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41 Cards in this Set
- Front
- Back
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Where is the vestibular system? What are the components of it? What is the overall function of this system. |
It is found in the inner ear. Its two components are the vestibular sacs and semicircular canals. The overall function is balance, maintenance of head in upright position, and adjustment of eye movements to compensate for head movement. |
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What are the individual functions of the 2 components of the vestibular system? What are the components of the vestibular sacs? |
Semicircular canals respond to angular acceleration, thus moving your head left and right. Vestibular sacs respond to force of gravity, so up and down movement Vasticular sacs = Utricle (lil' pouch) and Saccule (lil' sack) |
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What is an ampulla? What are the components of an ampulla? Where do the sensory receptors sit in the ampulla? |
An enlargement containing the organ in which the sensory receptors reside. It contains the cupulla and endolymph. The sensory receptors are hair cells similar to those found in the cochlea. Their cilia are embedded in a gelatinous mass called the cupula, which blocks part of the ampulla. |
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How do the sensory receptors work? What feature of the ampule allows for sheer force to be exerted on the cilia? |
The receptors respond to mechanical sheer and cause changes in membrane potential the same way as it does in the cochlea. The gelantinous cupula which contains the cilia has otoconia which are calcium carbonate crystals. The weight of the crystals causes the gelatinous mass to shift in position as the orientation of the head changes. |
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What are the two branches of the 8th cranial nerve? |
Vestibular and cochlear nerves |
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What is the vestibular ganglion? |
The afferent axons of the vestibular nerve where the bipolar cell bodies are. It is a branch of the 8th cranial nerve. |
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Where do the axons of the vestibular nerve synapse to in the brain? |
Most synapse within the vestibular nuclei of the medulla, but some go directly to the cerebellum. |
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After the vestibular nerve axons make their first stop, where do they go next? |
Neurons of the vestibular nuclei send their axons to the cerebellum, spinal cord, medulla, and pons |
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What brain stems projection of the vestibular pathway is responsible nausea, vomiting, and dizziness? |
Lower brain stem projections |
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What is the name of the reflect that controls neck muscles in order to maintain an upright position to compensate for sudden head movements? |
Vestibulo-ocular reflex |
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Which of the somatosenses provides information from skin about sense of touch and which provides information about body position and movements? |
Cutaneous senses relay skin and touch information whereas kinesthesia/proprioception provides info about body position and movement |
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What are the 4 types of encapsulated receptors found in glabrous (bald) skin that relays touch information? How do these differ? |
Small receptive fields with sharp borders: 1) Merkel's disks 2) Meissner's corpuscles Large, diffuse borders: 3) Rufini corpuscles 4) Pacinian corpuscles |
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How do the 4 encapsulated receptors produce membrane potentials? |
Movement and deformation of the skin causes ion channels to open causing a change in membrane potential |
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Which somatosensory pathway carries information pertaining to highly localized touch and which one carries poorly localized pain and temp signals? |
Poorly localized = spinothalamic tract Highly localized = dorsal columns |
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Somatosensation of highly localized and poorly localized touch pathways end at the ventral posterior nucleus of the thalamus after passing the medial lemniscus, how do the paths differ and what do they have in common? |
Commonality: Axons enter the CNS via the 5th aka trigeminal cranial nerve. Differences: Highly localized info ascends through the dorsal columns to the lower medulla before reaching the common pathway. Poorly localized info bypasses the medulla and goes straight to the common pathway entering at the medial lemniscus. |
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What is tactile agnosia? What are the 2 types of tactile agnosia? |
Inability to correctly recognize common objects by touch. This presents as apperceptive or associative tactile agnosia. |
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How do the 2 causes of tactile agnosia differ? |
Apperceptive agnosia is caused by parietal lobe damage Associative agnosia is caused by bilateral lesions of the angular gyrus |
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How do the manifestations of apperceptive agnosia differ from associative agnosia. |
Apperceptive agnosia is failure in recognition that is due to a failure of perception. In contrast, associative agnosia is a type of agnosia where perception occurs but recognition still does not occur |
