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634 Cards in this Set

  • Front
  • Back
What are the three layers of the eye?
The sclera, the choroid, and the retina
What forms the bulk of the ciliary body?
The choroid
What is the outermost layer of the eye?
The sclera
What is the innermost layer of the eye?
The retina
What produces the fluid inside the eye?
The ciliary body
What is the fluid inside the anterior and posterior chamber called?
The aqueous humor
What is the aqueous humor responsible for?
The intraocular pressure
What is the optic nerve and retinal vessels wrapped by?
Meninges
What happens to the eye if there is a build up in intracranial pressure?
Papilledema
What is papilledema?
A build up of intracranial pressure causing engorgement and elevation of the optic disc; retinal hemorrhage
What is glaucoma?
A build up in intraocular pressure
What causes glaucoma?
Anything that interferes with circulation or reabsorption of aqueous humor
What is the pathway of light?
Cornea
Iris
Pupil
Lens
What drains the fluid in the eye between the anterior and posterior chamber?
The canal of Schlemm
What is the fluid behind the lens called?
Vitreous humor
What does the vitreous humor contain?
Phagocytic cells that clean up debris
How does the image appear on the retina?
Inverted and reversed
What is the most powerful focusing element of the eye?
The cornea
(40D)
What is the focal point?
Where light rays are focused at a common point
What is a diopter?
The inverse of the focal length; used to describe the power of the lens
What is the focal length?
The distance from the lens to the focal point
What do convex lens do to the focal length?
Decrease focal length
What do concave lens do to the focal length?
Increase focal length
What is emmetropia?
Light rays are focused perfectly
What is myopia?
Nearsightedness
What causes myopia?
Too much curvature of the corneal surface or too long of an eyeball
What is hyperopia?
Farsightnedness
What causes hyperopia?
The eyeball being too short or the refractive power of the lens is too weak
How do we correct myopia?
Add a concave lens to increase the focal length
How do we correct hyperopia?
Add a convex lens to decrease the focal length
What is accomodation?
Controlling the refractive (bending) capacity of the lens
What controls accomodation?
Ciliary muscles and zonule fibers
What do the ciliary muscles control?
The "roundness" of the lens
What do the zonule fibers control?
The flatness of the lens
What happens when the lens fattens up?
We have more refractive power; looking at things close
What happens when the lens thins?
We have less refractive power; looking at things far away
What is the dominating force when looking at things far away?
The zonule fibers
What is the dominating force when looking at things close up?
The ciliary muscle
What is happening when we are focusing on objects close up?
The ciliary muscles are contracted and the zonule fibers are relaxed
What is happening when we are focusing on objects far away?
The ciliary muscles are relaxed and the zonule fibers are contracted
What happens to accomodation as we age?
It decreases
What is presbyopia?
The loss of accomodation; due to increased rigidity/loss of elasticity of the lens
What is the maximum a presbyopic lens can accomodate to?
21D
What increases the depth of field?
Reducing the size of the pupil or iris
What fibers innervate the iris?
Sympathetic and Parasympathetic
What are the dilator muscles of the iris innervated by?
Sympathetic neurons
How are the dilator muscles of the iris arranged?
Circumferentially
What are the spinchter muscles of the iris innervated by?
The parasympathetic neurons
How are the spinchter muscles of the iris arranged?
Radially
What do the dilator muscles of the iris do?
Dilate the pupil
What do the spinchter muscles of the iris do?
Closes the pupil
When our eyes accomodate, what three things happen?
The pupil constricts
The eyes converge
The eyes accomodate
What is the near reflex?
Accomodation, convergence, and constriction
What cranial nerve controls the near reflex?
Occulomotor
What is the retina?
Where light energy is converted to electrical activity so that signals can be sent to the brain
What are cone receptors?
Photoreceptors responsible for color vision
When are cone receptors active?
When there is a lot of light
What are rod receptors?
Photorecptors used during low levels of light; used at night
What are the output cells from the retina?
The ganglion cells
Where do ganglion cells send their axons?
To the brain telling the brain about signals detected in the retina
What are bipolar cells?
Relay information from the photoreceptors to the ganglion cells
What are the two kinds of bipolar cells?
Rod and Cone bipolar cells
What are horizontal cells?
Interneurons that mediate lateral interactions amongst cells in the outer plexiform layer
What are amacrine cells?
Interneurons that mediate lateral interactions amongst cells in the inner plexiform layer
What gives the retina nourishment?
The pigment epithelium
What happens in retinal dettachment?
The retina detaches from the pigment epithelium
How is light processed through the retina?
Light is detected by the rods and cones
Released to the bipolar cells
Bipolar cells release neurotransmitter to the ganglion cells
Ganglion cells output to brain
Do rod receptors fire action potentials or graded potentials when they receive light?
Graded potentials
What is the first cell layer to fire an action potential?
The ganglion cell layer
What are the outer segments of cones and rods densely packed with?
Rhodopsin
What is rhodopsin associated with?
Retinal
What happens when light hits the rhodopsin?
Retinal undergoes a confirmational change from cis-retinal to trans-retinal
What does the confirmational change of retinal do?
Alters the confirmation of rhodopsin
What does a confirmational change in rhodopsin do?
Activates transducin
What does the alpha subunit of transducin do?
Exchanges GDP for GTP and dissociates from the beta and gamma subunits and becomes activated
What does the exchange from GDP to GTP do?
Activates phosophodiesterase
What does phosphodiesterase do?
Lowers the amount of cGMP inside the cell
What happens when the cGMP levels fall?
Hyperpolarization
What happens when the cell becomes hyperpolarized?
It releases less neurotransmitter
Is the cell depolarized or hyperpolarized in the dark?
The cell is depolarized
Is there more or less neurotransmitter being released in the dark?
More neurotransmitter being released
How is the light signal terminated?
By arrestin which prevents rhodopsin from activating transducin and by retinal dissociating from rhodopsin
What does the exchange from GDP to GTP do?
Activates phosophodiesterase
What does phosphodiesterase do?
Lowers the amount of cGMP inside the cell
What happens when the cGMP levels fall?
Hyperpolarization
What happens when the cell becomes hyperpolarized?
It releases less neurotransmitter
Is the cell depolarized or hyperpolarized in the dark?
