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Cardiology > Neuro > Flashcards

Neuro Flashcards

1
Q

What is the somatosensory system?

A

Allows us to sense: touch, temperature, propioception, pain

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2
Q

What are teh exteroreceptive sense?

A

mechanoreceptor: touch
thermoreceptors: warming and cooling
nociceptors: sharp and burning pain

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3
Q

Receptive field?

A

area in the periphery where application of an adequate stimulus causes response

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4
Q

Stumulus transduction?

A

At peripheral terminal stimulus activates receptors and ion channels; generates receptor potential; receptor potential strong enough generates action potentials

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5
Q

Intensity of stimulus is encoded by what?

A

Each neuron through frate code of frequency

in many neurons through number of neurons firing the spatial summation code

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6
Q

what are the different types of nerve fibers?

A 
Aalpha, Abeta (both are large and mylenaited)
Adelta (thin and myelinated)
C fibers (unmyelinated)
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7
Q

Glaborous skin specializes in what?

A

Has severl different types of specilalized sensor receptor

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8
Q

Spatial resolution depends on what?

A

receptive field size and innervation density

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9
Q

What are mechanoreceptors?

A

mediate tactile/touch sensation, very sensitive to force(low threshold),have myelinated axons, superficial receptors in border between epidermis and dermis

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10
Q

What are merkel disks?

A

type of mechanoreceptorss: Responsible for fine touch, 2point discrimination, receptive field, multiple small spots, several disks for one axon, slowly adapting response encodes amount of force

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11
Q

What are Meissner’s corpuscles?

A

[mechanoreceptors] Fine touch, 2-point discrimination. Sense abrupt changes in edges. Help adjust grip. Receptive field: single spot. Corpuscle encloses a stack of flattened epithelial cells. Rapidly adapting responses encodes offset of skin indentation.

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12
Q

What are Ruffini Endings?

A

Sense stretch of skin, help determined shape of grasp objects. Receptive field: large and diffuse. Ruffini ending is encapsulated. Slowl adapting resposne sto stretching skin

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13
Q

What are pacinian corpsucles?

A

[mechanoreceptors] Respond to high frequency vibration; MOst sensitve mechanoreceptor even distribution throughout skin.
Receptive field: large and diffuse
Fluid filled capsule wrapped around bare nerve endings filters out sustained stimuli
Rapidly adapting response

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14
Q

What are hair follicle receptors?

A

[mechanoreceptors], respond tot movement of hairs, receptive field is around base of hair. Bare axon wraps around base of hair follicle; rapidly adapting response encodes velocity of hair

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15
Q

Spatial summation code is what?

A

OVerall picture in brain is due to sum of information provided by different active and silent fibers

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16
Q

Thermoreceptors are what?

A

Encode skin temp (warming, cooling). Discharge continuously (steady rate) @ normal skin temp

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17
Q

What are cooling receptors?

A

[thermoreceptor] increase firing when skin is cooled. Free nerve endings with myelinated axons. Small receptive fields; infrequent distribution

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18
Q

What are warming receptors?

A

increase firing rate when skin is warmed aboved 32 C. Stop firing when skin is cooled. Free nerve endings with unmyelinated axons

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19
Q

What are nociceptors?

A

Respond to stimuli that damage or threaten to damage tissue; 70% of DRG are nociceptors and provide almost all innervation to tooth pulp and cornea

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20
Q

What is Mechanonociceptors?

A

[nociceptor] Adelta axon
Respond to intense mechanical force, sometimes intense heat
free nerve ending
small receptive fields
slowly adapting response
mediate fast initial pain, sharp pricking, easy to localize

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21
Q

What are polymodal nociceptors?

A 
unmyelinated
Respond to intesne mechancial force, high heat, noxious chemicals
free nerve endings,
small receptive fields
slowly adapting response
mediate slow aching, "burning" pain
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22
Q

What does the DC/ML transmit sensations of?

A

light touch
pressure
vibration
propioception

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23
Q

What are teh components of the DC/ML system?

