Sensory

• Sensory organ


  Specialised organ that allows for the reception of a stimulus, the formation of an impulse and its transmission to the brain for interpretation
• Senses


  Means of detecting and interpreting stimuli of your external environment
• Main sense organs


  • Eyes
  • Ears
  • Olfactory organs in your nose
  • Taste buds on your tongue
  • Skin
• Sensory system


  Group of subsystems used for detecting and understanding the world around you
• Receptors


  Specialized neurons designed to obtain a particular type of information that is then sent to a particular part of the brain
• Types of receptors


  • Chemoreceptors
  • Mechanoreceptors
  • Electromagnetic Receptors
  • Thermoreceptors
  • Pain Receptors
• Tactility (touch)


  Considered a general sense, as opposed to the special senses discussed in this section. Group of sensory modalities that are associated with touch, proprioception, and interoception.
• Tactility modalities


  • Pressure
  • Vibration
  • Light touch
  • Tickle
  • Itch
  • Temperature
  • Pain
  • Proprioception
  • Kinesthesia
• Skin receptors - Free nerve endings


  Nocireceptors: Temperature, mechanical (pain, itching, tickle, stretching)

  Merkel Discs: Light pressure, mechanical (discriminative touch)

  Root Hair lexus: Hair movement, mechanical
• Skin receptors - Encapsulated Nerve Endings


  Meissner's Corpuscle: Light pressure mechanical, located in hairless areas, palms or hands and soles of feet (discriminative touch, vibrations)

  Ruffini's Corpuscle: Mechanical, thermal (rough and persistent touch)

  Krauses Corpuscle: Mechanical, thermal (touch, low frequency vibrations)

  Pacinian corpuscle: Deep pressure, mechanical (deep pressure, stretch, and high frequency vibrations)
• Muscle receptors - Encapsulated Nerve Endings


  Muscle Spindles: Stretch, mechanical, sense of muscle length, all skeletal muscle

  Golgi Tendon Receptors: Stretch mechanical, muscle tension
• Auditory (Hearing)


  The ear is divided into three major regions: external, middle, and inner
• Outer ear


  • Pinna - ear flap

  Auditory canal - channels waves to the ear drum; houses ceruminous glands

  Tympanic membrane - ear drum
• Middle ear


  • Eustachian tube - connects the ear to the throat and equalizes pressure

  Ossicles: Hammer (malleus), Anvil (incus), Stirrup (stapes)
• Inner ear


  • Vestibule

  Cochlea

  Organ of Corti

  Semicircular Canals

  Auditory Nerve

  Perilymph

  Endolymph
• Vision


  The special sense of sight that is based on the transduction of light stimuli received through the eyes. It converts light energy into electrical nerve impulses which are then interpreted by the brain as sight.
• Eye structures


  • Sclera

  Lens

  Lacrimal Gland

  Pupil

  Iris

  Choroid Coat

  Aqueous Humor

  Vitreous Humor

  Ciliary Body

  Suspensory Ligaments

  Retina

  Macula

  Optic Nerve

  Optic Disk

  Fovea Centralis

  Extrafovial Region
• Eye disorders


  Myopia (nearsighted)

  Hyperopia (farsighted)

  Cataracts

  Strabismus (cross-eyes)
• Gustation (taste)


  The special sense associated with the tongue. The receptors for taste, called taste buds, are situated chiefly in the tongue, but they are also located in the roof of the mouth and near the pharynx.
• Taste modalities


  • Salty

  Sweet

  Bitter

  Sour

  Umami
• Tongue structures


  • Taste buds

  Papillae
• Gustatory nerves


  Connected by the cranial nerves to the medulla oblongata, relay the message to the thalamus, to the gustatory center of the brain where the stimulus is interpreted.
• Olfactory (smell)


  The sense of smell, or olfaction, is responsive to chemical stimuli. The olfactory receptor neurons are located in a small region within the superior nasal cavity called the olfactory epithelium.
• Auditory (Hearing)


  The transduction of sound waves into a neural signal made possible by the structures of the ear. The ear is a dual organ, responsible for both the sense of hearing and the function of balance.