Neuro - Pt 4 Sensory Cont'd Flashcards
1
Q
Gate Theory:
- Touching, shaking, or rubbing an injured area will [] the pain from that area.
- Mechanism:
- [] [] fibers are stimulated when you shake/rub
- These fibers [] the afferent fibers form nociceptors [] at the dorsal root ofhte spinal cord
A
Gate Theory:
- Touching, shaking, or rubbing an injured area will decrease the pain from that area.
- Mechanism:
- Large afferent fibers are stimulated when you shake/rub
- These fibers inhibit the afferent fibers form nociceptors presynaptically at the dorsal root of the spinal cord
2
Q
Tooth Pain:
- Can be caused by mechanical, thermal, or chemical stimulation of [] or [] []
A
Dentin or dental pulp
3
Q
Nociceptors and Tooth Pain:
- Nerve fibers enter pulp at [] of root
- Dentinal nerve endings are []. A pain response can be initiated from area in the tooth [] nerve endings and [] different stimuli can cause a pain sensation
- Innervation [] is not uniform
- Pain receptors are not [] active
- [] enhances responses.
A
- Nerve fibers enter pulp at apex of root
- Dentinal nerve endings are unspecialized. A pain response can be initiated from areas in the tooth without nerve endings and many different stimuli can cause a pain sensation
- Innervation density is not uniform
- Pain receptors are not spontaneously active
- Inflammation enhances responses.
4
Q
- Tooth pain is transmitted in [] and [] fibers
- Pain pathway:
- Afferent Fibers –> [] nerve –> cell bodies in trigeminal [] –> medullary [] horn –> [] nuclei –> Thalamus –> []
A
- Tooth pain is transmitted in A-delta and C fibers
- Tooth pain pathway:
- Afferent Fibers –> trigeminal nerve –> cell bodies in trigeminal ganglion –> medullary dorsal horn –> trigeminal nuclei –> Thalamus –> Cortex
5
Q
Non-Nociceptive Sensations:
- Stimulation of dentin also causes sensations other than []
- [] threshold [] (with [] afferents) that convey information about mechanical forces acting on teeth
A
- Stimulation of dentin also causes sensations other than pain
- the pulp contains low threshold mechanoreceptors (with myelinated afferents) that convey information about mechanical forces acting on teeth
6
Q
Conduction velocity is related to nerve fiber [] and whether the fiber is [] or [].
A
Conduction velocity is related to nerve fiber diameter and whether the fiber is myelinated or unmyelinated.
7
Q
[] [] is related to nerve fiber diameter and whether the fiber is myelinated or unmyelinated.
A
Conduction velocity is related to nerve fiber diameter and whether the fiber is myelinated or unmyelinated.
8
Q
What are the 2 systems for sensory nerves in the spinal column?
A
- Dorsal column/Lemniscal System
- Anterolateral Tract: 2 subdivisions
- anterolateral spinothalamic tract and lateral spinothalamic tract
9
Q
Spinal Column Pathways for Sensory Nerves:
- Dorsal Column/Lemniscal System:
- responsible for fine [] & []sensation
- Anterolateral Tracts
- Anteriorlateral spinothalamic - fibers run to [], [], and [] []
- Lateral Spinothalamic - fibers run to [] and [] [], with some to thalamus and somatosensory cortex
A
- Dorsal Column/Lemniscal System:
- responsible for fine touch & vibration sensation
- Anterolateral Tracts
- Anteriorlateral spinothalamic - fibers run to thalamus, brainstem, and somatosensory cortex
- Lateral Spinothalamic - fibers run to brainstem and reticular formation, with some to thalamus and somatosensory cortex
10
Q
The Dorsal Column/Lemniscal
- Touch sensation requiring a high degree of [] of the stimulus
- Touch sensation requiring transmission of [] [] of intensity
- [] sensations
- Sensations that signal [] agaisnt skin
- [] sensations with fine degress of pressure intensity
A
- Touch sensation requiring a high degree of localization of the stimulus
- Touch sensation requiring transmission of fine gradatioins of intensity
- Phasic sensations
- Sensations that signal movement agaisnt skin
- Pressure sensations with fine degress of pressure intensity
11
Q
The Doral Column-Lemniscal System
- 1st order neuron - primary afferent with cell body in dorsal [] or [] ganglion
- 2nd order neuron - crosses in [] and ascends to []
- 3rd order neuron - relay nucleus of the thalamus ascends to [] cortex
- 4th order neuron - in a sensory area of []
A
The Doral Column-Lemniscal System
- 1st order neuron - primary afferent with cell body in dorsal root or cranial ganglion
- 2nd order neuron - crosses in brainstem and ascends to thalamus
- 3rd order neuron - relay nucleus of the thalamus ascends to somatosensory cortex
- 4th order neuron in a sensory area of cortex
12
Q
The Anterolateral System
- Main [] sensory system
- Thermal sensation, including both [] and []
- [] touch and pressure that can only be crudely [] on the surface of the body
- [] and []
- [] Sensations !!