The cell is depolarized
Is there more or less neurotransmitter being released in the dark?
More neurotransmitter being released
How is the light signal terminated?
By arrestin which prevents rhodopsin from activating transducin and by retinal dissociating from rhodopsin
What does the exchange from GDP to GTP do?
Activates phosophodiesterase
What does phosphodiesterase do?
Lowers the amount of cGMP inside the cell
What happens when the cGMP levels fall?
Hyperpolarization
What happens when the cell becomes hyperpolarized?
It releases less neurotransmitter
Is the cell depolarized or hyperpolarized in the dark?
The cell is depolarized
Is there more or less neurotransmitter being released in the dark?
More neurotransmitter being released
How is the light signal terminated?
By arrestin which prevents rhodopsin from activating transducin and by retinal dissociating from rhodopsin
What does the exchange from GDP to GTP do?
Activates phosophodiesterase
What does phosphodiesterase do?
Lowers the amount of cGMP inside the cell
What happens when the cGMP levels fall?
Hyperpolarization
What happens when the cell becomes hyperpolarized?
It releases less neurotransmitter
Is the cell depolarized or hyperpolarized in the dark?
The cell is depolarized
Is there more or less neurotransmitter being released in the dark?
More neurotransmitter being released
How is the light signal terminated?
By arrestin which prevents rhodopsin from activating transducin and by retinal dissociating from rhodopsin
What is rod mediated vision called?
Scotopic
When does scotopic occur?
Low levels of light
What is an example of using rods for vision?
Looking at stars at night
Are rods extremely sensitive to light?
Yes---they can detect a single photon
What is cone mediated vision called?
Photopic
When does photopic occur?
Bright light conditions
What happens if we lose rod vision?
Night blindness
What happens if we lose cone vision?
Legally blind
Are cones sensitive to light?
Much less sensitive than rods
Do rods or cones recover faster from light? Why?
Cones recover faster due to faster adaptation mechanisms
What are the three classes of cones?
Long wavelength (red)
Medium wavelength (green)
Short wavelength (blue)
What is the intensity of the response of a cone dependent on?
The number of photons absorbed
Where are the red and green opsin genes located?
On the X chromosome
Where does highest acuity vision occur?
Fovea
Where is the fovea?
In a depression within the macula lutea
What is rod mediated vision called?
Scotopic
When does scotopic occur?
Low levels of light
What is an example of using rods for vision?
Looking at stars at night
Are rods extremely sensitive to light?
Yes---they can detect a single photon
What is cone mediated vision called?
Photopic
When does photopic occur?
Bright light conditions
What happens if we lose rod vision?
Night blindness
What happens if we lose cone vision?
Legally blind
Are cones sensitive to light?
Much less sensitive than rods
Do rods or cones recover faster from light? Why?
Cones recover faster due to faster adaptation mechanisms
What are the three classes of cones?
Long wavelength (red)
Medium wavelength (green)
Short wavelength (blue)
What is the intensity of the response of a cone dependent on?
The number of photons absorbed
Where are the red and green opsin genes located?
On the X chromosome
Where does highest acuity vision occur?
Fovea
Where is the fovea?
In a depression within the macula lutea
What is the optic disk?
Where the axons of the ganglion cells leave the retina as the optic nerve
Does the optic disk contain any photoreceptors?
No--hence the "blind spot"
Does the density of cones increase or decrease in the fovea?
Increases
What is in the central pit of the fovea?
The foveola
Are there rods in the foveola?
No
Do blood vessels run through the foveola?
No
What are the cones in the foveola dependent on?
The pigemented epithelium for nutrients
Do cones synapse on one or multiple bipolar cells? Ganglion cell?
One bipolar cell and one ganglion cell
What are the ganglion cells that cones synapse on called?
The midgit ganglion cell
Does the midgit ganglion cell have a small or large receptive field?
Small receptive field
Is the conductance of midgit cells slow or fast?
Slow but maximal acuity
Do rods synapse on one or multiple bipolar cells? Ganglion cell?
Multiple rods synapse on multiple bipolar cells which synapse on one ganglion cell
What is convergence?
Rods converge on the same ganglion cell
Is the rod synapse sensitive or desensitive?
Very sensitive
Is the rod synapse fast or slow?
Very fast
Where are most of our rods located?
In the periphery
What is retinitis pigmentosa?
Results from mutations in rhodopsin that lead to apoptotic death of rods directly and indirectly to death of cones---progressive blindness
What is Age-related Macular Degeneration?
Progressive loss of central vision--photoreceptors die
What are the two types of AMD?
Wet AMD and Dry AMD
What is wet AMD?
Inappropriate, excessive growth of vasculature leaks blood and fluid into the retina which damages the photoreceptors
What is dry AMD?
The retinal epithelium gradually dies which leads to the death of photoreceptors
What is a detached retina?
The pigment epithelium separates from the outer segments of the photoreceptors--usually caused by trauma
What are the two types of bipolar cells?
On center and off center bipolar cells
What do on-center bipolar cells respond to?
Light in the center of their receptive field
What do off-center bipolar cells respond to?
Light in the concentric circle that lies around the center of the receptive field
What are the glutamate receptors on the on-center bipolar cells?
mGluR6
What happens to the on-center bipolar cells when glutamate is released?
They are hyperpolarized--leads to less neurotransmitter being released
What happens to the off-center bipolar cells when glutamate is released?
Depolarization of the bipolar cell
What are the glutamate receptors in the off-center bipolar cells?
AMPA and Kainate
Are the synapses with ganglion cells excitatory or inhibitory?
All excitatory
What does stimulation to a cone or rod do to on-center and off-center ganglion cells?
Stimulation leads to activation of an on-center ganglion cell and inhibition of an off-center ganglion cell
Where do axons of the ganglion cells go?
They exit the retina and form the optic nerve
What do axons encounter after becoming the optic nerve?
The optic chiasm
Where is the optic chiasm located in the brain?
The diencephalon
After the chiasm, where do the ganglion fibers run?
In the optic tract
Where do axons that came from the temporal side travel in the optic tract?
On the ipsilateral side
Where do axons that came from the nasal side travel in the optic tract?
On the contralateral side
Where is the major input for vision?
