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the special senses
chapter 16
| Question | Answer |
|---|---|
| gustatory receptors | -in the taste bud -contains a gustatory hair |
| Physiology of Gustation | -tastants stimulate gustatory receptor cells and are dissolved in saliva -makes contact w/gustatory hairs -neurotransmitter molecules are released -neurotransmitter trigger action potentials int the first order neurons that synapse w/gustatory cells |
| Olfactory receptor | A bipolar neuron with its cell body lying between supporting cells located in the mucous membrane lining the superior portion of each nasal cavity; transduces odors into neural signals. |
| physiology of olfactory | production of (cAMP) → opening of sodium ion (Na+) channels → inflow of Na+ → generation of depolarizing generator potential → triggering of action potential → propagation of nerve impulses along axon of olfactory receptor cell. |
| Functions of eyelids | -shades the eye during sleep -protects the eye from excessive light and foreign objects -spreads lubricating secretions over the eyeball |
| Functions of eyelashes and eyebrows | protect the eyeball from foreign objects, perspiration, and direct rays of the sun |
| conjunctivitis | -an inflammation of the conjunctiva -pink eye |
| Lacrimal fluid | -secreted by lacrimal glands -drains into lacrimal ducts -enter on to the surface of the conjunctiva of the upper lid -pass medially over the eyeball into the lacrimal punta->lacrimal canals->nasolacrimal duct->nasal cavity |
| Functions of lacrimal fluid | The fluid protects, cleans, lubricates, and moistens the eyeball. |
| How does the iris regulate pupil size? | It regulates the amount of light entering the pupil. |
| How does the iris regulate pupil size? | - its regulates pupil size though the circular muscles and radial muscles of the eye. |
| Functions of rods | -allow us to see dim light -no color vision -black, white, gray shades are seen |
| Functions of cones | -produce color vision -there are blue, red, and green cones -color vision comes form the stimulation of these cone |
| The flow of visual impulses from photoreceptors to the optic nerve | -outer synaptic layer->bipolar cells -bipolar cells->inner synaptic layer->ganglion cells->optic nerve |
| Why is the optic disc also called a blind spot | -no rods or cones -we can't see an image that strikes though the blind spot |
| Sequence of eye components a light ray experiences before reaching the retina | Light passes through the cornea, the aqueous humour, the pupil (which is just an opening in the iris), the lens, and the vitreous humour on its path through the eye to the retina. |
| why are corneal transplants highly successful? | -Since the cornea is avascular, antibodies in the blood that might cause rejection do not enter the transplanted tissue, and rejection rarely occurs |
| glaucoma | -an abnormally high intraocular pressure due to a buildup of aqueous humor within the anterior cavity. |
| cataracts | -loss of transparency of the lens |
| detached retina | -may occur due to trauma -various eye disorders or aging -detachment occurs between neural part of the retina and pigment epithelium -Fluid accumulates between these layers, forcing the thin, pliable retina to billow outward |
| refraction of light rays | -refraction is the bending of light between two transparent substances w/different densities -The cornea and lens refract light rays from distant objects so the image is focused on the retina. lens becomes more sphereical, refraction increases - |
| Role of Accomodation | -increase in curvature of the lens for near vision -ciliray body allows focusing of distance and close objects |
| myopia | -nearsightedness -the eyes focus incorrectly, making distant objects appear blurred -Nearsightedness occurs when the physical length of the eye is greater than the optical length -eyeglasses/contact lenses shift the focus point to the retina. |
| Astigmatism | -is an eye disorder in which the cornea (the clear tissue covering the front of the eye) is abnormally curved, causing out-of-focus vision. -Glasses or hard contact lenses will correct astigmatism |
| hyperopia | -Farsightedness -difficulty seeing objects that are nearby. -result of the visual image being focused behind the retina rather than directly on it. -Contacts/glasses change the way the light rays bend when entering the eye |
| Process by which photoreceptors respond to light | photoreceptors → bipolar cells → ganglion cells → optic nerve → primary visual cortex |
| The relationship between vitamin A and good vision | -photopigments contain Vitamin A, which comes from carotenoids -Good vision depends on adequate dietary intake of carotenoid-rich vegetables -Retinal is the light-absorbing part of photopigments. |
| Light and dark adaptation | -light adaptation: visual system adjusts in seconds to the brighter environment by decreasing its sensitivity. -dark adaptation: sensitivity increases slowly over some time |
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