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174 Cards in this Set

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The image on the retina is ________ and ________
Crossed and inverted
Upper visual field information travels to the ________ in the ________ lobe in the ________ gyrus
Loop of Meyer, Temporal lobe and lingual gyrus
Lower visual field information travels to the ________ lobe in the ________ gyrus
Parietal
Cuneus gyrus
Both visual reflexes synapse with what nucleus bilaterally?
Pretectal nucleus
Both visual reflexes will synapse with what important nuclei?
Edinger-Westphal
The light reflex enters the ________ after traveling through the optic tract.
Superior brachium
What are high velocity eye movements that orient the eyes toward the stimulus?
Saccadic movements
Describe the accommodation reflex pathway between the optic tract and pre-tectal nucleus
Lateral geniculate nucleus, optic radiation, visual cortex, frontal eye field (area 8), corticobulbar tract
Saccadic movements use what type of information?
Visual, somatic and auditory
The saccadic movements utilize what structure and brain area?
Superior colliculus
Area 8 (frontal eye field)
The superior colliculus receives information about ________ and is concerned with what 2 things?
Motion in visual field
Visual attentiveness and identification of broad outlines of objects
The frontal eye field receives information from the ________ and is concerned with what 2 things?
Primary visual cortex
Visual discrimination and saccadic movements to complex visual stimuli
What nerves are involved in the corneal reflex and what does each contribute to it?
CN V1: feels the stimulus
CN VII: winks
What is the white wall of the eye? What is the clear continuation of it?
Sclera
Cornea
What is the conjunctiva?
Thin lining over sclera and inside of eyelids
Why does it make sense that the macula is responsible for central vision and sharp detail?
Area of the retina with the least amount of vessels
What is the fovea?
Pit in macula where all retinal layers are shifted away to provide the least distortion
What are the 3 neuron layers of the retina from superficial to deepest?
Ganglion cells, bipolar cells, photoreceptors
What is the purpose of horizontal and amacrine cells?
Communication of bipolar cells and ganglion cells for convergence and lateral inhibition
Rods are ____ sensitive to light, have ___ photopigment of _____ type to capture ____ light.
More
More
1 type
More
Although they have poor acuity, rods are great for ________ vision
Night
When do rods saturate?
In day light
What photoreceptors are present in the fovea?
cones
What types of photopigments do the cones have?
Blue, red and green
Describe the peripheral retina.
Large amounts of rods and ganglion cells, decreased cones, and more sensitive to light
Since the dark membrane potential of the retina is ________, ________ is produced in the dark.
-40mV glutamate
What keeps the photoreceptors at -40mV?
Cyclic G --> cGMP --> Na channels kept open
What absorbs light and electromagnetic radiation?
Pigmented epithelium
What is the Young-Helmholtz trichromacy theory?
The relative excitation and inhibition of the 3 cone opsins account for color vision
What is Rhodopsin?
Retinol bound to opsin (7 transmembrane alpha-helix receptor) in rods
What does bleaching mean?
Configuration change from cis to trans
Closing of Na+ channels results in ________ resulting in (increased/reduced) glutamate release?
Hyperpolarization to -70
Reduced
What is the effector enzyme that breaks down cGMP?
Phosphodiesterase (PDE)
What is the cascade of events leading to hyperpolarization, thus decreased glutamate release?
Light --> bleach --> active opsin --> transducin --> PDE --> cGMP --> close Na+ --> hyperpolarization
During dark adaptation, ________ regenerates in the rods with the use of ________
Unbleached rhodopsin
Ca2+
What is the area of the retina when stimulated by L changes in the cell's membrane potential?
Receptive field (center and surround)
How do surrounding photoreceptors send information to the bipolar cell?
Via the horizontal cells
The receptive field centers and surrounds are ________ to each other.
Antagonistic
What receptors on ON bipolar cells cause depolarization?
G-protein coupled glutamate receptors
What causes OFF bipolar cells to depolarize?
Glutamate gated ion channels opening
In what situation do OFF bipolar cells depolarize?
When light is off
The center and surround receptive fields may ________ resulting in a ________ in polarization
Cancel each other out
No net change
Ganglion cells are mainly responsive to ________
Differences in illumination within their fields
Like bipolar cells, ganglion cells have ________ receptive fields
Antagonistic
What are the types of ganglion cells?
M (Magnocellular)
P (Parvocellular)
Describe the magnocellular cells.
