Unit 2 Flashcards
_______ pain is felt within 0.1 seconds after a stimulus is applied. Not felt in most deep tissues of the body such as the viscera.
Fast pain
______ pain is sharp, prickling, acute, electric
Fast pain
_____ pain is felt more than 1 sec after the stimulus is applied
Slow pain
_____ pain can arise in almost any tissue. Manifests as burning, aching, dull, throbbing, nauseous, chronic
Slow pain
What is the sensory ending type of pain receptors?
Free nerve endings
The stimuli of pain receptors that makes it polymodal are ______, ______ and _____
Mechanical
Thermal
Chemical
______ and ______ stimuli manifest as fast and slow pain
Mechanical and thermal
______ sitmuli stimulate slow pain only
Chemical
what are some examples of chemical stimuli that stimualte pain (8)
Bradykinin Serotonin Histamine Poteolytic enzymes K+ Acids Ach
What are 2 examples of chemicals that lower pain threshold?
Prostaglandins and substance P
Pain is ______. In the sense that the nociceptors will fire as long as the stimulus is present
Non-adapting
When pain intensity increases it is referred to as ______
Hyperalgesia
________ ____ pain manifest from mechanical or thermal stimuli and are more likely to react immediately
Fast sharp pain
Fast sharp pain transmits from ______ fibers and involved in quick immediate reactions
Adelta fibers
_____ _____ pain is mostly by chemical stimuli but also by persistent thermal or mechanical stimuli
Slow dull pain
Slow dull pain is transmitted through _______ fibers and is more likely to intensify over time
C type fibers
Slow dull pain is transmitted through _______ fibers and is more likely to intensify over time the neospinothalamic tract pain type and fiber
Fast pain
Adelta fibers
Where does the first order neuron terminate in the neospinothalamic tract?
Lamina 1 of the dorsal horn
Describe the second order neuron of the neospinothalamic tract
Second order neuron decussates through the anterior commissure to ascend the anterolateral tracts
In the neospinothalamic The second order neuron decussates through the _________ to ascend the _______tracts
Anterior commissure
Anterolateral tracts
In the neospinothalamic tract. The second order neuron terminations:
Some fibers end in the _______
Most fibers terminate in the _____
Some fibers end in the reticular area of the brain stem
Most terminate in the VPL ( or VPM for the head) of the thalamus
In the neospinothalamic tract the third order neuron projects from the _______ to the _____
Thalamus to the somatosensory cortex
In _________ tract. Fairly accurate localization with the help of simultaneous activation of neighboring tactile sensory activation
Neospinothalamic
What NT is released in the neospinothalamic tract?
Glutamate
_______ tract is associated with slow chronic pain (C fibers)
Paleospinalthalamic tract
First order neurons of the paleospinothalmic tract terminate in lamina ______ and ______ (________ of the anatomical naming system.
II and III
Substantia gelatinosa
In the paleospinothalamic tract, several interneurons connect laminas _____ and ______ with lamina _____
II and III with lamina V
In the paleospinothalamic tract, second order neurons decussate to the opposite side through the ________ and ascend via the ______
Decussate through the anterior commissure
Ascend via the anterolateral pathway
In the paleospinothalamic tract, what is the NT released in the cord?
Substance P
In the paleospinothalamic tract , most second order neurons terminate in what 3 areas?
Reticular formation of the brain stem
Tectal area of midbrain
Periaqueductal gray region
A FEW 2nd order neurons pass all the way to the ______
Thalamus
The __________ tract has poor localization of the source of the stimulus
Paleospinothalamic tract
Pain not ONLY is perceived in the ______ gyrus, but also in primitive areas as well such as the _____ , ______ and ______
Post central gyrus
Cortex, Thalamus and brain stem
The cortex of the brain interprets what component of pain?
Pain quality
The thalamus and brain stem feels what aspect of pain?
The unpleasantness/ suffering aspects of pain
Pain participates in the _____ system of the brain
Arousal
What two levels can pain perception be modified?
At the level of the brain and at the level of the spinal cord
How is pain perception modified at the level of the brain?
Analgesia system involves endogenous opiates
How can pain perception be modified at the level of the spinal cord?
By the gate control theory
what are the 4 components of the central analgesia system?