A

3 neurons
1st in sensory ganglion
2nd in spinal cord and/or braiinstem
3rd in thalamus

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24
Q

In the DC/ML system waht is the 1st neurons responsibility?

A

Peripheral process transmits info from mechanoreceptor
cell body i DRG
Central process transmits info via dorsal root and ascends within ipsilateral dorsal colum
terminates in dorsal column nuclei

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25
Q

What is the role of the 2nd Nueron in the DC/ML system?

A

Cell body in ucleus gracillis or nucleus cuneatus
terminates in ventral posterior lateral nucleus of thalamus
axon decussates to contralat side and ascends in medial lemniscus

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26
Q

What is the role of the 3rd neuron in the DC/ML system?

A

Cell body in VPL of thalamus
Axons pass through posterior limb of termial capsule
Terminates in SI cortex (postcentral gyrus, primary somatosensory cortex)

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27
Q

What does the faciculus gracilis contain?

A

Located medially, contains axons from below T7

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28
Q

What does the faciculus cuneatus contain?

A

Axons from about T7 in DC/ML system and it’s located laterally

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29
Q

What is the role of Somatotopy in the 1st neuron of the DC/ML system?

A

Sacral dermatomes located medially, and each level on the way up located progressively laterally helps perserve info about location and nature of stim

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30
Q

What occurs in a unilateral spinal cord leasion in relation to DC/ML system?

A

Loss of light touch, pressure, vibration and propioception on ipsilateral side below lesion

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31
Q

What happens in posterior cord syndrome?

A

Loss of light touch, pressure, vibration and propioception from dermatomes below level of lesion but other sensory and motor functions remain intact

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32
Q

What occurs in large central cord lesion?

A

Loss of everything but sacral region can be spared.

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33
Q

Where are the second neruon cell bodies located in the DC/ML system?

A

Caudal medulla, axons dessucate as internal arcuate fibers
axons form medial leminiscus through rostral medulla pons ad midbrain
terminate in VPL

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34
Q

What occurs with lesion of medial leminiscus?

A

Loss of light touch, pressure, vibrationa nd propioception from dermatomes below lesion on cotnralateral side of body (medial medullary system)

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35
Q

The third neuron for DC/ML system are located where?

A

Cell body in VPL(ventral posterior lateral nucleus) of thalamus
axons pass through posterior limb of interal capsule
terminates in SI cortex

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36
Q

What is teh difference between VPL ad VPM in the THalamus?

A

VPL(ventral posterior lateral nuclues) sensation from body

VPM (Ventral posterior medial nucleus) sensation from body

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37
Q

Somatotopy occurs how in hte the thalamus?

A

most medial is face goes to foot as move laterally

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38
Q

How do axons from thalamus fan out?

A

As the corona radiata, fiibers from VPL and VPM pass to SI cortex

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39
Q

What occus with lesions of thalamus or SI cortex?

A

Loss of sensation from contralateral half of body

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40
Q

What brodmann area is responsible for limb movement?

A

area 3a

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41
Q

What brodmann area is responsible for basic tactile information

A

area 3b

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42
Q

What brodmanna rea is responsible for motion and direction of movment of objects?

A

area 1

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43
Q

What brodmann area is responsible for limb position, shapes of objects

A

area 2

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44
Q

What is the relationship between SI and SII cortex?

A

Located along upper border of Sylvian fissure and insular cortex, SI neurons project to SII cortex

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45
Q

Parietal association corticiess, what is a unimodal association cortex?

A

vision, auditory or somatosensory and a lesion causes agnosias (inability recognize object)

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46
Q

what is multimodal parietal association cortices?

A

combine sensation with motivation, attention, relevane

lesions lead to contralateral neglect

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47
Q

Anesthesia means what?

A

lack of sensation

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48
Q

analgesia means?

A

lack of pain

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49
Q

hyperalgesia means what?

A

increased pain from normally painful stimulus

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50
Q

allodynia

A

pain froma normally non-painful stimulus

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51
Q

hypoalgesia means what?

A

Decreased pain sensation

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52
Q

Pruritus means what?

A

itching

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53
Q

nociceptive pain is what type of pain?