Large receptive fields, for object motion and low contrast stimuli, aid low resolution vision
Parvocellular cells are responsible for what 2 things?
Color vision, discrimination of fine details
P-cells have ________ receptive fields.
Small
What are the 2 P-cell opponent cells and what are they sensitive to?
R-G and B-Y wavelength
The lateral geniculate nucleus is numbered from ___ to ___
Posterior to anterior (1-6)
What layers contain M cells?
1 and 2
What layers receive ipsilateral information?
2, 3, 5

Remember: 2 + 3 = 5
What is the primary visual cortex?
Area 17 (striate cortex)
What do the histological layers I and II of the visual cortex receive?
Information from lateral geniculate body
What does layer III receive and where does it disseminate?
P-type information via the IVC beta
All cortical layers
What does layer IVB receive and where does it disseminate?
M-type information via the IVC alpha
All cortical layers
What does layer V connect to?
Superior colliculus and pulvinar
What does layer VI connect to?
LGB, bulk of optic radiation and claustrum
The IVC layer (alpha and beta) is organized in what?
Alternating ocular dominance columns
V2 is the ________ cortex, areas ____ and _____
Association visual cortex
18 and 19
The brain receives ____% of cardiac output and ____% of oxygen used in the body.
15%
20%
For auto regulation, why do the cerebral arteries dilate?
When systemic pressure drops, or arterial CO2 concentration raises
What is a drop in arteriole CO2 called?
Hypocarbnia
What is inadequate blood supply? What is it called if it results in cell death?
Ischemia
Infarction
What is inadequate blood supply?
Anoxia
What is the most common class of stroke and what is it due to?
Ischemic stroke (80%)
Blockage due to a clot or atherosclerosis
What is the rarest cause of stroke and how does it cause a stroke?
Hypotension, reduced oxygen supply causes the stroke
What are the 3 types of ischemic stroke (from most to least common)?
Thrombotic
Embolic
Lacunar
What is arterial stenosis?
Slow thickening, hardening, and narrowing until blood flow is reduced
How does a thrombus form?
Stenosis --> inflammatory response --> cytokine release --> repeat cycle
An injured arteriole fails to produce enough NO, which is critical for maintaining ________
Blood vessel elasticity
Why when there is a lack of NO, arteries cannot contract properly?
Calcification and lack of elasticity
What is an emboli?
Dislodged clot that travels through vessels
Describe the significance of atrial fibrillation as it pertains to embolic strokes.
15% of embolic strokes, blood pools in atria until a clot is formed, can break off and go to brain
Emboli are not uncommon with ________, ________, or ________ disorders
Heart failure/post heart attack
Artificial heart valves
Heart valve disorders
What are the rare sources emboli?
Fat particles, tumor cells, air bubbles
What are lacunar strokes and their symptoms?
Series of very tiny ischemic strokes
Clumsiness, weakness, and emotional variability
What percent of thrombotic strokes are actually lacunar strokes?
38%
Lacunar strokes are the most common subtype of strokes in ________ people
Japanese
In a hemorrhagic stroke, what is broken?
The blood brain barrier
What are the subtypes of hemorrhagic stroke (from most common to least)?
Parenchymal (10% of all strokes), subarachnoid (5%), arteriovenous malformations
________ glutamate receptors can let excess amounts of ________ into the brain leading to infarction
NMDA
Ca+
What stroke victims often are unable to recognize their symptoms?
Right parietal lobe stroke
What are parenchymal strokes the result of?
Hypertension combined with atherosclerotic vessels
Who is at an elevated risk of parenchymal stroke?
Hypertensives
Heart attack patients taking blood thinners (especially PPA)
What occurs in a subarachnoid hemorrhagic stroke?
Blood vessel bursts and leaks into subarachnoid space (very painful)
What is an arteriovenous malformation?
Abnormal connection between arteries and veins that may rupture
What can cause excessive hypotension?
Heart attack, heavy blood loss. infection, anesthesia and blood pressure medications
What age group is at the highest risk for stroke?
65 years or older
Which sex is at the highest risk of death by ischemic stroke?
Females
What ethnic groups are at high risk for stroke?
All minorities
African americans are ____ more likely to have a stroke, and ____ more likely to die than whites.
2-3x
4x
What area of the country has the highest risk for stroke?
Southeastern US (especially NC, SC, GA, MS, and CA)
________ contributes to 70% of all strokes.
Hypertension
The wider the spread between ________ and ________ the greater the risk for stroke.