Periventricular nulcei
Peri-aqueductal gray
Raphe magnus nulceus
Pain inhibitory complex
Of the central analgesia parts, the perventricular nulcei in the __________ surrounds the _______
Hypothalamus
3rd ventricle
Of the central analgesia parts, the peri-aqueductal gray surround aqueduct in the _______ and _______
Midbrain and upper pons
Of the central analgesia parts, the Raphe magnus nulceus is a thin midline nulceus in _________ and _______
Lower pons and upper medulla
Of the central analgesia parts, the pain inhibitory complex is in the _______
Dorsal horn of the spinal cord
______ and ______ secreting neurons are a key component in pain modulation in the central analgesia parts
Enkephalins - endogenous opiates
Serotonin
What activates the analgesia system?
Stress/limbic system
What can activate the analgesia system?
Both the stress of pain and the psychological.emotional state of the individual
Stress also activates the sympathetic NS and ACTH/cortisol release
Pain pathways terminate in many of the same areas that are part of the __________. Therefore pain pathways may lead to their own _____
Analgesia system
Inhibition
What are the 3 families of mediators of analgesia?
Enkephalins
Endorphins
Dynorphins
_______ is a precursor to endogenous opioid peptides called MSH and ACTH and beta-endorphin
POMC (pro-opiomelonocortin)
What occurs in gate control theory?
With gate control add in sensation from skin and mechanoreceptors. It has a side branch (lateral branch) that goes to the inhibitory neuron. So it excites an hibitory neuron which results in inhibition
When the mechanoreceptor are stimulated it tend to weak the stimulus up to the thalamus.
When you feel pain from an injury and you shake the body part or rub the area instinctively is referred to as an example of ___________
Gate control theory
__________ is where pain from a visceral organ is referred to a body surface
Referred pain
What is the mechanism of referred pain?
Visceral pain fibers and skin nerve fibers converge on the same second order neuron where cross talk can occur effect the dermatomes of the same spinal level.
________ is where the pain refers to the dermis that shares the same embryonic spinal level as the visceral organ and is a big part of the mechanism of referred pain.
Dermatomal rule
_______ is pain orignating in a visceral structure perceived as being from an area of skin innervated but the same segmental level as the visceral afferent
Referred pain
What does referred pain result from?
Cross talk in the dorsal horn where the convergence of somatic and visceral afferents on the same segmental level of the SC
Some referred pain from viscera follows ________ innervated by the same spinal nerves
Dermatomes
What are 5 causes of visceral pain?
Ischemia Chemical damage Spasm of smooth muscle in a hollow organ Excessive distension of a hollow organ Stretch of visceral CT
_______ fibers are involved with visceral pain and transit ______ type of pain
C type fibers
Chronic-aching- suffering type of pain
______ is accumulation of acidic metabolic end products, bradykinin and proteolytic enzymes
Ischemia
What are the viscera that are insensitive to pain?
Parenchyma of the liver (ex: hepatocytes)
alveoli of the lungs
Brain
What are examples of viscera that ARE sensitive to pain?
Peritoneum
Bile ducts
Bronchi
Pleura
Are Blood vessels (dural sinuses and middle meningeal artery) and meninges sensitive to pain?
Yes
Visceral disease leads to _______ pain
Poorly localized dull pain
Visceral disease causes _____ pain when inflammation spreads to partietal serous membranes
Sharp more localized pain
AKA parietal pain
Visceral disease can cause parietal pain
An intracranial headache has a pain referral pattern. Above the tentorum, pain is referred to the ______
Below the tentorum, pain is referred to ______
Forehead
Occipital area
An extracranial headache is referred to the _______
Face behind the eyes
What are examples of causes of intracranial headaches?
Meningitis Low CSF pressure Migraines Cluster headaches Alcohol
What are the extracranial causes of head aches?
Tension head aches
Nasal or sinus infection
Eye disorders
What are 4 types of head aches?
