Special senses

• Location of the cells that allow for special senses:

  • Touch - corpuscles are located throughout the body
  • Sight - retina of the eye
  • Hearing - organ of corti of the inner ear
  • Equilibrium - vestibular apparatus of the inner ear
  • Smell - olfactory epithelium of the nasal cavity
  • Taste - taste buds of the tongue, soft palate, cheek, pharynx, and epiglottis
• There are multiple types of touch receptors called corpuscles that respond to different stimuli; the receptors are located in the skin; all receptors are mechanoreceptor
• Types of corpuscles:

  • Meissner/encapsulated tactile corpuscles respond to touch
  • Pacinian/lamellated corpuscle respond to pressure
  • Ruffini endings respond to pressure
  • Krause endings respond to touch
  • free nerve endings respond to temperature and pain
  • hair follicle receptors respond to movement
• Corpuscles of the human body:

  A) encapsulated tactile corpuscle (Meissner) - touch

  B) Krause endings - touch

  C) lamellated corpuslce (Pacinian) - pressure

  D) hair follicle receptors - movement

  E) ruffini endings - pressure

  F) free nerve endings - temperature, pain

  
• Encapsulated tactile corpuslcles (Meissner) slide:

  A) epidermis

  B) dermal papillae

  C) Meissner (tactile corpuscle)

  
• Encapsulated tactile corpuscles (Meissner) slide:

  
• Lamellated corpuscle (Pacini)

  A) Pacini

  
• Accessory structures of the eye include: eyebrows, eyelids, conjunctivae, lacrimal apparatus, and extrinsic eye muscles
• Eye model:

  A) Tarsal plate

  B) Palpebral conjunctiva

  C) Tarsal glands

  D) Cornea

  E) Palpebral fissure

  F) Bulbar conjuctiva

  G) Conjunctival sac

  H) Lacrimal sac

  I) Medial commisure

  J) Lacrimal caruncle

  K) Lacrimal gland

  L) Excretory ducts of lacrimal glands

  M) Lateral commisure

  N) Lacrimal punctum

  O) Lacrimal canaliculus

  P) Nasolacrimal duct

  
• The internal anatomy of the eye consists of three layers:

  • fibrous layer: sclera, and cornea
  • vascular layer (urea): choroid, ciliary body (ciliary process and ciliary muscle), iris, and pupil
  • inner layer (retina): extends anteriorly to the ora serrata; photoreceptors, bipolar and ganglion neurson; optic disk/blind spot, optic nerve, and fovea centralis
• The lens divides the eye into two segments:

  • anterior segment (contains aqueous humor): subdivided into the anterior and posterior chambers, located in front of and behind the iris
  • posterior segment (contains vitreous humor)
• Eye anatomy:

  A) ora serrata

  B) ciliary body

  C) cornea

  D) iris

  E) pupil

  F) posterior segment

  G) Optic disc/blind spot

  H) optic nerve

  I) fovea centralis

  J) macula lutea

  K) retina

  L) sclera

  M) choroid

  
• Retina model:

  A) axons of ganglion cells

  B) ganglion cells

  C) bipolar cells

  D) rod

  E) cone

  F) amacrine cells

  G) horizontal cells

  H) nuclei of galnglion cells

  I) axons of ganglion cells

  J) nuclei of bipolar cells

  K) outer segments of rods and cones

  L) choroid

  M) nuclei of rods and cones

  N) pigmented layer of retina

  O) pigmented layer of retina

  
• The choroid provides nutrients to the retina
• Layers of the eye:

  A) retina

  B) cones and rods

  C) pigmented epithelium

  D) choroid

  E) sclera

  
• The sclera supports the eyeball
• The ear is divided into three main areas:

  • external ear - pinna, external acoustic meatus, and tympanic membrane
  • middle ear - three ossicles (malleus, incus, stapes), pharyngotympanic tube and (link between ear and nasopharynx)
  • internal ear - cochlea (organ of Corti), semi-circular canals (with cristae ampullares), vestibule (utricle and saccule with their maculae), and windows (oval and round)
• The internal ear is the only part of the ear that functions in equilibrium
• Ear model:

  A) external ear

  B) auricle (pinna)

  C) helix

  D) lobule

  E) external acoustic meatus

  F) middle ear

  G) tympanic membrane

  H) intenal ear (labyrinth)

  I) pharyngotympanic (auditory) tube

  J) malleus (hammer)

  K) incus (anvil)

  L) stapes (stirrup)

  M) auditory ossicles

  
• The receptors for olfaction and taste are classified as chemoreceptors because they respond to chemicals in solution
• Olfactor epithelium is a ciliated pseudostratified epithelium that is the organ of smell; located in the areas lining the roof of the nasal cavity
• The cells of the olfactory epithelium are:

  • basal (olfactory stem cells)
  • supporting cells
  • olfactory (bipolar neuron; olfactory sensory neuron cells)
• Olfactory epithelium model :

  A) olfactory epithelium

  B) olfactory tract

  C) olfactory bulb

  D) cribiform plate of ethmoid

  E) olfactory stem cell (basal)

  F) olfactory sensory neuron

  G) supporting cell

  
• Olfactory epithelium:

  A) olfactory cell (olfactory sensory neuron)

  B) support cell

  C) olfactory stem cell (basal)

  D) olfactory epithelium

  
• Taste buds contain specific receptors for the sense of taste
• Most taste buds are located in papillae (peglike projections of the mucosa) on the dorsal surface of the tongue
• There are four types of papillae: filiform, circumvallate, fungiform, foliate (rudimentary in adults)
• Taste bud model:

  A) folliate papillae

  B) fungiform papillae

  C) basal epithelial cells

  D) gustatory epithelial cells

  E) gustatory hair

  F) stratified squamous epithelium of the tongue

  G) circumvallate papilla

  
• Taste buds:

  A) papillae

  B) taste bud

  C) stratified squamous epithelium

  D) microvilli

  E) taste pore

  F) taste cell (gustatory cell)

  G) basal cell

  H) supporting cell