The lateral geniculate nucleus in the thalamus
Where do neurons from the LGN project?
To the visual cortex
Besides the visual cortex, where else are fibers projected?
The superior colliculus
Where is the superior colliculus located?
The midbrain
What is the superior colliculus projection important for?
Coordinating head and eye movements
Besides the visual cortex and superior colliculus, what is another projection point for visual fibers?
The pretectum
Where is the pretectum located?
Between the thalamus and the midbrain
What does the pretectum do?
Coordinates the pupillary light reflex
What is the suprachiasmic nucleus important for?
Regulating circadian rhythms
Where is the suprachiasmic nucleus located?
Hypothalamus
Where all do visual fibers project?
Visual cortex
Superior colliculus
Pretectum
Suprachiasmic nucleus
Do cones have low or high resolution?
High resolution
Do rods have low or high resolution?
Low resolution
What is the cone pathway called?
The parvocellular pathway
What is the rod pathway called?
Magnocellular pathway`
What are the three classes of ganglion cells that project to the LGN?
High acuity, color, and motion
Where is information from the left half of the visual world represented?
The right half of the visual cortex
Where do axons in the optic tract contain info from?
Both eyes
Where do axons in the optic nerve contain info from?
One eye
Information from the left visual field that is left superior would be how on the left retina?
Right inferior
Information that is left inferior on the right retina would be how in the right visual field?
Right superior
Where is the inferior visual world mapped to?
The superior visual cortex
Where is the superior visual world mapped to?
The inferior visual cortex
What is the suprachiasmic nucleus important for?
Regulating circadian rhythms
Where is the suprachiasmic nucleus located?
Hypothalamus
Where all do visual fibers project?
Visual cortex
Superior colliculus
Pretectum
Suprachiasmic nucleus
Do cones have low or high resolution?
High resolution
Do rods have low or high resolution?
Low resolution
What is the cone pathway called?
The parvocellular pathway
What is the rod pathway called?
Magnocellular pathway`
What are the three classes of ganglion cells that project to the LGN?
High acuity, color, and motion
Where is information from the left half of the visual world represented?
The right half of the visual cortex
Where do axons in the optic tract contain info from?
Both eyes
Where do axons in the optic nerve contain info from?
One eye
Information from the left visual field that is left superior would be how on the left retina?
Right inferior
Information that is left inferior on the right retina would be how in the right visual field?
Right superior
Where is the inferior visual world mapped to?
The superior visual cortex
Where is the superior visual world mapped to?
The inferior visual cortex
What separates the superior and inferior visual cortex?
The calacrine sulcus
Where is Meyer's loop?
In the inferior visual cortex
Where does Meyer's loop receive its info from?
The superior visual world
If you have a lesion in the right optic nerve, what will happen?
Loss of vision in the right eye
If you have a lesion in the optic chiasm, what will happen?
Bitemporal heteronomous hemianopsia--loss of peripheal vision
If you have a lesion in the right optic tract, what will happen?
Lose left half of visual world--left homonymous hemianopsia
If you have a lesion in the right Meyer's loop, what will happen?
Lose left superior visual field of each eye
If you have a lesion in the right striate cortex, what will happen?
"Macular sparing"--due to overlap of the MCA and the PCA--Lose left half of each eye visual field with the macula being spared
What is optic radiation?
The "fanning" out of fibers at the LGN
What is the optimal stimulus for cells in the visual cortex?
Bars in a certain orientation
What do cells in our cortex detect?
Edges
What layer is the big visual input layer?
Layer 4
How do the bars form from small spots of light?
They superimpose on each other
How is the visual cortex divided?
Into columns--ocular dominance columns
What would happen in the right eye was patched during the time of developement?
Once the patch is removed, then all the cells in the visual cortex will respond to the left eye. The right eye is working fine, but there are no axons there to receive the information--become blind in one eye
What is amblyopia?
Lose vision in one eye because it doesn't hook up right to the visual cortex
How many layers in the LGN/striate cortex?
Six
What are the major features of a visual stimulus that our nervous system extracts?
Form, color, and movement
What does the magnocellular pathway handle?
Motion information
What does the parvocellular pathway handle?
Form and color information
Where is the parvocellular pathway located?
In the temporal lobe
Where is the magnocellular pathway located?
In the parietal lobe
What is the magnocellular pathway processing?
The where
What is the parvocellular pathway processing?
The what
Where is the majority of input for the magnocellular pathway?
From the non-fovea region----the rods
Where is the majority of input for the parvocellular pathway?
From the fovea--the cones
Does the Magno pathway have large or small receptive fields?
Large receptive fields
Does the Parvo pathway have large or small receptive fields?
Small receptive fields
Does the Magno pathway have fast or slow conductance?
Fast conductance
Does the Parvo pathway have fast or slow conductance?
Slow conductance
What happens when the magno pathway is damaged?
Loss of motion sensitivity; inability to detect rapidly changing stimuli
What happens when the parvo pathway is damaged?
Damage results in impaired color and form recognition
What kind of ganglion cells are in the parvo pathway?
P ganglion
What kind of ganglion cells are in the magno pathway?
M ganglion
What is prosopagnosia?
Face recognition
What is achromatopsia?
Can't see colors
Once light enters the eye, where do these fibers synapse?
In the pretectum
In the pretectum, do axons go ipsilateral or contralateral?
Both
Where do axons project after leaving the pretectum?
Edinger Westphal nucleus
Where do neurons in the EW nucleus project?
Ipsilaterally to synapse on the parasympathetic neurons in the ciliary ganglion
What nerve are fibers leaving the EW nucleus traveling through?
Occulomotor
Where do neurons in the ciliary ganglion project?
To the pupillary spinchter muscle and cause it to constrict
Are the fibers traveling to the ciliary ganglion parasympathetic or sympathetic?
Parasympathetic
What kind of fibers are in the EW nucleus?
Preganglionic parasympathetic
What does too much light do to the pupils?
Causes them to constrict
What nerves are required for the pupillary light reflex?
Cranial nerves 2 and 3
If you shine a light in the left eye, what happens to the left and right eye?
They both constrict--left eye had direct response and the right eye had the consenual response
If both eyes constrict when light shines in one eye, which nerve is working correctly?
