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PHGY 209 > 6. CNS/Sensory > Flashcards

6. CNS/Sensory Flashcards

1
Q

CNS =

A

Brian + spinal cord

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2
Q

afferent neurons responsible for

A

sensory input

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3
Q

3 types of sensory afferents

A
  • cranial nerves: go straight to brain
  • spinal nerves: somatic sensation
  • visceral: inflammation, pain inputs
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4
Q

sensory afferents have their axons where?

A

going into CNS

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5
Q

efferent neurons responsible for

A

motor output

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6
Q

motor neurons have their cell bodies where?

A

in the CNS

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7
Q

types of motor efferents

A
  • cranial nerves + spinal nerves (contain mix of afferent and efferent)
  • somatic efferent: send signals which innervate skeletal muscles
  • autonomic efferent: innervates interneurons and smooth&cardiac muscles
  • enteric efferent: control digestive tract
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8
Q

spinal cord (anatomy)

A

meets brainstem at base of skull

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9
Q

brainstem consists of: (3)

A
  • Medulla
  • Pons
  • Midbrain
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10
Q

thalamus (anatomy)

A

relay station, sensory pathway

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11
Q

corpus callosum (anatomy)

A

major connection in middle, containing a bunch of neurons travelling between the 2 hemispheres

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12
Q

cerebrum aka…

A

cerebral cortex

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13
Q

cerebrum has foldings called…

A

gyrus and sulcus

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14
Q

4 parts of cerebrum

A
  • frontal
  • parietal
  • occipital
  • temporal
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15
Q

cerebellum (anatomy)

A

contains many neurons, contributing to motor skills

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16
Q

central sulcus

A

crack/folding that separates primary somatosensory processing from primary motor cortex

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17
Q

coronal splice

A

cutting down through the cerebral cortex

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18
Q

gray matter

A

where all cell bodies are

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19
Q

white matter

A

where axons are

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20
Q

ventricles

A

cavities where cerebral spinal fluid flows

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21
Q

cervical nerves innervate…

A

neck, shoulders, arms and hands

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22
Q

thoracic nerves innervate…

A

shoulders, chest, upper abdominal wall

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23
Q

lumbar nerves innervate…

A

lower abdominal wall, hips and legs

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24
Q

sacral nerves innervate…

A

genitals and lower digestive track

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25
Q

gray matter composed of

A
  • dorsal horn (back)
  • ventral horn (stomach)
  • central canal in middle
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26
Q

spinal segment composed of

A
  • dorsal root
  • ventral root
  • dorsal root ganglion
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27
Q

dorsal root carries…

A

sensory afferents

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28
Q

ventral root carries…

A

motor efferents

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29
Q

dorsal root ganglion is where…

A

cell bodies of sensory afferents are located

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30
Q

ectoderm

A

top part which develops into CNS

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31
Q

mesoderm

A

becomes muscles, organs

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32
Q

endoderm

A

big cavity that becomes the digestive system

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33
Q

dura

A

lining of CNS

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34
Q

early development of nervous system in weeks 1-3

A

inner cell mass develops into embryonic disk

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35
Q

early development of nervous system in weeks 3-4

A

ectoderm folds into groove which will then close to form the neural tube
-> becomes CNS and part of PNS

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36
Q

early development of nervous system in week 4

A

vesicles develop with cavity in middle, forming the forebrain, midbrain and hindbrain

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37
Q

early development of nervous system in following 8 months

A
  • forebrain becomes cerebral hemispheres + thalamus
  • midbrain becomes midbrain
  • hindbrain becomes cerebellum + pons + medulla
  • cavity becomes ventricles + central canal
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38
Q

Cerebral Spinal Fluid (CSF) is produced where and by what?

A

produced in the 4 ventricles by the chloroid plexus

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39
Q

4 ventricles in the brain

A
  • 2 lateral ventricles: largest ones, majorly producing CSF
  • 3rd ventricle in middle of thalamus
  • 4th ventricle attached to central canal
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40
Q

CSF composition

A

sterile, colorless, acellular fluid containing glucose

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41
Q

CSF circulates actively or passively?

