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174 Cards in this Set
- Front
- Back
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The image on the retina is ________ and ________
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Crossed and inverted
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Upper visual field information travels to the ________ in the ________ lobe in the ________ gyrus
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Loop of Meyer, Temporal lobe and lingual gyrus
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Lower visual field information travels to the ________ lobe in the ________ gyrus
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Parietal
Cuneus gyrus |
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Both visual reflexes synapse with what nucleus bilaterally?
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Pretectal nucleus
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Both visual reflexes will synapse with what important nuclei?
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Edinger-Westphal
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The light reflex enters the ________ after traveling through the optic tract.
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Superior brachium
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What are high velocity eye movements that orient the eyes toward the stimulus?
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Saccadic movements
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Describe the accommodation reflex pathway between the optic tract and pre-tectal nucleus
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Lateral geniculate nucleus, optic radiation, visual cortex, frontal eye field (area 8), corticobulbar tract
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Saccadic movements use what type of information?
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Visual, somatic and auditory
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The saccadic movements utilize what structure and brain area?
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Superior colliculus
Area 8 (frontal eye field) |
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The superior colliculus receives information about ________ and is concerned with what 2 things?
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Motion in visual field
Visual attentiveness and identification of broad outlines of objects |
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The frontal eye field receives information from the ________ and is concerned with what 2 things?
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Primary visual cortex
Visual discrimination and saccadic movements to complex visual stimuli |
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What nerves are involved in the corneal reflex and what does each contribute to it?
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CN V1: feels the stimulus
CN VII: winks |
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What is the white wall of the eye? What is the clear continuation of it?
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Sclera
Cornea |
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What is the conjunctiva?
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Thin lining over sclera and inside of eyelids
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Why does it make sense that the macula is responsible for central vision and sharp detail?
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Area of the retina with the least amount of vessels
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What is the fovea?
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Pit in macula where all retinal layers are shifted away to provide the least distortion
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What are the 3 neuron layers of the retina from superficial to deepest?
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Ganglion cells, bipolar cells, photoreceptors
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What is the purpose of horizontal and amacrine cells?
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Communication of bipolar cells and ganglion cells for convergence and lateral inhibition
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Rods are ____ sensitive to light, have ___ photopigment of _____ type to capture ____ light.
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More
More 1 type More |
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Although they have poor acuity, rods are great for ________ vision
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Night
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When do rods saturate?
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In day light
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What photoreceptors are present in the fovea?
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cones
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What types of photopigments do the cones have?
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Blue, red and green
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Describe the peripheral retina.
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Large amounts of rods and ganglion cells, decreased cones, and more sensitive to light
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Since the dark membrane potential of the retina is ________, ________ is produced in the dark.
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-40mV glutamate
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What keeps the photoreceptors at -40mV?
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Cyclic G --> cGMP --> Na channels kept open
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What absorbs light and electromagnetic radiation?
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Pigmented epithelium
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What is the Young-Helmholtz trichromacy theory?
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The relative excitation and inhibition of the 3 cone opsins account for color vision
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What is Rhodopsin?
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Retinol bound to opsin (7 transmembrane alpha-helix receptor) in rods
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What does bleaching mean?
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Configuration change from cis to trans
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Closing of Na+ channels results in ________ resulting in (increased/reduced) glutamate release?
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Hyperpolarization to -70
Reduced |
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What is the effector enzyme that breaks down cGMP?
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Phosphodiesterase (PDE)
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What is the cascade of events leading to hyperpolarization, thus decreased glutamate release?
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Light --> bleach --> active opsin --> transducin --> PDE --> cGMP --> close Na+ --> hyperpolarization
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During dark adaptation, ________ regenerates in the rods with the use of ________
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Unbleached rhodopsin
Ca2+ |
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What is the area of the retina when stimulated by L changes in the cell's membrane potential?
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Receptive field (center and surround)
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How do surrounding photoreceptors send information to the bipolar cell?
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Via the horizontal cells
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The receptive field centers and surrounds are ________ to each other.
