Neuro - Pt 4 Sensory Cont'd

Question 1

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

Answer 1

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

Question 2

Tooth Pain:

• Can be caused by mechanical, thermal, or chemical stimulation of [] or [] []

Answer 2

Dentin or dental pulp

Question 3

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.

Answer 3

• 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.

Question 4

1. Tooth pain is transmitted in [] and [] fibers
2. Pain pathway:
   
   1. Afferent Fibers –> [] nerve –> cell bodies in trigeminal [] –> medullary [] horn –> [] nuclei –> Thalamus –> []

Answer 4

1. Tooth pain is transmitted in A-delta and C fibers
2. Tooth pain pathway:
   
   1. Afferent Fibers –> trigeminal nerve –> cell bodies in trigeminal ganglion –> medullary dorsal horn –> trigeminal nuclei –> Thalamus –> Cortex

Question 5

Non-Nociceptive Sensations:

• Stimulation of dentin also causes sensations other than []
• [] threshold [] (with [] afferents) that convey information about mechanical forces acting on teeth

Answer 5

• 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

Question 6

Conduction velocity is related to nerve fiber [] and whether the fiber is [] or [].

Answer 6

Conduction velocity is related to nerve fiber diameter and whether the fiber is myelinated or unmyelinated.

Question 7

[] [] is related to nerve fiber diameter and whether the fiber is myelinated or unmyelinated.

Answer 7

Conduction velocity is related to nerve fiber diameter and whether the fiber is myelinated or unmyelinated.

Question 8

What are the 2 systems for sensory nerves in the spinal column?

Answer 8

• Dorsal column/Lemniscal System
• Anterolateral Tract: 2 subdivisions
  
  • anterolateral spinothalamic tract and lateral spinothalamic tract

Question 9

Spinal Column Pathways for Sensory Nerves:

1. Dorsal Column/Lemniscal System:
   
   1. responsible for fine [] & []sensation
2. Anterolateral Tracts
   
   1. Anteriorlateral spinothalamic - fibers run to [], [], and [] []
   2. Lateral Spinothalamic - fibers run to [] and [] [], with some to thalamus and somatosensory cortex

Answer 9

1. Dorsal Column/Lemniscal System:
   
   1. responsible for fine touch & vibration sensation
2. Anterolateral Tracts
   
   1. Anteriorlateral spinothalamic - fibers run to thalamus, brainstem, and somatosensory cortex
   2. Lateral Spinothalamic - fibers run to brainstem and reticular formation, with some to thalamus and somatosensory cortex

Question 10

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

Answer 10

• 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

Question 11

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 []

Answer 11

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

Question 12

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 !!

Answer 12

• 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 !!

Question 13

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 []

Answer 13

• 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

Question 14

Higher functions in the brain…

1. Primary sensory areas - spatial localization of signals from [] receptors, areas are directly involved with []
2. Sensory Association Areas - [] livel of sensory experience interpretation

Answer 14

1. Primary sensory areas - spatial localization of signals from peripheral receptors, areas are directly involved with processing
2. Sensory Association Areas - higher level of sensory experience interpretation

Question 15

Smell vs Taste:

1. Smell - Can project to the cortex without going through a [] in the thalamus. But also goies through a [] relay
2. Taste- neural pathway travels up the [] [] to the thalamus and projects to the [] []

Answer 15

1. Smell - Can project to the cortex without going through a relay in the thalamus. But also goes through a thalamic relay
2. Taste- neural pathway travels up the brain stem to the thalamus and projects to the postcentral gyrus

Question 16

Smell: Receptors:

1. Receptors are [] neurons located in the [] mucosa
2. Primary olfactory input is transmitted directly, via the olfactory nerve, to the [] bulb of the [] [] (but there is still a thalamic path)

Answer 16

1. Receptors are bipolar neurons located in the olfactory mucosa
2. 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)

Question 17

Smell: Receptor Stimulation

1. Airborne particles must be [] in the nusal mucosa to be smelled
2. Mechanism of generator potential is [] []
3. Odorant is bound to an olfactory protein receptor and signaling involves [] []-coupled receptors. –> opening of Ca++ and Na+ channels –> Action potential
4. Adaptation is [] and [] specific

Answer 17

1. Airborne particles must be dissolved in the nusal mucosa to be smelled
2. Mechanism of generator potential is not known
3. Odorant is bound to an olfactory protein receptor and signaling involves G protein-coupled receptors. –> opening of Ca++ and Na+ channels –> Action potential
4. Adaptation is rapid and odor specific

Question 18

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

Answer 18

• 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

Question 19

Taste: Receptors:

1. Receptors are specialized [] cells with microvilli at apical surface
2. [] receptors
3. Old taste cells are replaced by new cells from surrounding [] cells, epithelial cells [] to taste cells when they contact [] [] fibers
4. Each unmyelinated fiber wraps around [] taste cells

Answer 19

1. Receptors are specialized epithelial cells with microvilli at apical surface
2. Chemosensitive receptors
3. Old taste cells are replaced by new cells from surrounding epithelial cells, epithelial cells convert to taste cells when they contact afferent nerve fibers
4. Each unmyelinated fiber wraps around several taste cells

Question 20

Taste:

• Summary of pathway
  
  • [] –> [] –> [] –> []

Answer 20

Medulla –> Pons –> Thalamus –> Cortex

Question 21

The 5 basic modalities of taste:

Answer 21

Sweet

Salty

Sour

Bitter

Savory

Question 22

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)

Answer 22

• 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)

Question 23

Another name for savory taste….

Answer 23

umami

Question 24

Vestibular System:

1. Provides information that is important for [] []
2. Maintains [] in antigravity muscles
3. Coordinates adjustments made by [] and [] in response to postural changes
4. Important for reflexes of [] which also involve the [] and [] formation

Answer 24

1. Provides information that is important for equilibrium maintenance
2. Maintains tone in antigravity muscles
3. Coordinates adjustments made by eyes and limbs in response to postural changes
4. Important for reflexes of equilibrium which also involve the cerebellum and reticular formation

Question 25

The 2 vestibular organs: ...

Answer 25

Otolith organs and semicircular canals

Question 26

Vestibular Organs: * Anatomically associated with the [] [] * Located in the [] [] system * cavities filled with membranous [] and [] * Continuous with the [], but not part of th ear.

Answer 26

* 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.

Question 27

Otolith Organs: * [] in each ear * [] like * Detect [] [] including that due to [] * Utricle - more sensitive to [] acceleration * Saccule - more sensitive to [] acceleration

Answer 27

* **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

Question 28

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 []

Answer 28

* **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**

Question 29

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

Answer 29

* 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

Question 30

The 2 parts of the otolith organs are the [] and []

Answer 30

uticle and saccule

Question 31

Detection of movement by otolith organs: * the macula contains [] [] crystals called otoliths which are attached to the [] of hair cells

Answer 31

the macula contains **calcium carbonate** crystals called otoliths which are attached to the **cilia** of hair cells

Question 32

* T/F - Cilia have directional sensitivity * When cilia are bent one way they cause [], when they are bent the other way...they cause []

Answer 32

* True! * When cilia are bent one way they cause **depolarization**, when they are bent the other way...they cause **hyperpolarization**

Question 33

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)

Answer 33

* 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)

Question 34

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

Answer 34

* 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

Question 35

Detection of Movement by Semicircular Canals * Detects only [] []...or the starting and stopping

Answer 35

Detects only **rotational acceleration**...or the starting and stopping

Question 36

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 []

Answer 36

* 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**

Question 37

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 []

Answer 37

* 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**

Question 38

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

Answer 38

* 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