Exam #1 Flashcards
Name the function(s) of skeletal muscle
Locomotion
Body posture
Venous return
Thermogenesis
Involuntary or voluntary?
Smooth muscle
Involuntary
Involuntary or voluntary?
Cardiac muscle
Involuntary
Involuntary or voluntary?
Skeletal muscle
Voluntary
_________________ surrounds entire muscle.
Epimysium
________________ surrounds the fasciculi.
Perimysium
_____________ consists of muscle fibers.
Fasciculus
_________________ surrounds muscle fibers.
Endomysium
Muscle fiber consists of ______________ divided into ____________.
Myofibrils; sarcomeres
Name major components of skeletal muscle cell
Function: control center for the cell
Nucleus
Name major components of skeletal muscle cell
________________ is a polarized cell membrane.
Sarcolemma
Name major components of skeletal muscle cell
Function: receives stimuli from nervous system
Sarcolemma
Name major components of skeletal muscle cell
_________________ is the intracellular material.
Sarcoplasm
Name major components of skeletal muscle cell
Function: holds organelles & nutrients
Sarcoplasm
Sarcoplasm stores _________________ & _______________.
Glycogen ; myoglobin
Name major components of skeletal muscle cell
________________ are/is rod structures composed of myofilaments.
Myofibrils
Name major components of skeletal muscle cell
Function: responsible for muscle contraction
Myofibrils
Name major components of skeletal muscle cell
________________ are/is tubules running perpendicular to cell.
T tubules
Name major components of skeletal muscle cell
Function: carry action potential deep into muscle fiber
T tubules
Name major components of skeletal muscle cell
__________________ are interconnecting network of tubules running parallels.
Sarcoplasmic Reticulum (SR)
Name major components of skeletal muscle cell
Function: store and release calcium
Sarcoplasmic Reticulum (SR)
Name major components of skeletal muscle cell
________________ is a spherical-shaped organelle.
Mitochondria
Name major components of skeletal muscle cell
Function: major site of energy production
Mitochondria
___________________ are the basic contractile element of skeletal muscle.
Sarcomeres
Sarcomeres are aligned in series & _____________ to each other.
parallel
Sarcomeres
Dark stripes
A-bands
Sarcomeres
Light stripes
I-bands
Sarcomeres
Middle of the A band
H-zone
Sarcomeres
Middle of H-zone
M-line
Sarcomeres
Common boundary structure
Z-disk
Protein filaments in sarcomeres are used for ___________________.
muscle contraction
Actin are __________ filaments.
thin
Actin show up _______________ under microscope.
lighter
I-bands in the sarcomere contain only ___________ filaments.
actin
Myosin are _________ filaments.
thick
Myosin show up ______________ under microscope.
darker
A-band in the sarcomere contains both ___________ & _____________ filaments.
actin & myosin
H-zone in the sarcomere contains only ____________ filaments.
myosin
_______________ are two intertwined filaments with Globular heads.
Myosin
-Protrude 360 degrees from thick filament axis
-Will interact with actin filaments for contraction
Globular heads
-Contains z-line
-Protein structure between actin & myosin filaments
Titin
3 Proteins of Actin
Contains myosin-binding site
Actin
3 Proteins of Actin
Covers active site at rest
Tropomyosin
3 Proteins of Actin
Anchored to actin, moves tropomyosin
Troponin
-Along length of actin
-High affinity for calcium (binds easily with it)
Troponin
-Tube-like protein
-Wrapped around length of actin myofilament
Tropomysoin
During muscle contraction, what does tropomyosin do?
Closes off active sites
Membrane around an individual muscle is the _____________.
sarcolemma
Tendons transmit force from _____________ to ___________.
muscles ; bones
The _____________ is the cytoplasm that bathes muscle fibers.
sarcoplasm
Sarcoplasm contains large quantities of _______________ & ______________.
glycogen ; myoglobin
___________________ are the lateral network of tubes allow for rapid transmission of impulses to each muscle fiber.
T-tubules (transverse)
___________________________ is the long set of tubes, parallel to the myofibril, that house calcium ions.
Sarcoplasmic reticulum
Each muscle fiber is made up of many myofibrils, again made up of smaller contracting units called _______________.
sarcomeres
______________ are threadlike structures in muscle fibers running lengthwise in the cytoplasm & are the basic units of contraction.
Myofibrils
The sarcolemma lies ________________ the endomysium.
underneath
STUDY QUESTION
Skeletal Muscle Contraction (Excitation - Contraction Coupling)
1. Action potential (AP) starts in brain
2. AP arrives at axon terminal, releases acetylcholine (ACh)
3. ACh crosses synapse, binds to ACh receptors on plasmalemma.
4. AP travels down plasmalemma, T-tubules
5. Triggers Ca2+ release from sarcoplasmic reticulum (SR)
6. Ca2+ enables actin-myosin contraction
True or False?
