23.  The separate effects ofsympathetic and parasympathetic innervation of the pacemaker regionof the heart can best be described as _______.

a) synergistic    b)complementary   c)cooperative    d)antagonistic   e) none of these

24.  A decrease in bodytemperature is sensed by the ________ which communicates withthe       ________ of thebrainstem to __________ output to the sympathetic nervoussystem.

      a)cerebral cortex; pons;increase      b) hypothalamus;cardiac center; decrease

      c)thalamus; basal nuclei;increase      d) hypothalamus;vasomotor center; increase

      e)basal nuclei; pons;decrease

29. When Robin kicks a soccer ball,her leg makes contact with the ball by _______ of theknee.  This is an example of a/an __________ contractionof the quadriceps.

       a)  flexion;concentric         b)  flexion;eccentric      c)  extension;eccentric

       d) extension;concentric      e)  flexion;isometric     

31.  The relaxation phase ofa muscle twitch contraction coincides with

      a)calcium pumped back into the sarcoplasmic reticulum

      b)repolarization of the action potential   

      c)potassium voltage gates opening

      d)two of the above  

      e)all of the above

32.  Key differences betweenfast and slow muscle fibers include:

1. fast fibers always produces less force than slow fibers of thesame diameter
2. slow fibers have more mitochondria than fast
3. fast fibers generally fatigue more easily than slow
4. two of the above
5. all of the above

33.  Which of the followingcircumstances would cause a muscle fiber to produce lacticacid?

      a)activity which requires recruitment of oxidative (slow) motor unitsand fibers

      b)activity which requires recruitment of glycolytic (fast) motorunits and fibers

      c)both activities would yield the same amount of lactate

      d)neither activity would yield any lactate

34.  The smallest amount ofmuscle tissue that can be activated to produce force would be

      a)a single motor unit       

      b)a single muscle fiber

      c)all muscle fibers activated at the lowest frequency ofstimulation

      d)a whole muscle    

      e)none of the above

35. Which of these statements is correct regardingskeletal muscle contraction?

a)  all motor units are activated simultaneously.

b)  muscle contraction continues for long periodsafter nervous stimulation ceases.

c)  the crossbridges bind to the actin and shorten thesarcomeres.

d)  tropomyosin binds calcium so that troponin canexpose G actin binding sites.

e)  all of the above are correct