Sinus
Cluster
Tension
Migraine
______ head aches, pain is behind browbone and or cheeks
Sinus head ache
_______ headaches, pain is in and around one eye
Cluster head aches
______ headaches, pain is like a band squeezing the head
Tension
________ headaches, pain, nausea and visual changes are typical of classic form
Migraine
________ is the other part of the anterolateral system other than pain
Temperature/ thermal modalities
Thermoreceptors exhibit ______, feel abrupt change in temperature (especially cold) then subsides
Adaptation
Swings in temperature that occur due to _________ are usually not perceived. 31-36 degrees Celsius (88-97 degrees F)
Thermoregulation
_______ is body temperature regulation by vasomotoion of cutaneous blood vessels
Thermoregulation
________ has to do with the rate light is absorbed by atoms and re-emitted as light as it passes through a medium
Optical density
_______ is a common way to express the optical density of an object by comparing the density of medium in question with a vacuum
Refractive index
Velocity of light in vacuum/ velocity of light in medium
Describe refraction of light as it enters a medium perpendicularly
Light that enters a medium perpendicular to the surface of a medium slows but goes in a straight line
Describe refraction of light that enters a medium at an angle
Light that enters at an angle bends.
The degree of bending of light as it enters a medium at an angle depends on what 2 things?
The ratio of 2 refractive indices of the material involved
The degree of angulation of the second medium
_______ lenses causes convergence of light (______)
Convex lenses; focuses
__________ is the point away from the lens that light converges into one spot
Focal point
_________ is the distance from the lens to the focal point
Focal length
If you change the curvature of the lens, you can change the _________
Focal length
_________ lenses cause divergence of light
Concave
Light rays from a close POINT source is ________ as it hits the lens
Light rays from a DISTANT source are ________ as it hits the lens
Diverging
Parallel
Near point focal lengths is _______ (length)
Longer
To shorten a focal point for a near source a more ________ lens is needed
Convex
An _____ is a mosaic of many point sources
Image formation
As light from each point source is projected through a convex lens the image is _________
Inverted
Image detector (_______, ______) must be lined up at the __________ to create a sharp image
Film, retina
Focal points
The more a convex lens can be light, the ________ its refractive power
Greater
Refractive power is measured in _______.
1 meter focal length = ____
1/2 meter focal length =_____
1/4 meter focal length = ______
Diopters
+1 diopter
+2 diopters
+4 diopters
For a concave lens, refractive power is measured to the ____________.
Rate light diverges
If a concave lens diverges light rays as much as a +10 diopter lens converges them, the refractive power is _______ diopters
-10 diopters
What is the pathway of light through the interfaces of the eye?
Air -> cornea -> aqueous humor -> lens -> vitreous humor
The greatest change in refractive power is the transition from ______ to _______
Air to the cornea
______ is the strongest lens of the eye
The cornea
the refractive power of the eye is ___ diopters in an unaccommodated and distant light source
+59
Describe accommodation of the eye
The lens changes its shape and therefore its refractive power to focus the image
For near vision, the circular muscle ______ or ________ to focus.
contracts or Accommodates
The circular muscle _______ for far vision
Relaxes
________ controls the circular muscle that is involved in accommodation of the eye
Oculomotor nerve - parasympathetic
______ functions to change the amount of light that enters the eye. Ranges from _____ to ______mm
Iris
1.5 - 8mm
In regards to the Iris more light enters at ________ and less light enters during the _____. (Night or day)
Night
Day
Does a smaller or larger pupil give greater depth of focus?
Smaller pupil has greater depth of focus
The depth of focus is determined by what?
The size of the pupil
The smaller the pupil, the greater depth of focus
______ is a refractive disorder of the eye in which parallel light from a distant course is in focus and lens accommodation is normal.
Normal vision.
Emmetropia
_________ is a refractive disorder of the eye in which lens becomes less elastic and won’t round up during ciliary muscle contraction
Presbyopia
_________ is AKA farsightedness
Hyperopia
In ________ the focal point is behind the retina so the lens is used to focus for FAR vision; not enough left to focus for near vision.
Hyperopia (farsightedness)
__________ is AKA nearsightedness
Myopia
In _______ the relaxed eye the focal point is ahead f the retina. Cannot focus distant objects
Myopia (nearsightedness)
_________ is irregular shape of the cornea
Astigmatism
________ are cloudy areas in the lens caused by denatured eye proteins
Cataracts
Describe the differences between near and far sightedness with normal vision.
Normal vision: occurs when light is directly focuses on the retina rather than infront or behind it
Near sightedness: visual image is focused infront of the retina
Farsightedness: visual image is focused behind the retina
_______ is normal vision
_________ is myopia
20/20
20/100
What doe 20/100 visual acuity mean?