A

passive circulation: oozing out from chloroid plexus

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42
Q

Cerebral Spinal Fluid (CSF) functions (3)

A
  • support and cushion the brain: makes brain float in skull since gravity of brain and CSF are equal
  • provide nourishment to the brain: glucose
  • remove metabolic waste through absorption at the arachnoid villi
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43
Q

foramen of Monro

A

opening that connects lateral ventricles to 3rd ventricles

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44
Q

subarachnoid space

A

where CSF circulates around the brain

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45
Q

arachnoid villi

A

organelles that take CSF out of the subarachnoid space to empty it into venous blood

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46
Q

what covers the brain and spinal cord?

A

the membranes/meninges of CNS

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47
Q

3 meninges

A
  • Dura mater
  • Arachnoid membrane
  • Pia mater
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48
Q

Dura mater

A

tough covering protecting the CNS + contains dural sinus

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49
Q

dural sinus

A

where arachnoid villi empty CSF to the blood

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50
Q

arachnoid membrane

A

not as tough as dura but creates subarachnoid space

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51
Q

trabeculae

A

found in arachnoid membrane, produce subarachnoid space

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52
Q

pia mater

A

thin and delicate, attaches itself to the cortex

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53
Q

what % of total blood does brain receive?

A

15%

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54
Q

what substrate(s) is/are metabolised by the brain?

A

glucose + very little glycogen

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55
Q

brain requires continuous supply of

A

glucose and oxygen

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56
Q

how is glucose transported in the brain

A

automatically goes into neurons, no need for insulin

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57
Q

what carries blood to the brain

A

common carotid artery and vertebral artery

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58
Q

what carries blood to the rest of the body

A

aorta (85% of blood)

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59
Q

internal carotid artery

A

supplies base of the brain

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60
Q

external carotid artery

A

supplies outside of the head

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61
Q

basilar artery

A

the 2 vertebral arteries joined together

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62
Q

Circle of Willis

A

internal carotid + basilar artery form a loop, allowing for continuous supply of blood even if one of the carotids gets blocked

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63
Q

CSF circulation summary

A

chloroid plexus -> subarachnoid space -> dural sinus -> venous system

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64
Q

blood circulation summary

A

heart -> vertebral/carotid arteries -> Circle of Willis -> brain -> venous system

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65
Q

blood brain barrier

A

capillary wall with tight junctions between endothelial cells allows only a few things to leave the blood

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66
Q

what does the blood-brain barrier let through

A
  • lipid soluble substances: water, O2, CO2
  • small ions: Na+, K+, Cl-
  • glucose through active transport
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67
Q

what isn’t let through the brain barrier

A
  • plasma proteins
  • large organic molecules
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68
Q

glia

A

non-neuronal cells in brain which support neuron by regulating extracellular conditions

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69
Q

astrocytes

A

type of glia cells

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70
Q

astrocytes functions (3)

A
  • phagocytosis of debris
  • providing structural support
  • inducing tight junctions
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71
Q

sensation

A

awareness of sensory stimulation

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72
Q

perception

A

understanding of a sensation’s meaning

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73
Q

how do we perceive sensation

A

we perceive the neural activity/pattern produced by the energy of sensory stimulation

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74
Q

Law of Specific Nerve Energies

A

regardless off how a sensory receptor is activated, the sensation felt corresponds to that of which the receptor is specialised

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75
Q

Law of Specific Nerve Energies example

A

rubbing eyes creates a pressure which stimulates light to be perceived

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76
Q

Law of Projection

A

regardless of where in the brain you stimulate a sensory pathway, the sensation is always felt at the sensory receptors location

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77
Q

Law of Projection example

A

Phantom limb pain after amputation

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78
Q

modality

A

general class of a stimulus

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79
Q

summary of Laws of Perception/Sensation

A

the brain knows the modality and location of every sensory afferent

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80
Q

stimulus reception steps

A
  1. stimulus energy activates afferents
  2. receptor membrane/cell contain ion channels, which respond only to adequate stimulus
  3. transduction: stimulus activates ion channels at receptor membrane/cell
  4. action potential sent to the brain
  5. neurotransmitter release
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81
Q

what affects neurotransmitter release?

