THE NERVOUS SYSTEM

• the nervous system is the control center that coordinates all activities
• the central nervous system (CNS) consists of the brain and spinal cord
• the peripheral nervous system (PNS) includes nerves, ganglia, and sensory receptors
• also known as the nerve cell

  neuron
• thin fibers where electromagnetic waves travel along

  axons
• junctions between neurons


  synapses
• use chemical stimuli for mating, marking territories, setting trails, and identifying young

  animals
• flower attract bees with their scent

  plants
• respond to physical deformation of the cell membrane from mechanical energy (touch, stretch, motion, sound)

  mechanoreceptors
• respond to specific molecules often dissolves in a specific medium (saliva/mucus/airborne molecules)

  chemoreceptors
• respond to radiant energy

  photoreceptors
• respond to "noxious" stimuli or essentially anything that causes tissue damage

  nociceptors
• respond to heat or cold

  thermoreceptors
• the growth and development in response to light

  photomophogenesis
• the ability to use light to track time

  photoperiodism
• directional response that allows plants to grow towards or away from light

  phototropism
• ensures that roots grow into the soil and that shoots grow toward sunlight

  gravitropism
• shoot apical tip is upward

  negative gravitropism
• roots downward


  positive gravitropism
• leaves open at _ to collect sunlight

  day
• leaves close at _ to prevent water loss

  night
• true or false

  • plants don't have immune systems

  true
• willow trees produce _ to kill bacteria

  salicylic acid
• to describe the structures involved in major animal senses to explain how some organisms can maintain steady internal conditions

  sensory motor and mechanisms
• conscious sensation


  perception
• a decrease in strength of a sensation due to prolonged stimulus which may lead to perceptions fading or disappearing even though stimulus persists

  adaptation
• touch, pressure, vibration is detected by

  encapulated nerve endings
• itch and tickle is detected by


  free nerve endings
• meissner corpuscles, hair root plexuses

  rapidly adapting touch receptors
• merrel disks (T1) and ruffini corpuscles (T2)


  slowly adapting touch receptors
• sustained sensation felt over a larger area than touch

  pressure
• type 1 mechanoreceptors and lamellated (Pacinian) corpuscles

  pressure receptors
• corpuscles of touch


  lower frequency vibrations
• lamellated


  higher frequency vibrations
• stimulation of free nerve endings by certain chemicals like bradykinin, often a result of local inflammatory response

  itch and tickle
• 10-40


  cold receptors/epidermis
• 32-48


  warm receptos/dermis
• less than 10 and greater than 48


  nociceptors/painful
• painful sensations


  nociceptros
• pain felt in skin above or located near but not in organ

  referred pain