What a normal person can see at 100 feet, the nearsighted person can see at 20 feet
The bigger the bottom number the worse the vision
_______ is the ability to perceive relative distance of objects in the visual field
Depth perception
What are the 4 mechanisms of depth perception?
Sizes of images of known objects
Moving parallax
Stereopsis
Occlusion
How can size of known objects effect depth perception?
This wold get can be used to judge the distance away a person is relative to the size the image appears on the retina
When a person is moving foreground objects appear to be passing by faster than distant objects is the ____________ mechanism of depth perception
Moving parallax
_______ is AKA binocular vision. Light from distant objects project to more central points in the retina. Light from near courses project more laterally
Stereopsis of depth perception
When is binocular vision most useful?
In closer ranges
______ is the points in space whose images fall on corresponding points on the two retinas so that it appears as a single object
Horopter
Binocular disparity appears as ______
Double vision
Points neared than the Horopter have _______ disparity
Crossed
Points father than horopter have _______ disparity
Uncrossed
Binocular disparity can be ______ or _______
Crossed or uncrossed
In depth perception, _______ is used as a cue to depth to where if something is infront of another you obscure the vision to the object that is behind to focus on the thing infront.
Occlusion
________ is liquid formed by the ciliary processes of the eye
Aqueous humor
_________ circulates between the cornea and lens and is removed through the Canal of Schlemm
Aqueous humor
Aqueous humor circulates between the ______ and the _______ and is removed through the _________.
Circulates- between cornea and lens
Removed- canal of schlemm (scleral venous sinus)
The aqueous humor is removed through the canal of schlemm which empties into the _______ veins
Extraocular veins
______ exerts a pressure inside the eye to keep it distended (about 15mmHg)
Aqueous humor
________ occurs due to increased intraocular pressure due to aqueous humor outflow problems such as debris clogging canal of schlemm
Glaucoma
In glaucoma, pressure can be measured by ______. The pressure can compress _______ leading to permanent ______
Tonometry
Retina
Blindness
The main symptom of glaucoma is _________
Gradual loss of vision
What is chronic open angle glaucoma?
Loss of peripheral field vision happens first
What are some indications of acute angle glaucoma?
Sudden ocular pain and decreased vision Seeing halos around light Red eye Very high intraocular pressure Nausea and vomiting Fixed , mid-dilated pupil (oval pupil in some cases)
The light must pass through _______ to be detected by photoreceptors in the retina
Most of the retinal layers
The retinal layer arrangement causes _________ of visual acuity (loss or gain)
Some loss of visual acuity
_______ is where the ganglion cells converge to form the optic nerve
Blind spot
______ is the area of sharpest vision
Central fovea
What makes up the photoreceptor layers of the central fovea?
Almost all cones
In the central fovea, the Superficial layers of the retina are _______ to improve visual acuity of that area
Pushed aside
The retinal layers function to cause some loss of visual acuity which is why in the area of greatest visual acuity the retinal layers would be pushed aside
The ______ layer of the retina contains melanin and stores vitamin A
Pigment layer
What is the function of the melanin in the epithelium in the pigment layer?
Absorbs light so that it wont scatter within the eyeball
Albinos lack the _______ part of the pigment layer and therefore have _______ (better or poorer) visual acuity
Pigment (melanin)
Poorer visual acuity
What are the layers of the retina? External to internal
External limiting membrane Pigment epithelium Photoreceptor layer Outernuclear layer Outerplexiform nucleus Inner nuclear layer Inner plexiform layer Ganglion cell layer Nerve fiber layer Inner limiting membrane
What are the upper and lower borders of the retinal layers?
Upper- external limiting membrane
Lower - internal limiting membrane
What are the 3 layers of the photoreceptive cells (rods and cones)?
Outer segment
Inner segment
Synaptic endings
The _____ segment is light sensitive
The ______ segment is composed of the cytoplasm and nucleus
The synaptic endings synapse with _____ and _____
All are components of the photoreceptive cells
Outer segment- light sensitive
Inner segment - cytoplasm and nucleus
Synaptic endings - synapse with bipolar and horizontal cells
Outer segments of photoreceptors contain membrane shelves that contain either ______ and ______
Rhodopsin (rods) Color pigments (cones)
Rhodopsin is inactive, what is the active form of rhodopsin?
