SENSES

• What is the definition of a sense?

  Ability to perceive stimuli
• What is sensation?

  Conscious awareness of stimuli received by sensory neurons
• What are sensory receptors?


  Sensory nerve endings that respond to stimuli by developing action potentials
• What are the two main types of senses?

  • General senses
  • Special senses
• What are the characteristics of general senses?

  • Receptors over a large part of the body
  • Somatic provides information about the body and environment
  • Visceral provides information about internal organs, pain, and pressure
  • Includes touch, pressure, pain, temperature, and itch
• What are the special senses?

  • Smell
  • Taste
  • Sight
  • Hearing
  • Balance
• What do mechanoreceptors detect?

  Movement
• What do chemoreceptors detect?

  Chemicals
• What do photoreceptors detect?

  Light
• What do thermoreceptors detect?

  Temperature changes
• What do nociceptors detect?

  Pain
• What does Merkel’s disk detect?

  Light touch and pressure
• What do hair follicle receptors detect?

  Light touch
• Where are Meissner corpuscles located?

  Deep in the epidermis
• What do Ruffini corpuscles detect?


  Continuous pressure in the skin
• What do Pacinian corpuscles detect?

  Deep pressure, vibration, and position
• What is pain?

  An unpleasant perceptual and emotional experience
• What are the two types of pain?

  • Localized: sharp, pricking, cutting pain with rapid action potentials
  • Diffuse: burning, aching pain with slower action potentials
• What is local anesthesia?

  • Action potentials suppressed from pain receptors in local areas
  • Chemicals are injected near sensory nerve
• What is general anesthesia?

  • Loss of consciousness
  • Chemicals affect reticular formation
• What is referred pain?

  Pain that originates in a region that is not the source of the pain stimulus
• How is referred pain felt?

  When internal organs are damaged or inflamed, sensory neurons from superficial areas and neurons of the source pain converge onto the same ascending neurons of the spinal cord
• What is olfaction?

  The sense of smell
• How many different smells can humans detect?

  10,000 different smells
• How does olfaction work?

  1. Odors dissolve in a thin film of mucous in the nasal cavity.
  2. Olfactory neurons in mucous have enlarged dendrites with cilia.
  3. Dendrites pick up odor, depolarize, and carry it to axons in the olfactory bulb (cranial nerve I).
  4. Frontal and temporal lobes process the odor.
• Where are taste buds located?

  On papillae on the tongue, hard palate, and throat
• How many taste cells are inside each taste bud?

  40 taste cells
• What do taste hairs do?

  They extend into taste pores and contain receptors that initiate an action potential
• How does taste work?

  1. Taste buds pick up taste and send it to taste cells.
  2. Taste cells send taste to taste hairs.
  3. Taste hairs initiate an action potential carried to the parietal lobe.
  4. The brain processes taste.
• What are the types of tastes?

  • Sweet
  • Sour
  • Salty
  • Bitter
  • Umami
• How is taste linked to smell?

  Taste is linked to smell as certain taste buds are more sensitive to certain tastes and olfaction enhances flavor perception