Sensory Systems Flashcards
1
Q
What are the 5 somatic senses
A
- touch
- temperature
- pain
- itch
- proprioception
2
Q
What are the 5 special senses
A
- vision
- hearing
- taste
- smell
- equilibrium
3
Q
What are the 4 ways sensory receptors are classified
A
- Location
- Modality
- Receptor Complexity
- Stimulus duration and intensity
4
Q
What are the 3 types of location based sensory receptors
A
Interoreceptors
Exteroreceptors
Proprioceptors
5
Q
What are the 4 types of modality based sensory receptors
A
Chemoreceptors
Mechanoreceptors
Photoreceptors
Thermoreceptors
6
Q
What are the 3 types of complexity based sensory receptors
A
Simple nerve endings
Sensory neurons with connective tissue capsule
Non-neural sensory receptors synapses with a sensory neuron
7
Q
What are the 2 types of duration/intensity based sensory receptors
A
Tonic
Phasic
8
Q
What are the 3 ways a sensory stimulus is identified
A
- location
- duration and intensity
- modality
9
Q
What is a receptive field
A
the area where a stimulus activates a sensory neuron
10
Q
How is the receptive field tested
A
2 point discrimination test
11
Q
What is lateral inhibition
A
primary neuron reacts to stimulus, secondary neurons inhibit activity of peripheral tertiary neurons
12
Q
What is a sensory homunculus
A
neurons from specific body areas have pathways to specific areas of the somatosensory cortex i.e all neurons from fingers travel to the finger area of the cortex
13
Q
What do tonic receptors do
A
slow adapting that continuously signal intensity and duration
14
Q
What do phasic receptors do
A
fast adapting that only signal onset and offset of stimulus (lets stimulus fade into background)
15
Q
What is an adequate stimulus
A
the type of stimulus the receptor responds to
16
Q
What are the 2 types of sensory pathways
A
Specific and non specific
17
Q
What are specific sensory pathways
A
1 type of receptor to specific area of cortex
18
Q
What are non specific sensory pathways
A
info from 2+ receptor types to brainstem reticular formation and thalamus
19
Q
What are cutaneous exteroreceptors
A
skin receptors
20
Q
What do pascinian corpuscles detect
A
Vibrations and tickles
21
Q
What type of receptor is a pascinian corpuscles
A
mechanoreceptor
22
Q
What type of neuron complexity do pascinian corpuscles have
A
Capsule
23
Q
Are pascinian corpuscles phasic or tonic
A
Phasic
24
Q
What nerve fibre types do pascinian corpuscles use
A
A beta
25
What do Messiners Corpuscles detect
tapping
26
what type of receptor is Messiners Corpuscles
mechanoreceptor
27
what type of neuron complexity does Messiners Corpuscles have
capsule
28
Are Messiners Corpuscles tonic or phasic
phasic
29
What nerve type do all the touch receptors use
A Beta
30
What do merkel cells detect
light pressure
31
What type of receptor complexity is merkel cells
free nerve ending
32
What type of receptor is all the touch receptors
mechanoreceptors
33
Are merkel cells tonic or phasic
tonic
34
What does Ruffinis Corpuscle detect
hard pressure
35
What receptor complexity does Ruffinis Corpuscle have
capsule
36
are Ruffinis Corpuscle tonic or phasic
tonic
37
What receptor type are cold receptors
thermoreceptors
38
what receptor type are warm receptors
Thermoreceptor
39
What temperature range does cold receptors detect
20-30 degrees
40
What temperature range does warm receptors detect
30-40
41
Are cold and warm receptors tonic or phasic
tonic
42
What nerve fibre type do cold receptors use
A delta
43
What nerve fibre type do warm receptors use
C
44
What receptor types (modality) to nociceptors use
thermoreceptors and mechanoreceptors
45
What type of receptor complexity are nociceptors
free nerve endings
46
What nerve fibres do nociceptors use
A delta and C
47
What are the 4 types of proprioceptors
1. Golgi tendon organs
2. Muscle spindles
3. Joint capsules
4. Flexors
48
What is the role of joint capsules and flexors