Metarhodopsin II
______ and ______ can be recycled to form rhodopsin
Scotopsin and 11-cis retinal
Metarhodopsin II ( active rhodopsin) breaks into ______ and _______
Scotopsin and all trans-retinal
All trans retinal can be converted into ________ which is AKA vitamin A
All-trans retinol
________ is activated rhodopsin
Metarhodopsin II
What is the function of metarhodopsin II?
Excites the rods
What is the role of vitamin A in rhodopsin activation?
Needed to supply eye with retinal as needed;
Excess is stored in the pigment epithelium
In reconstituting rhodopsin, all trans retinal is converted to _______ and recombined with _____
11-cis retinal ; scotopsin
What is the result of vitamin A deficiency
Night blindness
Main cause of blindness world wide
Rods use ______, cones use _____
Rods - scotopsin
Cones- photopsins ( color opsins)
What are the 3 types of color opsins (photopsins)?
Blue-sensitive
Green-sensitive
Red sensitive
T/F: rod receptor potential is hyperpolarizing, not depolarizing
True
In the excitation of rods:
In the DARK state, _____ cGMP levels keep Na+ channels _______ making a RMP of -40mV
In the LIGHT state, _______ leads to hydrolysis of cGMP making Na+ channels ______
Dark state: high cGMP, Na channels open
Light state: activated rhodopsin leads to hydrolysis of cGMP; Na channels close
Mechanism of excitation of rods (5 steps):
Light activates rhodopsin Rhodopsin activates transducin Transducin activates phosphodiesterase Phosphodiesterase converts cGMP into GMP Therefore less cGMP is available to keep cGMP gated Na channels open
What type of channels are important in rhodopsin excitation?
cGMP-gated Na+ channels
The cascade from rhodopsin activation by photons to the activation of phosphodiesterase is ______. Such that a single photon can lead to _______ in Na+ conductance
Amplify
Significant drop in Na+ conductance
________ is the enzyme that inactivates the activated rhodopsin (metarhodopsin II) and the rest resets.
Rhodopsin kinase
What are the peaks of wavelengths the 3 photopsins are sensitive to?
Blue - 445 nm
Green - 535 nm
Red - 570 nm
The ______ portion of all visual pigments is the same
Retinal
Is the mechanism for excitation of cones the same as rods?
Yes
Are cones more or less sensitive to light than rods?
Less sensitive about 30-300 times
How does the brain interpret colors?
Based on the degree to which cone or cones respond to a particular wavelength of light.
The proportion to which each is stimulated determines color perception
What makes someone red-green color blind?
Absence of either green (deuteranope) or red cones (protanope)
______ is a type of color blindness inherited as an X-linked trait.
Red-green colorblind
_______ (______) is due to underrepresented blue cones it is rare and NOT X-linked
Blue weakness (tritanope)
_______ is total color blindness
Monochromacy
In rod monochromacy the retina has no _______
In cone monochromacy there is only ________ of the cones
Rod- retina has no cones
Cone- only has one of the 3 cones
What is used to test for color blindness?
Ishihara test plates
________ can see all colors
_________ reduced ability to see red
________ reduced ability to see green
Trichromacy
Protanopia
Deuteranopia
What is the mechanism of light adaptation?
When in bright light for a while, muscle of the photopigments in the rods and cones would be reduced to retinal and opsins. Some retinal will be converted to vitamin A. Therefore sensitivity will be reduced.
What is the mechanism of dark adaptation?
Retinal and opsin are re-converted to photopigments to increase sensitivity
Compare rods vs cones in adaptation
Cones adapt faster
Rods have a broader range of sensitivities
_________ synapse wiht bipolar cells and horizontal cells
Photoreceptors (rods and cones)
_________ transmit horizontal signals from photoreceptors to bipolar cells
Horizontal cells
_______ transmit signals vertically from photoreceptors and horizontal cells to the inner plexiform layer
Bipolar cells
_______ cells transmit either directly from bipolar cells to ganglion cells or horizontally within the inner plexiform layer or to other _____ cells
Amacrine
Amacrine
What three places do amacrine cells transmit their signals from?
1) directly from bipolar cells to ganglion cells
2) horizontally within the inner plexiform layer
3) to other amacrine cells
______ transmit output signals from the retina to the optic nerve
Ganglion cells
_________ cells are involved in retrograde signals that help control degree of contrast in the visual image
Interplexiform cells
What is the order of neural circuitry of the retina in the fovea?