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What structures identify temperature? What other senses use this structure? Where are these receptors found? |
Temp and pain are detected by free nerve endings. The cold receptors are close to the surface of the skin whereas the warmth receptors are underneath |
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What is the effect of cold on membrane potentials? |
Cold receptors slow the work of Sodium-Potassium pump and causes an intracellular accumulation of sodium and depolarization. |
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Pain involves tissue destruction induced by _____ stimuli and ____ force |
thermal, mechanical |
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Describe the pain receptors. What is the other name for pain receptors. |
Pain receptors are free branching unmyelinated nerve ending aka nociceptors |
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Where do opiates bind to to exert their analgensic effects? |
Periaqueductal gray and spinal cord |
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Painful stimuli activate two cortices. What are they, and what is the purpose of activating the limbic related cortex? |
Activates somatosensory and anterior cingulate gyrus. Anterior cingulate activation is involved in the aversiveness of future pain. |
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What 2 means can we use to reverse overdose? |
Naloxone and focal brain stimulation of the periaqueductal gray. |
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What are the 5 types of food receptors in the mouth and what information do they convey respectively? |
Sweet: Safe food Salty: Source of sodium ions Bitter: Poisonous foods and alkaloids Sour: Spoiled food Umami: Protein and glutamate |
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What factors contribute to flavor? |
Taste, olfaction, and temperature |
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What are papillae? What are the 3 types of papillae? |
Grouped receptive taste organs. There are fungiform, foliate, and circumvallate |
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One of the 3 types of papillae is located in folds of the tongue. Which one is it? |
Foliate papillae |
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What is the turnover of taste buds? Where do we find the taste bud? |
12-14 days. It is found in the trench circumventing the pappillae |
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______ are located at the end of each cell and project through the opening of the taste bud into the saliva that coats the tongue. Why are these protrusions necessary? |
Cilia. These are needed because tight junctions between adjacent taste cells prevent substances in the saliva from diffusion freely into the taste bud itself. |
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What is the ligand for each of the 5 types of food receptors respectively? Include any pertinent information about the receptor genes. |
Saltiness: NaCl since it's prob a sodium channel Sourness: H+ Bitterness: Alkaloids. Receptors are T2R genes with many isoforms Sweetness: Sugar. Receptors are T1R2 + T1R3 genes Umami: MSG. Receptors are T1R1 + T1R3 |
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The rostral 2/3rds of the tongue are innervated by 3 cranial nerves. What are they called? |
10th Vagus 9th Glossopharyngeal 7th Chorda tympany aka facial nerve |
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Why can an ear infection lead to loss of taste? |
This is because the chorda tympany aka 7th cranial nerve aka facial nerve passes behind the tympanic membrane so an ear infection can interfere with this nerve |
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The 3 cranial nerves project to an area of the medulla known as the ______ of the _____ ______, then to the ______, and then to the _______ ______ _____ |
nucleus of the solitary tract ---> Primary gustatory cortex --> Amygdala --> Hypothalamus |
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What are the 2 theories about how taste-responsive cells process information? |
Labeled line theory and Across fiber pattern theory |
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What do both theories about taste encoding have in common and how do they differ? |
They both ignore changes in firing rates over time aka temporal coding. Labeled line focuses on the response profile of individual cells where a specific cell has a specific stimulus that evokes the greatest change in potential. Across fiber focuses on groups of cells where similar tastes activate populations of cells all involved in processing of that taste. |
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Where are the olfactory receptors embedded and where do they project to? |
The receptors are embedded in the cribiform plate and extend directly into the olfactory bulb and then to the piriform cortex |
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What is the only sense that does not synapse at the thalamus before reaching the cortex? |
Gustation |
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What is the neural olfactory pathway? |
Receptors --> olfactory bulb --> Amygdala and 2 regions of the limbic cortex (piriform and entorhinal). Amygdala and Piriform cortex then both send information to the hypothalamus Entorhinal --> Hippocampus |
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How does the brain recognize different odorants |
Different activation patterns aka olfatopic coding |