positional info
49
What is the key concept for the gate control theory of pain
Activating touch receptors at the area of pain can activate inhibitory interneurons that inhibits the pain pathway
50
What is hearing defined as
the perception of energy carried by sound waves between 20-20000Hz
51
What is conductive deafness
defects in the conduction of sound to the inner ear
52
What are the common causes of conductive deafness
earwax build up
blockage of eustachian tube
inflammation (otitis)
damage to eardrum
otosclerosis (bone growth)
53
What is sensorineural deafness
damage to the hair cells
54
What are the common causes of sensorineural deafness
→ menieres disease
→ trauma to the ear
→ ageing
→ infection
→ drugs
55
What is nerve deafness caused by
damage to the auditory nerve
56
How can the auditory nerve get damaged to cause nerve deafness
→ lesions
→ ageing
→ infections
→ atherschlerosis
57
What are the common causes of tinnitus
→ degeneration in the organs of corti
→ external and middle ear problems
→ Menieres disease or acoustic neuroma (auditory nerve disease)
58
What components make up the outer ear
1. pinna
2. auditory canal
3. tympanic membrane
59
What components make up the ossicles
Malleus - the hammer
Incus - the anvil
Stapes - the stirrup
60
What components make up the cochlea
1. vestibular canal
2. ressiners membrane
3. middle canal
4. tectorial membrane
5. basilar membrane
6. tympanic canal
61
What canal is the organ of corti and the hair cells located
middle canal
62
How do hair cells turn vibrations into sound
stereocilia moves in response to vibrations it generates neurotransmitters
63
What structures make up the auditory pathway
Ear → Auditory Canal → Brainstem → Thalamus → Auditory Cortex
64
What happens when hair cells are exited
K+ channels open to depolarise the cell, generates neurotransmitter release and increases action potential frequency
65
What happens when hair cells are inhibited
K+ channels close, less neurotransmitter reduced action potential frequency
66
What are the 7 stages in sound transmission
1. Sound waves hit the tympanic membrane which converts it into vibrations
2. Ossicles carry the vibrations to the cochlea
3. Vibrations move through the oval window to fluid in the vestibular tract
4. vibrations move the fluid within cochlea and push on the membranes
5. frequency of sound affects the displacement of the basal membrane, high frequency sounds affect the membrane at the thicker end
6. moves hairs, pattern if movement and stimulation codes sound components
7. neurotransmitters bind to auditory nerve
67
What is equilibrium
the state of balance that allows us to position our body in a 3D space
68
What structures maintain equilibrium
Hair cells in the vestibular apparatus and the semicircular canals
69
What do hair cells detect (in equilbrium)
Gravity and acceleration
70
What are the 2 components of equilibrium
Dynamic and static
71
Where are the hair cells that detect dynamic equilibrium
ampulla in semicircular canals
72
Where are the hair cells that detect static equilibrium
in the otolith organs in the semicircular cabals
73
What are the 3 branches of the equilibrium pathway
Semicircular Canals → Vistibular Nerve
Branch 1 → Brainstem → Cerebellum
Branch 2 → reticular formation → thalamus → cortex
Branch 3 → medulla
74
What receptors detect sweet
T1Rs
75
Are T1Rs GPCRs or Ion channels
GCPR
76
What receptors detect salty
MDEG/ENaC receptors
77
What receptors detect sour
MDEG/ENaC receptors
78
What receptors detect bitter
T2Rs
79
What receptors detect umami
t-mGluR4
80
What modality are taste buds
Chemoreceptors
81
What are the 3 types of taste bud
1. circumvallate
2. foliate
3. fungiform
82
T1Rs, T2Rs and t-mGluR4 are what kind of receptors
7 pass transmembrane receptors and GPCRs
83
Why is there such a variation in taste perception
