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56 Cards in this Set

  • Front
  • Back
Define the Sarcolemma?
Muscle Cell Membrane
Name the 3 Types of Muscles and there characteristics?
-fast acting?
Skeletal:Striated, Fast Acting, and Voluntary

Smooth: Smooth, Slow Acting, and Involuntary

Cardiac: Striated, Fast Acting, Involuntary
Thin Filaments originate where?
@ the Z-line
Thin Filament is called what?
Thick Filament is called what?
In a relaxed state what should I see?
Thick Filaments will not extend over the entire length of the sacromere

Thin filaments dont meet at the midline
What is the A band?
Entire length of the thick filaments
What is the H band?
No thin filaments?
What is the M band?
Protein Rich
-Myomensin and C Protein and others
T or F: Thin and Thick filaments shorten during muscle contraction
Which band(s) shorten during muscle contraction?
H and I bands
Which band(s_ stay constant during muscle contraction?
A band
What law does muscle contraction abide by?
All of None
Strength of contraction depends on what?
# of Muscle fibers involved in that contraction
Release of ___ at the NMJ occurs when an AP reaches the end of the ____._____ diffuses across gap
Ach; Axon; Ach
Ach binds to a ____ receptor at the muscle end plate. This ____ the muscle cell membrane at the _____ from ______mV resting potential.
Nicotinic;Depolarizes;Motor End Plate -90mV
When the membrane is sufficently depolarized, a action potential along the Sarcolemma propogates ______ from the end plate to the ____.
Bidirectionally; t-Tubule
T- Tubule depolarization makes the ____ of the triads release ____ into the____.
Sarcoplasmic Reticulum; Ca++; Cytoplasm
Ca++ will then bind to ____ complex via the ____. This removes ___ from the active site of Actin.
Troponin-Tropomyosin Complex; TnC subunit;Tropomyosin
Myosin ATPase is also activated by the Ca++ and ___ is Hydrolyzed.However, the ADP and Pi remain bound to the myosin head. Myosin and actin bind
Pi is released first to do what?
Stabilize the bond between actin and myosin
ADP is released next which causes what to occur?
Thin filaments to be pulled to the center: "Power Stroke"
ATP binds to Myosin and the bond between actin and myosin is ____.
Clinical Consideration: What happens to the muscles when the dont have ATP?
Without ATP the myosin-actin complex can't disengauge thus, the myosin-actin complex remains and the muscles remain contracted- this is called Rigor Mortis
After some time Ca++ is removed from the cytoplasm to the Terminal Cisternae by the _____. In turn, the _____ is re-estabished and myosin cant bind to actin
Sarcoplasmic Reticulum; Troponin-Tropomyosin complex
A single Action Potential results in a ____.
Muscle Twitch
What is a Muscle Twitch
Brief Contraction followed by Relaxation
When does the twitch occur?
2 ms after depolarization of the membrane, which is during repolarization
What is resting membrane potential?
What is threshold?
-90 mV

-70 mV
Clinical Consideration: The Ca++ re-uptake mechanism is called the _____.
Ryanodine Receptor
Clinical Consideration con't: In some patients the Ryanodine Receptor is blocked, thus Ca++ is not taken up and the muscles continue to contact or "over-contract" which will result in what?
HUGE amounts of heat- called Malignant Hyperthermia
The Ryanodine receptor can be blocked by what anesthetic?
What drug can be given to a patient that is undergoing Malignant Hyperthermia?
Define Isometric, Isotonic, and Dynamic Contraction.
Isometeric: Same Length, Different Force (Tension)

Isotonic: Muscle Shortens, Same Force (Tension)

Dynamic: Both Length and Force Change
T or F. The amount of tension that a muscle is able to have depends on its length and with every length there is a maximum tension

*Regarding Isometeric Muscles
T or F: Sacromeres generate additional force?
False: b/c forces on each side of a z-line cancel out each other.
T or F: The total force generated by many sacromeres in series is the same as that of one sacromere.
Displacement of sacromeres ___ with the more sacromeres present b/c each sacromere shortens by a given amount.
Elaborated on the relationship between the sacromere and recruitement.
Sacromeres of the same myofibril DO NOT add any force so, if more force is needed the body must recruit more myofibrils
What does this statement mean:

The tension provided by a muscle can increase by increasing the cross-sectional area of each fibril
Recruitment- Add more fibrilsin parallel
T or F: If a muscle contracts isotonically the speed at which the muscle contracts varies inversly with the load
True: Meaning the heavier an object is the slower the contracton (shortening of the muscle)

If too heavy the speed of contraction will be ZERO which is Isometeric b/c you will not be able to move the weight
Name the 2 types of skeletal muscle fibers
Fast Twitch (White
Slow Twitch (RED)
What characteristics does a fast twitch fiber possess?
-Large Diameter
-Arranged w/ Few muscle fibers per unit area
-Use Glycolysis (usually function under aerobic conditions)
-Adapted for Rapid contraction (thus Myosin ATPase activity is high and SR and T-tubules are extensive)
What type of movement does a fast-twitch fiber permit?
Fine, Careful Movements
EX: Extraocular muscles of the eye
Why are Fast-twitch fibers white?
B/c they dont have Red Myoglobin
What are the characteristics of a Red-Slow twitch muscle fiber?
-Small Diameter
-Less Sarcoplasmic Reticulum and T-tubules
-Smaller Motor End Plate
-Adapted for long, sustained contractions
-Oxidative Metabolism is used for energy
-Greater Blood Supply
What permits the long sustained muscle contractions in the Red Slow Twitch Muscle fibers?
Lots of Mitochondria
Define Motor Unit
Lots of muscle fibers innervated by 1 nerve axon (called the alpha neuron)
If the motor nerve is destroyed what will happen to the muscle fibers of that nerve.
T or F: If the neural firing changes, then the muscle changes in type. (Determined by moter nerve)
True: Firing of ANY axon can be slow or fast depending on the neural signal
Each muscle fiber has 1 ___ that is innervated by 1 ___.
End Plate
Motor Neuron
ALL or None Means
All Motor Neuron imputs are excitatory and reach threshold

They all generate AP necessary to initiate contraction
Skeletal Muscle Motor Neuron Cell bodies are located where
In the VENTRAL Horn of the spinal cord gray matter
What type of axon carries information from Ventral horn to motor end plate of muscle
Single Myelinated Axon
Where does the initial signal come from?
Cerebral Cortex, Cerebellum, Specific Brain Nuclei, and basal Ganglia via Reflexes
What are single twitches
Elastic Elements (tendons//connective tissue)within a muscle and between muscles that must be stretched before active tension can occur.

Thus when contraction is initiated the elastic elements are contracted first and then the active twitch can occur