Sensory Organs - unit 3

Ear

The ear is a transducer. It converts electric acoustic energy (sound waves) into electrochemical energy that is transmitted to the auditory nerve in the brain.

Outer Ear

What you can see, the passageway into the inner ear. Energy is acoustic.

Middle Ear

Contains the ossicles, the energy is mechanical vibrations.

Inner Ear

Vestibular System and cochlea, energy is hydrodynamic wave motion.

Pinna/Auricle

In the outer ear, cartilaginous sound collector, collects sound from the environment. Whole outer ear, the part you see.

Helix

In the pinna, curved part around the outside.

Antihelix

Fold anterior to the helix, curved part on the inside next to helix, bifurcates by splitting into 2.

Tragus

Flap covering the entrance to the ear canal, cartilage is covered by epithelium.

Ear Lobe

Non-cartilaginous skin flap.

what is the External Auditory Meatus (EAM)

Ear canal, diameter: ~7mm, length: ~25mm, concha>eardrum.

Lateral 1/3 is cartilage, medial 2/3 is bone. Angle is ~55 degrees at the EAM and tympanic membrane (eardrum).

Ciliated epithelium gets the gunk out, and cue-tips push the gunk back in. Could cause the eardrum to stop moving.

Tympanic Membrane

Boundary between the outer and middle ear, functions like a drum, vibrates. If the membrane can't move, it can't transmit sounds, slightly concave when viewed from EAM.

Ossicles

In the middle ear, transmit energy from TM to inner ear, very tiny bones and all 3 fit on a dime. Malleus, Incus, Stapes.

Malleus

Hammer, contains manubrium (long part on the bottom), head (roundish part on top), and neck (separates manubrium and head is connected here). Malleus joins the TM along length of manubrium. Head articulates with the incus, largest of the ossicles.

Incus

Contains long process (parallel with the manubrium of malleus), body (articulates with malleus at the articular facet) and lenticular process (end of long process, articulates with stapes).

Stapes

Contains head (at the top, articulates with incus), neck (below head), footplate (articulates/joins oval window at bottom). Smallest of ossicles.

Oval Window

Part of the middle ear, fenestra vestibuli, connects with the stapes.

Round Window

Part of middle ear, fenestra cochlea, leads to scale tympani in inner ear.

Eustachian Tube

Runs from middle ear to the pharynx, drains middle ear, vestibular function is to keep air pressure equalized. This is happening when your ears pop.

Middle Ear Muscles

Reduce transmissions of high intensity sounds, part of auditory reflex.

Stapedius Muscle

Middle ear muscle that keeps high intensity sounds from entering the cochlea. More effective against high intensity, low frequency sounds.

Tensor Tympani

Middle ear muscle, when it contracts, it pulls the malleus which tightens the TM. Connected to the ossicles by a tendon and also protects cochlea from sounds. More effective against high intensity, low frequency sounds.

Bony Labyrinth

Bone and membrane.

Membraneous Labyrinth

Bone and membrane that is generally in the osseous labyrinth.

Semicircular Canals

Inner ear, sense balance, movement of the body in space.

Cochlea

Inner ear, helps with hearing.

Vestibule

Inner ear, in between the semicircular canals and cochlea. The entry to the inner ear space.

Anterior/Superior Semicircular Canals

On top, sense when the head moves to the shoulder.

Posterior/Vertical Semicircular Canals

Sense when your head moves up and down, nodding yes.

Horizontal/Lateral Semicircular Canals

In the middle, sense shaking no, side to side.

Ampulla

Wider part of the canal that contains fluid, fluid senses the movement.

Modiolus

Core, finely perforated bone at the core. Where fibers of the 8th vestibulocochlear nerve pass through.

Osseous Spiral Lamina

Bony shelves that extend from modulus, divide the cochlear labyrinth into 2 chambers: scala tympani and scala vestibuli.

Perilymph

Fluid that fills in the scala vestibuli and tympani.

Endolymph

Fluid that fills the scala media

Basilar Membrane

Floor of the scala media, organ of hearing is located along the basilar membrane, structures that arise from BM are inner ear hair cells.

Organ of Corti (spiral organ)

Includes auditory receptors

Outer Hair Cells (OHC)

Contains 3 rows.

