Term
| What are the five types of neurons in the retina? |
|
Definition
- Photoreceptors
- Horizontal cells
- Bipolar cells
- Anocrine cells
- Retinal ganglion cells
|
|
|
Term
| Axons of which neurons make up the optic nerve? |
|
Definition
| Retinal ganglion cell axons |
|
|
Term
| What is the structure of the photoreceptors? |
|
Definition
- Outer segment - stacks of membranous disks with photopigment
- Inner segment - contains nucleus mitochondria
- Synaptic terminal - contains synaptic vesicle, NT
|
|
|
Term
| What is the main NT for rods and cones? |
|
Definition
|
|
Term
| Where are rods and cones found in the retina? |
|
Definition
Rods - throughout except the fovea Cones - mainly in macula lutea (fovea is at the center of this) |
|
|
Term
| What are the functions of rods and cones? |
|
Definition
- Rods detect low levels of illumination (night vision)
- Cones detect high levels of illumination (day vision)
|
|
|
Term
| What is the photopigment in rods? |
|
Definition
|
|
Term
| Why does acuity improve after 10-20 minutes in the dark? |
|
Definition
| photopigment in rods increases with time in the dark |
|
|
Term
| What is the function of photopigment molecules? |
|
Definition
| Absorb photons of light and begins the phototransduction process |
|
|
Term
| How many photopigments are there? |
|
Definition
| 4: 1 in rods and 3 in cones |
|
|
Term
| When do the photopigment molecules for cones transduce light best? |
|
Definition
| At wavelengths for red, blue, and green |
|
|
Term
| What happens following the absorption of light by a photopigment molecule? |
|
Definition
| Conformational change causes activation of a G protein which works to close sodium channels |
|
|
Term
| True or False: Photoreceptors produce action potentials. |
|
Definition
| False, only changes in membrane potential to release glutamate |
|
|
Term
| When are sodium channels open in the the cones and rods? |
|
Definition
| In the dark Na channels are always open because the dark current (where they depolarize) is about 40 mV |
|
|
Term
| What do bipolar cells do? |
|
Definition
Excite or inhibit retinal ganglion cells; the receptor field is in the center and can be on (excited) or off (inhibited) with light directed on the center |
|
|
Term
| What are the divisions of the visual field? |
|
Definition
| Left, right, superior, inferior |
|
|
Term
|
Definition
| One spot without photoreceptors where axons of retinal ganglion cells exit (aka optic disc) |
|
|
Term
| What is the binocular zone? Monocular zone? |
|
Definition
| Area of overlap of the visual fields of both eyes; area only seen by one eye |
|
|
Term
| Outline the primary visual pathway: |
|
Definition
| Ganglion cells to thalamus (lateral geniculate nucleus LGN) to visual cortex in occipital lobe (V1 visual cortex, specifically the calcarine sulcus) |
|
|
Term
| Does the lateral geniculate nucleus receive contralateral or ipsilateral visual field info? the cortex? |
|
Definition
| Both receive contralateral info |
|
|
Term
| There are two projections from the lateral geniculate to the visual cortex. What are they and where does their input come from |
|
Definition
Optic radiation - info from inferior visual space Meyer's loop - info from superior visual space |
|
|
Term
| Where does the optic radiation projection terminate? Meyer's loop? |
|
Definition
| Upper bank of V1 (calcarine sulcus); lower bank of V1 |
|
|
Term
| A lesion to Meyer's loop would cause blindness where? Optic radiation? |
|
Definition
| Superior visual field; inferior visual field |
|
|
Term
| What cellular division make up the lateral geniculate nucleus? |
|
Definition
| Magnocellular division (layers 1 and 2) and parvocellular division (layers 3-6) |
|
|
Term
| What is the function of the magnocellular division? Where does its input come from? |
|
Definition
| motion perception; throughout the retina |
|
|
Term
| What is the function of the parvocellular divison? Where does its input come from? |
|
Definition
| Color perception and visual acuity; ganglion cells that get cone input |
|
|
Term
| In what lobes is the visual cortex located? |
|
Definition
| The whole occipital lobe plus parts of the parietal and temporal lobes |
|
|
Term
| Where is the primary visual cortex I? the extrastriate cortex? |