A

variations in stimulus energy strength

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82
Q

adaptation of afferent response

A

signals changes in stimulus energy, allowing us to be sensitive to changes in sensory input

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83
Q

non-adapting encodes…

A

stimulus intensity and slow changes

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84
Q

slowly adapting encodes…

A

some stimulus intensity and moderate stimulus change

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85
Q

rapidly adapting encodes…

A

fast stimulus changes

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86
Q

Receptive Field (RF)

A

region in space that activates a sensory receptor or neuron

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87
Q

where is the receptive field strongest?

A

at its centre

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88
Q

population code

A

overlapping receptive fields

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89
Q

acuity

A

ability to differentiate one stimulus from another

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90
Q

small RF =

A

high acuity, ie. lips
-> can tell location go stimulus more precisely

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91
Q

large RF =

A

low acuity, ie. back

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92
Q

bottom up mechanism

A

lateral inhibition, reducing activity of neighbouring neurons
–> have no control over

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93
Q

top down mechanism

A

use of background knowledge to interpret what we see
–> can be controlled

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94
Q

sensory information sharpened by…

A

bottom up and top down mechanisms

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95
Q

somatic senses

A

touch, pain, proprioception, temperature

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96
Q

somatosensory system stimulus energy

A

mechanical, thermal, chemical

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97
Q

somatosensory system receptor class

A

mechanoreceptors, chemoreceptors, thermoreceptors, nociceptors

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98
Q

touch receptors are called

A

mechanoreceptors

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99
Q

mechanoreceptors (touch)

A

specialised end organs that surround the nerve terminal, allowing only elective mechanical information to activate the nerve terminal

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100
Q

superficial layers of touch mechanoreceptors

A
  • Meissner’s corpuscle
  • Merkel disk
    –> closest to skin surface so most sensitive
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101
Q

Meissner’s corpuscle key points

A
  • fluid filled structure enclosing the nerve terminal
  • rapidly adapting
  • sensitive to light stroking and fluttering
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102
Q

Merkel disk keys points

A
  • small epithelial cells surrounding the nerve terminal
  • slowly adapting
  • sensitive to pressure and texture
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103
Q

deep layers of touch mechanoreceptors

A
  • Pacinian corpuscle
  • Ruffini endings
    –> less sensitive: require more energy to be activated
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104
Q

Pacinian corpuscle key points

A
  • large concentric capsules of connective tissue surrounding the nerve terminal
  • rapidly adapting
  • sensitive to strong vibrations
105
Q

Ruffini endings key points

A
  • nerve endings wrapped around spindle-like structure
  • slowly adapting
  • sensitive to stretching and bending of skin: can detect shape of object
106
Q

proprioception somatosensation anatomy

A

muscle spindles provide sense of static position and movement of limbs and body: motor control

107
Q

skin mechanoreceptor activation

A
  1. mechanical deformation of skin
  2. deformation of cell membrane of afferent neuron
  3. cytoskeletal strands stretched, pulling ion channels open
  4. receptor potential signalled
108
Q

temperature receptors are called

A

thermoreceptors

109
Q

thermoreceptors

A

free nerve endings containing ion channels that respond to different temperature ranges

110
Q

cold afferents thermoreceptors

A
  • 0-35 degrees
  • activated by menthol
111
Q

warm afferents thermoreceptors

A
  • 30-50 degrees
  • activated by capsaicin and ethanol
112
Q

what do extreme temperatures activate?

