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)

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

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

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

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

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)

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