Inner Hair Cells (IHC)

Contains 1 row near modulus, don't come in contact with tectorial membrane.

Tectorial Membrane

Has some functionality to the way we hear sound, related to proximity of outer hair cells.

Stereocilia

Sensory hairs on the surface of cells.

Cilia

Cilia are linked if stereo cilia move on one cell, bump into others making them move as well.

aqueous and vitreous humors

the watery fluid that fills the anterior and posterior chambers of the eye

choroid

the middle layer of the wall of the eye

ciliary body

the structure between the choroid and the iris that anchors the lens in place

cones

sensory cells in the retina that are sensitive to bright light and provide color vision

conjunctiva

a delicate external membrane that covers the exposed eyeball and lines the eyelid

cornea

a transparent tissue over the anterior center of the eye

extrinsic muscles

muscles attached to the outer surface of the eye that are responsible for changing the direction of viewing

iris

the anterior portion of the choroid, which gives the eye its color

lacrimal glands

tear secretors

lens

a transparent, flexible structure that is curves outward on both sides

optic chiasma

the point at which the optic nerves cross

pupil

the opening through which light rays enter the eye

retina

the innermost layer of the eye, containing light sensitive nerve endings that send impulses through the optic nerves to the brain

rods

sensory cells in the retina that are activated in dim light

sclera

the tough, fibrous outer layer of the eye

diplopia

double vision

astigmatism

blurred vision due to an irregular curvature of the cornea or lens

strabismus

crossed eyed

myopia

nearsightedness

hyperopia

farsightedness

vitreous humor

A

conjunctiva

B

lens

C

iris

D

aqueous humor

E

pupil

F

cornea

G

retina

K

choroid layer

L

sclera

M

The olfactory apparatus

a group of organs used for smell

Nasal cavity

is a large air filled space inside the nose, above and behind the nostrils.

Olfactory membrane, aka olfactory epithelium

is a specialized tissue inside the nasal cavity involved in smell. About the size of a postage stamp.

Mucus

a slimy substance secreted by mucous membranes and glands for lubrication, protection, etc.; odorant molecules dissolve into this and then they bind to the olfactory receptors

olfactory receptors

in the olfactory epithelium; these bind to odorant molecules

chemoreceptors

a sensory cell or organ responsive to chemical stimuli, found in the olfactory epithelium.

Olfactory bulb

a bulbous structure, an extension of the olfactory nerve, that connects the olfactory nerve to the olfactory membrane.

Olfactory nerve

It relays olfactory data to the brain.

Limbic system

a region of the brain concerned with instinct, memory and emotion. Some olfactory information passes through this, thus linking smells and emotional memory.

Frontal lobe

The frontal lobe, located at the front of the brain, is one of the four major lobes of the cerebral cortex in the mammalian brain. Where smell stimulus information is processed and interpreted.

Odorant molecules

Airborne particles that enter the nasal cavity and stimulate the olfactory receptors in the epithelium.

Gustation

the action of tasting, the ability to taste

Papillae

Small, bumpy structures on the upper surface of the tongue that are covered with taste buds. These give the tongue its characteristic rough texture.

Taste buds

Contain the taste receptor cells. Located on papillae on the upper surface of the tongue, soft palate, and the cheek.

Taste receptor cells

The gustatory system consists of these cells in the taste buds. Taste buds, in turn, are contained on structures called papillae. These cells contain sensory nerve fibers that bind with food molecules.

Sensory fibers

Microscopic hairs that bind to food molecules and begin the process of transduction of taste sensation to the brain.

The five taste sensations

salt, bitter, sour, sweet, umami

What is this?

olfactory bulb

What is this?

olfactory epithelium

What is this?

frontal lobe

What is this?

lymbic system

What is this?

taste bud

What is this?

chemoreceptors

the sense of taste

depends on the sense of smell; taste is thought to be 80% smell.

Olfactory adaptation

this occurs when a smell becomes less noticeable over time. Also known as olfactory fatigue, olfactory habituation, and odor fatigue.

Receptors

Stimulated by stimuli and they in turn stimulate sensory neurons which send messages to the brain for interpretation. Grouped according to the kind of stimulus they receive

Photoreceptor

Respond to visible wavelength of light

Mechanoreceptor

Sensitive to mechanical energy

Thermoreceptor

Sensitive to heat and cold