A
- Main pain sensory system
- Thermal sensation, including both warmth and cold
- Crude touch and pressure that can only be crudely localized on the surface of the body
- Tickling and Itching
- Sexual Sensations !!
13
Q
The anterolateral System:
- Lower degree of [] of intensity
- 1st order neuron - cell body in the [] horn
- 2nd order neuron - crosses in [] [] and ascends to [] and []
- 3rd order neuron - in a relay nucleus of the [] that projects to the []cortex
- 4th order neuron - in a sensory area of the []
A
- Lower degree of gradations of intensity
- 1st order neuron - cell body in the dorsal horn
- 2nd order neuron - crosses in spinal cord and ascends to brainstem and thalamus
- 3rd order neuron - in a relay nucleus of the thalamus that projects to the somatosensory cortex
- 4th order neuron - in a sensory area of the cortex
14
Q
Higher functions in the brain…
- Primary sensory areas - spatial localization of signals from [] receptors, areas are directly involved with []
- Sensory Association Areas - [] livel of sensory experience interpretation
A
- Primary sensory areas - spatial localization of signals from peripheral receptors, areas are directly involved with processing
- Sensory Association Areas - higher level of sensory experience interpretation
15
Q
Smell vs Taste:
- Smell - Can project to the cortex without going through a [] in the thalamus. But also goies through a [] relay
- Taste- neural pathway travels up the [] [] to the thalamus and projects to the [] []
A
- Smell - Can project to the cortex without going through a relay in the thalamus. But also goes through a thalamic relay
- Taste- neural pathway travels up the brain stem to the thalamus and projects to the postcentral gyrus
16
Q
Smell: Receptors:
- Receptors are [] neurons located in the [] mucosa
- Primary olfactory input is transmitted directly, via the olfactory nerve, to the [] bulb of the [] [] (but there is still a thalamic path)
A
- Receptors are bipolar neurons located in the olfactory mucosa
- Primary olfactory input is transmitted directly, via the olfactory nerve, to the olfactory bulb of the cerebral cortex (but there is still a thalamic path)
17
Q
Smell: Receptor Stimulation
- Airborne particles must be [] in the nusal mucosa to be smelled
- Mechanism of generator potential is [] []
- Odorant is bound to an olfactory protein receptor and signaling involves [] []-coupled receptors. –> opening of Ca++ and Na+ channels –> Action potential
- Adaptation is [] and [] specific
A
- Airborne particles must be dissolved in the nusal mucosa to be smelled
- Mechanism of generator potential is not known
- Odorant is bound to an olfactory protein receptor and signaling involves G protein-coupled receptors. –> opening of Ca++ and Na+ channels –> Action potential
- Adaptation is rapid and odor specific
18
Q
Smell discrimination:
- Receptors have a high [] but have a porr ability to [] how much of a substance is present
- Substances having a strong odor usually have a high [] and [] solubility
A
- Receptors have a high sensitivity but have a poor ability to discriminate how much of a substance is present
- Substances having a strong odor usually have a high lipid and water solubility
19
Q
Taste: Receptors:
- Receptors are specialized [] cells with microvilli at apical surface
- [] receptors
- Old taste cells are replaced by new cells from surrounding [] cells, epithelial cells [] to taste cells when they contact [] [] fibers
- Each unmyelinated fiber wraps around [] taste cells
A
- Receptors are specialized epithelial cells with microvilli at apical surface
- Chemosensitive receptors
- Old taste cells are replaced by new cells from surrounding epithelial cells, epithelial cells convert to taste cells when they contact afferent nerve fibers
- Each unmyelinated fiber wraps around several taste cells
20
Q
Taste:
- Summary of pathway
- [] –> [] –> [] –> []
A
Medulla –> Pons –> Thalamus –> Cortex
21
Q
The 5 basic modalities of taste:
A
Sweet
Salty
Sour
Bitter
Savory
22
Q
Modalities of Taste:
- Each taste receptor responds to [] than 1 taste, but each responds [] to 1 of the different modalities.
- Taste depends on the [] [] []
- Taste preference is a central ([]) phenomenon, and not due to [] [] (same with unpleasant sensations)
A
- Each taste receptor responds to more than 1 taste, but each responds best to 1 of the different modalities.
- Taste depends on the pattern of stimulation
- Taste preference is a central (cortical) phenomenon, and not due to taste buds (same with unpleasant sensations)
23
Q
Another name for savory taste….