Occulomotor nerve
If you shine a light in the right eye and nothing happens in the right or left eye, what is going on?
Right optic nerve is not working--can't sense the light there--since nothing happens to the right eye, nothing happens in the left eye
Is a damaged optic nerve an afferent or efferent defect?
An afferent defect
What do we capture sound with?
The pinna of the ear
What is sound?
Pressure waves that are generated by compression and rarefration of air molecules
How is sound transmitted to the brain?
Via electrical signals from the cochlea
What are the two important tasks that must be accomplished by the auditory system?
Sound localization
The frequency and intensity
What do sound waves contain?
Amplitude and Frequency
What is amplitude?
Loudness---measured in decibels
What is frequency?
Pitch--measured in hertz
What is the threshold of hearing?
0 db
What is the decibel level of normal speech?
60 db
What is the decibel level of the threshold of pain?
140 db
What decibel level can kill hair cells?
110 and higher range
What collects the sound waves and amplifies them?
The external and middle ear
When sound comes in the ear, what does it hit first?
The tympanic membrane
After hitting the tympanic membrane, where does sound travel?
Mallues, Incus, Stapes and finally oval window
Is there a gain or loss in pressure from the tympanic membrane to the oval window?
Gain in pressure so the fluid in the inner ear is able to be moved
What is considered to be the "transformer" in the ear?
The middle ear because it significantly increases the energy focused on the inner ear
Where does transduction of mechanical energy to electrochemical neural potentials take place?
In the cochlea
What is the map or organization of frequency called?
Tonotopy
Where are the cell bodies of the spiral ganglion located?
Embedded in the modiolus
What do the spiral ganglia contain?
Sensory fibers that convey sound information to the brain--axons comprise the auditory portion of 8th cranial nerve
What are the three chambers located in the cochlea?
Scala vestibuli
Scala tympani
Scala media
Which chamber of the cochlea contain the auditory receptors?
The scala media
What are the auditory receptors located in the scala media?
The hair cells in the Organ of Corti
Does the scala vestibuli and scala tympani contain endolymph or perilymph?
Perilymph
Does the scala media contain endolymph or perilymph?
Enodlymph
Is the perilymph high or low in potassium?
Low in potassium
Is the endolymph high or low in potassium?
High in potassium
What makes the endolymph?
The stria vascularis
How many inner and outer hair cells are in the Organ of Corti?
1 layer of inner hair cells and 3 layers of outer hair cells
What is the resting membrane potential in the scala vestibuli and scala tympani?
0 mV
What is the resting membrane potential in the endolymph?
80 mV
Is the basliar membrane symmetric?
No--it has a narrow end and a wide end
Where is the narrow end located?
Near the oval window called the base
Where is the wide end of the basilar membrane called?
The apex
Which end of the basilar membrane is referred to as the "stiff" end?
The base
Which end of the basilar membrane is referred to as the "floppy" end?
The apex
Where are high frequency sounds best deflected?
At the base
Where are low frequency sounds best detected?
At the apex
Do high frequency sounds produce narrow or wide waves?
Narrow waves
Do low frequency sounds produce narrow or wide waves?
Wide waves
What is the amount of frequency (Hz) that we can detect?
20-20,000 Hz
What is the spoken language range of frequency?
4 kHz to 8 KHz
Which hair cells receive the vast majority of innervation by the sensory afferent fibers?
The inner hair cells
Which hair cells receive the vast majority of innervation by the efferent fibers?
The outer hair cells
What is responsible for the amplification of low intensity sounds?
The outer hair cells
Which hair cells act as the Cochlear amplifier?
The outer hair cells
What are the outer hair cells responsible for?
Sharp tuning and high sensitivity to sound
Most hearing loss is due to the loss of which hair cells?
The outer hair cells
Can the outer hair cells contract? Why?
Yes----they contract increase the stimulus the inner hair cells are receiving
What is otoacoustic emissions?
Sounds that are measured in the outer ear canal that are produced by the OHC--newborn hearing test
What is the cause of tinnitus or ringing in the ears?
Uncontrolled contraction of the OHC's
What comprises the auditory component of CN 8?
The central processes of the spiral ganglion
Where do cranial nerve 8 axons enter the brain?
At the pontomedullary junction
Once cranial nerve 8 axons have entered the brain, where do they go?
To the cochlear nuclei
What pathway compares the input from 2 ears?
The binural pathway
What is the binural pathway involved in?
Sounds localization
What pathway has input from one ear only?
The monaural pathway
What is the monural pathway involved in?
Analyzes the frequency and intensity
To understand speech, do you need one or two ears?
Only one ear
Which cochlear nucleus is involoved in the binaural pathway?
The ventral cochlear nucleus
After synapsing in the ventral cochlear nucleus, where do the axons go?
To the ipsilateral and contralateral medial superior olivary nucleus
Where do axons project after leaving the MSO?
To the ipsilateral lemniscus
After leaving the ipsilateral lemniscus, where do the axons of the bianural pathway terminate?
In the inferior colliculus
Which cochlear nucleus is involved in the monaural pathway?
The dorsal cochlear nucleus
Where do axons from the dorsal cochlear nucleus go?
To the lateral lemniscus nucleus on the ipsilateral and contralateral side
After leaving the lateral lemniscus nucleus, where do axons project in the monaural pathway?
To the ipsilateral inferior colliculus
After leaving the inferior colliculus, where do the binaural and monaural pathways synapse?
In the medial geniculate complex
Where does detection of specific spectral and temporal combinations of sound occur?
In the medial geniculate complex
From the medial geniculate complex, where do the axons go?
To the primary auditory complex
Where is the primary auditory complex located?
Superior temporal gyrus
What are the two types of hearing loss?
Conductive and Sensorineural
What is affected in conduction hearing loss?
The middle ear--bones of the middle ear
What is affected in sensorineural hearing loss?
Damage to the inner ear; nerve damage
In presbycusis, what are the first sounds to be lost?
High frequency sounds--including f, sh, ch, p, s, and t
The hearing test in which the base of the vibrating tuning fork placed on the vertex of the skull is?
Weber test
What is the normal response of a weber test?
Hears equally well on both sides
If there is conduction deafness in one ear, what will be the outcome of the Weber test?
