Question | Answer |
The response of a muscle to a single threshold stimulus. | Simple muscle twitch. |
Name the 3 phases of the single muscle twitch. | 1. latent
2. contraction
3. relaxation |
What causes the myosin heads to be released from the actin active sites? | The addition of ATP |
What causes the myosin heads to "recock" back to their high-energy position? | The hydrolysis of ATP (Adenosine Triphosphate) splits to become ADP (Adenosine Diphosphate)+ P + energy. |
Ach is contained in the ___________. | Synaptic vesicles. |
Action potential moving down the axon causes the ______________ to open. | Calcium Ion (Ca++) channels |
What causes the synaptic vessicles to move to the bottom of the axon terminus? | The influx of Ca++ in the axon |
The space between the axon terminus and the motor end plate is the ____________. | Synaptic cleft |
A nerve cell whic stimulates or innervates a muscle. | Motor neuron |
What stops the action potential along the sarcolemma? | An enzyme at the motor end plate called acetylcholinesterate (AchE)hydrolyzes the Ach, stopping the action potential down the sarolemma and t-tubules. This means that the SR doesn't release Ca++ into the sarcoplasm. |
What would happen if AchE was inhibited? | The muscles could not relax - they would be in a constant state of contraction. |
What would happen if an Ach receptor was blocked? | The muscle would not contract. ex) Botox |
The light part of muscle striations | I-band |
The dark part of muscle striations | A-band |
rod-shaped organelle responsible for contraction that is composed of sarcomeres joined end-to-ed | Myofibril |
A bundle of muscle fibers is called a _________ and is wrapped in a connective tissue called __________. | Fascicle/Perimysium |
The ___________, _____________, and ___________ combine at the end of a skeletal muscle to form tendon. | epimysium / perimysium / endomysium (connective tissues) |
Name the 3 main functions of skeletal muscles: | 1) Movement 2) Generate heat 3) Stabilize joints |
What causes the appearance of striations in muscles? | The presence of alternating A-bands and I-bands. |
What is the equation for the hydrolysis of ATP? | ATP + H20 --> ADP + P + energy |
The period between the introduction of stimulus and the beginning of the contraction phase: | Latent period |
A motor neuron and all the muscle fiber it innervates (stimulates): | Motor Unit |
The smooth, but steady increase in muscular tension produced by increasing the number of active motor units: | Recruitment |
Small motor units produce __________ contractions, with __________ movements. | weaker / fine, more precise |
Large motor units produce __________ contractions, with ___________ movements. | stronger / gross, less precise motor |
The resting tension in a skeletal muscle - Random, asynchronous motor unit contractions providing a nearly constant state of low-level tension and resistance to stretch: | Muscle Tone |
A function of muscle tone: | stabilizing the positions of bones and joints. |
What produces tension? | Sarcomere shortening and muscle fiber stimulation. |
Describe what is happening during the Latent Period: | Action potential development, Ca++ released into the sarcoplasm, cross-bridges begin to cycle. |
Describe what is happening during the Period of Contraction: | Sarcomeres shorten (speed of contraction depends on weight being lifted and muscle type) |
Describe what is happening during the Period of Relaxation: | Ca++ transported back to sarcoplasmic reticulum, cross-bridge cycle decreases and ends, tension is reduced and muscle returns to original length. |
Name the 3 factores which affect muscle tension: | 1) Frequency of stimulation 2) Number of motor units recruited 3) Degree of muscle stretch |
When a 2nd stimulus arrives before the relaxation phase has ended, a second, more powerful contraction occurs. This is called the ______________. | Temporal (wave) summation |
The gradual increase in muscular contraction following rapidly repeated simulation. | Treppe (German for staircase) |
A muscle producing almost peak tension during rapid cycles of contraction and relaxation. During this phase, there is still some degree of relaxtation present. | Incomplete (unfused) tetanus |
Higher stimulation frequency completely eliminates the relaxation phase. Reason: the SR does not have time to reclain the Ca++ in the sarcoplasm. The abundance of Ca++ keeps the cross-bridge cycle going. (flat line on graph) | Complete (fused) tetanus |
Condition that results from build-up of lactic acid, lack of ATP, and ionic imbalances due to action potential generation. (slope downward on graph) | Muscle fatigue |
How do you correct muscle fatigue? | Rest and adequate blood supply. |
A stimulus that does not evoke a visible response. The number of motor units responding is not sufficient to cause a visible response. | Subthreshold stimulus |
The minimum stimulus that can evoke a response | Threshold stimulus |
A stronger response than threshold because additional motoe units join in to increase in tension. | Recruitment |
When all motor units are being recruited and more intense stimulus does not evoke a greater response. | Maximal stimulus |
The Length-Tension Relationship states that the strength of a muscle __________ can be altered by changing the starting _________ of a muscle. | contraction / length |