A
umami
24
Q
Vestibular System:
- Provides information that is important for [] []
- Maintains [] in antigravity muscles
- Coordinates adjustments made by [] and [] in response to postural changes
- Important for reflexes of [] which also involve the [] and [] formation
A
- Provides information that is important for equilibrium maintenance
- Maintains tone in antigravity muscles
- Coordinates adjustments made by eyes and limbs in response to postural changes
- Important for reflexes of equilibrium which also involve the cerebellum and reticular formation
25
Q
The 2 vestibular organs: …
A
Otolith organs and semicircular canals
26
Q
Vestibular Organs:
- Anatomically associated with the [] []
- Located in the [] [] system
- cavities filled with membranous [] and []
- Continuous with the [], but not part of th ear.
A
- Anatomically associated with the inner ear
- Located in the boney labyrinth system
- cavities filled with membranous sacs and fluids
- Continuous with the cochlea, but not part of th ear.
27
Q
Otolith Organs:
- [] in each ear
- [] like
- Detect [] [] including that due to []
- Utricle - more sensitive to [] acceleration
- Saccule - more sensitive to [] acceleration
A
- 2 in each ear
- Sac like
- Detect linear acceleration including that due to gravity
- Utricle - more sensitive to horizontal acceleration
- Saccule - more sensitive to vertical acceleration
28
Q
Semicircular Canals:
- [] in each ear
- Detect [] (angular) acceleration
- Horizontal (x) - plane [] to earth
- Vertical (y) - plane passing through center of head towards []
- Posterior Vertical (z) - plane passing through center of head towards []
A
- 3 in each ear
- Detect rotational (angular) acceleration
- Horizontal (x) - plane parallel to earth
- Vertical (y) - plane passing through center of head towards eye
- Posterior Vertical (z) - plane passing through center of head towards ear
29
Q
Hair Cells:
- Are receptor cells in the [] organs
- in the otolith organs, they are located in a mass of tissue called the []
- In the semicricular canals they are located in a mass of tissue called the []
- Ouput of hair cells is sensed via the [] nerve
A
- Are receptor cells in the vestibular organs
- in the otolith organs, they are located in a mass of tissue called the macula
- In the semicricular canals they are located in a mass of tissue called the cupula
- Ouput of hair cells is sensed via the vestibular nerve
30
Q
The 2 parts of the otolith organs are the [] and []
A
uticle and saccule
31
Q
Detection of movement by otolith organs:
- the macula contains [] [] crystals called otoliths which are attached to the [] of hair cells
A
the macula contains calcium carbonate crystals called otoliths which are attached to the cilia of hair cells
32
Q
- T/F - Cilia have directional sensitivity
- When cilia are bent one way they cause [], when they are bent the other way…they cause []
A
- True!
- When cilia are bent one way they cause depolarization, when they are bent the other way…they cause hyperpolarization
33
Q
Detection of movement in Otolith:
- Utricle
- Macula lie in a [] plane
- Crystals bear weight when the head is in a [] orientation
- detects head movement with respect to [] (up or down body movement)
- head [] (forward/backward body movement)
A
- Utricle
- Macula lie in a horizontal plane
- Crystals bear weight when the head is in a normal orientation
- detects head movement with respect to gravity (up or down body movement) and
- head acceleration (forward/backward body movement)
34
Q
Detection of Movement by Otolith:
- Saccule
- Macula lies in a [] plane
- crystals bear weight when the head is not [] (or laying down, tilted)
- Head movement with respect to [] is detected
- Macula lies in a [] plane
A
- Saccule
- Macula lies in a vertical plane
- crystals bear weight when the head is not vertical (or laying down, tilted)
- Head movement with respect to gravity is detected
- Macula lies in a vertical plane
35
Q
Detection of Movement by Semicircular Canals
- Detects only [] []…or the starting and stopping
A
Detects only rotational acceleration…or the starting and stopping
36
Q
Detection of Movement by Semicircular Canals
- When rotation first begins:
- Head rotates in plane of the canal and the [] moves with [] to the fluid
- [] moves when the canal moves
- The fluid in the canal [] [] move yet
- The [] bend
- Hair cells within cupula are []
A
- When rotation first begins:
- Head rotates in plane of the canal and the canal moves with respect to the fluid
- Cupula moves when the canal moves
- The fluid in the canal does not move yet
- The cupula bends
- Hair cells within cupula are stimulated
37
Q
Detection of Movement by Semicircular Canals:
- As Rotation continues
- fluid in the canal begins to [] with the canal and there is no further net flow through the []
- Cupula is no longer []
- Hair cells are no longer []
A
- As Rotation continues
- fluid in the canal begins to move with the canal and there is no further net flow through the cupula
- Cupula is no longer bent
- Hair cells are no longer stimulated
38
Q
Detection of Movement by Semicircular Canal
- When head stops rotational movement
- Canal [] rotating immediately
- [] continues to rotate
- Cupulua is moved in the [] direction
- [] [] within the cupular are stimulated
A
- When head stops rotational movement
- Canal stops rotating immediately
- Fluid continues to rotate
- Cupulua is moved in the opposite direction
- Hair cells within the cupular are stimulated
