Nervous, Immune, Sensory, and Motor Mechanisms

• White matter is ____ ; gray matter is ____

  myelinated; unmyelinated
• Hormones


  Long-lasting chemicals released from glands
• Exoskeletons and endoskeletons differ in that

  Exoskeletons are external to the soft tissues, and endoskeletons are internal
• Worms use a hydrostatic skeleton to generate movement. How do they do this?


  The change in body structure is caused by contraction of muscles compressing the watery body fluid
• Which of the following statements best describes the sliding filament mechanism of muscle contraction?

  Actin and myosin filaments do not shorten, but rather, slide past each other
• Place the following events in the correct order

  1. Sarcoplasmic reticulum releases Ca2+.
  2. 2. Myosin binds to actin.
  3. Action potential arrives from neuron.
  4. Ca2+ binds to troponin.

  3, 1, 4, 2
• How do the muscles move your hand through space

  By contraction and by attaching 2 bones across a joint
• Desiccation


  A barrier against pathogens provided by the skin
• Cytokinin


  Hormone that helps plants respond to drought
• How may a plant respond to severe heat stress?

  By producing heat-shock proteins, which may protect the plant’s proteins from denaturing
• Thigmotropism


  Directional growth in response to touch
• Geotropism


  Growth or movement in the direction determines by the direction of earth’s gravity
• Phototropism


  Growth or movement in the direction determined by the direction of a light stimulus.
• Hydrotropism


  Growth or movement in the direction determines by the availability of water.