A

Pain resulting from tissue damage
well localized, throbbing quality
typically responds to NSAIDS

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54
Q

What type of pain is neuropathic pain?

A

Pain directly from damage to nerves
often has burning, lancinating, electrical qualty
resistant to NSAIDS and opoids

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55
Q

What sensation does the anterolateral system transmit?

A

Pain and temperature sensation to higher brain levels

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56
Q

What is the input to the anterolateral system?

A

noxious mechanical, thermal, or chemical stimulus to free nerve endings of Adelta or C fibers of nociceptors

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57
Q

Adelta fibers mediate what type of pain?

A

Mediate initial pain which is immediate, short-lasting, pricking quality

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58
Q

C fibers mediate what type of pain?

A

delayed, long lasting, burning quality

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59
Q

Where do central processors of nociceptors enter as part of teh anterolateral system?

A

Enter spinal cord dorsal horn, and synapse onto second order spinal neurons in lamina I/II. Some nociceptors synapse in lateral endge of spinal cord and a few near central canal.

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60
Q

What chemical synapse is involved at the second order spinal neruon synapse in anterolateral system?

A

Chemical synapses involves glutamage and substance P

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61
Q

What is the spinothalamic tract?

A

the majoroity of the second order ascending fibers termiante in thalamus, most prominent pain pathway

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62
Q

What is the Ventral posterior lateral nucleus?

A

Part of thalamus, 3rd order axons to SI cortex. Principally relays nucleus for discriminatory somatosensory info, localize pain

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63
Q

What is the central lateral nuclues?

A

Part of the thalamus (intralaminar nucleus), 3rd order axons project to many areas of cortex particulary limbic. Involved in emotional suffering

64
Q

What is the spinoreticular tract?

A

Many 2nd order axons ascend from spinal cord and terminate in medulla and pons, in reticular formation.
MEDIATES change in attention to painful stimulus

65
Q

What is teh spinomesencephalic tract?

A

Some 2nd order axons terminate in teh midbrain in teh superior colliculus and in a region of gray matter surrounding cerebral aqueduct; and is involved in pain modulation

66
Q

Lesion of the insular cortex results in what?

A

integrates sensory, affective and congitive components of pain and when lesioned the patient don’t display appropiate emotional response to pain

67
Q

What descending pathways inhibit pain?

A

Neurons that have cells in periaqueductal gray midbrain send axons down to raphe nuclei in medulla and locus ceruleus

68
Q

What trigeminal nuclei is involved in fine touch?

A

Main sensory nucleus in the pons

69
Q

What trigeminal nuclues is involved in pain and temp?

A

Spinal trigeminal nucleus, a long column-like nucleus extending from pons to cervical spinal cord.

70
Q

Where do nociceptors of teh face synapse at?

A

They descend spinal trigeminal tract and terminate in spinal trigeminal nucleus of V

71
Q

What is Temperomandibular Joint Disorder

A

is a chronic pain localized at teh temperomandibular joint or in muscles of mastication and recurrent headaches

72
Q

What are the layers of the cornea in order from outside to inside?

A 
Epithelium
bowman's membrane
stroma
descemets membrane
endothelium
73
Q

What s the bowmans membrane?

A

acelluluar layer of unorganized collagen fibers, barrier to infection

74
Q

What is the Stroma?

A

Organized type 1 collagen bundles, binds water, maintains corneal clairty, contributes to corneal thickness

75
Q

What is the Descemet’s membrane?

A

THe corneal endothelial cells, increases in thickness with age

76
Q

What is the endothelium of the cornea?

A

Simple squamous eppithelia that pumps water outof the stroma

77
Q

What is the major refractive structure of the eye?

A

The cornea, ~50 D, protect the eye from the environment

78
Q

What are the three structures of the Uvea?

A

Choroid, Cillary body, Iris

79
Q

What are the three layers of the choroid out to in?

A

veseel layer
choriocapillary layer (capillaries arragned in one plane, fenestrated)
Bruch’s membrane 3-4 micronsamorphous hyaline membrane that retinal pigment epithelia rests on

80
Q

Describe the cillary body of the eye?

