Anatomy and Physiology Ch 17 - The Special Senses

What two factors determine the focal distance?

1. distance of the object from the lens. 2. shape of the lens

What wavelengths are human eyes able to see?

700-400 nm, ROYGBIV-the spectrum of visible light

lacrimal sac (eye)

a small sac that the lacrimal canaliculi lead to

scotoma (eye)

abnormal blind spot that may appear in the field of vision at positions other than at the optic disc.

cones (eye)

allow for color vision.

glaucoma

an eye disease that occurs when too much intraocular pressure pushes the optic nerve outward, damaging its nerve fibers.

lysozyme (eye)

antibacterial enzyme within the secretions of the tears.

olfactory cortex

area of the cerebral cortex responsible for processing olfactory information

lacrimal lake (eye)

area where tears accumulate at the medial canthus

What 3 types of cones do we have?

blue, green, and red cones

corneal limbus (eye)

border between the sclera and cornea

optic disc (blind spot)

circular region medial of the fovea that is the origin of the optic nerve

nyctalopia (night blindness)

condition at night when the dim light proves insufficient to activate rods

retina (inner layer) (eye)

consists of a thin, outer layer - pigmented part, and a thick, inner layer - neural part. pigmented part - absorbs light, prevents light from bouncing back. neural part - does preliminary processing and integration of visual info.

lamina propria

consists of areolar tissue, blood vessels, nerves, and olfactory glands.

posterior cavity (vitreous chamber) (eye)

contains a gelatinous substance called the vitreous body, fluid is vitreous humor. helps to stabilize the shape of the eye.

fungiform papilla

contains about 5 taste buds each.

iris (eye)

contains blood vessels, pigment cells, and 2 layers of smooth muscle fibers - papillary muscles to change the size of the pupil.

palpebrae (eyelids)

continuation of the skin that keeps the surface of the eye lubricated and protected.

ocular conjunctiva (bulbar conjunctiva) (eye)

covers the anterior surface of the eye.

palpebral conjunctiva (eye)

covers the inner surface of the eyelids

cataract or senile cataract (eye)

crystallins that are no longer clear create a cloudy appearance in the visual area. senile come with the aging process.

chalazion

cyst that results from an infection in the tarsal gland.

hearing

detecting and interpreting sound waves

retinopathy

disease of the retina

odorants

dissolved chemical compounds that bind to a G protein-coupled olfactory receptor.

focal distance (eye)

distance between the center of the lens and its focal point

gustatory receptors

distributed over the tongue, pharynx, and larynx that bind to chemicals that produce tastes.

rods (eye)

do not distinguish colors, sensitive to light and allows us to see in dim light.

nasolacrimal duct (eye)

duct that passes through the nasolacrimal canal to drain over produced tears causing a runny nose.

olfactory epithelium

epithelial cells that contain olfactory receptors, supporting cells, and regenerative basal (stem) cells. covers the inferior surface of the cribriform plate, superior portion of the perpendicular plate, and superior nasal conchae of the ethmoid bone.

conjunctiva (eye)

epithelium covering the inner surfaces of the eyelids and the outer surface of the eyeball

anterior chamber (eye)

eye chamber between the cornea and iris

posterior chamber (eye)

eye chamber between the iris and lens

astigmatism (eye)

eye condition where the degree of curvature in the cornea or lens varies from one axis to another

What are the accessory structures of the eyes?

eyelids; superficial epithelium; structures involved with production, secretion, and removal of tears.

intraocular pressure

fluid pressure that stabilizes the position of the retina, pressing the neural part against the pigments part.

aqueous humor

fluid that circulates within the anterior cavity of the eye

lens (eye)

focuses the visual image on the photoreceptors

foliate papilla

folds found on the lateral margins of the posterior tongue.

palpebral fissure

gap that separates the free margins of the upper and lower eyelids.

vitreous body (eye)

gelatinous mass that contains the fluid, vitreous humor. stabilizes that shape of the eye.

olfactory receptor

highly modified neurons with an exposed tip that forms a prominent knob that projects beyond the epithelial surface of the nasal passage.

lens fibers (eye)

highly specialized cells have lost their nuclei and other organelles.

visual acuity

how well someone see and is rated by comparison to a "normal" standard. 20/20 is defined as the level of detail seen at a distance of 20 ft by a person with normal vision.

conjunctivitis (pinkeye)

inflammation of the conjunctiva

anterior cavity (eye)

interior eye cavity consisting of two chambers, anterior and posterior chambers, filled with a clear, watery "aqueous humor".

organization of the retina - inside to outside

light - ganglion cells - amacrine cells - bipolar cells - horizontal cell - rods and cones - pigment

lacrimal caruncle (eye)

mass of soft tissue that contains glands producing thick secretions.

detached retina

neural part of the eye becomes separated from the pigmented part.

lingual papillae

nipple-shaped mound, 4-types: filiform (thread) papillae, fungiform (mushroom)papillae , vallate (wall) papillae, foliate papillae.

ciliary processes (eye)

numerous folds in the ciliary muscle of the eye

What are the five special senses?

olfactory (smell), gustation (taste), vision, equilibrium (balance), and hearing.