|
Definition
| Calcarine sulcus (aka area 17, V1, striate cortex); all remaining visual cortex outside of V1 |
|
|
Term
| The object recognition processing stream has input from where, projection to, and responds to? |
|
Definition
| Input from parvocellular division of LGN; projects to V1, V2, V4, and infertemporal cortex; responds to specific objects |
|
|
Term
| The motion/spatial processing stream has input from where, projection to, and responds to? |
|
Definition
| Input from magnocellular division of LGN; Projects to V1 and V3 to medial temporal cortex; Responds to motion and direction changes |
|
|
Term
| What is the macula lutea and fovea? |
|
Definition
| Macula lutea has high concentration of cones and the fovea is at the center of the macula lutea |
|
|
Term
| 2 sturctures that move the lens: |
|
Definition
- Ciliary body
- Suspensory ligaments
|
|
|
Term
|
Definition
| Clear protective layer with nociceptors |
|
|
Term
| The retina has a temporal and nasal portion. Where does each portion send its axons? |
|
Definition
Temporal - ipsilaterally Nasal - contralaterally |
|
|
Term
|
Definition
| the perception of a pressure wave |
|
|
Term
|
Definition
| Amount of energy/power of pressure wave |
|
|
Term
| What is loudness and how is it measured? |
|
Definition
| Perception of intensity; measured in dB |
|
|
Term
| What is pitch and how is it measured? |
|
Definition
| the perception of frequency; measured in Hz |
|
|
Term
|
Definition
|
|
Term
| What is the spiral ganglion? |
|
Definition
| sensory neurons of cochlea whose axons form the cochlear nerve; forms the peripheral part of the auditory system |
|
|
Term
| how are basilar membrane and organ of Corti related? |
|
Definition
| Basilar membrane runs along the length of the cochlea and the organ of corti sits on top of it and contains the hair (receptor) cells |
|
|
Term
| To what sensation do hair cells respond? |
|
Definition
| Pressure causing them to bend |
|
|
Term
| How are hair cells and stereocilia related? |
|
Definition
| There are about 20 stereocilia on each hair cell |
|
|
Term
| Describe the transduction of sound. |
|
Definition
| Air pressure changes cause small bones to vibrate; pressure waves in cochlea cause movement of fluid and basilar membrane which is mechanically specialized |
|
|
Term
| How is the bm mechanically specialized? |
|
Definition
| High frequencies are at the base (skinny) end of the cochlea at the oval window and low frequencies are at the apex (fat central) end of the cochlea |
|
|
Term
| What transmitter is usually released from the hair cell? |
|
Definition
|
|
Term
| What happens with the displacement of the stereocilia bundle toward and away from the tallest stereocilium? |
|
Definition
| Depolarization and hyperpolarization |
|
|
Term
| What are tip links? What do they do? Where are they? |
|
Definition
| Elastic filaments between adjacent stereocilia that allow hairs to bend together; they open mechanically sensitive ion channesl on the tips of the stereocilia |
|
|
Term
| Describe the sound transduction process. |
|
Definition
| Displacement of the BM moves sterocilia which opens voltage sensitive Ca channels to release NT from hair cell to cause AP in spiral ganglion neurons and output to CNS |
|
|
Term
| What are the two types of hearing loss? |
|
Definition
Conductive - mechanical interference with transmission of pressure wave (ie from ear infection) Sensory neural - damage to auditory NS (permanent damage) |
|
|
Term
| What is the path of the core auditory pathway? |
|
Definition
- Spiral ganglion afferent fiber projects to dorsal cochlear nucleus
- cross contralaterally and ascend to inferior colliculus
- ascend to medial geniculate body of the thalamus
- then ascend to the primary auditory (transverse temporal gyrus of Heschl) cortex in the temporal lobe
|
|
|
Term
| What is the function of the core auditory pathway? |
|
Definition
| Sound discrimination through intensity/loudness/frequencies/pitch |
|
|
Term
| What is the function of the Belt Auditory pathway? |
|
Definition
|
|
Term
| Trace the Belt Auditory Pathway. |
|
Definition
- Each spiral ganglion neuron sends axons to both dorsal and ventral cochlear nuclei in medulla
- Cross the trapezoid body at the level of pons
