Pain and Vision Flashcards
Cornea
shields the eye from germs and dust; bends the light
Iris
Colored disc inside the eye; separates the cornea from the lens
What are the 2 chambers in the iris?
the anterior chamber (between the cornea and the iris) and the posterior chamber (between the iris and the lens)
Eye color determined by
the iris
The ____ controls the amount of light entering the eye
iris
During the activation of the parasympathetic nervous system, the sphincer pupillae is _____, and the dilator pupillae is ______
contracted, relaxed
During the activation of the sympathetic nervous system, the sphincer pupillae is _____, and the dilator pupillae is ______
relaxed, contracted
As distance increases… (changes in lens shape, ciliary muscles, suspensory ligament)
lens is less convex (more flat); tension on suspensory ligaments, ciliary muscles relax
As distance decreases… (changes in lens shape, ciliary muscles, suspensory ligament)
lens is more convex, ciliary muscles contract, less tension on suspensory ligaments
the retina
processes light by converting visual stimulus into neural activity
What is the pathway of light
ganglion cells, bipolar cells, photoreceptors
What does the Muller glia do in the retina?
helps light go through without modification; like a tunnel
The outer segment of the rods and cones…
where we find a lot of pigment- sensing the light
The inner segment of the rods and cones…
contains things that help with the cellular functions; synapses occur here
true or false: is it retinal that is sensitive to light
true- it changes shape because of light
Do rods and cones fire action potentials?
no- they do not fire action potentials
In the dark is 11-cis retinal present or 11-trans retinal
11-cis retinal
In the light is 11-cis retinal present or 11-trans retinal
11-trans retinal
In the dark, are the photoreceptors depolarized or hyperpolarized
depolarized
In the dark are neurotransmitters released?
Yes- because it is depolarized- it releases neurotransmitter
In the light, are the photoreceptors hyperpolarized or depolarized?
hyperpolarized
In the light, do photoreceptors release neurotransmitters?
no- because they are hyperpolarized
What is the ligand for the CNG channel?
cGMP
in the _____, there is an increased level of cGMP
dark
What would happen to the photoreceptor if the CNG channels would not open? (what ions are flowing, de/hyperpolarized, when does this happen)
Only K+ would be flowing out making the photoreceptor more negative- leads to hyperpolarization- this happens in light
What happens when the CNG channels are opened
influx of positive ions (Na+ and Ca2+)
What is the role of transducin?
When activated, it decreases the concentration of cGMP
How does transducin decrease the cGMP concentration?
by activating phosphodiesterase
Do bipolar cells generate action potentials?
no sir (they respond to glutamate with graded potentials)
On bipolar cells
detect light objects in a dark background
Off bipolar cells
detect dark objects in a light background
On bipolar cells are ….. by glutamate
hyperpolarized (because it inhibits on bipolar cells)
Off bipolar cells are ….. by glutamate
depolarized (because it activates off bipolar cells)
What do the retinal ganglion cells do
They detect shape and movement
Type P ganglion cells characteristics
color sensitive, small concentric receptive field, slowing adapting
Type M ganglion cells characteristics
larger than P cells, synapses with many bipolar cells, color insensitive, fast adapting
What is the order of visual processing
receptors, bipolar cells, retinal ganglion cells, lateral geniculate nucleus (in thalamus)
M-Pathway is for
movement
P-blob pathway is for
color
P-interblob pathway is for
form and depth
Horizontal cells
synapse with surrounding photoreceptor cells; they affect how you are going to send message to the bipolar cells; important in providing contrast (lateral inhibition)
Amacrine cells
synapse with bipolar cells and ganglion cells; provide lateral connections
When there is diffuse light on both center and surrounding of the eye what are the responses from the on-center and off-center retinal ganglion cells
both have a weak response from ganglion cell
What are the two types of pain fibers
A delta and C fibers
The lateral geniculate nucleus receives info about… and how does it process it
stimulus location and contrast (rod pathways are separate from cone pathways- parallel processing)
M cells and P cells are types of
retinal ganglion cells
the M pathway, the P blob pathway, and the P inter-blob pathway are found where
the lateral geniculate nucleus
V4 percieves
color
The inferior temporal cortex is the
face recognition cortex