A

Contacts three regions, has projections called cillary processes. trabecular meshwork within cillar body near limbus (aqueous humor rains from anteriror chamber via the trabecular meshwork)

81
Q

Describe the parts of the Iris?

A

Covers lens, anterior aspect made of vascular loose CT and determines eye color
posterior surface lined with double layer of pigmented epithelium to absorb light
two muscles masses rest upon pigmented epithelium

82
Q

What are the two muscle masses that rest upon the pigmented eithelium and regulate iris opening?

A

Radially arranged myoepithelial cells form the dilator pupillae between teh vascular and pigment layer contract to dialate the eye
The concentric smooth muscle bundles at the pupil margin form the sphincter pupillae muscle, cotnract constricts

83
Q

What is the anterior chamber of the eye?

A

Contains aqueous humor that is avascular. Involved in maintaining intraocular pressure [drection of aqueous flow: from cillary procsses to posterior chamber to trabecular meshwork to Schlemm’s canal to veins of sclera)

84
Q

What is the Lamina Cribosa?

A

Network of collagen fibers through which the fibers of the optic nerve exit the eye

85
Q

What is the structure of the lens?

A

transarent, structure(avascular, little ECM, no organelles) capsule surrounds lens, epitherlium is on the anterior surface, lens fibers forms the body of the lens

86
Q

What is the secondary structure of refactive power in the eye?

A

The lens which is supported by system of fibers attatched to the cillary body

87
Q

What is accomodation of the lens?

A

Lens thinner when focused on distant objects and thicker when on neaer objects

88
Q

What action of the cillary muscle causes the lens to get thinner?

A

When the cillary muscle is relaxed

89
Q

What is the vitreous body?

A

nearly acellular, major macromolecules are type 2 collagen and hyaluronic acid.
It’s transparent 99% water and avascular nutritive

90
Q

Where is the ganglion cell layer not present?

A

At the fovae

91
Q

Where are cones the most present as opposed to rods?

A

At foavae cones are most present, and then most rods around fovae

92
Q

What are the major funtions of the retinal pigment epithelium?

A

absorbs light
transports nutrients
spatial buffering of ions in the subretinal space
reisomerization of all-trans retinal
outer segment renewal
secretion of growth factors for maintenance and structural integritiy of retina

93
Q

What are the two suppliers of blood ot the retina?

A

inner retina from central retinal artery, and the choroid artery from the short posterior cillary atery from the cillary artery systems

94
Q

What are the anatomical fovaeal specializations?

A

Avascular zone, excavation of inner retinal neruons, foveal pit, high cone desnity, absence of rods

95
Q

What is an important difference between rods and cones withthe amount of light?

A

Rods “saturate from light and cones do not, and at room light rods are usually saturated

96
Q

WHat do photoreceptors in response to light?

A

They hyperpolarize

97
Q

What is the photopigment used?

A

Made up of a chromophore (11-cis retinal) and a protein component which normally absorbs light at 375 nm
opsin “red-shifts”

98
Q

Where do rods most strongly absorb light in the spectrum?

A

in the blue-green area

99
Q

How does phototransduction occur?

A

isomerization of chromophore (11-cis to trans)
opsin activates transducin
transducin activates PDE
PDE converts cGMP to GMP
Low cGMP closes ion channels
cone hyperpolarizes (inward flux of Ca2+ and Na+)

100
Q

What is the mechanism by which viagra can cause visual disturbances?

A

It is a PDE inhibitor, leading to vasodilation
results n an increase in cGMP
results in an opening of cyclic-nucleotide-gated ion channel and thus depolarization of the cell

101
Q

All photreceptors act in the same way by hyperpolarizing which causes them to waht?

A

Release less neurotransmitter

102
Q

When a cone is depolarized at the off center position it releases what neurotransmitter?

A

Glutamate

103
Q

Activiity of a single cone gives rise to what?

A

2 parallel pathways, by connecting two different bipolar cell types,an ON CENTER type
and an OFF CENTER type
glutamate hyperpolarizes the ON center bipolar and depolarizes teh off center bipolar

104
Q

Bipolar cells in the retina talk to what cells?