Systolic and diastolic measurements
SMoking increases the risk for ________ and ________ stroke by 2.5x
Hemorrhagic and ischemic stroke
What sugar related syndromes are stroke risks?
Diabetes and insulin resistance
What form of obesity has the highest stroke risk?
Weight centered around the abdomen (apple shaped)
What body lipid seems important for preventing strokes?
HDLs
Excessive alcohol is associated with ________ and ________ strokes
Ischemic and hemorrhagic
Seven or less drinks of alcohol a week can lower your risk for which type of stroke?
ONLY ischemic
Who does 3+ cups of coffee a week endanger?
Older men with hypertension
Which drugs are associated with stroke in younger individuals?
Cocaine, methamphetamines, steroids
What mental and emotional factors can effect stroke risk?
Intense stress response, chronic stress, depression
For younger individuals, what factors can raise the risk of stroke associated with migraines?
Oral contraceptives (with auras), smoking, decongestants, Raynaud's syndrome
What may be the second greatest risk factor for stroke and what does it occur along side?
Elevated homocysteine
Vitamin B6, B12, and folic acid deficiencies
In general, how does an infection increase the risk for stroke?
Play a role in atherosclerosis by initiating the inflammatory response
What are 3 specific infections that are related to stroke?
Lung infections (chlamydia pneumonia), periodontal disease, varicella zoster virus
What may cause a stroke in children?
Varicella zoster causing cerebral vasculitis (inflamed brain blood vessels)
What is a focal loss of neurological function that usually resolves within 24 hours?
Transient Ischemia Attack
What is the major indicator of the source of a major ischemic stroke?
Speed of symptom onset
Symptoms of TIAs in the basilar artery are usually ________
Bilateral
When a ________ causes stroke, the onset is usually gradual. What if it's a fast onset?
Thrombosis
Large embolism
What are the suddenly evolving symptoms of cerebral and parenchymal hemorrhagic strokes?
Headache, nausea and vomiting, altered mental state
What are the symptoms of the 'leaky' vessels prior to a subarachnoid hemorrhagic stroke?
Headache, nausea and vomiting, light sensitivity and neurological abnormalities
How do silent brain infarctions differ from lacunar strokes?
Although both may go unnoticed, SB's will lead to mental impairment
What is a syncope?
Sudden loss of consciousness that results from temporary global cerebral ischemia
A syncope inducing ischemia can be due to what 4 things?
Hypotension, decrease cardiac output, blood/metabolic disorders, CNS disorders
What is hemiplegia? Paraplegia?
One side paralyzed/weak
Entire upper and lower half paralyzed/weak
The middle cerebral artery supplies nearly all the lateral brain except which gyri?
Superior frontal, inferior temporal, parietoccipital, superior portions of the anterior and superior central, superior parietal lobe
What structures are covered by the posterior cerebral artery?
Inferior temporal, cuneus, lingual, hippocampal, splenium and thalamus
What structures of the medial brain are covered by the anterior cerebral artery?
Precuneus, cingulate, superior frontal, paracentral, most of corpus callosum and fornix
ICA infarctions tend to induce the territories of which arteries?
Anterior and middle cerebral
What are the visual symptoms of an ICA infarction?
Dimming, color changes, scotomas
In an ICA infarction, what occurs if the dominant hemisphere is affected?
Broca's or Wernicke's aphasia
In an ICA infarction, what occurs if the non-dominant hemisphere is affected in the parietal lobe?
Astereognosis/neglect
________ paralysis and sensory loss occurs in an ICA infarction.
Contralateral spastic
________ paralysis and sensory loss of the ________ occurs in an anterior cerebral infarction.
Contralateral spastic paralysis of lower extremities (paracentral lobule)
What are the mental symptoms of anterior cerebral infarction and their locations?
Mental confusion (pre-frontal)
Abulia (bilateral pre-frontal)
The internal capsule contains what fibers and tracts?
Corticospinal
Thalamic tracts
Sensory fibers
What are the symptoms of an anterior choroidal infarction and what area is lesioned?
Contralateral spastic and loss of body and face (internal capsule), contralateral homonymous hemianopsia (LGB)
What are the symptoms of an anterior choroidal infarction and what area is lesioned?
Contralateral homonymous hemianopsia with sparing of macula
Striate cortex
What are the symptoms of a distal occlusion of the posterior cerebral and what area does it affects?
