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The condition of perfect focus is called
emmetropia
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If the lens and cornea focus the image internal to the retina, the condition is called
myopia
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If the image is focused external to the retina, the condition is called
hyperopia
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Normally, light rays pass first through ______ and are ____ by the lens, this focuses an image on the _______ surface.
cornea; bent (refracted); receptor
-
Lower energy =
longer wavelength
*radio waves, microwaves
-
Visible spectrum
color corresponds to wavelength
-
Higher energy =
shorter wavelength
*Ultraviolet, x-rays, Gamma rays
-
Wavelength corresponds to
hue or color
-
The distance between the crest and trough of the wave is the
amplitude;
-
Amplitude corresponds to the
brightness of the light
-
Rods are
specialized to code for the presence or absence of light.
rods can detect as few as 1-3 photons
-
Cones are
specialized to code for color information
color = wavelength of light
-
Light changes shape of
retinal
-
Retinal is made from
Vitamin A
-
Retinal + opsin =
rhodopsin, the visual transducer in rods
-
Transduction causes changes in rods
-In darkness, open Na+ channels keep rod depolarized (more+)
-Glutamate is the neurotransmitter; more glutamate is released in the dark
-Photons cause Na+ channels to close
-This hyperpolarizes the rod
-Glutamate release is turned off in the light
-Weird: when your eyes are closed and you are asleep is when rods are the most active
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Therefore, axons from the left nasal retina and right temporal retina, which carry information from the left half of the world, join together at the _____ ______ and form the right _____ _____. The right optic tract ends in the right side of the thalamus. The right thalamus then sends axons through the right _____ ________ to the right ______ _______ in the occipital lobe.
optic chiasm; optic tract; optic radiations; visual cortex
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Olfaction is the sense of
smell
-
Olfactory receptors found on
superior surface of sinuses (superior nasal concha)
-
Olfactory receptor surface in humans about the size of a
postage stamp
-
Odorants are
small molecules, carried by air, that are dissolved in the mucus layer that covers the olfactory epithelium.
-
Olfactory Transduction:
-Odorant molecule binds to receptor protein.
-This activates a G protein pathway.
- Second messenger opens a Na+ channel
-
After the olfactory stimulus is analyzed by the cells of the ________ _________, the processed signal is passed via the _______ _____ through the _______ ______ of the skull to the ________ bulb which lies along the ventral surface of the frontal lobe. There, the signal is processed further, and is transferred via the _______ _____ to the _______ ______ in the temporal lobe.
olfactory epithelium; olfactory nerve; ethmoid bone; olfactory; olfactory tract; olfactory cortex
-
The delicate nerve axons which pass through the cribriform plate of the ethmoid bone are easily torn by head trauma. When this happens, the patient permanently loses the sense of smell, a condition called
anosmia
-
Smells have direct access to the emotional centers of
the brain, which is why an old friend's cologne can trigger a strong emotional response.
-
Olfactory pathway is the only sensory pathway that is not relayed through the
thalamus
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