of fibers; Z lines come together
How many myosin molecules are attached at any time
about half the myosin molecules
Cross bridges are maintained until Ca2+ levels
decrease
Ca2+ is released in response to the
the action potential delivered by the motor neuron
Ca2+ ATPase pumps Ca2+ ions back into the
SR, using more ATP
RIGOR MORTIS
Ca2+ ions leak from SR causing binding of actin and myosin and some contraction of the muscles
Rigor Mortis lasts
Lasts ~24 hours, then enzymatic tissue disintegration eliminates it in another 12 hoursq
The Motor Unit
Motor Neuron + Muscle Fibers to which it connects (Synapses)
The size of Motor Units varies:
Small and large
Small motor unit
two muscle fibers/unit (larynx, eyes)
large motor unit
hundreds to thousands/unit (biceps, gastrocnemius, lower back muscles)
The individual muscle cells/fibers of each motor unit are spread throughout
the muscle for smooth efficient operation of the muscle as a whole
Myogram:
a recording of muscle contraction
Stimulus:
nerve impulse or electrical charge
Twitch:
: a single contraction of all the muscle fibers in a motor unit (one nerve signal)
- latent period:
delay between stimulus and response
Myogram stages
- latent period
- contraction phase
- relaxation phase
- refractory period
- contraction phase:
tension or shortening occurs
- relaxation phase:
relaxation or lengthening
refractory period
time interval after excitation when muscle will not respond to a new stimulus
All or None Rule:
all the muscle fibers of a motor unit contract all the way when stimulated
Contraction force can be altered in 3 ways:
- changing the frequency of stimulation (temporal summation)
- changing the stimulus strength (recruitment)
- changing the muscle’s length
Twitch does not provide much
force
Force of muscle contraction varies depending on
How much tension is needed
sliding filament happens at what level
sarcomere
bare zone or m line is for what
to allow for the overlapping of the sarcomere
sliding filament theory
m line allowing for overlapping and bringing of the z lines together
calcium is the on and off site of the
troponin
Power stoke needs what to happen
atp
Cocking is also called
the ratchet movement
ratchet effect
binding to actin dropping down until we get that overlap together
The only way acetylcholine can be broken down is with
acetylcholineesterase
acetylcholineesterase does what
take acetylcholine off that receptor thus stoping contractions
When would you want to use acetylcholineesterase
muscle relaxer block the receptors of acetylcholine
Can you just isolate one muscle when you take a muscle relaxor
acetylcholine
myasthenia gravis
autoimmune. loss of function of the acetylcholine receptors. Person has muscle weakness.
muscles never push they only
pull
muscles are always named based
based on the distal end of the point (the insertion) coming to the origin
Contraction is talking about the insertion point of that muscle
coming closer to the origin
Rigor mortis explain how
within 24 hrs the binding of calcium on to troponin moving tropomyosin causing actin and mysoin to be stuck together our body stays in state of contraction
Rigor mortis doesn’t stop until
atp is diffused
The entire bicep contracting as one unit is
multiple motor units
These motor unit nerves…
branch out to make sure it covers all the muscle fibers throughout any muscle
The size of the motor unit depends on
how strong that contraction needs to be
Temporal (wave) summation
contractions repeated before complete relaxation, leads to progressively stronger contractions
unfused (incomplete) tetanus
frequency of stimulation allows only incomplete relaxation
fused (complete) tetanus
frequency of stimulation allows no relaxation
Treppe: the staircase effect
“warming up” of a muscle fiber
Multiple Motor Unit Recruitment (Summation)
The stimulation of more motor units leads to a more forceful muscle contraction
The Size Principle
As greater force is required, the nervous system will stimulate more motor units, and motor units with larger fibers and larger numbers of fibers to achieve the desired strength of contraction.
