Vision Sensory System Flashcards
What is light with regards to reception by the eye?
The visual signal.
What are the three criteria that “perceiving” a visual signal requires?
1) The eyes capable of detecting, focusing, and responding to light
2) The appropriate neural pathways
3) Brain regions to interpret the signal
Define visual perception.
The ability to detect light and interpret it.
What is the purpose of rod and cone cells?
To convert visually transduced light into electrical signals.
Where are rods and cones located within the eye?
The retina.
Name the steps of visual perception starting with light passing through the threshold.
1) Threshold passage
2) Transduction by receptors
3) Conduction by afferent neurons
4) Processing by brain
5) Perception
Define wavelength (l).
The distance between successive peaks of EMR.
Between what wavelengths can the human eye perceive and what is this portion of the EMR called?
400-750 nm.
Visible spectrum.
What distinguishes one color from another when an eye receives a light input?
Different wavelengths are what dictates the color perceived.
What portion of the EM spectrum can snakes “see”?
Infrared light.
When light passes through a concave medium, what happens?
The light is refracted to diverge relative to the original vector.
When light passes through a convex medium, what happens? What is effective formed?
The light is refracted to converge to form a focal point.
What is a focal point? (EMR)
The point at which light vectors converge and intersect.
Define what focal length is and what surfaces it is often associated with.
Focal length is the distance from a CONVEX surface to the focal point of light passing through the original medium.
With respect to light, which of its characteristics is responsible for why we can see objects that do not emit light? How can this property be defined?
Reflection is responsible for why we can see objects. Reflection is when light waves strike and bounce off surfaces we see.
When light bounces off of a surface, why do we see objects in different colors?
Different objects will absorb non-perceived wavelengths of the light striking it.
Define refraction.
Refraction is when light passes through transparent mediums of varying density.
Briefly given an overview of the eyes organization.
The eye is a 3 layered fluid filled ball that is divided into 2 chambers.
What does Layer-1 of the eye consist of? (3 items)
1) Sclera (outer layer)
2) White connective tissue capsule around eye
3) Clear cornea at the front
What does Layer-2 of the eye consist of? (4 items)
1) Choroid
2) Iris
3) Ciliary muscle
4) Zonular fibers
What is the suspensory ligament composed of?
Ciliary muscle and zonular fibers.
What does Layer-3 of the eye consist of? (2 items)
1) Retina
2) Photoreceptors
What are the two chambers of the eye and where are each located in the eye?
1) Aqueous humor (anterior)
2) Vitreous humor (posterior)
Define the function of the iris and what components of it accomplish this function.
Regulates the size of the pupil via circular and radial muscles. Therefore, determines the amount of light that enters the eye.
What is the optic nerve and what is its function?
Axons of ganglion neurons in the retina that carry info to the brain.
How does pupil size change relative to light intensity?
Bright light = smaller pupil diameter
Low light = bigger pupil diameter
In weak light, which muscles are responsible for pupil size increasing? What kind of nerves are these muscles stimulated by?
Outer radial muscles are responsible for pupil size increase and they are stimulated by parasympathetic nerves.
In strong light, which muscles are responsible for pupil size decreasing? What kind of nerves are these muscles stimulated by?
Inner circular muscles are responsible for pupil size decrease and they are stimulated by sympathetic nerves.