Sound will be louder in the damaged ear
If there is nerve deafness in one ear, what will be the outcome of the Weber test?
Sound will be louder in the normal ear
The hearing test in which the base of the tuning fork is placed on the mastoid process until the subject no longer hears it and is then held next to the ear is?
The Rinne test
What is the normal response of the Rinne test?
Hears vibration in air after bone conduction is over
If there is conduction deafness in one ear, what will be the outcome of the Rinne test?
The vibrations in the air is not heard after the bone conduction is over
If the is nerve deafness in one ear, what will be the outome of the Rinne test?
The vibration will be heard in air after bone conduction is over but will be depreciated
Does olfaction go to the hypothalamus?
No--it goes straight to the cortex
What are the senses taste and smell enriched with?
Emotion and memory
What is the firing rate of action potentials of olfactory neurons?
Constantly firing
How often does olfactory nerve turn over?
Every 30-60 days
How many different olfactory receptors are there?
1,000
What serves as the "incoming" for smell?
Cilia
How are odorants transported to the chemosensitive cilia of the olfactory receptor neuron?
By the olfactory binding protein
Once in the cilia, what do odorants react with?
The olfactory receptors on the ciliary membrane
What type of receptors are the olfactory receptors?
G-protein linked receptors
What does binding of an odorant to its receptor activate?
A G protein (Golf)
What does the activated Golf stimulate?
Adenylate cyclase
What does stimulated adenylate cyclase in the olfactory cells do?
Increases intraciliary cAMP concentration which opens a cation channel--depolarization
What is another second messenger used to amplify the odorant signal?
Phosopholipase C--breaks down PIP2--IP3 causes increase in calcium
How are oderant signal terminated?
Protein kinases and enzymes--catalyze covalent modification
Where are the voltage gated channels in the olfactory system?
At the cribiform plate
Are the "potentials" in the olfactory system receptor/generator potentials or voltage gated?
Coming in the nose, they are receptor potentials but voltage gated channels at the cribiform plate
Does the olfactory system have a high or low sensitivity of odor detection?
High sensitivity (Low threshold)
How many separate odors do humans recognize?
20,000
How many of the recognized odors are pleasant?
20%
Where do the odor neurons first synapse and converge?
The glomeruli
Does the olfactory bulb contain inhibitory neurons?
Yes--it processes incoming olfactory information and efferent signals suppress the smells
Is adaptation to smell slow or fast?
Fast
What is another name for the primary olfactory cortex?
The piriorm and periamygdaloid cortex
Where does the olfactory tract send its secondary sensory neurons?
To the primary olfactory cortex, amygdala, and the olfactory tubercle
What is thought to be associated with the amygdala?
The emotion to a specific smell
Where is the primary olfactory cortex located?
In the medial temporal lobe
Where is the otomap located?
In the olfactory bulb
What is anosmia?
Inability to smell
What are some ways anosmia can be caused?
Mechanical block of airway
Tumor
Infection
Fracture of the cribiform plate
What is Kallman's syndrome?
Genetic defect where OR neurons fail to reach olfactory bulb--associated with hypogonadism
Are the "potentials" in the olfactory system receptor/generator potentials or voltage gated?
Coming in the nose, they are receptor potentials but voltage gated channels at the cribiform plate
Does the olfactory system have a high or low sensitivity of odor detection?
High sensitivity (Low threshold)
How many separate odors do humans recognize?
20,000
How many of the recognized odors are pleasant?
20%
Where do the odor neurons first synapse and converge?
The glomeruli
Does the olfactory bulb contain inhibitory neurons?
Yes--it processes incoming olfactory information and efferent signals suppress the smells
Is adaptation to smell slow or fast?
Fast
What is another name for the primary olfactory cortex?
The piriorm and periamygdaloid cortex
Where does the olfactory tract send its secondary sensory neurons?
To the primary olfactory cortex, amygdala, and the olfactory tubercle
What is thought to be associated with the amygdala?
The emotion to a specific smell
Where is the primary olfactory cortex located?
In the medial temporal lobe
Where is the otomap located?
In the olfactory bulb
What is anosmia?
Inability to smell
What are some ways anosmia can be caused?
Mechanical block of airway
Tumor
Infection
Fracture of the cribiform plate
What is Kallman's syndrome?
Genetic defect where OR neurons fail to reach olfactory bulb--associated with hypogonadism
Are the "potentials" in the olfactory system receptor/generator potentials or voltage gated?
Coming in the nose, they are receptor potentials but voltage gated channels at the cribiform plate
Does the olfactory system have a high or low sensitivity of odor detection?
High sensitivity (Low threshold)
How many separate odors do humans recognize?
20,000
How many of the recognized odors are pleasant?
20%
Where do the odor neurons first synapse and converge?
The glomeruli
Does the olfactory bulb contain inhibitory neurons?
Yes--it processes incoming olfactory information and efferent signals suppress the smells
Is adaptation to smell slow or fast?
Fast
What is another name for the primary olfactory cortex?
The piriorm and periamygdaloid cortex
Where does the olfactory tract send its secondary sensory neurons?
To the primary olfactory cortex, amygdala, and the olfactory tubercle
What is thought to be associated with the amygdala?
The emotion to a specific smell
Where is the primary olfactory cortex located?
In the medial temporal lobe
Where is the otomap located?
In the olfactory bulb
What is anosmia?
Inability to smell
What are some ways anosmia can be caused?
Mechanical block of airway
Tumor
Infection
Fracture of the cribiform plate
What is Kallman's syndrome?
Genetic defect where OR neurons fail to reach olfactory bulb--associated with hypogonadism
What is specific anosmia?
Lowered sensitivity to a single odorant or related compounds
What is hyposmia?
Diminshed sense of smell
What are examples of hyposmia?
Head cold
Cystic Fibrosis
Parkinson's Disease
What is cacosmia?
Olfactory hallucinations of smells (aura)
Who usually senses an aura?
Epileptics before having a seizure
What is dysosmia?
Distorted sense of smell--damage to the olfactory epithelium--"When I eat turkey, I smell Chanel"
Where are taste buds located?
3 different types of papillae on the tongue
What cranial nerves can also sense taste?