Due to variation in amino acid make up of receptors and patterns of dimerisation
84
What dimerisation of the T1Rs detects L-amino acids
T1R1 + T1R3
85
What is the taste pathway
Nerve → brainstem → thalamus → gustatory cortex
→ hypothalamus
→ amygdala
86
What is the transduction of sweet ligands binding
glucose binds to gustductin receptor → activates cAMP → depolarises cell → triggers Ca2+ into cell → exocytosis of neurotransmitter
87
What is the transduction of bitter ligands binding
bitter ligand binds to transducin receptor → releases Ca2+ into cell → exocytosis of neurotransmitter
88
What is the transduction of salty and sour ions binding
depolarisation → Ca2+ → neurotransmitter
89
What is the olfactory pathway
Oderant molecules dissolve in the mucus that lines the nasal cavity → olfactory sensory cell → Mitral cells in the olfactory bulb → olfactory tract → olfactory cortex
90
What is the smell transduction pathway
smelly molecule binds to G protein in olfactory sensory cilia → cAMP → Calcium channel → Ca2+ → Cl- out of cell → action potential
91
What modality is olfactory neurons
chemoreceptors
92
What negative feedback loop regulates smell transduction
→ Ca2+ → CaM → CaMK → /AC
93
How does the olfactory pathway use lateral inhibition
to focus on specific smells, inhibits other mitral cells
94
Outline topography within the olfactory tract
olfactory epithelium seperated into 4 zones, between septum and turbinate sides, neurons that begin in a specific area will only project to specific areas in the olfactory bulb
95
What is the competition model of smell
mutated olfactory neurons in mice were replaced by functional neurons if the appropriate ligand is present
could explain why some people can’t detect smells if they aren’t exposed to them
96
What is the role of suspensory ligaments and ciliary muscles
hold lens in place and manipulate shape
97
What is the inner plexiform layer
synaptic connections between bipolar cells, amacrine cells and the ganglion cells
98
What is the inner nuclear layer
contains the cell bodies of bipolar cells, horizontal cells and amacrine cells
99
What is the outer plexiform layer
synaptic connections between photoreceptors, bipolar cells and horizontal cells
100
What is the outer nuclear layer
contains the cell bodies of photoreceptors
101
What are the 3 types of cones
red, blue and green
102
What is the role of the pigmented epithelium
absorbs excess light
103
What is the order of retinal layers from inner to outermost
1. inner plexiform layer
2 inner nuclear layer
3 outer plexiform layer
4 outer nuclear layer
5 photoreceptors
6 pigmented epithelium
104
What is the visual pathway
Eye → Optic Nerve → Optic Chiasm → Optic Tract → Lateral Geniculate Body (Thalamus) → Visual Cortex
105
How is light transduced
Light → rods and cones → bleaches rhodopsin → opsin causes decrease in cGMP → Na channels close → hyperpolarisation of cell → decreased neurotransmitter release
106
How is the lens manipulated to focus in on a near object
ciliary muscles contract to make lens fat
107
How is the lens manipulated to focus on a distant object
ciliary muscles relax and sus ligaments pull lens flat
108
What happens to light refraction in an hyperopic eye
Light refracts beyond retina
109
What type of corrective lens can fix a hyperopic eye
converging lens
110
What type of corrective lens can fix a myopic eye
a diverging lens
111
What happens to light refraction in an myopic eye
Light refracts to just before the retina
112
What are scotomas
Defects of the central field
113
What are the causes of scotomas
→ retinal lesions can be caused by occlusion of blood vessels or the optic nerve
→ B12 deficiency
→ drugs
114
What causes glaucoma
increased intraocilar pressure
115
What is meant by bleaching rhodopsin
Light activated retinal stops binding to opsin
116
What is rhodopsin made from
opsin and retinal
