Chapter 8 Special Senses

Chemical Senses Taste Reception Taste Buds – Repair in 7-10 days have 10,000 – gustatory cells respond to chemical dissolved in saliva – papillae peglike projections Primary Taste Sensations – sweet- tip of tongue – sour- sides of tongue – salty- tip of tongue – bitter - base of tongue

Chemical Senses – Gustatory pathways facial nerve (VII) glossopharyngeal (IX) vagus nerve (X) – saliva – taste adaptations minutes – tactile: texture, temperature and irritation (pain) – olfaction plays a part in taste perception 80%

Chemical Senses Olfaction - smell closely tied to emotion – olfactory cells - neurons – olfactory nerve – olfactory hairs – olfactory cells secrete mucus – mucus is constantly replaced – chemoreceptors which detect: chemicals

Chemical Senses Primary Odors – seven camphoraceous - alcohol ketones musky floral peppermint like etheral - ethers pungent - stinging putrid - rotten Smells associated w/ danger – sympathetic nervous

Changes Ansomias – loss of smell – age, cold, allergies, smoking, head injuries – low levels of Zinc Sensitivity & Adaptation – adapt to unchanging stimulus Pain Receptors – irritants, harmful

The Eye & Vision Accessory Structures – orbital cavities location of the eyes fat & bone – eyebrows protect the eyes shade them prevent infiltration of perspiration prevent objects contacting them from above

The Eye & Vision Accessory Structures – eyelids & eyelashes protection lubricate w/ glands (oily secretion) – conjunctiva membranes edge of cornea to eyelid conjunctivitis is pink eye – lacrimal apparatus - tears dilute salt solution antibodies lysozyme - enzyme kills bacteria – extrinsic muscles move eyeball

Eye Structure Fibrous tunic – anterior portion cornea - transparent nerves, no blood vessels – posterior portion sclera - outermost protects thick, white connective tissue Vascular tunic (uvea) – choroid pigments that absorb light (middle layer) dark purple – ciliary body muscles move lens – iris pigmented smooth muscles change size of pupil – pupil - opening

Eye Structure Retina – innermost layer – transparent layer absorbs light & stores vitamin A – nervous layer photoreceptors – rods - shades of gray – cones - color, red, blue, green – color blindness – blind spot - optic disc where optic nerve enters – fovea centralis - lateral to blind spot, only cones greatest visual cavity

Eye Structure Internal Chambers – Anterior-aqueous humor corneal shape & nutrition – canal of Schlemm- drains aqueous humor – glaucoma increased aqueous humor increase pressure Lens – flexible, biconvex, crystal like – held by ligaments – Cataract- clouding of lens posterior chamber Vitreous humor - gel, eyeball shape

Physiology of Vision Light Energy – electromagnetic spectrum- wavelengths color: cones Dark and light : rods Focusing Processes – refraction bending of light – myopia nearsighted, eyeball too long, cornea curved – hypertrophy farsighted, flat lens, eyeball too short – astigmatism unequal curvatures in lens or cornea blurry vision

Physiology of Vision Focusing of Processes – lens accommodation focus close or far – pupil constriction for close vision for bright light – eye convergence close objects

Physiology of Vision Photoreception – visual pigments light absorption choroid coat - deep purple – excitation of rods shades of gray – excitation of cones all cones ---> white color

Physiology of Vision Light and Dark Reception – into light - faster – into dark - slower minutes – night blindness rods function decreased, Vitamin A deficiency Visual Pathways – optic nerve – occipital lobe – cerebrum Binocular Vision – eyes anterior – depth perception 3 dimensional vision

The Ear Structure – outer ear auricle capture sounds shell shaped external auditory canal ceruminous glands - make ear wax tympanic membrane - eardrum

The Ear Structure – middle ear infections otitis media air filled cavity bones – ossicles transmit vibrations – hammer ---> anvil ---> stirrup oval window eustachian tube to throat “auditory”

The Ear Structure – inner ear labyrinth – maze of bony chambers into temporal filled w/ fluid – vestibule – pull of gravity – sacs semicircular canal – equilibrium cochlea – spiral shaped – organ of corti - receptors – for hearing - hairs

Physiology of the Ear Sound waves – frequency – amplitude Outer and middle ear – reception – increase & decrease sound Cochlea – organ of hearing sound ---> cochlear nerve ---> temporal lobe Pitch transmission – frequency specific hairs Loudness transmission – amplitude – more hairs stimulated

Homeostasis Imbalances Deafness – conduction deafness - hearing aid – sensorineural deafness loud noise damage organ of corti Tinnitus – ringing in ears, clicking Meniere’s Syndrome – arteriosclerosis – cranial nerve fluid pressure & “howling” Motion Sickness – sensory input