Chapter 15: The Special Senses

olfactory neurons

15.1: Olfaction

• olfactory receptor cells

• found in the olfactory epithelium

• bipolar

olfactory epithelium

15.1: Olfaction

pseudostratified columnar epithelium tissue located in the nasal cavity that plays a crucial role in the sense of smell

airborne molecules

15.1: Olfaction

what enters the nasal cavity and gets dissolved in the fluid covering the olfactory epithelium?

papillae

15.2: Taste

projections on the surface of the tongue, often mistaken for taste buds

filiform papillae

15.2: Taste

• a major type of papillae that is filament-shaped

• has no taste buds

• most numerous papillae

• provide a rough surface on the tongue

vallate papillae

15.2: Taste

• a major type of papillae that means “surrounded by a wall”

• largest, but least numerous

• 8-12 of the form a V-shaped raw along the border between the anterior and posterior parts of the tongue

foliate

15.2: Taste

• a major type of papillae that is leaf-shaped

• distributed in folds on the sides of the tongue

• contain the most sensitive taste buds

• located posteriorly

fungiform

15.2: Taste

• a major type of papillae that is mushroom-shaped

• scattered irregularly over the superior surface of the tongue

• appear as small, red dots interspersed among the far more numerous filiform papillae

taste buds

15.2: Taste

• sensory structures that detect taste

• oval structures embedded in the epithelium of the tongue and mouth

• consist of basal cells, supporting cells, and taste cells

• each one has about 50 taste cells

tastants

15.2: Taste

• substances that, when dissolved in saliva, enter the taste pores and stimulate the taste cells

• There are five major classes: salt, sour, sweet, bitter, and umami

eyebrows

15.3: Visual System: Accessory Structures

• short hairs on the bony ridge above the eyes

• prevent perspiration from running down the forehead and into the eyes

• shades eyes from sunlight

eyelids

15.3: Visual System: Accessory Structures

• The movable fold of skin in front of the eyeball

• also called palpebrae

• protects the eyes from foreign objects

eyelashes

15.3: Visual System: Accessory Structures

• Hair at the margins of the eyelids

• ciliary glands are modified sweat glands that open into the follicles to keep these lubricated

  • a sty forms when one of these glands is inflamed

conjunctiva

15.3: Visual System: Accessory Structures

• a thin, transparent mucous membrane covering the anterior surface of the eyeball and lining the lids

• when this is inflamed, caused by an infection or irritation, it’s called pink eye

lacrimal apparatus

15.3: Visual System: Accessory Structures

consists of a “tear” gland in the superolateral corner of the orbit of the eye and a duct system that extends from the eye to the nasal cavity.

extrinsic eye muscles

15.3: Visual System: Accessory Structures

• muscles located outside the structure (eye) being moved

• the eye has six of these

  • four of these run more or less straight anteroposteriorly

  • two are positioned at an angle to the globe of the eye

distant vision

when the ciliary muscles are relaxed

fovea centralis

15.3: Visual System: Anatomy

the area of greatest visual acuity

anterior chamber

15.3: Visual System: Anatomy

• Chamber of the eye between the cornea and the iris (separator)

• filled with aqueous humor

posterior chamber

15.3: Visual System: Anatomy

• Chamber of the eye between the iris (separator) and the lens

• filled with aqueous humor

vitreous chamber

15.3: Visual System: Anatomy

• larger chamber of the eye

• completely surrounded by the retina

• filled with a transparent, jelly-like substance called [term part] humor that holds the lens and retina in place

fibrous tunic

15.3: Visual System: Anatomy

• outer layer of the eye

• consists of the sclera and the cornea

  • sclera: a tough white outer layer that protects the eye

  • cornea: the transparent, anterior part of the eye that allows light to enter (avascular)

• firm, opaque tissue layer

vascular tunic

15.3: Visual System: Anatomy

• middle layer of the eye

• consists of the choroid, ciliary body, and iris

  • choroid: A vascular layer that nourishes the retina and contains blood vessels. 

