Perception opportunity 1 notes2

Myopia

________ or nearsightedness: inability to see distant objects clearly.

Hyperopia

________ or farsightedness: inability to see nearby objects clearly.

Corrective lenses

________ are needed for close activities, such as reading.

Accommodation results

________ when ciliary muscles are tightened which causes the lens to thicken.

cornea

The ________ and lens focus the light to a sharp image on retina.

Neurons

________ are surrounded by a solution containing ions.

Peripheral retina

________ has both rodsandcones.

Light rays

________ pass through the lens more sharply and focus near objects on retina.

Convergence

________: allows a neuron to receive input from many neurons in a network.

Blind spot

________: place where optic nerve leaves the eye.

Electrical signals

________ are generated when such ions cross the membranes of neurons.

Transduction

________ is the conversion of physical energy into electrical nrg.

Threshold

________ for light is lowest in the middle of the spectrum.

Observer

________ is light adapted.

Macular degeneration

________: Fovea and small surrounding area are destroyed, Creates a "blind spot "on retina, Most common in older individuals.

Lack of Convergence

________ Causes the Cones to Have Better Acuity.

Retinitis pigmentosa

________: Genetic disease, Rods are destroyed first, Foveal cones can also be attacked, Severe cases result in complete blindness.

Excitatory transmitters

________ cause depolarization.

Purkinje shift

________: enhanced sensitivity to short wavelengths during dark adaptationwhen the shift from cone to rod vision occurs.

Inhibitory transmitters

________ cause hyperpolarization.

retina

The ________ shows visual pigmentbleaching.

Retinal changes

________ its shape, which is known as isomerization.

selective permeability

Membranes have ________.

visual pigment

The receptors contain ________.

Small electrodes

________ are used to record from single neurons.

Reference electrode

________ is outside the fiber.

spectral sensitivity

Difference in ________ is due toabsorption spectra of visual pigments.

Rods

________ have greater convergence, which results in summation of the inputs of many ________ into ganglion cells increasing the likelihood of response.

Absorption of all cones

________ equals the peak of 560nm in the spectral.

Ions

________ carry an electrical charge.

Refractive myopia

________: cornea or lens bends too much light.

observer

Once the ________ is dark adapted, she adjusts the intensity of a test light.

Light

The Stimulus for Vision

Rods

large and cylindrical

Cones

small and tapered

Macular degeneration

Fovea and small surrounding area are destroyed, Creates a "blind spot" on retina, Most common in older individuals

Retinitis pigmentosa

Genetic disease, Rods are destroyed first, Foveal cones can also be attacked, Severe cases result in complete blindness

Number

about 120 million rods and 6 million cones

Blind spot

place where optic nerve leaves the eye

Presbyopia

"old eye"

Myopia or nearsightedness

inability to see distant objects clearly

Refractive myopia

cornea or lens bends too much light

Axial myopia

eyeball is too long

Hyperopia or farsightedness

inability to see nearby objects clearly

Then sensitivity levels off for seven to ten minutes

the rod-cone break

Purkinje shift

enhanced sensitivity to short wavelengths during dark adaptationwhen the shift from cone to rod vision occurs

Have a refractory period of1 ms

upper firing rate is 500 to 800 impulses per second

Sodium ions (Na+)

positive charge

Chlorine ions (Cl-)

negative charge

Potassium ions (K+)

positive charge

Convergence

allows a neuron to receive input from many neurons in a network