Cones -> bipolar cells -> ganglion cells
In the fovea there is ______ convergence, ______ system for sharp color and _______ and ____ cells cause lateral inhibition
Little convergence
Fast system for sharp color
Also horizontal and amacrine cells cause lateral inhibition
What is the neural circuitry in the peripheral retina?
Both rods and cones -> bipolar cells -> amacrine cells -> ganglion cells (some bypass amacrine)
In the fovea and the peripheral retina ______ and ______ cells have lateral inhibition roles
Horizontal
Amacrine
Retinal cells except _______ cells do not form action potentials
Ganglion cells
What is the only cell in the retina that actually forms an AP?
Ganglion cell
How do the retinal cells conduct signals to the deeper layers of the retina?
direct Electrical current
Direct electrical current in the retina allows for ________ conduction instead of _________
Graded conduction instead of all or none conduction
Photoreceptors have a _____ membrane potential
Bipolar cells have a _______ membrane potential
Hyperpolarizing
Depolarizing
_______ cells connect laterally between rods, cones and bipolar cells
Horizontal cells
Is the output of horizontal cells inhibitory or excitatory
Always inhibitory
________ prevents lateral spread of light excitation on the retina visual field
Lateral inhibition through the horizontal cells
What is essential for transmitting contrast borders in the visual image?
Lateral inhibition
What are examples of amacrine cell functions of different types of amacrine cells
1) direct pathway for rod vision
2) responds rapidly to stimulus onset
3) responds rapidly to stimulus off set
4) responds to both onset and offset
5) group is directionally sensitive
T/F: visual information is processed before the signals leave the eye
True
There are many more rods and cones than ganglion cells, therefore there are a lot of __________ circuits within the retina
Convergence
In the fovea there is _____ (more or less?) convergence than in the periphery
Less
What features of the fovea improve acuity?
Much less convergence than in the periphery
Cones are slender to pack in more photoreceptors
In the peripheral retina, the rods are ________ light sensitive and there is ______ convergence
Much more sensitive to light
More convergence
What features of the peripheral retina improve dim light perception?
Rods are much more light sensitive
There is more convergence in rods
Ganglion cell axons converge to form the ______ that leaves the eye at the ______
Optic nerve
Blind spot
Ganglion cells produce _______ potentials while rods, cones and other retinal cells produce _________ types of potentials.
Ganglion cells - action potentials (AP)
Rods cones and other cells- electrotonic conduction
What are the two ganglion cell populations?
P cells (parvocellular) M cells (magnocellular)
P cells have \_\_\_\_\_\_\_ receptive fields \_\_\_\_\_\_ impulse conduction \_\_\_\_\_\_\_\_ responses to stimuli \_\_\_\_\_\_\_\_ to color stimulus
Smaller receptive fields
Slower impulse conduction
More sustained responses to stimuli
Sensitive to color stimulus
M cells are more sensitive to contrast _______ and ______ stimuli
Contrast black and white stimuli
The opthalmic artery gives rise to what 2 artery’s that supply the eye?
Central retinal artery
Posterior ciliary arteries
What is the blood supply to the retina itself?
Central retinal artery
the central retinal artery enters the _________ to enter the _______ of the eye then branches throughout the retina
Optic nerve
Blind spot
What is the blood supply to the choroid coat and outer segments of the rods and cones?
Posterior ciliary arteries
retinal detachment is when the neural retina occasionally detaches from the _______
Pigment epithelium
What are 2 examples of causes of retinal detachment?
Injury
Pulling effect by defective vitreous humor fibers
The direct visual pathway from the ganglion cells to the visual cortex is:
Ganglion cells form the _______
Optic nerves from both eyes converge on the _________. The fibers emerge from chiasm as the ________ which terminates in the _________
Optic nerve
Optic chiasm
Optic tract -> lateral geniculate nucleus of the thalamus
In the visual pathway once the optic tract terminates in the lateral geniculate nucleus, second order fibers project ot the ________ via the ______
Occipital cortex via the geniculocalcarine tract (aka optic radiations)
The primary visual cortex is in brodmanns area _____ in the gyri next to the _______ fissure
17
Calcarine fissure
Optic nerves converge at the optic chiasm. There is a ______ retina that decussates and a _____ retina that does not
Nasal retina decussates
Temporal retina does not
Lateral visual field projects to the ______ retina
Medial visual field projects to the _____ retina
Medial retina (nasal retina) Lateral retina (temporal retina)
Nasal retina of ______ eye (R or L?) and the temporal retina of the _____ eye(R or L?) projects to the right visual cortex
Nasal retina of left eye
Temporal retina of the right eye
Project to the right visual cortex
What are 3 older areas of the brain that the visual pathways also connect?
