Senses and Perception Flashcards
(126 cards)
1
Q
what is tactile input
A
this is the type of mechanical stimulation on the skin
2
Q
what is the quality of tactile input
A
the type of touch
3
Q
what is the magnitude of tactile input
A
this is how big the input is
4
Q
what is the duration of tactile input
A
this is how long and how often the stimulus lasts
5
Q
where does most bodily innervation go as the first point of entry
A
the spinal cord
6
Q
how do we convert a stimulus into an electrical signal
A
through modality specific sensory receptors
7
Q
how is information transmitted faithfully to the central nervous system
A
through modality specific sensory pathways
8
Q
wat is the first cell involved in the sensation pathway
A
the sensory neuron
9
Q
what do sensory neurons do
A
they relay information from the periphery into the central nervous system
10
Q
what is the morphology of the sensory neuron
A
pseudounipolar structure
11
Q
describe the structure of the sensory neuron
A
cell body with two axons
first branch is in the periphery and innervates the skin, and a second brnach which projects into the central nervous system
12
Q
what is found at the end of the peripheral branch of sensory neurons
A
receptor endings
13
Q
what is found at the central terminal of sensory neurons
A
synaptic vesicles, which allow for synaptic release to recruit target neurons in the sensory pathway
14
Q
list the events of a general stimulus on primary sensory receptors
A
- stimulus
- receptor endings activated
- action potential generated
- relayed centrally
- neurotransmitter released at central terminal
- recruitment of post synaptic targets
15
Q
how are stimulus properties coded
A
according to quality, intensity, duration and location
16
Q
what are the main stimulus types
A
mechanical
thermal
noxious
chemical
light
17
Q
describe the stimulus and receptor for the sensation of touch
A
mechanical stimulus
mechanoreceptor
18
Q
describe the stimulus and receptor for the sensation of temperature
A
thermal stimulus
thermoreceptor
19
Q
describe the stimulus and receptor for the sensation of pain
A
noxious stimulus, nociceptor
20
Q
describe the stimulus and receptor for the sensation of taste and smell
A
chemical stimulus, chemoreceptor
21
Q
describe the stimulus and receptor for the sensation of vision
A
light stimulus
photoreceptor
22
Q
which receptors are found on free nerve endings
A
nociceptors
23
Q
what are the different mechanoreceptors found in the skin
A
meissners corpuscle
merkel disk
hair follicle receptor
pacinian corpuscle
ruffini ending
24
Q
what is this
A
meissners corpuscle
mechanoreceptor in the skin
25
what is this
merkels disc
a mechanoreceptor found in the skin
26
what is this
hair follicle receptor
mechanoreceptor found in the skin
27
what is this
pacinian corpuscle
a mechanoreceptor found in the skin
28
what is this
ruffini ending
mechanoreceptor found in the skin
29
what features are found in all sensory neurons
cluster of peripheral nerve branches with its own receptor endings
30
what is a receptive field
this is the distribution of receptor endings found in each neuron
31
do receptive fields remain separate
they often overlap to allow for two point discrimination
32
how large are receptive fields in the periphery
small
33
how large are receptive fields in the trunk of the body
very large
34
what is two point discrimination
this is the ability to discern two separate mechanical stimuli
it is a measure of spatial resolution and an indication of the size of the receptive field
35
describe the temporal sequence of stimulus transduction
- stimulus
- change in receptor membrane permeability
- influx of cations
- depolarisation on the receptor potential
- action potential
36
what is the resting membrane potential on most cells
-70mV
37
what are the two subtypes of receptor
ionotropic and g protein coupled
38
describe the kinetics and modalities of ionotropic receptors
fast kinetics
mechanoreceptors and chemoreceptors
39
describe the kinetics of g protein coupled receptors
slow kinetics and chemoreceptors
40
describe signal transduction of ionotropic mechanoreceptors
- there is a lipid bilayer that has been interrupted by an ion channel
- the ion channel is tethered to the membrane by fibrils on the intracellular aspect of the membrane
- when inactive, the channel is closed
- when mechanical stimulus is applied, the deformation of the cell membrane pulls on the underlying fibrils which pulls the fibres away to open the channel
- potassium leaves and sodium enters
41
describe the signal transduction in ionotropic chemoreceptors
- ion channel is too narrow in the inactive state
- extracellular surface has ligand binding receptor sites
- this becomes active when the ligands bind
- conformational change allows the pore to open
- sodium and potassium can cross over
42
describe signal transduction in g protein coupled receptors
receptor is more complex as there are many proteins linekd to it.
the ligand binding site changes conformation to cause a response on the ion channel
when inactive, the channel is closed. the specific ligand will bind to the receptor, cause an intracellular signalling cascade, and then the channel can open.