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Antagonistic
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What receptors on ON bipolar cells cause depolarization?
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G-protein coupled glutamate receptors
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What causes OFF bipolar cells to depolarize?
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Glutamate gated ion channels opening
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In what situation do OFF bipolar cells depolarize?
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When light is off
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The center and surround receptive fields may ________ resulting in a ________ in polarization
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Cancel each other out
No net change |
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Ganglion cells are mainly responsive to ________
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Differences in illumination within their fields
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Like bipolar cells, ganglion cells have ________ receptive fields
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Antagonistic
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What are the types of ganglion cells?
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M (Magnocellular)
P (Parvocellular) |
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Describe the magnocellular cells.
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Large receptive fields, for object motion and low contrast stimuli, aid low resolution vision
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Parvocellular cells are responsible for what 2 things?
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Color vision, discrimination of fine details
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P-cells have ________ receptive fields.
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Small
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What are the 2 P-cell opponent cells and what are they sensitive to?
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R-G and B-Y wavelength
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The lateral geniculate nucleus is numbered from ___ to ___
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Posterior to anterior (1-6)
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What layers contain M cells?
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1 and 2
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What layers receive ipsilateral information?
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2, 3, 5
Remember: 2 + 3 = 5 |
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What is the primary visual cortex?
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Area 17 (striate cortex)
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What do the histological layers I and II of the visual cortex receive?
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Information from lateral geniculate body
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What does layer III receive and where does it disseminate?
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P-type information via the IVC beta
All cortical layers |
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What does layer IVB receive and where does it disseminate?
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M-type information via the IVC alpha
All cortical layers |
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What does layer V connect to?
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Superior colliculus and pulvinar
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What does layer VI connect to?
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LGB, bulk of optic radiation and claustrum
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The IVC layer (alpha and beta) is organized in what?
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Alternating ocular dominance columns
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V2 is the ________ cortex, areas ____ and _____
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Association visual cortex
18 and 19 |
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The brain receives ____% of cardiac output and ____% of oxygen used in the body.
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15%
20% |
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For auto regulation, why do the cerebral arteries dilate?
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When systemic pressure drops, or arterial CO2 concentration raises
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What is a drop in arteriole CO2 called?
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Hypocarbnia
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What is inadequate blood supply? What is it called if it results in cell death?
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Ischemia
Infarction |
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What is inadequate blood supply?
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Anoxia
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What is the most common class of stroke and what is it due to?
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Ischemic stroke (80%)
Blockage due to a clot or atherosclerosis |
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What is the rarest cause of stroke and how does it cause a stroke?
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Hypotension, reduced oxygen supply causes the stroke
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What are the 3 types of ischemic stroke (from most to least common)?
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Thrombotic
Embolic Lacunar |
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What is arterial stenosis?
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Slow thickening, hardening, and narrowing until blood flow is reduced
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How does a thrombus form?
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Stenosis --> inflammatory response --> cytokine release --> repeat cycle
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An injured arteriole fails to produce enough NO, which is critical for maintaining ________
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Blood vessel elasticity
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Why when there is a lack of NO, arteries cannot contract properly?
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Calcification and lack of elasticity
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What is an emboli?
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Dislodged clot that travels through vessels
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Describe the significance of atrial fibrillation as it pertains to embolic strokes.
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15% of embolic strokes, blood pools in atria until a clot is formed, can break off and go to brain
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Emboli are not uncommon with ________, ________, or ________ disorders
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Heart failure/post heart attack
Artificial heart valves Heart valve disorders |
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What are the rare sources emboli?
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Fat particles, tumor cells, air bubbles
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What are lacunar strokes and their symptoms?
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Series of very tiny ischemic strokes
Clumsiness, weakness, and emotional variability |
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What percent of thrombotic strokes are actually lacunar strokes?
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38%
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Lacunar strokes are the most common subtype of strokes in ________ people
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Japanese
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In a hemorrhagic stroke, what is broken?