A

pain receptors

113
Q

nociceptors

A

free nerve endings containing ion channels that open in response to intense mechanical deformation, excessive temperature of chemicals

114
Q

pain receptors are called

A

nociceptors

115
Q

visceral pain receptors are activated by…

A

inflammation inside internal organs

116
Q

nociceptor activation

A
  1. skin poked with knife: nociceptors activated
  2. action potential sent by afferents
  3. substance P released in spinal cord, activating 2nd order neurons
  4. pain experienced
117
Q

Hyperalgesia (def)

A

bottom up mechanism which increases the threshold for pain to tell the body to let it heal without using it

118
Q

Hyperalgesia (steps)

A
  1. follows nociceptor activation
  2. enhancement of surrounding nociceptors by injured tissue + mast cells release histamine
  3. substance P causes dilation of nearby blood vessels
119
Q

Touch and Proprioception pathway

A
  1. AP enters through spinal nerve
  2. goes up dorsal root ganglion and dorsal columns ipsilaterally
  3. medulla: midline crossed
  4. thalamus –> somatosensory cortex (contralaterally)
120
Q

An injury to the dorsal root leads to loss of somatosensations at which level

A

at the level of the lesion only

121
Q

Temperature and Pain pathway

A
  1. AP enters through spinal nerve
  2. goes through dorsal root ganglion and dorsal horn ipsilaterally
  3. cross midline at central canal
  4. anterolateral columns (contralaterally)
  5. branches into reticular formation –> thalamus –> somatosensory cortex
122
Q

an injury to the anterolateral columns leads to loss of pain and temperature at which level?

A

at the level of lesion and below

123
Q

where do all somatic senses arrive in the brain?

A

somatosensory cortex

124
Q

somatotopic map

A

illustrates higher acuity in some places due to more neurons and therefore smaller receptive fields

125
Q

referred pain

A

visceral and somatic pain afferents synapse on the same 2nd order neuron so the brain doesn’t know which afferent was responsible for the AP signal
-> skin assumed

126
Q

what do descending pathways regulate?

A

nociceptive information

127
Q

Analgesia

A

reduction of pain through top down mechanism (controlled)

128
Q

analgesia pathway

A
  1. neurons come down spinal cord through midbrain and reticular formation (medulla) and dorsolateral funiculus
  2. opiate neurotransmitter released
  3. substance P transmission inhibited
129
Q

visual sensory system stimulus energy

A

light

130
Q

visual sensory system receptor class

A

photoreceptors

131
Q

outer eye anatomy

A
  • sclera
  • cornea
  • pupil
  • iris
132
Q

cornea

A

clear section of sclera

133
Q

pupil

A

opens/closes to let more/less photons in

134
Q

iris

A

controls the pupil

135
Q

inner eye anatomy

A
  • lens
  • vitreous humor
  • retina
  • retinal pigment epithelium
  • fovea centralis
  • optic disk
136
Q

lens

A

focusing light on retina

137
Q

vitreous humour

A

clear jelly containing blood vessels which block photoreceptors

138
Q

retina

A

contains neurons and photoreceptors

139
Q

retinal pigment epithelium

A

lining behind the retina, contributing to transduction

140
Q

fovea centralis

A

highest visual acuity spot, centre of vision containing cones photoreceptors

141
Q

optic disk

A

blind spot where optic nerve leaves from, containing no photoreceptors

142
Q

light refraction

A

lens bends/refracts light to a single point

143
Q

what part of the eye refracts light?

