Test Your Knowledge ofTerms and Facts

1. A graded whole muscle contraction is produced in vivo primarily by variations in a. the strength of the fiber's 5. contraction.

b. the number of fibers that are contracting.

c. both of these.

d. neither of these.

2. The series-elastic component of muscle contraction is responsible for a. increased muscle shortening to 6. successive twitches.

b. a time delay between contraction and shortening.

c. the lengthening of muscle after contraction has ceased.

3. Which of these muscles have motor units with the highest innervation ratio?

a. leg muscles b. arm muscles c. muscles that move the fingers d. muscles of the trunk

4. The stimulation of gamma 8. motoneurons produces a. isotonic contraction of intrafusal fibers.

b. isometric contraction of intrafusal fibers.

c. either isotonic or isometric contraction of intrafusal fibers.

d. contraction of extrafusal fibers. In a single reflex arc involved in the knee-jerk reflex, how many synapses are activated within the spinal cord?

a. thousands b. hundreds c. dozens d. two e. one

Spastic paralysis may occur when there is damage to a. the lower motor neurons.

b. the upper motor neurons.

c. either the lower or the upper motor neurons.

When a skeletal muscle shortens during contraction, which of these statements is false?

a. The A bands shorten.

b. The H bands shorten.

c. The I bands shorten.

d. The sarcomeres shorten. Electrical excitation of a muscle fiber most directly causes a. movement of tropomyosin.

b. attachment of the cross bridges to action.

c. release of Ca2+ from the sarcoplasmic reticulum.

d. splitting of ATP.

9. The energy for muscle contraction is most directly obtained from a. phosphocreatine.

c. anaerobic respiration.

d. aerobic respiration.

10. Which of these statements about cross bridges is false?

a. They are composed of myosin.

b. They bind to ATP after they detach from actin.

c. They contain an ATPase.

d. They split ATP before they attach to actin.

11. When a muscle is stimulated to contract, Ca2+ binds to a. myosin.

b. tropomyosin.

d. troponin.

12. Which of these statements about muscle fatigue is false?

a. It may result when ATP is no longer available for the cross-bridge cycle.

b. It may be caused by a loss of muscle cell Ca2+.

c. It may be caused by the accumulation of extracellular K+.

d. It may be a result of lactic acid production.

13. Which of these types of muscle cells are not capable of spontaneous depolarization?

a. single-unit smooth muscle b. multiunit smooth muscle c. cardiac muscle d. skeletal muscle e. both b and d f. both a and c

14. Which of these muscle types is striated and contains gap junctions?

a. single-unit smooth muscle b. multiunit smooth muscle c. cardiac muscle d. skeletal muscle

15. In an isotonic muscle contraction, a. the length of the muscle remains constant.

b. the muscle tension remains constant.

c. both muscle length and tension are changed.

d. movement of bones does not occur.

Was this article helpful?

0 0
Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

Get My Free Ebook


Responses

  • Neave
    Which of these types of muscle cells are not capable of spontaneous depolarization?
    8 years ago
  • Tonya
    Which type of muscle is not capable of spontaneous depolarization?
    8 years ago
  • berardo
    Do crossbridges bind to atp after they detach from actin?
    8 years ago
  • layla
    Do cross bridges split atp before they attach to actin?
    8 years ago
  • Joseph
    Which of these statements about cross bridges is false?
    8 years ago
  • Abaalom Isaias
    How many synapses are crossed in a single reflex arc?
    8 years ago
  • Tewelde Yemane
    Which of the following muscle types has the slowest contraction time?
    8 years ago
  • juana arnold
    Which type of muscle cell is not capable of spontaneous depolarization?
    8 years ago
  • brandon
    Which muscles are not capable of spontaneous depolarization?
    8 years ago
  • Tiia
    Which types of muscles are not capable of spontaneous depolarization?
    7 years ago
  • Islay
    Which muscle cells arenot capable of spontaneous depolarization?
    7 years ago
  • lance loomis
    When a skeletal muscle shortens during contraction, which of these statements is false?
    4 months ago

Post a comment