1. Senses
A particular sensitivity to a distinct environmental change
Changes detected by sensory neurons (in sense organs) and sent to the CNS
Sense Organs: eye, ear, skin, nose, taste buds
Senses: seeing, hearing, feeling, smelling, tasting
Eye:
Accessory Structures:
Eyebrows, eyelids, eyelashes,
6 eye muscles, glands (oil and
sweat), tear ducts (dilute saline)

2. Eye Structure: Conjunctiva: mucous membrane covering the eye
Conjunctivitis: “pink eye”
(infection; pus)
Sclera: “white of the eye”
(gives shape; protection;
anchors eye muscles)
Cornea: transparent
(pain fibers)
Iris: colored muscle
Pupil: hole (Dim: dilates Bright: constricts)
Lens: magnifies image
As age increases, ability to accommodate decreases
Cataracts: covering over lens

3. Retina: contains nerve tissue
Rods: sensitive to darkness
Cones: sensitive to color
Optic Nerve: carries visual message to the brain
“Blind Spot”: where optic nerve leaves the retina
Fovea Centralis: sharpest vision (only rods)
Aqueous Humor (fluid)/Vitreous Humor (gel): give shape
Glaucoma: build up of pressure due to fluid

4. Refraction of Light: Rays of light bend
Near-Sighted (Myopia): see near – not far
Eyeball too long
Image in front of retina
Concave Lens
Far-Sighted (Hyperopia): see far – not near
Eyeball too short
Image behind retina
Convex Lens
Astigmatism: blurred vision
Shape of cornea irregular

5. Ear: Hearing Center: brain Outer Ear: Middle Ear:
Auricle (made of cartilage)
External Auditory Canal (Contains hairs, wax glands)
Middle Ear:
Tympanic Membrane: ear drum
3 Ear Bones: malleus (hammer),
incus (anvil), stapes (stirrup)
Eustachian Tube: connects
middle ear to the throat (maintains
equal air pressure on both sides
of the eardrum)
Oval Window: opening which
leads to the Inner Ear

6. Semicircular Canals: important for balance/equilibrium
Inner Ear:
Round Window: opening between Middle and Inner ear
Cochlea: contains tiny hairs in fluid
which respond to sound waves
Auditory Nerve: connects to cochlea;
sends sound messages to the brain
Semicircular Canals: important for balance/equilibrium
Vertigo: a sensation of dizziness
Deafness:
Mechanical (interference of sound vibrations to Inner Ear)
Sensorineural (damage to cochlea)

7. Nose: (olfactory organ)
Olfactory Center: brain
Smell: an ability to detect chemicals (as gases)
Nerve receptors in the upper part of the nasal cavity
Related to the sense of taste
Taste Buds: (on tongue)
Taste Center: brain
4 primary taste sensations: sweet, sour, salty, bitter
Skin:
Touch Center: brain
Touch and Pressure Receptors
Temperature Receptors
Pain Receptors