Lecture 26 Flashcards
What are the 4 types of pain?
fast pain | slow pain | referred pain | phantom pain
What is the characteristic of fast pain?
sharp and localized
What is the characteristic of slow pain?
dull and diffused
What is referred pain?
one area causes pain perception in other areas | pain in a body part is telling you that some other body part is in pain
What is phantom pain?
pain sensed from missing body parts | common in amputees
What is the gate control model of pain?
C-fiber and inhibitory neuron | noxious stimulus inhibits inhibitory neuron for the stimulus to go to CNS
What role does the A-beta fiber play in the gate control model of pain during a noxious stimulus?
activates the inhibitory neuron so that the noxious stimulus decreases = alleviates the pain
What is a nociceptor?
receptors that respond to pain stimulus
What is a noxious stimulus?
pain stimulus
What is the iris?
muscle that will close or open up the pupil
What is the pupil?
just an opening = aperture | reacts to light
What is the sclera?
white part of the eye | connective tissue allowing the liquid in the eye to be enclosed within its pressure chamber
What are the lacrimal glands?
secrete tears
What is the nasolacrimal duct?
drains tears into nasal cavity
What is the cornea?
thin layer of epithelial tissue right in front of the eye | sensitive with nerve endings
What is the aqueous humor?
thin watery liquid
What is the lens?
made up transparent tissue of which light can go through it
What is the retina?
neural part of the eye | can correct refractive errors of the refracted light info
What is the optic nerve?
convergence point of the retina where light info is carried to the brain
What is the vitreous humor?
gelatinous liquid within the eye
What is the foveal pit?
pit in retina = site of high resolution vision/image in color bc high concentration of cones | aligned with central axis of the eye | no bipolar or ganglion cells
What is the peripheral retina?
low resolution and detects small amount of light | used for night vision
What is the electromagentic spectrum and do all species have the same range?
visible light = what mammalian retina recognizes | each species have slight different ranges (700nm-400nm)
Why is the retina red?
due to the pigment in the pigment epithelium
What is the optic chiasm?
where the optic nerve of both eyes converges and info splits from one side of the brain to the other
What is the lateral geniculate nucleus (LGN)?
in the thalamus = where visual info goes thru before going into visual cortex
What contributes to the refractive error?
anything that the path of light passes through
What becomes the optic nerve?
axon bundles of ganglion cells
What are the 2 types of photoreceptors?
rods and cones
What are rod photoreceptors?
grey detectors (monochromic vision)
What are cone photoreceptors?
color detectors
What are the horizontal and amacrine cells?
sending lateral info
What are the bipolar cells?
has 2 poles = acting as the connection between the photoreceptors and the ganglion cells
What is phototransduction?
process of light energy is converted into electrical energy
What structures in the retina are responsible for phototransduction?
photoreceptors
What is the macula?
center of the visual field in the retina
Which part of the retina can judge between day and night and why?
ganglion cells = has light sensitivity
What is rhodopsin?
pigment in photoreceptors | first found in rods | retinal + opsin = rhodopsin
What is a fundus?
image of the retina
What are the 3 basic types of cones?
blue | green | red
What are blue cones?
has blue pigment | detect violet to yellow light
What are green cones?
has green pigment | detect blue to orange light
What are red cones?
has red pigment | detect red to green light
What do the discs in photoreceptors contain?
rhodopsin molecules with retinal inside it
When are photoreceptors most active?
when it is dark
What is the signal for neurotransmitter release? Light or dark?
darkeness
What happens when light bleaches rhodopsin?
retinal moves out of rhodopsin = opsin (bleached pigment) = takes time to recuperate