A

cornea and lens but mostly cornea

144
Q

point where photons are refracted

A

retina

145
Q

how does the image appear at the retina

A

focused and inverted

146
Q

accomodation for near vision

A

lens changes shape to adapt to changes in object location

147
Q

what happens if object becomes closer to eye

A
  • focus point is behind the retina
  • lens accommodates by contacting ciliary muscles
    –> bends more light so focal point can be brought back on retina
148
Q

nearsightedness

A
  • eye is myopic
  • focal point appears before retina: too much refraction
149
Q

cause of nearsightedness

A

eyeball is too long

150
Q

farsightedness cause

A

eyeball is too short

151
Q

farsightedness

A
  • eye is hyperopic
  • focal point is behind the retina
152
Q

astigmatism

A

lens or cornea are not spherical

153
Q

presbyopia

A

lens gets stiff and is unable to accomodate for near vision

154
Q

cataract

A

change in lens color (opaque), blocking photons from reaching retina

155
Q

what can be found at the back of the retina

A

cones and rods

156
Q

convergence in retina

A

shift from many photoreceptors to way less photoreceptors in ganglion cells

157
Q

what forms the optic nerve

A

axons from ganglion cells

158
Q

phototransduction process

A
  1. light activates opsin molecule
  2. opsin changes conformation, causing chromophore to come off
  3. G-protein cascade triggered: cGMP converted to GMP
  4. sodium channels close since they are only activated in presence of cGMP
  5. photoreceptors become hyperpolarised, causing a reduction of neurotransmitter release
159
Q

opsin

A

proteins that capture photons

160
Q

chromophore

A

attached to opsin, needed for vitamin A

161
Q

how many different opsin molecules?

A

4

162
Q

which photoreceptor has high sensitivity and night vision

A

rods

163
Q

which photoreceptor has low sensitivity and day vision

A

cones

164
Q

which photoreceptor contains more rhodopsin

A

rods to capture more light

165
Q

which photoreceptor has high amplification?

A

rods

166
Q

which photoreceptor has a faster response time?

A

cones

167
Q

which photoreceptor is more sensitive to scattered light?

A

rods

168
Q

which photoreceptor is more sensitive to direct axial rays?

A

cones

169
Q

photoreceptor system with high acuity

A

cone system: less convergent
–> concentrated in the fovea

170
Q

photoreceptor system with high convergence

A

rod system: many rods drive same ganglion cell
–> low acuity

171
Q

which photoreceptor system contains multiple types of opsin?

A

cones: 3 types of opsin
-> chromatic: color perception

172
Q

which photoreceptor system is achromatic?

A

rods: only contain 1 type of opsin

173
Q

which photoreceptor is active in bright light? why?

A

cones active, rods inactivated
–> rods so sensitive that all opsin molecules broken down and they have no chromophore attached

174
Q

which photoreceptor is active in dark? why?

A

rods active, cones inactive
–> not enough photons to activate cones

175
Q

dark adaptation: bright light –> dark

A

temporary blindness:
- takes time for rods to re-activate
- cones no longer working due to absence of photons

176
Q

light adaptation: dark –> bright light

A

temporary blindness:
- rods initially saturated: too much opsin so all rods activated at once = very bright input until opsin depleted
- cones take over due to presence of many photons

177
Q

what bond does light break

A

bond between opsin and chromophore

178
Q

what does retina report

A

the relative intensity of light: brightness depends on surroundings

179
Q

2 types of receptive fields on retinal ganglion cells

A
  • excitatory centre (+), inhibitory surround (-)
  • inhibitory centre (-), excitatory surround (+)
180
Q

when do excitatory (+) centre RF in retinal ganglion cells fire more AP?

A

when bright centre and dark surround

181
Q

when do inhibitory (-) centre RF in retinal ganglion cells fire more AP?

A

when dark center and bright surround

182
Q

what do retinal ganglion cells signal?

A

the relative differences of light (ie contrast) across their receptive fields

183
Q

types of cones

A
  • blue cones
  • red cones
  • green cones
  • black cones
184
Q

what are photoreceptors sensitive to?

A

the wavelength of photons –> color they carry

185
Q

colorblindness

A
  • missing a specific opsin molecule
  • more common in men since opsin molecule found on X chromosome
186
Q

what do retinal ganglion cells have that is specific to the fovea only?

A

color-opponent receptive fields

187
Q

what does the output of retina encode?