Unstretched muscle has overlapping ___________, and produces a relatively _________ contraction. | thin filaments (or actin) / weak |
What degree of stretch provides the best conditions for good contraction? | Moderately stretched muscle. FYI: the filaments are aligned such that all the crossbridges can participate in contraction. |
Thin filaments pulled almost to the ends of thick filaments, so little tention can be developed. Results in straining, tearing, or pulling a muscle. | Over stretched muscle |
Glycolysis takes place exclusively within the ________. | cytoplasm |
Glycolysis does not require __________. | oxygen |
How many molecules of ATP does glycolysis produce? | 2 |
Glycolysis produces __ pyruvate molecules. After glycolysis, each pyruvate molecule enters the __________ single file. | 2 / mitochondria |
The ______ _______ turns once per pyruvate molecule. Therefore, 1 glucose molecule = 2 ______ _______ turns. | Kreb's cycle / Kreb's cycle |
2 Kreb's cycle turns produces __ ATP molecules | 2 |
What is the Kreb's cycle's most important function? | Hydrogen harvesting |
________is the final acceptors in the electron transport chain. | Oxygen |
The majority of ATP produced by aerobic respiration is produced here: | Electron transport chain (32-34 ATP, when starting with 1 glucose molecule) |
Name 3 products of the Kreb's cycle: | Carbon dioxide (CO2), Hydrogen, and 2 ATP molecules. |
The Hydrogen molecules produced by the Kreb's cycle are each made up of 1 _______ and 1 _________. | proton / electron |
At each step down the ETC, the ________ loses _______. | electron / energy |
If O2 is present, muscles prefer to burn ________ for energy. | fatty acids |
Name the products of fermenation (anaerobic respiration) | 2 ATP per 1 glucose molecule; lactic acid, which is released into the blood |
What is the equation for direct phosphorylation? | 1 molecule of Creatine Phosphate + ADP --> 1 molecule of ATP + creatine |
Duration of energy provision for aerobic respiration: | Hours |
Duration of energy provision for anaerobic respiration (fermentation): | 30-60 seconds |
Duration of energy provision for direct phosphorylation? | 15 seconds |
Aerobic respiration produces _________ water. | metabolic |
Creatine phosphate is stored in the _______ ______. | muscle cells |
Do have a high or low myoglobin content? | high |
The primary pathway for ATP production in red slow twitch fibers is: | Aerobic respiration |
The primary pathway for ATP production in white fast twitch muscle fiber is: | Anaerobic (fermentation) glycolysis. |
Do have high or low glycogen stores? | Low (their primary fuel is fat - remember: if O2 is present after glycolysis, muscles preferable fuel for ATP production is FATTY ACID) |
Do white fast twitch fibers have high or low glycogen stores? | High. (their primary fuel for ATP production is glucose!!) |
Are red slow twitch fibers fatigable or fatigue-resistant? | Fatigue resistant. (which makes sense, since they primarily use aerobic respiration, which has an energy provision of "hours") |
Are white fast twitch fibers fatigable or fatigue-resistant? | fatigable (since they use fermentation, which has a very short enrgy provision of 30-60 seconds) |
Which type of muscle fiber has many mitochondria? | red slow twitch (which makes sense, since its primary method of energy production is aerobic.....which occurs in the mitochondria) |
Which type of muscle fiber has few capillaries? | white fast twitch (doesn't need as much oxygen, since uses fermentation!) |
Best type of muscle fiber for endurance activities like running a marathon: | red slow twitch |
Best type of muscle fiber for intense, short, powerful movements (like hitting a baseball)? | white fast twitch |
A red pigment found in muscles, which stores oxygen: | myoglobin |
Muscles that are attached to bones: | Skeletal muscle |
Make up the walls of hollow organs: | Smooth muscle |
Make up the heart: | Cardiac muscle |
This type of muscle is striated and multinucleated: | Skeletal muscle |
Which muscle types are striated? | Skeletal muscle and Cardiac muscle |
Which muscle types are nonstriated? | just one: Smooth muscle |
Which muscle types are uninucleated? | Smooth muscle and Cardiac muscle (cardiac muscle is TYPICALLY uninucleated) |
Which muscle type contains intercalated discs? | Cardiac muscle. Typically, only one nucleus is found between two intercalated discs. |
Which muscle types are involuntary? | Smooth muscle and Cardiac muscle |
Does skeletal muscle have large or small cells? | Large |
Does smooth muscle have large or small cells? | Small |
Does cardiac muscle have large or small cells? | Large |
The slow-contracting muscle type: | Smooth muscle |
The fast-contracting muscle type: | Skeletal muscle |
Cardiac muscle's speed of contraction is: | Moderate |
__________ muscles cannot divide. | Skeletal |
Cardiac muscles have a _________ capacity for division. | limited |
Smooth muscles have a _________ capacity for division. | limited |
__________ muscle has a larger capacity for regeneration than the other 2 muscle types. | Smooth muscle |
Which muscle types contain sarcomeres? | Skeletal muscle and Cardiac muscle (which makes sense, since they are the two that are striated) |