(NOT FINISHED) Chapter 15: The Special Senses

olfactory neurons

15.1: Olfaction

• olfactory receptor cells

• found in the olfactory epithelium

• bipolar

airborne molecules

15.1: Olfaction

what enters the nasal cavity and are 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

• 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

anterior chamber

15.3: Visual System: Anatomy

• Chamber of the eye between the cornea and the iris

• filled with aqueous humor

posterior chamber

15.3: Visual System: Anatomy

• Chamber of the eye between the iris 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

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

• 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