Suprachiasmatic nucleus (hypothalamus) Prerectal area (midbrain) Superior colliculus
_________ has visual fibers involved and functions to control circadian rhythms
Suprachiasmatic nucleus (hypothalamus)
________ is a older area of the brain associated wiht the visual pathways in which reflex movements of the eyes and activating pupillary light reflex
Prerectal area (midbrain)
_______ is an older area of the brain also associated with the visual pathway; it functions in controlling rapid directional movements of the two eyes
Superior colliculus
the lateral geniculate nucleus has 2 layers of cells. Magnocellular and pravocellular. Layers 1 and 2 receive information from ________ cells.
Layers 3-6 receive information from _______cells
Layers 1 and 2: M cells (magnocellular)
Layers 3-6: P cells (parvocellular)
Layers 1 and 2 of the lateral geniculate nucleus are magnocellular layers which have _______ vision and poor ________
Black and white vision
Poor point -point discrimination
Layers 3-6 of the lateral geniculate nucleus are parvocellular layers which have _____ vision, good ________ and ______velocity
Color vision
Point-point discrimination is good
Slower velocity
What are other names for the visual cortex?
V1 and striate cortex
Where does the visual cortex lie?
Along the calcarine fissure of the medial occipital lobe
Brodmanns area 17
In the primary visual cortex, signals from the ______ are most posterior and _______ is more anterior
Macula most posterior
Peripheral vision most anterior
Where in the primary visual cortex does the upper retina project to? Lower retina?
Upper retina- gyrus superior to the calcarine fissure
Lower retina - goes lower to the lower gyrus
What is another name for secondary visual cortex?
V2, visual association area
Secondary visual cortex surrounds the ________. Brodmanns area _____
Primary area
18
V1 (primary visual cortex has _________ layers
6
________ fibers of the primary visual cortex mainly terminate in layer IV
Geniculocalcarine
The M cells and P cells terminate in different subsections of layer ______ then signals are passed vertically to more superficial and deep layers.
layers I-III transmit ______ distances
Layers V-VI transmit ______ distances
IV
Short
Further
________ columns processes a bit of visual information. Some columns form _________ which are primary areas for deciphering color
Vertical neuronal columns; color blobs
T/F: signals from the two eyes remain separate until they reach the cortex for comparison
True
Lateral retina of the left eye P ganglion cell -> _______ layer layers 3-5-> a particular visual column in the ______ visual cortex
Ipsilateral LGN
Left visual cortex
Columns from the left and right eye in the cortex are ______ to each other and are compared there to check if the images are ________
Adjacent ; “in register”
What is the basis of stereopsis and important to adjust the directional gaze so the eyes are focused not he object of interest?
Columns for the left and right in the cortex are adjacent to each other like stripes and are compared there to check if the images are in register
Cortical visual analysis has a ______ and ______ pathway
Fast and slow
The fast pathway for cortical visual analysis is for _______ and _______
Position and motion
slower pathway of cortical visual analysis are for ______ and _____
Accuracy and color
_______ pathway of ______ analyzes gross physical form of the scene and detects motion
Fast pathway of cortical visual analysis
Fast pathway of cortical visuala nalysis mainly uses information from _______ ganglion cells (______, _____)
M ganglion cells (rapid signals, no color)
After the fast pathway leaves V1 it goes to ________ cortex where it merges with signals from the somatic association area
V2 occipitoparietal cortex (secondary visual cortex)
The slower pathway of cortical analysis is for ______ and _______
Accuracy and color
________ analyses visual detail and color. Uses information from P ganglion cells as well as M
Slower pathway of visual cortical analysis
After the slower pathway leaves the primary cortex it goes tot eh secondary visual cortex in the _______ and ______ areas of the ______ and _____ cortex
Inferior ventral and medial
Occipital and temporal
Which pathway In cortical visual analysis is necessary for reading, seeing texture and detailed color?