- To superior olivary nuclei (which receives bilateral projections)
- Ascends to inferior colliculus
- Ascends to medial geniculate body of thalamus
- Ascends to auditory association cortex of temporal lobe
|
|
|
Term
| How many auditory association areas are there in the temporal lobe? |
|
Definition
|
|
Term
| What is the purpose of the superior olivary nucelus receiving bilateral input? |
|
Definition
| Determines differences in arrival of sound between both ears to compute interaural time and intensity |
|
|
Term
| How do the neurons of the Belt pathway ascend? |
|
Definition
| through the lateral lemniscus |
|
|
Term
| How are visual and auditory pathways parallel? |
|
Definition
| Follow same path but audition is caudal to rostral (midbrain to MGN) and vision is rostral to caudal (LGN to sup. coll.) |
|
|
Term
| Where are the otoliths located and to what do they respond? |
|
Definition
In the vestibule (chamber separating semicircular canals from cochlea) Respond to linear acceleration and head tilt |
|
|
Term
| What are the 2 otolith organs and to what movements do they respond? |
|
Definition
Utricle - mvmt in horizontal plane Saccule - mvmt in vertical plane |
|
|
Term
| To what movement do the semicircular canals respond? |
|
Definition
| Angular acceleration or head rotation |
|
|
Term
| What is unique about the endolymph? |
|
Definition
| High potassium concentration; endolymph potassium > intercellular concentration thus K will move into cell down its concentration gradient |
|
|
Term
| How are hair cells polarized? |
|
Definition
Through organization of cilia - group of small stereocilia
- single larger kinocilium
|
|
|
Term
| What is the anatomy of the otolithic organs? |
|
Definition
| Hair cells are imbedded in the otolithic membrane whose surface is coated with calcium carbonate crystals (otoconia) |
|
|
Term
| What is the anatomy of the semicircular canals? |
|
Definition
| Tips of hair cells embedded in gelatinous substance (cupula) |
|
|
Term
| Describe the process of sensory transduction in the vestibular system? |
|
Definition
- Head movement leads to endolymph movement
- Which leads to displacement of hair cells (embedded in otolithic membrane or cupula)
- Movement of stereocilia toward kinocilium leads to opening of K channels and depolarization
- Depolarization opens voltage gated Ca channels
- NT are released
- Increased frequency of AP in CN VIII
|
|
|
Term
| What happens with movment of stereocilia away from kinocilium? |
|
Definition
|
|
Term
| What is Meniere's disease? What are the symptoms? |
|
Definition
| Distubance of fluid pressure in inner ear which may result in rupture of labyrynth due to inc production of endolymph |
|
|
Term
| What are symptoms of Meniere's disease? |
|
Definition
| Vertigo, imbalance, nausea and vomiting, hearing problems (can cause changes in endolymph in cochlea) |
|
|
Term
|
Definition
| Benign Paroxysmal Positional Nystagmus; otoconia break off of the otolithic membrane and get stuck in semicircular canals interfereing with the cupula |
|
|
Term
| What are the symptoms of BPPN? |
|
Definition
| vertigo, imbalance, nausea, hearing NOT affected (not a cochlear problem as with Meniere's) |
|
|
Term
| What happens during intoxication to cause alcohol induced vertigo? |
|
Definition
| Cupula absorbs alcohol because it is highly vascular and is now less dense than endolymph and floats; gives illusions of movement as head tilt activates semicircular canals (normally responds to angular acceleration or head rotation) |
|
|
Term
| What happens in a hangover? |
|
Definition
| Alcohol leaves cupula first leaving cupula more dense than endolymph and cupula sinks and any head movment moves cupula |
|
|
Term
| What path does the primary visual pathway follow? |
|
Definition
| From the eyes along the optic nerve; may or may not cross in the optic chiasm (both ipsilateral and contralateral projections); along optic tract to the LGN (thalamus) where it synapses for the first time; 2nd order neuron goes through the optic radiation (a tract in the cortex) to the striate cortex |
|
|
Term
| Does the primary visual pathway have ipsilateral or contralateral projections? |
|
Definition
| Both ipsilateral and contralateral |
|
|
Term
| Outline the path which controls circadian rhythms. |
