Chapter 6 (Sensation) + Chapter 7 Flashcards
(60 cards)
___: any energy capable of exciting a receptor
Stimulus
To Perceive a Sensation . . . (4 Steps)
- A stimulus sufficient to initiate a response in the NS must be present
- A receptor must convert the stimulus to a nerve impulse
- The conduction of the nerve impulse must be transmitted from the receptor to the brain
- Interpretation of the impulse must occur in a specific portion of the brain
The level of response is determined by the _____ of the stimulation
intensity
(– Rate law!!)
These types of receptors continue to fire at a relatively constant rate as long as
the stimulus is maintained . . . Slow/fast to adapt
tonic receptors, slow to adapt
(example sitting down for a while, the constant pressure is being sensed by the tonic receptors)
These types of receptors respond with a burst of APs when the stimulus is first
applied . . . But quickly ____ their rate of firing when the stimulus is maintained . . .
Phasic Receptors, reduce
(example sitting down, the sudden sensation of sitting down is done by phasic receptors)
_____ are specialized nerve cells that transduce energy into neural signals
(T/F the have Axons?)
receptors
(F, they form synapses with dendrites of other sensory neurons)
Receptors are “___” specific
mode,
“Law of Specific Nerve Energies”: sensory messages
are carried via separate pathways to different areas of
the brain, but all use the same neural impulse
You would use your ____ to detect EMR emitted by objects.
Color is related to ___
Brightness is related to ____
visual system
wavelength
Intensity
An eye consists of: (3 parts)
– Aperture (pupil) to admit light
– Lens that focuses light
– Photoreceptive elements (retina) that transduce the light stimulus
The path of light: (6 steps)
cornea, aqueous humor, pupil, lens, vitreous humor, retina
This type of eye movement has the eyes rotate to keep an object on corresponding
parts of the retina (coming closer and farther away)
Vergence movements
This type of eye movement is following an object to keep it on the same part of the
retina (the fovea, to maximize detail and color appreciation). The eye is moving up, down, left, right
Pursuit movements
This type of eye movement has the eyes fixate on objects during “smooth pursuit”
* Eyes also “jump back and forth” – they are not stationary! (constant refresh on your visual system)
Saccadic Movements
What are the three layers of the retina
– Photoreceptor layer (back of the eye): receptors in this layer
transduce light into electrochemical impulses (eventually,
action potentials)
– Bipolar layer
– Ganglion cell layer
The ganglion cell layer is _____ and the photoreceptor layer is the ____ from the light
closest to the light, farthest
This type of photoreceptor is
* Light sensitive (not color)
* Found in periphery of retina
* Low activation threshold
Rods
This type of photoreceptor are
* color sensitive
* Found mostly in fovea (center of retina)
Cones
This is where photopigments are located…
in the membrane of the outer segment of rods and cones
Each pigment consists of an ____ and ____
opsin (protein), retinal (a lipid)
Why is light important to seeing?
The effect of light is to hyperpolarize the photoreceptors and reduce the release of NT
- light hits photoreceptor becomes deactivated in response, inhibit the bipolar cell less (release less NT), cause the bipolar cell to become relatively activated causing action potentials (rate law) releasing NT
the relationship between the photoreceptor and the bipolar cell is ____
ihibitory
the relationship between the bipolar cell to the ganglion cell is ___
excitatory
Meyers loop processes:
superior vision (upper half)
What happens if we lesion the parvocellular layers of the LGN in the right hemisphere?
their left visual field would be without color
