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143 Cards in this Set
- Front
- Back
Where do preganglionic neurons of the sympathetic NS originate?
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T1-T12; L1-L3 (or just T1-L3) (throacolumbar region)
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Where do preganglionic neurons of the parasympathetic NS originate?
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S2-S4 (craniosacral region) and in the nuclei of cranial nerves
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Where do preganglionic fibers syjnapse in the adrenal gland?
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in the chromaffin cells of the adrenal medulla
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Notes on Chromaffin
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Chromaffin cells of the adrenal medulla are innervated by the splanchnic nerve and secrete adrenaline, noradrenaline, and enkephalin into the bloodstream. As such, they play an important role in the fight-or-flight response. They are also referred to as granules and this is where the enzyme dopamine-hydroxylase catalyzes the conversion of dopamine to norepinephrine.
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What do chromaffin cells do?
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secrete epinephrine (80%) and norepinephrine (20%) into the circulation
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What is pheochromocytoma?
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tumor of the medullary gland --> over secretion of catecholamines --> increased VMA levels (VMA is found in vanilla ice cream)
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what is the NT of adrenergic neurons?
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NorEpi
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What is the NT of cholinergic neurons?
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ACh
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What are some types of nonadrenergic and noncholinergic neurons, and what do they secrete?
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some postganglionic parasympathetic neurons of the GI tract
- secrete substance P, vasoactive intestinal peptide (VIP), or NO |
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Give the chart for NT in ganglion for sympathetic and parasympathetic neurons and the same thing for the effector organs
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ACh for symp and para in ganglion
NorEpi for symp and ACh for para in effetor organs (one exception: Sweat glands (Sympathetic effector organ) uses ACh |
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What is the receptor type at the effector organ for parasympathetic neurons?
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Muscarinic
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What is the receptor type at the effector organ for sympathetic neurons?
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a1, a2, b1, b2
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What is the receptor type at the effector organ for somatic (PNS) neurons?
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nicotinic
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Where do you find alpha 1 receptors?
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- vascular smooth muscle of skin and splanchinc regions
- GI and bladder sphincters, and - radial muscle of iris |
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What are the effects of ligand binding to alpha 1 receptors?
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excitation (contraction or constriction)
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What is a Jacksonian Seizure?
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Jacksonian seizures are initiated with abnormal electrical activity within the primary motor cortex. They are unique in that they travel through the primary motor cortex in succession, affecting the corresponding muscles, often beginning with the fingers. This is felt as a tingling sensation. It then affects the hand and moves on to more proximal areas. Symptoms often associated with a Jacksonian seizure are sudden head and eye movements, tingling, numbness, smacking of the lips, and sudden muscle contractions. Most of the time any one of these actions can be seen as normal movements, without being associated with the seizure occurring. They occur at no particular moment and last only briefly.
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What is the function of white fat?
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Most adipose tissue is white, the focus of this review. White adipose tissue serves three functions: heat insulation, mechanical cushion, and most importantly, a source of energy.
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What is the function of brown fat?
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Its primary purpose is to generate body heat. In contrast to white adipocytes (fat cells), which contain a single, large fat vacuole, brown adipocytes contain several smaller vacuoles and a much higher number of mitochondria. Brown fat also contains more capillaries since it has a greater need for oxygen than most tissues.
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What are the three divisions of the autonomic nervous system?
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1. sympathetic
2. parasympathetic 3. enteric |
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What are the two nervous system branches?
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1. autonomic nervous system
2. somatic nervous system |
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Where are the preganglionic neurons of the sypathetic nervous system found?
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T1-L3
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Where are the preganglionic neurons of the parasympathetic NS found?
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- nuclei of cranial nerves
- S2-S4 |
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IS the Adrenal medulla a ganglion of the sympathetic or parasympathetic NS?
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Sympathetic NS
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Where do preganglionic fibers synapse to in the adrenal medulla?
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Chormaffin cells
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WHat do chromaffin cells secrete?
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80% epi
20% norepi |
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Where are a1 receptors found?
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-vascular smooth mucle of skin and splanchnic regions
- GI sphincters - bladder sphincters - radial muscle of iris |
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What do a1 receptors do?
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produce excitation (contraction/constriction)
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What do a1 receptors respond to?
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equally sensitive to eoorepi and epi, but only norepi is released in high enough concentrations
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What is the mechanism of action of a1 receptors?
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Gq protein stimulates phospholiase C --> increased IP3 and intracellular Ca
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Where are a2 receptors found?
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- presynaptic nerver terminals
- platelets - fat cells - walls of the GI tract |
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What do a2 receptors do?
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inhition (relaxation/dilation)
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What is the mechanism of action of a2 receptors:
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Gi protein inhibits adenylate cyclase and decreases levels of cAMP
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Where are B1 receptors found?
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- SA node
- AV node - ventricular muscle of heart |
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What do B1 receptors do?
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produce excitation
- increase HR - increase conduction velocity - increase contractility |
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What are B1 receptors sensisitive to?
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-both norepi and epi and are more sensitive than a1 receptors
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What is the mechanism of action of B1 receptors?
