What is the purpose of alpha-gamma coactivation?
A. Prevents simultaneous activation of fast twitch and slow twitch muscles.
B. Coordinates reciprocal reflex innervation.
C. Coordinates the actions of the basal ganglia and cerebellum.
D. Maintain muscle spindle sensitivity when extrafusal muscle fibers contract.
E. Prevents contraction of an antagonist muscle when the agonist is contracting.
ANS: D
Rationale: To maintain muscle spindle sensitivity when the extrafusal muscle fibers contract, when alpha motor neurons fire gamma motor neurons to the spindle in the same muscle also fire. The gamma signals cause the ends of the intrafusal muscle fibers to contract, maintaining the stretch of the central region of intrafusal fibers when the extrafusal muscle fibers actively contract.
You might also like to view...
A client visits a health-care unit with acute immune thrombocytopenic purpura. Which is a unique feature of acute immune thrombocytopenic purpura?
1. Occurs in children 2. Occurs in adults 3. Occurs in persons aged between 20 to 50 years 4. Occurs twice as often in men than in women
In December 2013, the United States spent approximately what percentage of its gross domestic product on health care?
A. 6 percent B. 18 percent C. 29 percent D. 42 percent
Which source of water makes up 95 percent of the world's supply of fresh water?
A. precipitation B. ocean water C. groundwater D. surface water
If a person's heart stops, it must be restarted within how many minutes to prevent death?
A) 2 B) 4 C) 5 D) 6