A

relative values of brightness and color

188
Q

flow of visual information to the brain (steps)

A
  1. information leaves through optic nerve: contains information from one eye with both visual fields
  2. the 2 optic nerves come together at the optic chiasm, where nerves on nasal side of retina cross
  3. visual fields divide into optic tract: contains information from both eyes with contralateral visual field
  4. visual information reaches the thalamus
  5. optic radiations travel from thalamus to visual cortex in occipital lobe
189
Q

lesion between eye and optic chiasm causes

A

loss of vision in ipsilateral eye

190
Q

lesion between optic chiasm and thalamus causes

A

loss of vision in contralateral visual field

191
Q

lesion at optic chiasm causes

A

bilateral loss of temporal visual hemifields: only see inner visual field

192
Q

lesion in visual cortex causes

A

loss of vision in contralateral visual field

193
Q

the ‘where’ visual stream

A

parietal visual stream

194
Q

primary visual cortex information received

A
  • small RFs
  • simple image features: oriented line segments
  • divides into 2 pathways
195
Q

parietal visual stream ‘where’

A
  • large RFs: spatial features + motion
  • polymodal: visual combined with other sensory modalities
196
Q

the ‘what’ visual stream

A

temporal visual stream

197
Q

temporal visual stream

A
  • large RFs: complex image features
  • object recognition: faces
198
Q

pupillary reflex

A

shining light in one eye causes both pupils to contract
-> if brain bleeding: region containing optic nerve compressed so only 1 pupil constricts

199
Q

auditory system stimulus energy

A

sound

200
Q

auditory system receptor class

A

mechanoreceptors

201
Q

sound amplitude

A

difference in pressure wave that form around the head
ie. the loudness

202
Q

sound frequency

A

number of cycles per second
ie. pitch

203
Q

ability to hear depends on…

A

amplitude and frequency

204
Q

decibel (dB)

A

unit for measuring relative loudness of sounds
-> increase in 1dB = 10fold magnitude increase

205
Q

dB =

A

20log(relative pressure)
(log base 10)

206
Q

damage threshold

A

below pain threshold, can damage hearing above this point

207
Q

hearing threshold

A

smallest amplitude that can reliably be detected

208
Q

presbycusis

A

loss of sensitivity to hearing as you get older

209
Q

ear anatomy

A
  • tympanic membrane
  • malleus, incus and stapes
  • inner ear
  • cochlea
210
Q

tympanic membrane (eardrum)

A

vibrates as pressure waves change

211
Q

malleus, incus and stapes

A

3 smallest bones in body, link tympanic membrane to inner ear

212
Q

cochlea

A

contains neurons, where transduction occurs

213
Q

flow of sound energy

A
  • air pressure force causes oval window to go back and forth, creating a pressure wave
  • fluid behind oval window amplify sound waves, ie. cochlear duct
  • scala muscles contract when loud sounds occur to reduce movement of tympanic membrane
214
Q

cochlear duct

A

middle fluid compartment of inner ear

215
Q

basilar membrane

A

lines cochlear duct, moves up/down cochlear duct depending on sound frequency

216
Q

sound frequency increases so local vibrations move…

A

closer to sound output

217
Q

organ of corti

A

where basilar membrane motion converted into neuronal activity

218
Q

hair cells in organ of corti

A
  • outer hair cells
  • inner hair cells
219
Q

outer hair cells (organ of corti)

A
  • receive more efferents which command them to contract
  • actively shaping the motion of basilar membrane: electromotility
220
Q

inner hair cells (organ of corti)

A

have many afferents for transduction

221
Q

tip links

A

molecular strings connecting each stereocilia, mechanically gating ion channels

222
Q

auditory transduction (steps)

A
  1. hair cells contain stereocilia which is affected by basilar membrane movement
  2. stereocilia moves, creating tension on tip links
  3. causes ion channels to be pulled open
  4. potassium enters hair cell: depolarisation
  5. calcium flows into hair cell, activating afferents
  6. afferent neurons produce AP
223
Q

why is depolarisation different in the cochlear duct?

