What is leukopenia? (Multiple Choice)

What is leukopenia?
 
  A) Low white blood cell counts B) Malformed white blood cells
  C) High white blood cell counts D) White blood cells attacking healthy cells

Question 2

_____ Action potential
 
  A. The portion of the neuron that receives information from the environment
  B. The portion of the neuron that conducts action potentials
  C. The tiny space between the neuron sending the signal and the cell receiving the signal
  D. Special chemicals used to send a signal across the synapse
  E. A wave of depolarization and repolarization that travels down an axon
  F. A lipid sheath that surrounds and insulates the axon
 
  Fill in the blank(s) with correct word

Question 3

This substance is released by the nervous system and excites muscle cells (resulting in muscle contraction).
 
  A) actin
   B) myosin
   C) ATP
   D) calcium
   E) acetylcholine