CN 7,9, and 10
What are the three cell types that compose the sense of taste?
Supporting cells
Basal cells
Neuroepithelial cells
Do the neuroepithelial cells have a short or long lifespan?
Short life span--turn over every 10 days to 2 weeks
Where do afferent fibers synapse on the neuroepithelial cell?
At the base
Where does the sensory transduction takes place in the mouth?
Microvilli
What is the only part of the receptor cell exposed to the compounds in the oral cavity?
The microvilli
What are the five basic taste modalities?
Sweet, bitter, amino acid (umami), sour and salt
Where do we taste sweet?
Front of tongue--cranial nerve 7
What is specific anosmia?
Lowered sensitivity to a single odorant or related compounds
What is hyposmia?
Diminshed sense of smell
What are examples of hyposmia?
Head cold
Cystic Fibrosis
Parkinson's Disease
What is cacosmia?
Olfactory hallucinations of smells (aura)
Who usually senses an aura?
Epileptics before having a seizure
What is dysosmia?
Distorted sense of smell--damage to the olfactory epithelium--"When I eat turkey, I smell Chanel"
Where are taste buds located?
3 different types of papillae on the tongue
What cranial nerves can also sense taste?
CN 7,9, and 10
What are the three cell types that compose the sense of taste?
Supporting cells
Basal cells
Neuroepithelial cells
Do the neuroepithelial cells have a short or long lifespan?
Short life span--turn over every 10 days to 2 weeks
Where do afferent fibers synapse on the neuroepithelial cell?
At the base
Where does the sensory transduction takes place in the mouth?
Microvilli
What is the only part of the receptor cell exposed to the compounds in the oral cavity?
The microvilli
What are the five basic taste modalities?
Sweet, bitter, amino acid (umami), sour and salt
Where do we taste sweet?
Front of tongue--cranial nerve 7
Where do we taste salty on the tongue?
Front side--cranial nerve 7
Where do we taste sour on the tongue?
Middle to back side--Cranial nerve 7 and 9
Where do we taste bitter?
In the back of the tongue
What are the cranial nerves that involve the tongue?
CN 5,7,9, 10, and 12
What type of voltage gated ion channels do taste receptor cells have?
Na+, K+ and Ca2+
Do taste receptor cells have indirect ligand gated channels?
Yes
Are taste receptor cells capable of generating an action potential?
Yes--if they reach threshold
What does a change in membrane conductance cause?
Depolarization
Depolarization in the tongue causes Ca+ to be released. This causes what?
Release of excitatory neurotransmitter (Glutamate or serotonin)
Releasing glutamate causes what?
A postsynaptic potential (EPSP)
If the EPSP reaches threshold, what happens?
An action potential will be fired ont he afferent sensory nerve and transmitted to the CNS
Do gustatory neurons respond to one or many taste qualities?
Many taste qualities
What are the three types of information transmitted from chemical stimuli?
Quality (sweet, sour, umami, etc)
Intensity
Hedonic value (pleasant or unpleasant)
What type of receptors do bitter/sweet/umami bind to?
G-protein coupled receptors--slow
What do bitter tastes bind to?
G-proteins and gustducin
What does gustducin do?
Bitter taste--stimulates IP3 second messenger to release Ca2+
What do sweet tastes bind to?
G-proteins that stimulate and increase in cAMP
What do sour/salty tastes bind to?
Act directly on ion channels--fast
What ion do sour and sweet tastes allow to come in when they act on the ion channel?
Na+--generates an action potential
What does amilioride do?
Blocks the Na+ channel allowing glutamate to come in and activate the G-protein
What is the first synapse in the sensation of taste?
Neuroepithelial cells with afferent primary sensory nerves (CN 7, 9, 10)
What is the second synapse in the sensation of taste?
In the brain stem--Rostral solitary nucleus in the medulla
What is the third synapse in the sensation of taste?
VPM
What is the fourth synapse in the sensation of taste?
The cortex--insula
What are the two types of ligand gated channels?
Direct/Inotropic/Fast
Indirect/Metabotropic/Slow
What do indirect ligand channels require to be opened?
G-proteins/2nd messengers
What do direct ligand channels require to be opened?
Nothing
What are voltage gated channels looking for?
Changes in charge
What do mechanical channels respond to?
Stretch--GTO, muscle spindles, tip links
What are the three groups of neurotransmitters?
Amnio acids
Biogenic amines
Ach
What are the neurotransmitters that are amino acids?
Glycine
GABA
Glutamate
What are the inhibitory amnio acid transmitters in the CNS?
Glycine and GABA
What do drugs that block the action of GABA produce?
Excitability and convulsions
What are the two types of GABA receptors?
GABAa and GABAb
What two classes of drugs modulate GABAa receptors?
Benzodiazepines and barbituates
What ligand channel does GABAa contain?
Direct ligand gated channel--increased Cl- conduction
What ligand channel does GABAb contain?
Indirect ligand gated channel--blocks Ca2+ and activates K+ channels
What acts as an agonist to GABAa?
Muscimol
What acts as an antagonist to GABAa?
Picrotoxin
What acts as an agonist to GABAb?
Baclofen
What acts as an antagonist to GABAb?
Bicuculline
Where is GABA mostly found?
In the CNS
What is glycine?
An inhibitory neurotransmitter
What type of receptor does glycine have?
A direct ligand gated channel--allows Cl- in
Where is glycine mostly found?
In the spinal cord and lower brainstem
What blocks gylcine channels?
Strychnine
What does strychnine produce?
Convulsions by blocking the glycine channels
What is an excitatory amino acid transmitter in the CNS?
Glutamate--the most common
What are the two major categories of glutamate receptors?
NMDA and non-NMDA
What is unique about the NMDA receptor?
It is both direct ligand gated and voltage gated
What is an antagonist to the NMDA receptor?
PCP--angel dust
What are the non-NMDA receptors?
Kainate
Quisqualate-A
Quisqualate-B
What type of channel is Kainate?
Ligand gated--direct
What type of channel is Quisqualate-A?
Ligand gated--direct
What type of channel is Quisqualate-B?
Ligand gated-indirect
What type of 2nd messenger does Quisqualate-B work through?
DAG and IP3
What are the biogenic amines?