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The blood brain barrier
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What are the subtypes of hemorrhagic stroke (from most common to least)?
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Parenchymal (10% of all strokes), subarachnoid (5%), arteriovenous malformations
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________ glutamate receptors can let excess amounts of ________ into the brain leading to infarction
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NMDA
Ca+ |
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What stroke victims often are unable to recognize their symptoms?
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Right parietal lobe stroke
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What are parenchymal strokes the result of?
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Hypertension combined with atherosclerotic vessels
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Who is at an elevated risk of parenchymal stroke?
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Hypertensives
Heart attack patients taking blood thinners (especially PPA) |
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What occurs in a subarachnoid hemorrhagic stroke?
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Blood vessel bursts and leaks into subarachnoid space (very painful)
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What is an arteriovenous malformation?
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Abnormal connection between arteries and veins that may rupture
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What can cause excessive hypotension?
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Heart attack, heavy blood loss. infection, anesthesia and blood pressure medications
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What age group is at the highest risk for stroke?
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65 years or older
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Which sex is at the highest risk of death by ischemic stroke?
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Females
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What ethnic groups are at high risk for stroke?
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All minorities
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African americans are ____ more likely to have a stroke, and ____ more likely to die than whites.
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2-3x
4x |
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What area of the country has the highest risk for stroke?
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Southeastern US (especially NC, SC, GA, MS, and CA)
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________ contributes to 70% of all strokes.
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Hypertension
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The wider the spread between ________ and ________ the greater the risk for stroke.
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Systolic and diastolic measurements
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SMoking increases the risk for ________ and ________ stroke by 2.5x
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Hemorrhagic and ischemic stroke
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What sugar related syndromes are stroke risks?
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Diabetes and insulin resistance
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What form of obesity has the highest stroke risk?
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Weight centered around the abdomen (apple shaped)
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What body lipid seems important for preventing strokes?
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HDLs
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Excessive alcohol is associated with ________ and ________ strokes
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Ischemic and hemorrhagic
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Seven or less drinks of alcohol a week can lower your risk for which type of stroke?
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ONLY ischemic
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Who does 3+ cups of coffee a week endanger?
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Older men with hypertension
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Which drugs are associated with stroke in younger individuals?
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Cocaine, methamphetamines, steroids
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What mental and emotional factors can effect stroke risk?
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Intense stress response, chronic stress, depression
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For younger individuals, what factors can raise the risk of stroke associated with migraines?
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Oral contraceptives (with auras), smoking, decongestants, Raynaud's syndrome
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What may be the second greatest risk factor for stroke and what does it occur along side?
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Elevated homocysteine
Vitamin B6, B12, and folic acid deficiencies |
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In general, how does an infection increase the risk for stroke?
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Play a role in atherosclerosis by initiating the inflammatory response
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What are 3 specific infections that are related to stroke?
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Lung infections (chlamydia pneumonia), periodontal disease, varicella zoster virus
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What may cause a stroke in children?
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Varicella zoster causing cerebral vasculitis (inflamed brain blood vessels)
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What is a focal loss of neurological function that usually resolves within 24 hours?
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Transient Ischemia Attack
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What is the major indicator of the source of a major ischemic stroke?
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Speed of symptom onset
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Symptoms of TIAs in the basilar artery are usually ________
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Bilateral
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When a ________ causes stroke, the onset is usually gradual. What if it's a fast onset?
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Thrombosis
Large embolism |
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What are the suddenly evolving symptoms of cerebral and parenchymal hemorrhagic strokes?
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Headache, nausea and vomiting, altered mental state
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What are the symptoms of the 'leaky' vessels prior to a subarachnoid hemorrhagic stroke?
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Headache, nausea and vomiting, light sensitivity and neurological abnormalities
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How do silent brain infarctions differ from lacunar strokes?
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Although both may go unnoticed, SB's will lead to mental impairment
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What is a syncope?
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Sudden loss of consciousness that results from temporary global cerebral ischemia
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A syncope inducing ischemia can be due to what 4 things?