Alexia
Splenium
What are the symptoms of a distal bilateral occlusion of the posterior cerebral and what area does it affect?
Anton's syndrome
Basilar junction
The spastic paralysis resulting from a middle cerebral infarction is found where?
Face and UPPER extremity
What is alexia?
Inability to read
What is Anton's syndrome?
Failure to recognize blindness
What is apraxia and what occlusion is it related to?
Able to move but don't know how (pre-motor cortex)
Middle cerebral
What are the visual symptoms related to a middle cerebral infarction? Name the effected areas.
Contralateral homonymous hemanopsia (optic radiation)
Contralateral conjugate gaze (frontal eye field)
The acute conjugate gaze of a middle cerebral infarction occurs in what direction?
Eyes fixed in the direction of disaster
What are the symptoms of the proximal posterior cerebral infarction?
Contralateral sensory and thalamic syndrome, hemiballism (subthalamic nucleus) and all midbrain symptoms
Why does a large hemorrhage within the brain stem result in coma or death?
Failure of central control of respiration
What is locked in syndrome?
Large infarction in ventral pons paralyzing all voluntary movements except of the eye
What arteries are involved in medial syndromes of the medulla and pons?
Anterior spinal (medulla)
Pontine (pons)
In a medial syndrome, where is the paralysis and DS loss and what structures are affected?
Contralateral paralysis of bod (pons/pyramid corticospinal fibers)
Contralateral DS of body (medial lemniscus)
What specific issues would occur with an inferior pons pontine infarction?
Medial strabismus of ipsilateral side (CN VI damaged) and horizontal gaze looking away from stroke
What specific issues would occur with a superior pons pontine infarction?
Internuclear opthalmoplegia (no communication of CN VI and CN III)
What specific symptoms with lateral infarctions in the medulla (PICA) and pons (AICA)
Ipsilateral tongue paralysis (CN XII injured)
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
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
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
Common symptoms with lateral infarctions in the medulla (PICA) and pons (AICA)

__________ due to destruction of the vestibular nuclei
Nystagmus
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
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
What is Horner's syndrome? What is it caused by?
Ptosis, miosis, anhydrosis, enopthalmos
Disruption of sympathetics and cervical ganglion to the head
What is Wallenberg syndrome?
PICA
Vagal symptoms (CN X, solitary tract, and nucleus ambiguus damaged)
What are the lower pons independent symptoms?
Ipsilateral Bell's Palsy (CN VII)
Deafness (CN VIII)
What are the midpons independent symptoms?
Inability to chew and jaw deviation (CN V)
What is a dorsal midbrain syndrome also known and what often causes it?
Perinaud's syndrome
Pinealoma
What are the symptoms of a dorsal midbrain syndrome. What specific structures are lesioned?
Paralysis of upward gaze
Loss of papillary/light reflex (pretectal nucleus)
What is a ventral midbrain syndrome also known as? Central midbrain syndrome?
Weber's Syndrome
Claude's Syndrome
What are the symptoms of oculomotor palsy?
Ptosis, mydriasis, dilated unresponsive pupil, lateral strabismus
What are the symptoms of a central midbrain syndrome?
Ipsilateral oculomotor palsy, hemiballism, contralateral loss of all sensation
What are the symptoms of a ventral midbrain syndrome. What specific structures are lesioned?
Contralateral paralysis of body and face (corticospinal/bulbar)
Ipsilateral oculomotor palsy (CN III)
A combination of the ventral and central midbrain syndrome is called __________
Benedikt syndrome
Since autonomics have no __________, neurotransmitters diffuse __________ before reaching their targets
Synaptic specifications, great distances
Pre-ganglionic autonomic terminals release __________
Nicotinic Ach
Sweat glands are __________
Postganglionic sympathetic
What are the neuropeptides that function directly on tissue or have a modulator role?
Neuropeptide Y, substance P, neurotensin, somatostatin, enkephalins
Post-ganglionic sympathetic terminals release __________ that are received by __________ receptors.
NE, alpha 1 and 2, beta 1, 2, 3, receptors
Distal blood supply is often __________ driven.
Sympathetically
Where are the pre-ganglionic sympathetic cells located?
intermediolateral gray of T1 - L2
Pre-ganglionic sympathetic fibers exit through the __________, form the __________ and enter the __________
Ventral root
White rami communicantes Paravertebral sympathetic ganglion
At what level do pre-ganglionic sympathetic fibers synapse with the sympathetic chain ganglion?
Higher
Same and lower levels