Muscles Flashcards
(22 cards)
The Muscle that provides the major force to producing a specific movement is a(n)
antagonist
A muscle that immobilizes a bone, or a muscle’s origin so that the prime mover has a stable base
fixator
You could conclude that a muscle with the term “rectus” included in its name is a muscle who’s fibers run
parallel
Muscle power is primarily dependent on
the number of cells in the muscle
Bones and muscle work together to move your body. In this case one bone is ____ and a second bone is the ___
level; load
Which class of levers has the load between the fulcrum and effort
Second class
Which class of levees is flexing the forearm with the biceps brachia
Third class
The muscles of the ___ are rather unusual for muscles because they insert onto the skin or other muscles
face
picture of chest muscles
pectoralis minor
picture of the back muscles
trapezius muscle
picture of the back muscles
latissimus dorsi
What muscle elevates and adducts the scapula?
Trapezius muscle
Chest muscle
Deltoid
Chest and neck muscles
sternocleidomastoid
Brian decided to enter a 5-mile race designed to raise money for a class trip. He did not do any preconditioning, nor has he ever jogged before. The morning after the race, Brian had so much pain in both his shins, he was unable to go to school. What caused this pain?
Brian was not conditioned for this type of run, and he now has shin splints. This is a condition in which the anterior tibialis muscle is irritated, and as the inflamed muscle swells, its circulation is impaired by the tight fascia! wrappings, causing pain and tenderness.
Describe the muscle condition called tetanus. Is this a normal or a pathological event? If it is normal, what is the function? If it is pathological, what is the cause? The bacterium Clostridium tetani causes a disease called tetanus or lockjaw; you may have been vaccinated against tetanus, especially if you ever had hospital treatment for a skin wound. Speculate on whether or not the name of this disease is related to the muscle condition and why the disease can be fatal.
Tetanus is a state of maintained contraction that occurs as a result of increased frequency of stimulation by the nerve that does not allow enough time between twitches for the muscle to relax. Tetanus is a normal event, which allows a muscle to develop its maximal force. The bacterial disease results in maintained contraction that is similar in charter to the tetanus that can result from high frequency muscle stimulation. The disease is fatal if respiratory muscles are unable to relax because then breathing would stop.
The graph below was generated by students in a physiology lab. The top trace (myogram) shows contraction force, the bottom (EMG) shows the electrical stimulus. On the graph, label a muscle twitch. What property of muscle is being tested here? What caused the increase in force (and subsequent decrease)?
The clearest single twitches are the first few and last few peaks on the myogram. The muscle is being stimulated at an increasing rate (frequency), as evidenced by the decreasing time between subsequent stimulus pulses. This caused fusion of the twitches (summation), producing partial then complete tetanus, as well as an increase in peak force produced. Though the stimulus is maintained, the peak force starts to fall as the muscle fatigues. The students then decreased the stimulus frequency, allowing recovery from fatigue.
Put these events in the correct chronological sequence:
1. End-plate potentials trigger action potentials.
2. Transverse tubules convey potentials into the interior of the cell.
3. Acetylcholine binds to receptors on the motor end plate.
4. Ca2+ is released from the sarcoplasmic reticulum.
3,1,2,4
List and explain the functions of the regulatory molecules in a sarcomere, specifying how the on and off positions are controlled and its impact on the crossbridges formed.
Troponin and tropomyosin and the primary regulatory proteins.
Tropomyosin wraps around the actin of the thin filament to restrict access of the myosin to its binding site on the actin molecule.
When intracellular calcium concentration is low such that troponin is not bound by calcium (resting muscle), the tropomyosin is in the off position and myosin is weakly bound to actin (low force crossbridge).
When muscle is stimulated, the increasing calcium binds to the troponin (C subunit) to shift the tropomyosin into the on position. In the on position, the crossbridges that are formed are high force.
Factors playing a role in fatigue can be classified into 2 categories. Define those two categories and provide an example of each
Central fatigue, peripheral fatigue. Central fatigue arises in the central nervous system. Peripheral fatigue arises anywhere between the neuromuscular junction and the contractile elements of the muscle. Examples of central fatigue: subjective feeling of tiredness and a desire to cease activity. Example of peripheral fatigue is depletion of muscle glycogen stores, increases in inorganic phosphate concentration, or ion imbalance.
Myasthenia gravis is a disease characterized by reduction in the number of acetylcholine receptors on skeletal muscles. Which physiological process would be affected? What would someone afflicted by this disease experience? How may this disease be treated?
Neuromuscular transmission would be affected, and therefore excitation-contraction coupling. Skeletal muscles would be less excitable, and muscle tone and strength would decrease. A treatment that could increase the amount of acetylcholine released or prolong its action, such as a treatment interfering with acetylcholine breakdown, would offer some improvement.