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Hypotension, decrease cardiac output, blood/metabolic disorders, CNS disorders
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What is hemiplegia? Paraplegia?
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One side paralyzed/weak
Entire upper and lower half paralyzed/weak |
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The middle cerebral artery supplies nearly all the lateral brain except which gyri?
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Superior frontal, inferior temporal, parietoccipital, superior portions of the anterior and superior central, superior parietal lobe
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What structures are covered by the posterior cerebral artery?
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Inferior temporal, cuneus, lingual, hippocampal, splenium and thalamus
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What structures of the medial brain are covered by the anterior cerebral artery?
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Precuneus, cingulate, superior frontal, paracentral, most of corpus callosum and fornix
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ICA infarctions tend to induce the territories of which arteries?
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Anterior and middle cerebral
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What are the visual symptoms of an ICA infarction?
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Dimming, color changes, scotomas
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In an ICA infarction, what occurs if the dominant hemisphere is affected?
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Broca's or Wernicke's aphasia
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In an ICA infarction, what occurs if the non-dominant hemisphere is affected in the parietal lobe?
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Astereognosis/neglect
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________ paralysis and sensory loss occurs in an ICA infarction.
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Contralateral spastic
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________ paralysis and sensory loss of the ________ occurs in an anterior cerebral infarction.
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Contralateral spastic paralysis of lower extremities (paracentral lobule)
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What are the mental symptoms of anterior cerebral infarction and their locations?
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Mental confusion (pre-frontal)
Abulia (bilateral pre-frontal) |
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The internal capsule contains what fibers and tracts?
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Corticospinal
Thalamic tracts Sensory fibers |
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What are the symptoms of an anterior choroidal infarction and what area is lesioned?
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Contralateral spastic and loss of body and face (internal capsule), contralateral homonymous hemianopsia (LGB)
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What are the symptoms of an anterior choroidal infarction and what area is lesioned?
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Contralateral homonymous hemianopsia with sparing of macula
Striate cortex |
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What are the symptoms of a distal occlusion of the posterior cerebral and what area does it affects?
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Alexia
Splenium |
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What are the symptoms of a distal bilateral occlusion of the posterior cerebral and what area does it affect?
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Anton's syndrome
Basilar junction |
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The spastic paralysis resulting from a middle cerebral infarction is found where?
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Face and UPPER extremity
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What is alexia?
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Inability to read
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What is Anton's syndrome?
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Failure to recognize blindness
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What is apraxia and what occlusion is it related to?
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Able to move but don't know how (pre-motor cortex)
Middle cerebral |
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What are the visual symptoms related to a middle cerebral infarction? Name the effected areas.
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Contralateral homonymous hemanopsia (optic radiation)
Contralateral conjugate gaze (frontal eye field) |
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The acute conjugate gaze of a middle cerebral infarction occurs in what direction?
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Eyes fixed in the direction of disaster
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What are the symptoms of the proximal posterior cerebral infarction?
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Contralateral sensory and thalamic syndrome, hemiballism (subthalamic nucleus) and all midbrain symptoms
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Why does a large hemorrhage within the brain stem result in coma or death?
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Failure of central control of respiration
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What is locked in syndrome?
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Large infarction in ventral pons paralyzing all voluntary movements except of the eye
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What arteries are involved in medial syndromes of the medulla and pons?
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Anterior spinal (medulla)
Pontine (pons) |
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In a medial syndrome, where is the paralysis and DS loss and what structures are affected?
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Contralateral paralysis of bod (pons/pyramid corticospinal fibers)
Contralateral DS of body (medial lemniscus) |
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What specific issues would occur with an inferior pons pontine infarction?
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Medial strabismus of ipsilateral side (CN VI damaged) and horizontal gaze looking away from stroke
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What specific issues would occur with a superior pons pontine infarction?