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Gs protein stimulates adenylate cyclase and increases cAMP
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Where are B2 receptors found?
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- vascular smooth muscle of skeletal muscle, bronchial smooth muscle, and walls of GI tract and bladder
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What do B2 receptors do?
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relaxation (dilation/relaxation)
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What do B2 receptors respond to?
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more sensitive to epi than to norepi
more sensitive to epi than a1 receptors |
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What is the mechanism of action of B2 receptors?
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Gs protein stimulates adenylate cyclase and increases cAMP
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Where are nicotinic receptors found?
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- autonomic ganglion
- neuromuscular junction - adrenal medulla |
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What are nicotinic receptors activate by?
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- Ach
- nicotine |
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What are the actions of nicotonic receptors?
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- activation
- binds to alpha subunit and allows passage of Na and K |
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What are nicotinic receptors blocked by?
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- ganglionic blockers (hexamethonium)
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What is hexamethonium?
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Hexamethonium is an nAch receptor antagonist which acts in autonomic ganglia by preventing the acetylcholine molecules from binding to the site of the cholinergic receptor. It has no effect on the muscarinic acetylcholine receptors, or mAChRs.
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Where does hexamethonium act?
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at the autonomic ganglia, but not at the neuromuscular junction
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Name the types of muscarinic receptors and where they're found
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M2: heart
M3: smooth muscle and glands |
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How do muscarinic receptors act in the heart?
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are inhibitory:
decreased HR decreased condiction velocity in AV node |
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How do muscarinic receptors act at the smooth muscle and glands?
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excitatory:
- increased GI motility - increased secretion |
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What activates muscarinic receptors?
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ACh and muscarine
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What blocks muscarinic receptors?
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atropine
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How do muscarinic receptors act on the Heart?
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AT the SA node, Gi protein inhibits adenylate cyclase, whcih leads to opening of the K+ channels. This slows the rate of spontaneous Phase 4 depolarization and decreases heart rate
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How do muscarinic receptors act on the smooth muscles and glands?
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Gq protein stimulates phospholipase C increases IP3 and intracellular Ca2+
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Name the autonomic centers in the medulla
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1. vasomotor center
2. respiratory center 3. swallowing, coughing, and vomiting centers |
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Name the autonomic centers in the pons
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pneumotaxic center
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Name the autonomic centers in the midbrain
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micturation center (urination)
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name the autonomic centers in the hypothalamus
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- temperature regulation center
- thirst and food intake regulatory centers |
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Name the 5 mechanoreceptors
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1. Pacinian corpuscles
2. joint receptors 3. stretch receptors in muscle 4. hair cells in auditory and vestibular systems 5. baroreceptors in carotid sinus |
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Name the 4 chemoreceptors
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1. olfactory receptors
2. taste receptors 3. osmoreceptors 4. carotid body O2 receptors |
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Give an example of a slowly adapting, or tonic receptors
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muscle spindle.
- responds repetitively to a prolonged stimulus |
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Give an example of a rapidly adapting or phasic receptor
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Pacinian corpuscle
- detects the onset and offset of a stimulus |
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Where are cell bodies of the primary afferent neurons found?
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- dorsal root
- spinal cord ganglion |
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What does the dorsal column sense?
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- fine touch
- pressure - two-point discrimination - vibration - proprioception |
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What types of fibers make up the dorsal column system?
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group II fibers
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Describe the course of the dorsal column
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cell bodies are in dorsal root.
- axions ascend ipsilaterally to the nucleus gracilis and nucleus cuneatus of the medulla - cross at the medulla - synapse at the VPL |
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What does the anterolateral system sense?
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- temperature
- pain - light touch |
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What types of fibers make up the anterolateral system?
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- group III and IV fibers
- enter the spinal cord and termiante in the dorsal horn |
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Describe the course of the anterolateral system.
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second order neurons cross the midline at the anterolateral quadrant of the spinal cord
- ascend to the contralateral VPL |
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What happens whn you have destruction of the thalamic nuclei?
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loss of sensation from the contralateral side of the body
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Which are the main somatosensory areas of the cortex?
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SI and SII
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Pacinian corpuscle: description
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onion like structions in the subcutaneous kins (surroundeing unmyelinated nerve endings)
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pacinian corpuscles: sensation carried
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vibration, tapping
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pacinian corpuscles: adaptation
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rapid
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meissner's corpuscle: description
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found in non-hairy skin
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meissner's corpuscle: sensation carried
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velocity
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meissner's corpuscles: adaptation
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rapid
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Ruffini's corpuscle: description
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enclapsulated
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ruffini's corpuscle: sensation carried
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pressure
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ruffini's corpuscle: adaptation
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slowly adapting
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merkel's disk: description
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transducer is on epithelial cells
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merkel's disk: sensation carried
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location
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merkel's disk: adaptation
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slow
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what is the NT for nociception?
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substance P
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How do you inhibit substance P release?
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opiods
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how is fast pain transmitted?
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by group II fibers
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how is slow pain transmitted?
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by C fibers
- throbbing, aching - poorly localized |
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how is refractive power of a lens measured?
