Homework assignment #3 (20 points): Turn in this assignment in class, Monday, 11/19/00.
Name:
1. Which is not found in the A band?
- a. H zone
- b. Z-Line
- c. myosin
- d. actin
- e. tropomyosin
2. Which is not present in the H zone?
- a. myosin
- b. actin
- c. actin & tropomyosin
- d. actin, tropomyosin, and troponins
- e. All are present in the H zone.
3. Which event is responsible for sarcomere shortening?
- a. Depolarization-induced Ca++ release
- b. tropomyosin movement
- c. ATP hydrolysis
- d. myosin head swivel
- e. myosin head binding to actin
4. Which event by itself is responsible for tension development?
- a. Depolarization-induced Ca++ release
- b. tropomyosin movement
- c. ATP hydrolysis
- d. myosin head swivel
- e. myosin head binding to actin
5. Increased muscle size as a consequence of exercise is caused in part by:
- a. skeletal muscle hyperplasia (increased cell numbers)
- b. myofiber hypertrophy (increased size)
- c. both hyperplasia and hypertrophy
- d. decreased blood flow to vessels
- e. increased muscle cell ATP production
6. In the body smooth, sustained muscle responses are produced by:
- a. synchronous motor unit discharge, each motor unit firing in pattern of incomplete tetanus
- b. asynchronous motor unit discharge, each motor unit firing in pattern of incomplete tetanus
- c. synchronous motor unit discharge, each motor unit firing in pattern of complete tetanus
- d. asynchronous motor unit discharge, each motor unit firing in pattern of complete tetanus
- e. None of the above
7. Which response is possible in a muscle but not a myofiber?
- a. tetanus
- b. wave summation
- c. treppe
- d. motor unit summation
- e. all of the above are possible in a myofiber.
8. In the myoneural junction:
- a. there is no synaptic cleft
- b. ACh receptors are located on the presynaptic terminal
- c. epinephrine is stored in presynaptic vesicles.
- d. motor end plate potentials are graded.
- e. acetylcholinesterase is stored in presynaptic vesicles
9. Which of the following occurs during the latent period of an isometric contraction?
- a. cross bridge swivel
- b. action potential propagation
- c. filament movement
- d. sarcomere shortening
- e. calcium rentry into terminal cisternae.
10. Which molecule inhibits interactions of actin with myosin?
- a. tropomyosin
- b. troponin C
- c. troponin I
- d. troponin T
- e. both troponin T and tropomyosin
11. Which of the events in muscle contraction produces the actual shortening of the sarcomere?
- a. L-tubule Ca+2 release
- b. T-tubule Ca+2 release
- c. myoneural ACh release
- d. L-tubule re-binding
- e. myosin head swivel
12. Which molecule(s) form(s) the thick filament?
- a. actin
- b. myosin
- c. tropomyosin
- d. troponin C
- e. choices a, c, and d
13. All of the following events are steps of the sliding filament theory of muscle contraction; which of them occurs LAST?
- a. a muscle action potential is generated at the neuromuscular synapse.
- b. myosin forms crossbridges with actin.
- c. acetylcholine is released at the motor end plate.
- d. myosin heads ratchet, pulling actin filaments in toward the sarcomere center.
- e. Ca++ ions are released from storage.
14. Which of these is/are NOT required for muscle contraction?
- a. calcium ions Ca++
- b. ATP
- c. oxygen
- d. depolarization of the sarcolemma
- e. B and C are true
15. Crossbridge detachment results from
- a. Ca++ uptake by the sarcoplasmic reticulum
- b. Myosin head swivel - the power stroke
- c. Depolarization of the sarcolemma
- d. ATP binding to myosin head
- e. Ca++ binding to troponin C
Match the following skeletal muscle terms with the appropriate phrase below:
A. tropomyosin
B. troponin
C. sarcoplasmic reticulum
D. myosin
E. actin
F. sarcolemma
G. T-tubules
H. mitochondria
________ Skeletal muscle cell membrane.
________ Principal protein of thin filaments; two twisted strands of globular monomers.
________ Calcium binding protein of thin filaments.
________ Storage site for Ca++ ions in a muscle cell.
________ Organelle that produces ATP to power contractions.