A

Amacrine cells which provide lateral connections

Ganglion cells produce action potential

105
Q

What are the two types of ganglion cells?

A

parasol ganglion cells-large with large receptive field projecting to magno layer
midget ganglion cells project to parvo layers and are smaller celsl with smaller receptive fields but are more sustained

106
Q

What are photoreceptors interconnected by?

A

Elaborate system of inhibitory interneurons called horizontal cells, whhich havea reciptrocal inhibitory synaptic relationship

107
Q

What is achromatopsia?

A

Autosommal recessive disesase where cones cannot hyperpolarize in response to light

108
Q

A tumor that presses onto the side of the optic chiasm tends to alter what field of vision?

A

The lateral field, “blinder”

109
Q

Where is the majority of V1 located?

A

Inside the calcarine

110
Q

What is teh result of a unilateral optic nerve lesion?

A

Blindness in affected eye only

111
Q

What is the result of lesion of the optic chiasm?

A

Causes bitemporal hemianopia b/c it interrupts the fibers from nasal portion of retina

112
Q

What is the result of unilateral optic tract lesion?

A

Causes contralateral homonymous hemianopia because it interrupts fibers from temporal portions of the retina on the ipsilateral side and the nasal portion on the opposite side

113
Q

What is the result of unilateral lesion of optic radiation in anterior temporal lobe (Meyer’s loop)

A

leads to contralateral upper quadrantanopia

114
Q

What is the result of unilateral lesion of optic radiation in the parietal lobe?

A

Leads to contralateral lower quadrantanopia

115
Q

What is the role of occipital lobe lesion?

A

Can lead to homonymous hemianopia. B/c the optic radiation fans out widely before entering visual cortex, lesionso f the occipital lobe tend to spare foveal vision.

116
Q

What is the result of lesion of cortical areas of occipital pole?

A

Represents the macula and characterized by a homonymous hemianopic central scotoma.

117
Q

What is teh central pathway for teh light reflex?

A

afferent limb=CN2

efferent=CN3

118
Q

What is pretectal area?

A

connects chiasm to edinger-westphal nuclei; and visceral

119
Q

Edinger-westphal nucleus of the midbrain givves rise to waht?

A

preganglionic parasympathetic fibers, which exit the midbrain with oculomotor nerve and synapse with post-ganglionic neurons at cilary ganglion

120
Q

What happens when lesion of pulvinar of thalamus occurs?

A

Leads to lateral neglect

121
Q

What is the superior colliculus?

A

Mesencephalic laminated structure
receives input primarily from parasol cells
involved in controlling eye muscles and orienting reflex

122
Q

What si damage of V5/MT resulting in?

A

Associated with an impairment in the detection of motion.

123
Q

What happens when V4 is damaged?

A

cerebral achromatopsia

124
Q

What is the Pinna?

A

The eterior of the ear that channels and filters sound to external canal, amplifies freq @ 3000 Hz

125
Q

What is the structure of the tympanic membrane?

A

3 layer translucent membrane, with 1 cm^2 vibratory surface

126
Q

What are the mechanisms used to amplify sound to overcome transfer of waves from air to sound?

A

Area ratio of tympanic membrane to oval window
lever action of the ossicular chain: malleus longer than incus
Buckling of the TM

127
Q

What is teh mechansim of the basilar membrane mechanics?

A

The base is narrow and stiffer, vibrates more at high sounds

apex is wider and loose allowing for lower sound

128
Q

How does the cochlea determine pitch?

A

Position of maximum wave on basilar membrane in cochlea

129
Q

How do hair cilia work?

A

Endolymph has high K+ and hair have very low K+, tiplinks openwhen hair cells moved by acoustic energy, resulting in hyperpolarization, tip links linked by actin

130
Q

What are the two types of hearing losss?

A

Conductive adn sensorineural

131
Q

How does sensorinerual occur?

A

congenital
noise exposure/trauma
medication
age

132
Q

What is the main region for auditory processing?