Stretch: Length-Tension Relationship
Stretch (sarcomere length) determines the number of cross bridges
extensive overlap of actin with myosin is what tension
less tension
optimal overlap of actin with myosin is what tension
most tension
Twitch
single contraction of ALL the muscle fibers in one motor unit aka bicep curl
Biceps curl is what
one single contraction or twitch
Refractory period
you wont be able to repsond to signals saying to conract
When you see contraction what is happening
sliding filament shortening and pulling towards each other
Depending on the motor unit size affects the
time of the muscle twitch
reduced overlap of actin with myosin is what tension
less tension
charlie horse or spazam is what kind of summation
unfused incomplete tetanus
Summation or production of contractions without allowing it to completely relax will always
intensify that contraction. causing it to become more forceful of a contraction
Summation
multiple motor unit recruitment
In summation… The more motor units we involve
the more forceful movement or stronger the contraction
3 motor units recruited
large fibers
Optimal overlap
most cross bridges available for the power stroke and least structural interference
Can sarcomeres be different lengths?
yes
Optimal length - Lo has what number of cross bridges
maximum number
normal working muscle range in optimal length
70 - 130%
Isometric Contraction
Muscle does not shorten
Tension increases
Isotonic Contraction:
tension does not change
Muscle (length) shortens
Types of skeletal muscle contractions
isomeric and isotonic contractions
Muscle Tone
Regular small contractions caused by spinal reflexes
what helps maintain posture
muscle tone
where is muscle tone found in the body
e.g., neck, back and leg muscles
Muscle tone responds to
Respond to tendon stretch receptor sensory input
Muscle tone activates
Activate different motor units over time
Muscle tone provides
Provide constant tension development
How are the muscles in muscle tone
muscles are firm
but do not shorten
Three ways to replenish ATP:
- Creatine Phosphate energy storage system
- Anaerobic Glycolysis – Lactic Acid system
- Aerobic Respiration
Muscle metabolism energy availability
Not much ATP is available at any given moment
ATP is needed for cross bridges and Ca++ removal
Maintaining ATP levels is vital for continued activity
Direct Phosphorylation – Creatine Phosphate System or CrP is stored in
cell
Direct Phosphorylation – Creatine Phosphate System Allows for?
atp replenishment
How much Direct Phosphorylation – Creatine Phosphate System is avaliable
Only a small amount available (10-30 seconds worth)
is O2 required in an anaerobic system
no
How efficient is Anaerobic Glycolysis – Lactic Acid System
Very inefficient, does not create much ATP
how long is Anaerobic Glycolysis – Lactic Acid System useful
useful in short term situations (30 sec - 1 min)
what does Anaerobic Glycolysis – Lactic Acid System produces as a by product
lactic acid
Aerobic System uses…
Uses oxygen for ATP production
The Oxygen in the aerobic system comes from the
RBCs in the blood and the myoglobin storage depot
What substrates does aerobic system use
carbohydrates, lipids, proteins
What is aerobic system good for
Good for long term exercise
Aerobic system may provide what percentage of ATP needed during these periods
May provide 90-100% of the needed ATP during these periods
Oxygen Debt
The amount of oxygen needed to restore muscle tissue (and the body) to the pre-exercise state
what must be restored after any vigorous exercise
Muscle O2, ATP, creatine phosphate, and glycogen levels, and a normal pH
Circulating lactic acid is converted/recycled back to
glucose by the liver
Factors Affecting theForce of Contraction
- Number of muscle fibers contracting (recruitment)
- Size of the muscle
- Frequency of stimulation
- Degree of muscle stretch when the contraction begins
- Series elastic elements
Series Elastic Elements
All of the noncontractile structures of a muscle:
internal load and external load
All of the noncontractile structures of a muscle:
Connective tissue coverings and tendons
Elastic elements of sarcomeres
Internal load:
force generated by myofibrils on the series elastic elements
External load:
force generated by series elastic elements on load
Muscle Fiber Type: Speed of Contraction
Slow oxidative fibers
Fast oxidative fibers
Fast glycolytic fibers
Slow oxidative fibers
contract slowly, have slow acting myosin ATPases, and are fatigue resistant (red)
Fast oxidative fibers
contract quickly, have fast myosin ATPases, and have moderate resistance to fatigue
Fast glycolytic fibers
contract quickly, have fast myosin ATPases, and are easily fatigued (white)
I-band
- actin filaments,
A-band -
myosin filaments which may overlap with actin filaments,
H-band -
zone of myosin filaments only (no overlap with actin filaments) within the A-band,
Z-line -
zone of apposition of actin filaments belonging to two neighbouring sarcomeres (mediated by a protein called alpha-actinin),
M-line -
band of connections between myosin filaments
Parallel muscles
Long strap like muscles with parallel fascicles.