Dopamine
Norepi
Epi
Serotonin
Histamine
What type of channels do the biogenic aminies work through?
Ligang gated-indirect-Gprotein coupled receptors
What are dopamine, norepi, and epi all derived from?
Tyrosine
What are the prominent dopamine containing nuclei in the brainstem?
Sunstantia Nigra
Nucleus Acumbens
Prefrontal cortex
Hypothalamus
Where does the substantia nigra project?
To the basal ganglia
What is the substantia nigra important in?
Motor control
Where does the ventral tegmental area project?
To the nucleus accumbens
What is the nucleus accumbens important in?
Reward and addiction circuits
Where do both the substantia nigra and vta project to?
The prefrontal cortex
What is the prefrontal cortex important in?
Motivation and cognition
What are nigrostriatal dopaminergic fibers and where are they located?
Located in the substantia nigra and do motor regulation
What are the mesolimbic dopaminergic fibers and where are they located?
Located in the nucleus accumbens and do reward/prediction behavior
What are the mesocortical dopaminergic fibers and where are they located?
Located in the prefrontal cortex and do working memory processes
Where does the hypothalamus project?
To the arcuate nuclues
What does the arcuate nucleus important in?
Releasing dopamine to inhibit prolactin
Where are all the prominent dopamine containing nuclei located?
In the midbrain/mesocephalon
What inhibits the release of dopamine?
Lithium and antipsychotics
What are the D1 receptors involoved with?
"Flashbulb" memories
What are the prominent dopamine containing nuclei in the brainstem?
Sunstantia Nigra
Nucleus Acumbens
Prefrontal cortex
Hypothalamus
Where does the substantia nigra project?
To the basal ganglia
What is the substantia nigra important in?
Motor control
Where does the ventral tegmental area project?
To the nucleus accumbens
What is the nucleus accumbens important in?
Reward and addiction circuits
Where do both the substantia nigra and vta project to?
The prefrontal cortex
What is the prefrontal cortex important in?
Motivation and cognition
What are nigrostriatal dopaminergic fibers and where are they located?
Located in the substantia nigra and do motor regulation
What are the mesolimbic dopaminergic fibers and where are they located?
Located in the nucleus accumbens and do reward/prediction behavior
What are the mesocortical dopaminergic fibers and where are they located?
Located in the prefrontal cortex and do working memory processes
Where does the hypothalamus project?
To the arcuate nuclues
What does the arcuate nucleus important in?
Releasing dopamine to inhibit prolactin
Where are all the prominent dopamine containing nuclei located?
In the midbrain/mesocephalon
What inhibits the release of dopamine?
Lithium and antipsychotics
What are the D1 receptors involoved with?
"Flashbulb" memories
Where is norepi released from?
ANS postganglionic sympathetic neurons in the sympathetic nervous system
Where is norepi produced?
In the locus ceurleus ("Blue spot")
Once norepi is produced, does it stay in the locus ceruleus or does it spread out all over?
It is spread out all over--releaseed throughout the entire nervous system
What type of receptors does norepi bind to?
Adrenergic--alpha or beta
What is the inhibitory effect of norepi?
It blocks the slow calcium-activated potassium channels allowing more actions potentials to be fired at one time
What is the excitatory effect of norepi?
Stimulatory effects on the heart--Beta1 adrenergic receptors
What type of protein receptors does norepi bind to?
Indirect ligand gated receptors
What is imdolamine?
Serotonin (5HT)
What is serotonin derived from?
Tyrptophan
What nuclei do we find serotonin?
Raphe nuclei
Is serotonin locally or widely dispersed throughout the CNS?
Widespread throughout the CNS
What is imidazole?
Histamine
Where is histamine released from?
Tuberomamillary nucleus--small area of the hypothalamus
Does histamine have a localized or widespread affect?
Widespread
What does histamine innervate?
Neurons, glial cells, and small blood vessels
What do histaminergic neurons regulate?
Brain energy metabolism and wakefulness
Is Ach an amino acid?
No--it is produced from choline
What are the types of Ach receptors?
Cholinergic--nictotinic and muscarinic
Which Ach receptor is ligand gated direct?
Nicotinic
Which Ach receptor is ligand gated indirect?
Muscarinic
What is an agonist of a nicotinic receptor?
Nicotine
What is an agonist of a muscarinic receptor?
Muscarine
What inactivates the cholinergic receptors/
Achesterase
What blocks the nicotinic receptors?
Curare
Rabies
Bungarotoxin
What blocks the muscarinic receptors?
Atropine
What is the receptor al ALL nerve-skeletal muscle junction?
Nicotinic Ach receptors
What is the transmitter and at ALL preganglionic neurons?
Ach and receptors
What is the transmitter at ALL parasympathetic postganglionic neurons?
Ach
Where is Ach produced?
The basal nucleus of Meynert in the forebrain
Where is the nucleus basalis located?
In the temporal lobe hippocampus
Innervation of the hippocampus by cholinergic neurons is important for what?
Memory--Alzheimer's Disease affects the nucleus basalis
Where are the upper motor neurons located?
In the motor cortex in the frontal lobe
What does the supplementary motor area participate in?
Rehearsing a motor activity--practicing a dive before you actually dive
What goes on in the prefrontal cortex?
Personality, goal setting, cognition of who we are
Where is the frontal eye field?
In the frontal cortex
What is the frontal eye field responsible for?
Conjugate eye movements to the contralateral side
What is the lowest level of the motor system?
Spinal cord and brainstem
What is the lowest level of the motor system responsible for?
Executing movements--stereotyped reflex movements, goal directed movements, postural adjustments--Al's
What is the intermediate level of the motor system?
Cerebellum and motor cortex
What is the intermediate level of the motor system responsible for?
Combining descending motor info with ascending sensory info to produce a spatiotemporal sequence of muscle contractions--remembering movements to ride a bicycle
What is the highest level of the motor system?
The neocortex association areas, basal ganglia
What is the highest level of the motor system responsible for?
Strategy--assoicate all sensory input to coordinate a motor otput
If dopamine is lacking, what part of the motor system is affected?
The highest level--neocortex and basal ganglia--lack dopamine can't strategize and can't get started
What happens in basal ganglia damage?
Slow movement/hypokinesia; Parkinson's
What is ataxia?