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Internuclear opthalmoplegia (no communication of CN VI and CN III)
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What specific symptoms with lateral infarctions in the medulla (PICA) and pons (AICA)
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Ipsilateral tongue paralysis (CN XII injured)
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Common symptom with lateral infarction in the medulla (PICA) and pons (AICA
________ loss of pain and temperature from the body. Due to destruction of the ________ located in the ________ |
Contralateral
Spinothalamic tracts Anterolateral system |
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Common symptoms with lateral infarctions in the medulla (PICA) and pons (AICA)
__________ loss of pain and temperature from face. Due to destruction of the __________ located in the __________ |
Ipsilateral
Nucleus of spinal tract of the trigeminal Medulla |
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Common symptoms with lateral infarctions in the medulla (PICA) and pons (AICA)
__________ loss of touch from the face. Due to destruction of the __________ located in the __________ |
Ipsilateral
Chief sensory nucleus Pons |
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Common symptoms with lateral infarctions in the medulla (PICA) and pons (AICA)
__________ due to destruction of the vestibular nuclei |
Nystagmus
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Common symptoms with lateral infarctions in the medulla (PICA) and pons (AICA)
Cerebellar symptoms such as these 6 things? |
Ataxia, intention tremors, dysmetria, dysdiadochokinesia, pendular reflexes, hypotonia
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Common symptoms with lateral infarctions in the medulla (PICA) and pons (AICA)
What occurs if the reticular formation is lesioned? |
Ipsilateral Horner's syndrome and hiccup
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What is Horner's syndrome? What is it caused by?
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Ptosis, miosis, anhydrosis, enopthalmos
Disruption of sympathetics and cervical ganglion to the head |
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What is Wallenberg syndrome?
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PICA
Vagal symptoms (CN X, solitary tract, and nucleus ambiguus damaged) |
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What are the lower pons independent symptoms?
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Ipsilateral Bell's Palsy (CN VII)
Deafness (CN VIII) |
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What are the midpons independent symptoms?
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Inability to chew and jaw deviation (CN V)
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What is a dorsal midbrain syndrome also known and what often causes it?
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Perinaud's syndrome
Pinealoma |
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What are the symptoms of a dorsal midbrain syndrome. What specific structures are lesioned?
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Paralysis of upward gaze
Loss of papillary/light reflex (pretectal nucleus) |
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What is a ventral midbrain syndrome also known as? Central midbrain syndrome?
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Weber's Syndrome
Claude's Syndrome |
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What are the symptoms of oculomotor palsy?
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Ptosis, mydriasis, dilated unresponsive pupil, lateral strabismus
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What are the symptoms of a central midbrain syndrome?
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Ipsilateral oculomotor palsy, hemiballism, contralateral loss of all sensation
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What are the symptoms of a ventral midbrain syndrome. What specific structures are lesioned?
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Contralateral paralysis of body and face (corticospinal/bulbar)
Ipsilateral oculomotor palsy (CN III) |
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A combination of the ventral and central midbrain syndrome is called __________
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Benedikt syndrome
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Since autonomics have no __________, neurotransmitters diffuse __________ before reaching their targets
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Synaptic specifications, great distances
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Pre-ganglionic autonomic terminals release __________
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Nicotinic Ach
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Sweat glands are __________
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Postganglionic sympathetic
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What are the neuropeptides that function directly on tissue or have a modulator role?
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Neuropeptide Y, substance P, neurotensin, somatostatin, enkephalins
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Post-ganglionic sympathetic terminals release __________ that are received by __________ receptors.
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NE, alpha 1 and 2, beta 1, 2, 3, receptors
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Distal blood supply is often __________ driven.
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Sympathetically
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Where are the pre-ganglionic sympathetic cells located?
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intermediolateral gray of T1 - L2
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Pre-ganglionic sympathetic fibers exit through the __________, form the __________ and enter the __________
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Ventral root
White rami communicantes Paravertebral sympathetic ganglion |
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At what level do pre-ganglionic sympathetic fibers synapse with the sympathetic chain ganglion?
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Higher
Same and lower levels |
