Myasthenia gravis is a disease that is believed to be caused by autoimmune disorder, resulting in the loss of ACh receptors at the motor end plate of muscle fibers. Which of the following is likely to be a symptom of myasthenia gravis?
A) dehydration with headache
B) weakness of muscle
C) seizures and uncontrollable muscle movement
D) coma and loss of voluntary muscle movement
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Question 2) Curare is a poisonous plant extract. Curare molecules have a chemical structure like the neurotransmitter ACh. Curare can bind to the ACh receptor site on the chemically gated ion channels in the motor end plate.
Even though curare will bind to the receptor site it will not open the ion channel and no ions will pass through. What do you think the symptoms of curare poisoning would look like?
A) Curare will only affect muscles with ACh receptors, paralyzing them.
B) Smooth muscles will become stimulated causing quick movement of nutrients through the digestive system.
C) Curare will only affect cardiac muscle, causing fibrillations of the heart.
D) Muscles will respond too quickly and cause a severe tremor.
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Question 3) What is the primary function of wave summation?
A) increase muscle tension
B) prevent muscle relaxation
C) prevent muscle fatigue
D) produce smooth, continuous muscle contraction
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Question 4) Creatine phosphate functions in the muscle cell by ________.
A) forming a temporary chemical compound with myosin
B) forming a chemical compound with actin
C) storing energy that will be transferred to ADP to resynthesize ATP
D) inducing a conformational change in the myofilaments
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Question 5) A myosin molecule in the thick filaments can be considered a protein having a quaternary structural level. Which of the following best describes this structural level?
A) Myosin molecules consist of two heavy and to light polypeptide chains.
B) Myosin has an ATP binding site, actin binding site and flexible hinge region.
C) Myosin is a primary component within a myofibril.
D) Myosin is involved in the power stroke of muscle contraction.
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Question 6) Approximately 80 of a muscle fiber's volume are the myofibrils. This characteristic reflects muscles ability to ________.
A) store oxygen molecules that can be used in aerobic respiration
B) produce relatively high amounts of ATP
C) produce movement through contractile force
D) generate and propagate action potential
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Question 7) Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period called the ________ period during which the neurotransmitter is released by exocytosis, diffuses across the synaptic cleft, and binds to its receptors
.
A) relaxation
B) refractory
C) latent
D) contraction
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Question 8) What does excess postexercise oxygen consumption represent?
A) the difference between the amount of oxygen needed for totally aerobic muscle activity and the amount actually used
B) the amount of oxygen equal to the oxygen already used
C) the amount of oxygen taken into the body immediately after the exertion
D) amount of oxygen needed for aerobic activity to accomplish the same amount of work
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Question 9) During development embryonic cells will fuse to form muscle fibers. This will result in ________.
A) the coordination of nerve signals to muscle fibers
B) the striations that appear in skeletal and cardiac muscle tissues
C) multinucleated muscle fibers that can extend as long as 30 centimeters
D) interlocking of cells that can prevent the filaments from sliding
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Question 10) What structure in skeletal muscle cells functions in calcium storage?
A) intermediate filament network
B) sarcoplasmic reticulum
C) mitochondria
D) myofibrillar network
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