Convergent muscles
Fascicles that radiate out from a small to wider point of attachment like a blade in a fan.
Pennate muscles
Feather like in appearance. Uniquely different types of fascicle attachments that in some ways resemble a old plume pen
Fusiform muscles
Fascicles that may be close to parallel in the centre or ‘belly’ of the muscle but converge to a tendon at one or both ends
Spiral muscles
Such as the latissimus dorsi, have fibres that twist between their points of attachment
Circular muscles
Often circle body tubes or openings such as the mouth and anus
Prime mover
Used to describe a muscle that directly performs a specific movement.
Agonist
Same as the prime mover. Directly performs a specific movement
Synergists
Are muscles that contract at the same time as the prime movers. They complement prime mover actions so that the prime moves produces a more effective movement
Antagonists
Are muscles that when contracting, directly oppose prime movers. They are relaxed while the prime mover is contracting
First class lever
Fulcrum lies between the effort and the load
Second class lever
Load is in the middle
Third class lever
The effort is in the middle
What can affect tension
how many fibers are there (myosin and actin crossing over) and size of muscle
Fewest cross bridges
more lag space and streched out… less tension
When sarcomere is stretched out
less tension reduces overlap
More overlapping causes
less tension not optimal for contraction. Cant bring them any closer togther
The length of muscle fiber
determines the tension in the muscle
Tone or tonicity
muscles being in a slight state of contraction
Creatine Phosphate energy storage system
where atp comes from in the muscles
Fatigue
no energy loss of atp
when we run out of oxygen in order for me to contract we take an alternate pathway we
break down sugar to get ATP anarobic glycolysis
byproduct of anarobic glycolysis
lactic acid
myglobin is
specifically where the oxygen is stored in the muscle
glycolisis is
the breakdown of glycogen
distrophin
develops sarcolemma
Duchenne Muscular Dystrophy:
Inherited lack of functional gene for formation of a protein, dystrophin, that helps maintain the integrity of the sarcolemma
Onset in early childhood, victims rarely live to adulthood
DO…
CHP
8 MOTIONS KNEE SHOUDLDER JOINTS
9 ACTIONS AND GROUPS
10 CHART UNDER LAB
Muscle tissue develops from
Cembryonic mesoderm called myoblasts (except the muscles of the iris of the eye and the arrector pili muscles in the skin)
Multinucleated skeletal muscles form by
fusion of myoblasts
With age, connective tissue _____ and muscle fibers_____
increase
decrease
When older muscles become
Muscles become stringier and more sinewy
By age 80, how much muscle mass is lost (sarcopenia)
50%
What reverses scrapopenia
regular exercise
Body strength per unit muscle mass, however, is the
same in both sexes
Atherosclerosis may
block distal arteries, leading to intermittent claudication and causing severe pain in leg muscles
Men’s skeletal muscle makes up
42% of body mass
Women’s skeletal muscle makes up
36% of their body mass
Muscular development reflects
neuromuscular coordination
Athletics and training can improve
neuromuscular control
Satellite (stem) cells can
fuse to form new skeletal muscle fibers
Smooth muscle has good
regenerative ability
Cardiac cells lack
satellite cells
Cardiac and smooth muscle myoblasts do not
not fuse but develop gap junctions at an early embryonic stage
Multinucleated skeletal muscles form by
fusion of myoblasts
The growth factor agrin stimulates the clustering of ACh
receptors at newly forming motor end plates