A

cochlear duct has different ionic composition fo K+ becomes the depolarising ion

224
Q

auditory transduction key points

A
  • sound waves are low energy
  • fast: direct channel activation
  • no amplification of transduction
225
Q

visual transduction key points

A
  • photons are high energy but hard to catch
  • slow: G-protein cascade
  • amplification: 1 photon closes many ion channels
226
Q

central auditory pathway

A
  1. afferents send information through cranial nerve
  2. reach medulla: half cross the midline
  3. on both sides: goes to midbrain, then thalamus then primary auditory cortex
227
Q

central auditory pathway is…

A

bilateral: auditory input used to localise sound

228
Q

vestibular system stimulus energy

A

gravity, acceleration

229
Q

vestibular system receptor class

A

mechanoreceptors

230
Q

vestibular organs found in

A

the inner ear

231
Q

vestibular organs

A
  • semicircular canals
  • utricle
  • saccule
232
Q

angular acceleration involves which vestibular organ(s)?

A

semicircular canals: head rotations

233
Q

linear acceleration involves which vestibular organ(s)?

A
  • utricle: horizontal movements
  • saccule: vertical movements
234
Q

vestibular occular reflex

A

when the head rotates, the eyes rotate in the opposite direction so the gaze stays constant

235
Q

how angular acceleration leads to transduction

A
  1. head rotation causes fluid to move, creating pressure and causing cupula to bend
  2. hair cells dont move but stereocilia bends
  3. transduction with tip links
236
Q

how linear acceleration leads to transduction

A
  1. head rotation causes stereocilia to bend but otoliths have inertia so lag behind
  2. transduction with tip links
237
Q

gustatory system stimulus energy

A

chemical

238
Q

gustatory system receptor class

A

chemoreceptors

239
Q

gustatory organ

A

tongue

240
Q

taste pore

A

where substances bind to chemoreceptors

241
Q

taste bud

A
  • line the papillae pores on tongue
  • contain taste cells which all correspond to 1 of the 5 tastes
242
Q

saliva role

A

dissolve molecules

243
Q

salty taste transduction

A

sodium ions from food flow through ion channels causing transduction

244
Q

sour taste transduction

A

high acidity so high protons, which interact with ion channels leading to transduction

245
Q

bitter taste transduction

A
  • bitter molecules block channels
  • or bitter molecules trigger G-protein cascade
246
Q

bitter

A

body’s way of telling a substance is harmful

247
Q

sweet taste transduction

A

sweet molecules (glucose) bind to receptors encoding sweet: activates G-protein cascade, leading to transduction

248
Q

umami taste transduction

A

glutamate receptors activate G-protein cascade, leading to transduciton

249
Q

central taste pathway

A
  • doesn’t cross the midline: only ipsilateral
  • cranial nerves -> medulla -> thalamus -> gustatory cortex
250
Q

olfactory system stimulus energy

A

chemical

251
Q

olfactory system receptor class

A

chemoreceptors

252
Q

olfactory receptor cells

A

specific to different types of molecules + contain cilia

253
Q

what forms the olfactory nerve

A

short axons from olfactory receptor cells

254
Q

where do olfactory neurons synapse?

A

at the olfactory bulb

255
Q

cilia

A

line mucus membrane

256
Q

where do molecules bind in the olfactory system?

A

in the cilia of olfactory receptor cells

257
Q

olfactory signal transduction

A
  1. molecules enter through nasal cavity
  2. molecules dissolved in olfactory epithelium
  3. odorant binds to odorant receptor cells in cilia in olfactory receptor cells
  4. G-protein cascade activated
  5. ion channel opening causes olfactory receptor cell to send AP to olfactory bulb
258
Q

central olfactory pathway

A

projects from olfactory bulb directly to different parts of the brain, mostly the Limbic system

259
Q

how is the central olfactory pathway notably different from other sensory pathways?

A

it doesn’t involve the thalamus

PHGY 209 (8 decks)

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