What are the 3 distinct layers of the wall of the eye?

outer fibrous layer, intermediate vascular layer (uvea), and deep inner layer (retina).

fibrous layer (eye)

outermost layer of the eye that consists of the sclera and cornea. supports/protects and attaches extrinsic eye muscles, and helps in focusing.

olfactory organs

paired organs that are located in the nasal cavity that gives the sense of smell. consists of olfactory epithelium and lamina propria.

consensual light reflex

parasympathetic activation in response to bright light causing the pupils to constrict

sceral venous sinus (canal of Schlemm)

passageway that extends completely around the eye at the level of the corneal limbus where aqueous humor enters and is delivered to the sclera.

vascular layer (uvea) (eye)

pigmented region that includes the iris, ciliary body, and choroid. provides route for blood vessels/lymph vessels, regulates amount of light entering the eye, secretes and reabsorbs aqueous humor between chambers, controls the shape of the lens.

umami

pleasant, savory taste corresponding to the flavor of broth.

fornix (eye)

pocket created where the palpebral conjunctiva becomes continuous with the ocular conjunctiva

lacrimal apparatus (eye)

produces, distributes, and removes tears. consists of a lacrimal gland, lacrimal canaliculi, lacrimal sac, and nasolacrimal duct.

filiform papilla

provide friction that helps the tongue move objects around in the mouth, without taste buds.

What are the three types of cones for visual pigment (trichromat)?

red, blue, green

intrinsically photosensitive retinal ganglion (ipRGC) (eye)

respond to different levels of brightness and influence the body's 24-hr circadian rhythm.

ciliary zonule (suspensory ligament) (eye)

ring of fibers that attaches the lens to the ciliary processes.

ciliary muscle (eye)

ring of smooth muscle the projects into the interior of the eye.

eyelashes

robust hairs that help prevent foreign matter from reaching the surface of the eye.

What are the 2 main types of photoreceptors? Third type?

rods and cones; ipRGC - intrinsically photosensitive retinal ganglion.

tarsal glands (Meibomian glands)

secrete a lipid-rich product that helps keep the eyelids from sticking together along inner margin of the eyelids.

olfactory glands

secretions absorb water and form thick, pigmented mucus

equilibrium

sense of balance, inform us of the position of the head in space by monitoring gravity, linear acceleration, and rotation.

vision

sense of sight

olfaction

sense of smell

gustation

sense of taste

fovea centralis (eye)

site of the sharpest vision on the retina, establishes the visual axis (line of sight) of the eye from the center of an object.

lacrimal canaliculi (eye)

small canals that that lacrimal puncta drain into.

taste pore

small narrow opening that taste hairs extend through.

floaters (eye)

small spots that drift across the field of vision.

visual pigments

special organic compounds located in each photoreceptor's outer segment, in flattened membraneous plates called discs

taste buds

specially formed epithelial cells, sensory structures. contain between 40-100 receptor cells each and basal cells.

focal point (eye)

specific point of intersection of light rays on the retina

What are the four primary taste sensations? Other two less known?

sweet, bitter, salty, sour. umami, water.

gustatory receptor cells

taste receptors that extend microvilli (taste hairs) into the surrounding fluids.

lacrimal gland (eye)

tear gland that is found at the lateral portion of the superior fornix.

ciliary body (eye)

thickened region that begins deep to the junction between the cornea and the sclera, consists of the ciliary muscle, ciliary processes, and ciliary zonule.

cornea (eye)

transparent part of the outer fibrous layer of the eye

crystallins (eye)

transparent proteins that give the lens both its clarity and its focusing power, very stable

lacrimal puncta (eye)

two small pores that drain the lacrimal lake

vallate papilla

up to 12 form a V-shape near the posterior margin of the tongue, with up to 100 taste buds each.

choroid (eye)

vascular layer that separates the fibrous layer and inner layer posterior to the ora serrata, delivers oxygen and nutrients to the retina.

corneal epithelium (eye)

very delicate squamous epithelium that is 5-7 cells thick.

rhodopsin (visual purple)

visual pigment found in rods that consists of a protein, opsin and bout to the pigment retinal.

retinal (retinene)

visual pigment that is synthesized from vitamin A.

photoreceptors (eye)

visual receptors located in the inner layer of the eye that detect photons, basic units of visual light

dark-adapted state (eye)

visual system is extremely sensitive. (i.e. night-time)

refraction (eye)

when light is bent, as it passes from one medium to another medium with a different density.

macula (eye)

where a visual image arrives after it passes through the cornea and lens that consists of roughly 6 million cones but no rods.

medial and lateral canthus

where the upper and lower eyelids connect.

sclera (eye)

white of the eye