chapter 8 special senses. chemical senses taste reception taste buds – repair in 7-10 days have...
TRANSCRIPT
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 - 1-5 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: 30 - 1000
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 chamberVitreous 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 20-30 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