  • ciliary body: A ring-shaped structure that produces aqueous humor and contains the ciliary muscles that control lens shape

  • iris:The colored part of the eye that controls the amount of light entering the pupi

• contains many blood vessels

nervous tunic

15.3: Visual System: Anatomy

• the inner layer of the eye

• consists of the retina

  • retina: The light-sensitive tissue at the back of the eye where images are formed. 

retina

15.3: Visual System: Anatomy

• the nervous tunic of the eyeball

• consists of:

  • outer pigmented layer: composed of pigmented simple cuboidal epithelium

  • inner neural layer: responds to light with numerous photoreceptor cells (120 million rods and 6-7 million cones), and numerous relay neurons

• covers the inner surface of the eyeball posterior to the ciliary body

rods

15.3: Visual System: Anatomy

• photoreceptor in the retina of the eye

• responsible for noncolor vision in low-intensity light.

cones

15.3: Visual System: Anatomy

• photoreceptor in the retina of the eye

• responsible for color vision

process of vision

15.3: Visual System: Functions

1. as light passes through the pupil of the iris, it is focused on the retina by the cornea, lens, and humors

2. the light striking the retina is converted into action potentials

3. the optic nerve conveys these action potentials to the brain

external ear

15.4: Hearing and Balance

consists of the auricle and the external acoustic meatus

middle ear

15.4: Hearing and Balance

connects the external and inner ears

tympanic membrane

15.4: Hearing and Balance

the structure in the middle ear that is stretched across the external acoustic meatus

the auditory ossicles

15.4: Hearing and Balance

the three structures (malleus, incus, and stapes) that transmit vibrations from the tympanic membrane to the oval window

malleus

15.4: Hearing and Balance

• Largest of the three auditory ossicles

• attached to the tympanic membrane

• the hammer

incus

15.4: Hearing and Balance

• middle of the three ossicles in the middle ear.

• the anvil

stapes

15.4: Hearing and Balance

• Smallest of the three auditory ossicles

• attached to the oval window

• the stirrup

oval window

15.4: Hearing and Balance

• membranous structure to which the stapes attaches

• transmits vibrations to the inner ear

mastoid air cells

15.4: Hearing and Balance

Spaces within the mastoid process of the temporal bone that are connected to the middle ear by ducts.

auditory tube

15.4: Hearing and Balance

• the structure that connects the middle ear to the pharynx

• equalizes pressure between the middle ear and outside air

inner ear

15.4: Hearing and Balance

• a canal system within the temporal bone that contains perilymph and the membranous labyrinth

• a bony labyrinth

bony labyrinth

15.4: Hearing and Balance

• Part of the inner ear

• contains the membranous labyrinth that forms the cochlea, vestibule, and semicircular canals.

membranous labyrinth

15.4: Hearing and Balance

Membranous structure within the inner ear consisting of the cochlea, vestibule, and semicircular canals.

endolymph

15.4: Hearing and Balance

• the fluid found within the membranous labyrinth of the inner ear

• high concentration of K+ and a low concentration of Na+

perilymph

15.4: Hearing and Balance

• the fluid that fills the space between the membranous labyrinth and the bony labyrinth in the inner ear

• low concentration of K+ and a high concentration of Na+

vestibule

15.4: Hearing and Balance

• middle region of the inner ear containing the utricle and saccule

• involved in balance

semicircular canals

15.4: Hearing and Balance

• Canal in the petrous portion of the temporal bone that contains sensory organs that detect kinetic or dynamic equilibrium

• Three [term] are within each inner ear.

cochlea

15.4: Hearing and Balance

• a fluid-filled, spiral-shaped structure in the inner ear

• crucial for hearing, converting sound vibrations into electrical signals that the brain interprets as sound

• divided into three regions by the vestibular and basilar membranes

scala vestibuli

15.4: Hearing and Balance

• Division of the cochlea lying above the spiral lamina and vestibular membrane

• contains perilymph

scala tympani

15.4: Hearing and Balance

• Division of the spiral canal of the cochlea lying below the spiral lamina and basilar membrane.

• contains perilymph

round window

15.4: Hearing and Balance

Membranous structure separating the scala tympani of the inner ear from the middle ear

cochlear duct

15.4: Hearing and Balance

• Interior of the membranous labyrinth of the cochlea

• filled with endolymph

• contains the spiral organ

• also called cochlear canal or scala media

spiral organ

15.4: Hearing and Balance

• Organ of Corti

• rests on the basilar membrane and consists of the hair cells that detect sound.

• found within the cochlear duct

action potential

15.4: Hearing and Balance

Fill-the-blank

In the spiral organ (organ of Corti), sound vibrations cause basilar membrane movement, which in turn stimulates hair cells and their stereocilia. This mechanical stimulation leads to the opening of ion channels, resulting in an influx of ions and the generation of a(n) [term].

utricle and saccule

15.4: Hearing and Balance

• Part of the membranous labyrinth

• contains a sensory structure, the macula, that detects static equilibrium.