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in diopters
- the reciprocoal of the focal distance |
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emmetropia
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normal
- light focuses on retina |
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hypetropia
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farsighted
- light focuses behind retina - corrected by convex lens |
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myopia
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nearsighted
- light focuses in front of the retina - corrected by biconcave lens |
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astigmatism
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curvature of lens is not uniform.
- corrected by cylindric lens |
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presbyopia
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loss of accommodation power of lens
- comes with aging |
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What do pigment epithelial cells do?
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- absorb stray light and prevent light scatter
- convert 11-cis retinal to all-trans retinal |
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what do bipolar cells synapse to?
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receptor cells synapse to one bipolar cell, which then synapses to single ganglion cell
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What is the ratio of cones to bipolar cells in the fovea?
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1:1
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What other cell types form local circuits with bipolar cells?
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horizontal and amacrine cells
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what cells are the output of the retina?
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ganglion cells
- they form the optic nerve! |
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where do axons of the gaglion celsl go?
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form the optic nerve and optic tract. end in the lateral geniculate body of the thalamus
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What is rhodopsin composed of?
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1. opsin (G-protein coupled receptor)
2. retinal (aldehyde of vit A) |
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what is photoisomerization?
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UV converting 11-cis retinal to all-trans retinaa
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what is one of the metabolites formed from photoisomerization?
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metarhodopsin II
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what happens during vit A deficiency?
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night blindness
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what does metarhodopsin II activate?
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transducin (a G-protein)
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what does transducin activate?
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phosophodiesterase
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what does the phosphodiesterase do during the phototransduction cascade?
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converts cGMP to 5'-GMP and cGMP levels decrease
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what happens with decreased cGMP levels during the phototransduction cascade?
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- closure of Na channels -> hyperpolarization
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What do simple cells respond to?
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bars of light
pay attention to origentation and position |
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what do complex cells respond to?
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moving bars or edges of light with the correct orientation
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What do hypercomplex cells respond to?
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lines with a particular length
- curves and angles |
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What is frequency measured in?
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Hz
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What is sound intensity measured in?
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decibels
dB = 20log P/P_o P = sound pressure being measured P_o= reference pressure measured at the threshold frequency |
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what do you find in the middle ear?
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- tympanic membrane
- auditory ossicles (M,I,S) |
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What do you find in the inner ear?
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- semicircular canals
- cochlea - vestibule consists of bony and membraneous labyrinth |
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what are the three types of scala, and what types of fluid fill them?
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scala vestibuli
scala media scala tympani Na - perilymph K - endolymph Na- perilymph |
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Where do you find the organ of corti?
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basilar membrane
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What types of cells are found in the organ of corti?
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inner and outer hair cells. the cells have cilia that are embedded in the tectorial membrane
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describe inner hair cells
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- arranged in a single row
- few in number |
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describe outer hair cells
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- arranged in parallel rows
- many in number |
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what do you find in the spiral ganglion?
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cell bodies of the CN VIII
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what happens when the cilia bend on the hair cells?
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K+ conductance changes. depolarization in one direction and hyperpolarization in the other direction
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what results from the oscillating potential cuased by the bending of cilia?
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cochlear microphonic potential
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which part of the basilar membrane detects high frequency sounds?
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base of basilar membrane
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which part of the basilar membrane detects low frequency sounds?
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apex of the basilar membrane
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Describe the vestibular organ
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- 3 semicircular canals
- utricle - saccule |
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what detects angular acceleration or rotation?
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semicircular canals
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what detects linear acceleration?
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utricle and saccule
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what structure contains the embedded ciliar of the receptor hair cells of the vestibular organ?
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cupula
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what is the single long cilium called?
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kinocilium
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what are the smaller cilia on hair cells called?
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stereocilia
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in which direction does nystagmus occur?
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same direction as head movement
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in which direction does postrotatory nystagmus occur?
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in the opposite direction of the head rotation
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what types of fibers make up the CN I nerve?
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unmyelinated C fibers
- among the smallest and slowest of the nervous system |
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what else innervates the olfactory epithelium other than CN I
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- CN V
- detects noxious and painful stimuli (e.g. ammonia) |
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hyposmia
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- reduced sense of smell
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anosmia
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- no sense of smell
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which are the second order neurons of the olfactory pathway?
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Mitral cells
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what is the output of the mitral cells?
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olfactory tract --> piriform cortex
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describe the signal transduction of olfaction
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odorant molecules bind to olfacotry receptor proteins on the cilia of the olfactory reeceptor cells
- G_olf is activate --> activates adenylate cyclase - increase in intracellular cAMP opens Na channes --> depolarizing receptor potietial |
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where are taste receptor cells found?
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on taste buds that are found on papillae
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describe the anterior 2/3 of the tongue
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- fungiform papillae
- salty and sweet - innervated by CN VII (chorda tympani) |
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describe the posterior 1/3 of the tongue
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- circumvallate and foliate papillae
- sour and bitter - CN IX (glossopharyngeal) |
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what is the back of the throat innervated by?
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CN X
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describe the taste pathway
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CN VII, IX, and X enter the medulla
- ascend the solitary tract - synapse at the solitary nucleus - project to the VPM and then to the taste cortex |