Slower pathway of cortical visual analysis
A blind spot is found ab out ______ degrees _______ to the central point of vision
15 degrees lateral
What occurs when there is a lesion of the right optic nerve?
Total blindness of the right eye
What occurs due to a lesion involving the right perichiasmal area?
Right nasal hemianopia
What occurs due to a midline chiasm always lesion?
Bipolar (Bitemporal) hemianopia
What occurs due to a lesion o pressure on the right optic tract?
Left homonymous hemianopia
What occurs due to a lesion of the right occipital
Left homonymous hemianopia
What eye muscles moves eyes sideways
Medial and lateral recti
What muscles moves eyes up and down?
Superior and inferior recti
What muscles rotate eyeballs to keep visual fields upright?
Superior and inferior oblique
CN III innervates what eye muscles?
CN IV?
CN VI?
III - all other extraocular muscles
IV- superior oblique
VI- lateral rectus
Medial longitudinal fasciculus (MLF) receives information from what 4 areas?
Vestibular nuclei (equillibrium) Lateral lemniscus (hearing) Superior colliculus (visual) Frontotectal tract (voluntary movements)
What are the efferents of the medial longitudinal fasciculus?
CN III, IV, VI to control extraocular muscles
_______ functions to coordinate head and eye movements in response to visual, auditory, balance and voluntary signals
Medial longitudinal fasciculus
_______ is within the brain stem and links the vestibular nuclei with the nuclei supplying the extraocular muscles and coordination of the head and eye movements
MLF
How is voluntary fixation controlled?
The premotor area in the frontal lobe
How is involuntary fixation controlled?
Controlled by area in secondary visual cortex
What si the difference between voluntary and involuntary fixation?
Voluntary - voluntarily setting your gaze
Involuntary- locks the gaze on the object.
Can only be unlocked by voluntary override or by closing eyes
The eyes have a continuous tremor, to _______ and may drift its gaze.
To keep the visual stimulus fresh
When an object drifts for the fovea as a result of these continuous tremors, the eyes reflexively move the object back (______)
Saccades
The mechanism of involuntary fixation’s effect is mediated by the _________
Superior colliculus
Superior colliculus also causes you to turn your head toward a visual disturbance involuntary
What are 2 examples of saccadic movement?
Optokinetic movements (when riding in a car, the eyes fix on successive objects then jump to the next)
Reading (eyes do not smoothly can from left to right when reading. Does a series fo saccades from one group of words to the next)
________ is fixation on a moving object
Pursuit movement
Fixation on a moving object is ______ (smooth or choppy)? The eyes get fixed on amoving object, then move with the object wot keep it in the _______
Smooth ; fovea
In ________ of visual images, the two eyes must be aimed the correct direction in order for the points of the same image to land on both fovea. If not the image will not be ________
Fusion of visual images
Fused
In ________ because the eyes are about 2 inches apart, images can never be completely fused. The closer an object is to the face the more interference there will be
Stereopsis
What is the basis of binocular depth perception?
Stereopsis
_________ is due to lack of fusion between the 2 eyes?
Strabismus
_______ is Often due to some damage to one of the ocular CN‘s
Strabismus (lack of fusion between 2 eyes
Strabismus may be due to cortical reasons as well when the brain ignores one eye due to _______
Prolonged issuers wiht poor fusion or focus (amblyopia or lazy eye)
Explain the pupillary light reflex. And what are the 2 types?
Shining a light into one eye causes bilateral pupil constriction (sphincter of the iris)
Direct (same eye) consensual (opposite eye)
The pupillary light reflex’s motor pathway is similar to cause _________
Lens focus (ciliary muscle)
Interruption in Sympathetic innervation to iris is called _______
Horner’s syndrome
Interruption of the sympathetic pathway to the head leads to ______, _______ and ______
Mitosis (pupil constriction)
Anhydrosis (lack of sweating on affected side)
Ptosis (droopy eyelid)
What are 3 effects of accommodation (focusing for near objects)?
Constriction of the pupils
Increased lens thickness (ciliary muscle contraction)
Medial convergence of eyes
What is the pathway of accommodation reflex?
Blurred retinal image-> retinal nervous elements -> optic nerve -> optic chiasma -> optic tract -> LGB (thalamus) -> optic radiation -> primary visual area (17); occipital lobe and association visual area (18 and 19)