|
Definition
| Retinohypothalamic pathway: Retina through optic chiasm into hypothalamus |
|
|
Term
| Outline the path which controls eye movement. |
|
Definition
| Retinal ganglion axons cross or goe ipsilaterally in optic tract going toward LGN but BYPASS it and continue to superior colliculus (in midbrain) |
|
|
Term
| Where is the superior colliculus? |
|
Definition
|
|
Term
|
Definition
|
|
Term
| What does the retinohypothalamic pathway control? |
|
Definition
| Light/dark cycles (circadian rhythms) |
|
|
Term
| What is the stimuli for the sweaty odor quality? Stinging? |
|
Definition
| Isovaleric acid (30% can't sense it); formic acid |
|
|
Term
| What are the cell types in the olfactory epithelium? |
|
Definition
| Olfactory receptor cells (CNI); basal cells (progenitor cells); sustentacular cells (supporting cells); and Bowmand glands (mucous secreting) |
|
|
Term
| How often do the basal cells of the olfactory epithelium regenerate? |
|
Definition
|
|
Term
| What is the structure of the olfactory receptor neuron? |
|
Definition
Bipolar: distal end with cilia and receptor sites on cilia proximal end with unmelinated axons (olfactory nerve) through cribiform plate |
|
|
Term
| What binds to the receptors ont he cilia in the nose? |
|
Definition
| An odorant plus a odorant binding protein |
|
|
Term
| What happens following the binding of the receptors on the cilia? |
|
Definition
They act through a 2nd messenger system (G proteins), 2 pathways: IP3 pathway to open Ca channel to depolarize cAMP to open Na channel to depolarize |
|
|
Term
| What is the ratio of odorant receptor to olfactory nerve? |
|
Definition
|
|
Term
| What is the pathway from odorant receptor to lateral olfactory tract? |
|
Definition
| One odorant receptor per olfactory nerve. Olfactory nerves converge on glomeruli (of same type) in olfactory bulb; dendrites of mitral cells carry info into lateral olfactory tract |
|
|
Term
| where is the amygdalal found? Why is it significant? |
|
Definition
Amygdala found in the periamygdaloid cortex of the primary olfactory cortex (in medial aspect of temporal lobe) Important for sensing an expressing emotion of fear (part of the limbic system - motivation) |
|
|
Term
| Is thalamic relay involved in olfaction? |
|
Definition
| No; olfactory info reaches primary olfactory cortex without thalamic relay |
|
|
Term
| Is olfaction ipsilateral or contralateral? |
|
Definition
|
|
Term
| What parts make up the primary olfactory cortex? |
|
Definition
| Piriform cortex, periamygdaloid cortex, and entorhinal cortex |
|
|
Term
| What is the definition of complete loss, partial loss and distorted sense of smell? |
|
Definition
| Anosmia and hyposmia and dysosmia |
|
|
Term
| What stimuli are associated with the qualities of salty, sweet, sour, and bitter? |
|
Definition
| NaCl, sucrose, HCl, and quinine |
|
|
Term
| How frequently are the receptor cells of taste buds replaced? |
|
Definition
|
|
Term
| How do receptor cells of taste buds and olfactory cells differ? How are they similar? |
|
Definition
| Taste buds have microvilli and olfacotry cells have cilia; they are both somewhat bipolar except taste buds have a NT on distal end to activate nerve and olfacotry cells have an unmelinated axon |
|
|
Term
| What pathways do the salty, sweet, bitter, and sour tastes work? |
|
Definition
- Sweet - G prot- inc AC, inc cAMP, inc PKA, close K channels to depolarize
- Bitter - G prot - multiple pathways - ultimately inc in Ca (from ER) to cause depolarization
- Salty - Na (of NaCl) inside cell leads to depolarization
- Sour - H (of HCl) closes K channels to inc pos. charge in cell and depolarize
|
|
|
Term
| What are taste bud innervations? |
|
Definition
- Anterior 2/3 - chorda tympani (VII) and lingual n. (V3)
- Posterior 1/3 glossopharyngeal
- Soft palate - superior petrosal n. VII
- Esophagus and epiglottis -superior laryngeal - X
|
|
|
Term
| What are the definitions of total and partial loss of taste and aberant taste sensation? |
|
Definition
| ageusia, hypogeusia, dysgeusia |
|
|
Term
| Outline the central gustatory pathway for VII, IX, and X |
|
Definition
| Go through nucelus of the solitary tract (medulla) to VPM (thalamus) to primary taste cortex (insular cortex) |
|
|