A

Heschel’s Gyrus, A1 in the temporal region

133
Q

What are teh central auditory pathway?

A

VCN involved in localizing sounds
DCN involved in recognizing sounds

Nerve to medulla to pons to mibrain to thalamus to cortex

134
Q

What are the three parts of the vestibular apparatus?

A

Bony labyrinth
membranous labyrinth
sensory receptors

135
Q

What detect linear acceleration in the inner ear?

A

Maculae in the utricle and saccule

136
Q

How are hair cells depolarized in response to linear acceleration?

A

The stereocilia bundles are polarized towards a ridge and when deflection toward the kinocilium occurs it leads to cell depolarization

137
Q

What is the ridge of sensory epithelium in the ampulla called?

A

Crista ampullaris, this senosry epithelium is covered by gelatinous material that makes up the cupola

138
Q

Rotation of the head causes endolymph in the ampula to move this allows what?

A

THe semicircular canals, and endolymph pushes on teh sensosry epithelium in response to change in speed of head rotation

139
Q

What are the four vestibular nuclei?

A 
Caudal Pons:
superior vestibular nucleus
Lateral vestibular nucleus
Rostral medulla:
Medial vestibular nucleus
Inferior vestibular nucleus
140
Q

What is the role of the lateral vestibulospinal tract?

A

Maintains balance and posture on the ipsilateral side of the bodyu

141
Q

What is the role of the medial vestibulospinal tract?

A 
adjusts head position in response to postural changes
coordinates eye movements, with head movements and each  other
vestibuloocular reflex (VOR)
142
Q

What does the vestibuloocular reflex do?

A

maintains eye postion during head movemnt

143
Q

What si teh central pathway for VOR?

A

semicircular canals detect head movment and this sends to vesitbular nuclei
vestibular nuclei project to brainstem nuclei that control extraocular muscles
extraocular muscles contract moving eyes to maintain fovveattion

144
Q

What is nystagmus?

A

rhytmic oscillations of eyeballs
temperature generated convection current causes them
observigna moving object causes tehm
rotation of the head causes them

145
Q

What type of diziness is usually otologic?

A

verticgo

nystagmus specifically is uasually ear generated and casuses sensation of spinning

146
Q

What si Ewalds first law?

A

Stimulation of a semicircular canal generates eye movement in the plane of the that canal

147
Q

What are the three clinical mechanisms to uncover teh otological weakness ?

A

head thrust test
gaze evoked nystagmus
head shake teest

148
Q

What is Alexander’s law?

A

gaze in the direction of the fast phase of nystagmus increases amplitude and frequency

149
Q

What is Ewalds second law?

A

excitatory responses for the VORare greater than inhib responses

150
Q

What is superior canal dehiscence?

A

loss of bone covering over the superior canal, ecitation by various stimuli
tones
excercise
pressure

151
Q

What is BPPV?

A

Benign paroxysmal postional vertigo
posterior canal canalithiasis
posterior canal actviated by movement-otoconia move in canal simulating movement
nystagmus is toward affected ear and rotary in nature

152
Q

What is labyrinthitis

A 
medical emergency
viral or bacterial in origin
hearing loss
elicit signs of unilateral weakness
loss of vestibular function in al canals
153
Q

What is vestibular neuronitis?

A

horizontal and superior canals, posterior canal spared
acute phase nystagmus beating away from affected ear
loss of unilateral VOR
Acute Phase:
1st week sudden and intesnse vertigoand imbalance
need to stay still
nausea and vomitting
1-6 month episodic vertigo, motion sensitivity, gradual improvememnt
greater than 6 mos after initial attack
weakness in balance Fx
30% develop anxiety
may develop BPPV

154
Q

What is Menieres disease

A 
inner ear fluid imbalance
episodic vertigo
fluctuating hearing loss
recurrent and episodic vertigo short period
minimal imbalance btw attacks
low frequency tinnitis
155
Q

Vestibular migraine?

A

30-50% of migrainers, and can occur not during headache
spontaneous vertigo both internal and external
positional vertigo, but not specific like BPPV
visuall induced

Cardiology (12 decks)

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