Uncoordinated movement
Where do motor inputs go in the thalamus?
VA and VL
Who is the "comparator?"
The cerebellum--compares the cortex goal with the sensory information
What disease is classic for too much movement?
Huntington's disease
What is the corticospinal tract?
Goes from the motor cortex (UMN) to the spinal cord
What is the corticobulbular tract?
Goes from the motor cortex to the brain stem
Who are the "AL's" involved with the corticospinal tract?
Skeletal muscle
Who are the "AL's" involved with the corticobulbular tract?
Cranial nerve 7, 12
Does the cerebellum innervate "AL's" at all?
No, not directly
What is voluntary movement?
Purposeful; able to use different strategies in different circumstances

Goal directed; external sensory stimuli not required to generate movement

Improves with experience and practice
What is reflex movement?
Not voluntary--rapid, stereotyped, involuntary, and graded by stimulus strength
What is rhythmic motor patterns?
Walking, chewing, etc--combine features of voluntary and reflex--repetitive movements continue automatically in a reflex manner--termination of movement is under voluntary control
The motor system requires information about what?
The envirnoment and body
Will an UMN and a LMN have weakness with lesions?
Yes--both UM and LM neurons
Will an UMN and a LMN have atrophy with lesions?
UMN-No

LMN-Yes
Will an UMN and a LMN have fasiculations with lesions?
UMN-No

LMN-Yes
Will reflexes be increased or decreased with an UMN lesion?
Increased
Will reflexes be increased or decreased with a LMN lesion?
Decreased
Will an UMN lesion have a positive Babinski's sign?
Yes
Will a LMN have a positive Babinski's sign?
No
Is the tone increased or decreased in an UMN lesion?
Increased
Is the tone increased or decreased in a LMN lesion?
Decreased
What is the job of the autonomic nervous system?
Regulate and maintain a steady state in the body
What muscles does the ANS activate unconsciously?
Smooth muscle, cardiac muscle, and glands
Where are the cell bodies located in the somatic division?
In the CNS
Where are the cell bodies located in the autonomic division?
Outside the CNS in the sympathetic chain ganglia
Where does inhibition in the ANS occur?
Either at the pre or postganglionic neurons
What cranial nerves are assoicated with the PNS?
CN 3, 7, 9, and 10
What are the exceptions in the SNS when NE is not released at the 2nd synapse?
On sweat glands, errector pilo, and small blood vessels--Ach released on muscarinic receptors instead of NE

Renal vasculature--Dopamine released onto D1 receptor instead of NE

Adrenal medulla--Releases NE/E directly into the blood

Somatic skeletal muscle--only one synapse--Ach releases onto a nictonic directly on the muscle
What blocks the muscarinic receptors?
Atropine
What blocks the nicotinic receptors?
Curare
Will reflexes be increased or decreased with an UMN lesion?
Increased
Will reflexes be increased or decreased with a LMN lesion?
Decreased
Will an UMN lesion have a positive Babinski's sign?
Yes
Will a LMN have a positive Babinski's sign?
No
Is the tone increased or decreased in an UMN lesion?
Increased
Is the tone increased or decreased in a LMN lesion?
Decreased
What is the job of the autonomic nervous system?
Regulate and maintain a steady state in the body
What muscles does the ANS activate unconsciously?
Smooth muscle, cardiac muscle, and glands
Where are the cell bodies located in the somatic division?
In the CNS
Where are the cell bodies located in the autonomic division?
Outside the CNS in the sympathetic chain ganglia
Where does inhibition in the ANS occur?
Either at the pre or postganglionic neurons
What cranial nerves are assoicated with the PNS?
CN 3, 7, 9, and 10
What are the exceptions in the SNS when NE is not released at the 2nd synapse?
On sweat glands, errector pilo, and small blood vessels--Ach released on muscarinic receptors instead of NE

Renal vasculature--Dopamine released onto D1 receptor instead of NE

Adrenal medulla--Releases NE/E directly into the blood

Somatic skeletal muscle--only one synapse--Ach releases onto a nictonic directly on the muscle
What blocks the muscarinic receptors?
Atropine
What blocks the nicotinic receptors?
Curare
Where are sympathetic preganglionic neurons located?
In the IML T1-L3
What does SNS activation cause release of directly onto the effector organ?
Norepi
Where are parasympathetic preganglionic neurons located?
CN 3, 7, 9, and 10 and S2-S4
Are the sympathetic ganglia embedded in the effector organ?
No
Are the parasympathetic ganglia embedded in the effector organ?
Yes
What kinds of actions do PNS and SNS have on each other?
Antagonistic
Does the PNS operate as a whole system or is each action individualized?
Never operates as a whole unit
What type of receptors are muscarinic?
Indirect ligand gated
What type of receptors are nicotinic?
Direct ligand gated
What type of receptors are adrenergic?
Indirect ligand gated
What type of receptors are peptidergic?
Indirect ligand gated
What type of receptors are dopaminergic?
Indirect ligand gated
Which system of the ANS predominates at rest?
The parasympathetic
Which organs receive SOLE innervation by the SNS?
Adrenal medulla
Blood vessels
Kidney
Liver
Pilomotor muscles
Sweat glands
What is the regulation of the blood pressure under the control of?
The sympathetic nervous system
Which muscle of the eye controls the lens accomodation?
Ciliary muscle
Which muscle of the eye controls the constriction of the pupil?
The spinchter part of the iris muscle
Which muscle of the eye controls the dilation of the pupil?
The radial part of the iris muscle
What does near vision do to the PNS?
Increases the PNS
Contracts the ciliary muscle
Lens becomes round
What does far vision do to the PNS?
Decreased the PNS
Relaxes the ciliary muscle
Lens becomes flat
What regulates blood pressure?
The barorecptor reflex
What does an increase in blood pressure do to the barorecptor firing rate?
Increases the barorecptor firing rate
How does the CNS respond to the increase in firing by the barorecptors?
Inhibits the SNS and stimulates the PNS
What is the vestibulo-spinal reflex (VSR)?
Keeps the body balanced--when you are standing up on a moving bus
What is the vestibulo-ocular reflex (VOR)?
Maintains retinal image stability as the head is moving