Axon terminal does not touch fiber
True
Space between fiber & terminal that the signal is sent across
Synaptic cleft
Action potential from t-tubule to __________________ & it releases stored calcium.
endoplasmic reticulum (ER)
Where two body systems meet
Neuromuscular junction
Innervate muscle fibers to stimulate/activate
Alpha-motor neurons
A single alpha-motor neuron & all fibers it activates.
Motor neuron
True or False?
All fibers do activate all at the same time
False
Name reason(s) why some are stronger than others
- Recruit more fibers through strength training
- Situations can cause body to override
-Site of communication between neuron & muscle
-Consists of synapse between alpha-motor neuron & muscle fiber
Neuromuscular junction
People appear to have more muscle because they have more muscle fibers & more myofilaments allowing them to produce more ______________ & produce more ____________.
cross-bridge ; force
Between actin & myosin causing force
Cross-bridge attachments
Troponin binds w/ _________________ —–> Tropomyosin shifts away from ________________ —-> ____________ bonds to actin active sites
calcium ; active sites ; Myosin
STUDY CARD: SLIDING FILAMENT THEORY
Involves the following:
1. The force of contraction generated by the process that slides the actin filament over the myosin filament.
2. The lengths of the thick & thin filaments do not change.
3. Length of the sarcomere decreases as the actin filaments slides over the myosin filament & pulls the Z-disks towards center of the sarcomere
During muscle contraction, what happens to the following?
A-band
stays the same length
During muscle contraction, what happens to the following?
I-band
decrease in size
During muscle contraction, what happens to the following?
H-zone
gets smaller
During muscle contraction, what happens to the following?
Myosin
Stays the same
During muscle contraction, what happens to the following?
Actin
stays same
What happens to the H-zone and I-band?
Eventually disappear in stage 4
Pulls actin towards center of sarcomere
Power stroke
An enzyme that splits ATP & converts it to ADP
ATPase
How Muscles Create Movement
_______________ State
-No actin-myosin interaction at binding sites
-Myofilaments overlap a little
Relaxed
How Muscles Create Movement
_______________ State
-Myosin head pulls actin toward sarcomere center (power stroke)
-Filaments slide past each other
-Sarcomeres, myofibrils, muscle fiber all shorten
Contracted
Name Muscle Fiber Type
- ~50% of fibers in an average muscle
- Peak tension in 110 ms (slow twitch)
Type I
Name Muscle Fiber Type
-2 subtypes
-Peak tension in 50 ms (fast twitch)
Type II
In endurance athletes, type ______ muscle fibers predominate.
I
In power athletes, type ____ muscle fibers predominate.
II
Name Type II Muscle Fibers
-Poor aerobic endurance, fatigue quickly
-Produce ATP anaerobically
General type II
Name Type II Muscle Fibers
-More force, faster fatigue
-Short, high-intensity endurance events
Type IIa
Name Type II Muscle Fibers
-Seldom used for everyday activities
-Short, explosive splints
Type IIx
Aging in muscles causes the loss of_______ motor units.
type II
Name the contraction type
-Most force produced
Isometric
Name the contraction type
-Muscle length does not change
-Many cross-bridges produced
Isometric
Name the contraction type
Ex.) pushing on wall
Isometric
Name the contraction type
-Muscle shortens while producing force
-Most familiar type of contraction
-Sarcomere shortens, filaments slide toward center
Concentric
Name the contraction type
Positive (+) contraction
Concentric
Name the contraction type
Ex.) bicep curl with dumbbell
Concentric
Name the contraction type
-Muscle lengthens while producing force
-Cross-bridges form but sarcomere lengthens
Eccentric
Name the contraction type
-Training this way can create injuries
-Can create more soreness after workout
-Needs to be introduced slowly
Eccentric
Name the contraction type
Ex.) Lowering heavy weight
Eccentric
If you take a hike up a hill, walking or stepping up is a ________________ contraction.
Concentric
If you walk down a hill, stepping down or walking down is a _____________ contraction.
eccentric
Name energy reaction
-Any physical or chemical process that releases energy to its surroundings
-Represent “downhill” processes because of a decline in free energy
Exergonic
Name the energy reaction
-Chemical reactions that store or absorb energy
-Represent “uphill” processes & proceed with an increase in free energy
Endergonic
Type I muscle fibers have a ____________ twitch.
slow
Type IIa muscle fibers have a ____________ twitch.
fast
Type IIx muscle fibers have a ____________ twitch.
fast
Type _____ muscle fibers are slow oxidative
I
Type ____ muscle fibers are fast oxidative/glycolytic.
IIa
Type _______ muscle fibers are fast glycolytic.
IIx
Type IIx ATPase is ___________.
highest
Type IIa ATPase is ____________.
high
Type I ATPase is _________.
low
Slow muscle fibers have _________ neuron type.
Alpha^2
Fast muscle fibers have ______ neuron type
Alpha^1
Conduction velocity of slow muscle fibers is _________.
slow
Conduction velocity of fast muscle fibers is __________.
fast
A(n) _________________ is a small piece of muscle removed that is frozen, sliced, examined under microscope.
muscle biopsy
Regardless of fiber type, all muscle fibers reach peak power at _________ peak force.
~20%
