A&P Special Senses

Otitis Media

• middle-ear infection) is common in children

  • Auditory tube is short and horizontal

  • Infections easily spread from throat to tympanic cavity and mastoid air cells

bony labrynth

• passageways in temporal bone

• Membranous labyrinth—fleshy tubes lining bony labyrinth

  • Filled with endolymph: similar to intracellular fluid

  • Floating in perilymph: similar to cerebrospinal fluid

Stereocilia

Hair of the ear, bathed in K+ fluid

Embedded in tectorial membrane

sensorineural deafness

death of hair cells or any nervous system elements concerned with hearing

vestibular apparatus

Consists of three semicircular ducts and two chambers

static equilibrium

the perception of the orientation of the head when the body is stationary

dynamic equilibrium

perception of motion or acceleration

macula

• a 2 by 3 mm patch of hair cells and supporting cells in the saccule and utricle

  Macula sacculi: lies vertically on wall of saccule

Macula utriculi: lies horizontally on floor of utricle

otoliths

calcium carbonate–protein granules that add to the weight and inertia and enhance the sense of gravity and motion

photopupillary reflex

• pupillary constriction in response to light

  • Mediated by autonomic reflex arc

emmetropia

State in which eye is relaxed and focused on an object more than 6 m (20 ft) away

Near response

1. convergence of eyes

2. restriction of pupils

3. Accomodation of lens

duplicity theory of vision

• explains why we have both rods and cones

  • A single type of receptor cannot produce both high sensitivity and high resolution

stereoscopic vision

depth perception —ability to judge distance to objects