10 - Senses

Eye

Detects light, converts into electrical signals, sends to brain via optic nerve.

General senses

Receptors widely distributed in body. Visceral organs, skin, muscles, joints

Special senses

Receptors localized in particular area

Sensory receptors

Respond to stimuli > trigger impulse in receptor. Action potentials travel to cerebral cortex, processed & interpreted

Chemoreceptors

Detect change in chemical concentration of substances. Taste & smell

Mechanoreceptors

Detect change in pressure or movement in fluids. Proprioceptors in joints, receptors for hearing & equilibrium.

Nociceptors

Pain receptors. Tissue damage & extremes in temp. May continue to send signals after stimulus is removed

Thermoreceptors

Detect change in temp. Most in lips, least in trunk. 10x more cold receptors than heat

Photoreceptors

Detect light energy. Vision

Bulbus oculi

Eyeball

Fibrous tunic

Outer layer of eye

Sclera

White, tough part of eye. Maintains shape, protects inner structures

Cornea

Transparent front part. Refracts light & helps focus it on retina

Vascular Tunic/Uvea

Middle layer of eye

Ciliary body

Contains ciliary muscles that controls lens shape for focusing

Iris

Colored part of eye, controls pupil size to regulate light entering

Pupil

Central opening in iris, where light passes

Retina

Inner layer of eye. Light-sensitive nerve tissue. Captures images, concerts into electrical signals, sends to brain via optic nerve for vision

Rods

Detect light only

Cones

Detect colors

Optic disc

Where optic nerve exits. No photoreceptors, “blind spot”

Lens

Transparent, bioconvex structure behind iris. Focuses light onto retina. Held by suspensory ligaments connected to ciliary muscles

Anterior chamber

Between cornea & iris, contains aqueous humor

Posterior chamber

Between iris & lens, contains aqueous humor

Vitreous chamber

Behind lens, contains vitreous humor (gel-like). Maintains eye shape & transmits light

Eyelids & eyelashes

Protect eye from dust & injury

Extraocular muscles

Move eye in different directions (6 per eye)

Orbital cavity

Eye socket. 7 cranial bones

Outer ear

Collects sound

Middle ear

Transmits & amplifies sound

Inner ear

Converts sound to nerve signals, controls balance

Pinna/Auricle

Visible part of ear; funnels sound into ear canal

External Auditory Canal (Meatus)

Tube leading to eardrum, produces cerumen to trap dust

Tympanic Membrane

Ear drum. Thin membrane that vibrates in response to sound. Collects sound waves & directs toward middle ear

Ossicles

3 tiny bones that amplify sound vibrations. Malleus (hammer), Incus (anvil), Stapes (stirrup)

Eustacian Tube

Connects middle ear to nasopharynx, equalizes pressure

Oval window

Membrane connecting stapes to inner ear, amplifies sound waves

Cochlea

Spiral-shaped organ for hearing. Hair cells convert vibrations to nerve impulses. Lymph Fluids help transmit.

Vestibule

Central chamber of inner ear, helps with balance

Semicircular canals

3 canals in different planes, detect rotational movement

External nose

Nasal bones, cartilage (lateral, alar, septal) & nostrils (nares). Covered w/ skin, lined internally w/ mucous membrane. Fx: air intake & protection

Internal nose

Nasal cavity. Divided by septum. Contains nasal conchae (turbinates)

Nasal conchae/Turbinates

Superior, Middle & Inferior. Increase surface area to warm, moisten, & filter air.

Nasal meatuses

Spaces under each conchae. Superior, middle, inferior. Drain paranasal sinuses & nasolacrimal duct.

Paranasal sinuses

Air-filled spaces in surrounding bones. Frontal; forehead. Maxillary; cheeks. Ethmoid; between eyes. Sphenoid; behind nasal cavity. Reduce skull weight, produce mucus, enhance voice.

Olfactory region

Located in roof of nasal cavity. Detects smell signals sent to brain via cranial nerve. Rich vascular network; warms air & can cause nosebleeds

Mouth

2 regions. Vestibule (between lips/cheeks & teeth) & oral cavity proper (space inside teeth)

Lips

Muscular folds controlling entry of food & speech

Cheeks

Form lateral walls, contain buccinator muscles

Oral fissure

Opening of mouth

Hard palate

Bony anterior roof of mouth; separates oral & nasal cavities

Soft palate

Muscular posterior roof, ends in uvula. Prevents food from entering nasal cavity during swallowing.

Tongue

Muscular organ on floor of mouth, covered w/ mucous membrane.

Papillae

Contain taste buds (sweet, sour, bitter, salty, umami)

Lingual Frenulum

Tissue connecting tongue to floor of mouth

Floor of mouth

Supports tongue, assists swallowing. Muscles: mylohyoid, geniohyoid.

Chem/o

CF: chemical

Gust/o

CF: taste

Lacr/o

CF: tears

Macul/o

CF: spot, depression

Mechan/o

CF: mechanical

Noci-

Prefix: harm, damage

-ceptor

Suffix: receptor

Phot/o

CF: light

Ot/o & aur/o

CF: ear

Rhin/o & nas/o

CF: nose

Laryng/o

CF: larynx (voice box)

Olfact/o

CF: smell

Or/o & oral/o

CF: oral

Ophthalm/o & opt/o & ocul/o

CF: eye

-osmia

Suffix: smell

Rhod/o & rubr/o & erythr/o

CF: red

Sens/o

CF: senses

Therm/o

CF: heat

Blephar/o & palpebr/o

CF: eyelid

Proprioception

Allows you to senes location & rate of movement of 1 body part vs another

Vitamin A

Good for eyes

B-complex vitamins

Good for sensory nerve fx

Vitamin C

Protection & repair, immune support

Vitamin D

Sensory nerve support

Vitamin E

Nerve protection

Omega 3 fatty acids

Vision & nerve signaling

Snellen eye chart

Stand 20’ away. Cover other eye, don’t close

Ishihara test

Color blindness test

Myringotomy

Incision in eardrum

Tympanostomy

Tube in incision of eardrum

Rinne’s test

Tests air conduction (AC) & bone conduction (BC) of sound. Tuning fork placed on bone then moved to ear. Normally AC better than BC.

Weber’s Test

Determines type of hearing loss. Places vibrating tuning fork on mid forehead. Normal hearing; sound heard equally in both ears

Ear irrigation

Remove cerumen impaction, foreign objects, ear infection. Uses distilled water, 0.9% saline, H2O2

Eye irrigation

To remove foreign objects, infection, dry eye. Not for stye.

Nyctalopia

Night blindness

Presbycusis

Age-related hearing loss

Presbyopia

Age-related vision loss

Myopia

Near sighted. Can’t see far.

Hyperopia

Far sighted. Can’t see near.

Conjunctivitis

Pink eye. Inflammation of membrane of eyelid & eyebal

Strabismus

Eyes don’t line up

Esotropia

Cross eyed

Exotropia

Lazy eye. One turns out

Sensorineural deafness

Sound can’t reach inner ear