The Special Senses Flashcards
Receptors for special senses located in complex sensory organs in head
Smell olfaction Taste Gustation Vision Hearing Equilibrium
Primary senses
Sour Produced by acids H+ Sweet Elicited by many organic substances Bitter Elicited by alkaloids and some nonalkaloid Salty Produced by metal ions Umami Elicited by amino acids glutamate and aspartate
Olfactory I
Superior area of nasal cavity
Olfactory receptor cells
First order bi polar neurons
Hairs respond to inhaled chemicals
Odorant binding proteínas of cells
Bind with dissolved odorant
Produced generator potential ( depolarized)
Leads to action potential if threshold
Gustation
Receptor in gustatory hair
Bind with tastant dissolved in saliva
Produced receptor potential if threshold
Variable threshold depending on taste sweet or sour
Quick adaptation decrease sensitivity within minutes after continuous stimulation
Eyelids
Shade protect Spread lubricant over eyeball Obricularis oculo closes Meibomian gland secrete fluid keeps eyelids from adhering to each other Conjunctive Protective mucous membrane
Eyelashes and eyebrows
Help protect the eyeballs from foreign objects
Perspiration and direct rays of the sun
Lacrimal fluid
Tears
Dilute saline solution contain mucus antibodies and lysozyme
Blinking spreads tears toward medial commissure
Tears enter paired lacrimal canaliculi via lacrimal puncta
Then drain into lacrimal sacs and nasolacrimal duct
Conjunctiva
Palpebral Lines eyelid Bulbar Covers white Conjunctival sac Between palpebral and bulbar Where contacts lens rest
Ciliary body
Ciliary processes secrete aqueous humor
Zonular fibers
Attach lens and hold position
Ciliary muscles control shape of lens
Retina
Optic disc
Site where axons from neural layer form optic nerve and exits the eyeball
No photoreceptors so blind spot
Retina nerves
Central retinal artery and vein
Bundled with optic nerve
Forvea centralis
Central posterior portion of retina with highest visual acuity and color vision
Optic disc blind spot
Sure where optic nerve leaves eye
Lacks photoreceptors
Quarter billion
Ross and cones
retina Rods
Allow night and dim light
Black and white shades of gray
Stimulated by even low light levels
Absents from fovea centralis
Cones
Produce color vision
Three types
Blue green and red cones
Stimulated by bright lights
Anterior chamber
Between cornea and iris
Posterior chamber
Between iris and zonular fibers and lens
Photoreceptors of the retina
A) the outer segments of rods and cones are embedded in the pigmented layer of the retina
B) rhodopsin
The visual pigment in rods is embedded in the membrane that forms discs in the outer segment
Image formation
Refraction of light rays
Bending of light rays at each surface of the cornea and the convex lens
Focuses an inverted image in the forvea centralis of the retina
Image formation accommodation
Increase in curvature of lens for near vision
Image formation refraction abnormalities
Myopia nearsightedness
Hyperopia farsightedness
Astigmatism
Partial distorsión of image
Myopia
Concave lenses that diverge the light before it entered eye or laser
Hyperopia far
Convex corrective lenses to converge light more strongly for close vision
Astigmatism
Unequal curvature in cornea
Special cylindrically ground lenses or laser procedures
Pupil central opening
Close vision and bright left
Circular muscles contract pupils constrict
Distant vision and dim light
Dilator pupillae (radial muscles) contact pupils dilate sympathetic fibers
Changes in emotional state
Pupils dilate when subject matter is appealing or requires problem solving