so it is a lot slower because the pathway is more complex than in ionotropic receptors
43
what is the stimulus property for type of receptor
quality
44
what is the stimulus property for action potential frequency
magnitude or intensity
45
what is the stimulus property for number of neurons activated
magnitude or intensity
46
what is the stimulus property for duration of action potential firing
duration or timing
47
what is the stimulus property for receptive field
location
48
what does the quality of the receptor depend on
type of receptor
49
what does the magnitude of the stimulus depend on
the action potential frequency and the number of neurons that has been activated
50
what does the duration of the stimulus depend on
duration of the action potentia firing
51
what does the location of the stimulus depend on
the receptive field
52
what does an increase in stimulus intensity do to the action potential
increases the action potential frequency
53
describe the coding of receptive fields
each one is coded by a particular sensory neuron which activates a pathway that prokects and ends in a discrete region in the brain
each one has its own cortical region in the brain
54
what does the sensory homunculus show
the distinct structures of the cerebral cortex that are responsible for different nerve functions
55
what are the main principles of receptive fields
size
distribution
density
56
where is the cortical representation for the brain
the homunculus
57
what do peripheral nerves contain
axons from two functionally distinct types of nerve cells
58
what are afferents
sensory neurons
59
what are efferents
motor neurons
60
how do axons exit the spinal cord
via the peripheral nerves
61
what is the function of the epineurium
mechanical protection and support to the neuron
62
what surrounds the individual fascicles in the neurons
perineurium connective tissue
63
are unmyelinated axons larger
no
64
why are there blood vessels within the nerves connective tissue
conduction of action potentials is metabolically demanding and needs blood supply to remove by products and provide oxygen and glucose
65
describe myelinated axons in the peripheral nervous system
they have a series of schwann cells lined up along the axon, each having a wrapped coating of myelin insulating the axon
66
describe unmyelinated axons in the peripheral nervous system
encased by schwann cells cytoplasm, but there is no wrapped coating of myelin around the axons
67
which axon types are myelinated
A alpha
A delta
A beta
68
which axon types are unmyelinated
C fibres
69
describe A alpha axons from the skin
thickest axon and thickest myelin sheath
very fast conduction speed of 80-120 metres a second
70
what are the sensory receptors with A alpha axons
proprioreception in skeletal muscle
71
describe A beta cells
thick axon and thick myelin sheath
fast conducting speed at 35-75 metres a second
72
which type of sensory receptors have a beta axons
mechanoreceptors of the skin
73
describe a delta fibres
thin diameter and a conduction speed of 5-30 metres a second
74
which type of sensory neurons have A delta fibres
pain and temperature sensation
75
what is the diameter of A alpha axons
13-20 micrometers
76
what is the diameter of a beta axons
6-12 micrometers
77
what is the diameter of a delta fibres
1-5 micrometers
78
what is the diameter of c fibres
0.2 -1.5 micrometers
79
what is the speed of c fibres
0.5 - 2 metres a second
80
which axons are associated with sensation of pain and temperature
A delta and C
81
what can spinal cord grey matter be divided into
dorsal horn
intermediate horn
ventral horn
82
what is the target of peripheral nerves
the spinal cord
83
how many dorsal root ganglia are there
31 pairs
84
what is the dorsal root
this is the medial portion of the sensory nerve that goes from the root ganglia into the spinal cord
85
what is the dorsal root made up of
only the centrally projecting axons, no myelin
86
where do sensory neurons enter the spinal cord
dorsal horn
87
where are the cell bodies of motor neurons found
the ventral horn of the grey matter
88
how do motor neurons exit the spinal cord
through ventral roots, to innervate muscle in appropriate regions
89
can a peripheral nerve carry both afferent and efferent information
yes they all do
90
describe how the spinal cord is arranged along the torso and what this gives rise to
it has a segmental arrangement and this gives rise to dermatomes, which are strip like structures along the body that indicate specific spinal segments that receive information from them
91
which branches of the trigeminal nerve are sensory only
the opthalmic division and the maxillary division
92
which branches of the trigeminal nerve are both sensory and motor
the mandibular branch, as it gives general sensation but also innervates the muscles of mastication
93
what is the principle innervation for sensation on the face
the trigeminal nerve
94
what does the opthalmic division of the trigeminal nerve innervate
most of the scalp and forehead, and the dorsum of the nose
95
what does the maxillary division of the trigeminal nerve supply
the lateral region of the face and under the eyes, cheeks
96
where is the temporalis muscle found
in the temporal fossa on the lateral aspect of the face above the ear
97
what sensation is touch
mechanreception
98
what sensation is pain
nociception
99
is the facial innervation pathway the same as the spinal nerve pathway
no
100
what are sensory pathways comprised of
three interconnected neurons - the primary, secondary and tertiary neurons
101
describe the general sensory pathway with its interconnecting pathways
- primary sensory neurons are the first and they deliver information from the periphery along the peripheral nerve into the central nervous system
- they target the secondary sensory neuron to relay information along the axon toward the axon terminal, which triggers the release of neurotransmitter
- this recruits the tertiary sensory neuron which projects into the cerebral cortex to the appropriate region
102
where is most of the primary sensory neuron found
the periphery
103
is the information relayed by sensory pathways relayed to the sensory cortex on the same or the opposite side of the body
the opposite - there is a cross over in the thalamus when the information goes to the secondary neuron
104
what is cortical representation
this is how every sensory neuron's receptive field is represented in the cortex, as there are body regions with higher sensory innervation due to a higher density of receptor endings, and these regions have greater cortical representation
105
what is somatic mechanoreception
perception of innoxious tactile sensation
106
what is the brain stem continuous with
the cerebral hemispheres
107
describe the route of the primary sensory neuron in the dorsal column medial lemniscal pathway
when information goes to the spinal cord, there is a small branch that terminates in the spinal cord and another that ascends up the spinal cord to the medulla oblongata
108
describe the route of the secondary sensory neuron in the dorsal column medial lemniscal pathway
axon crosses over to the other side of the body before it relays through the brainstem toward the thalamus
once it reaches the thalamus it synapses with the tertiary neuron
109
describe the route of the tertiary neuron in the dorsal column medial lemniscal pathway
goes from the thalamus to the cerebral cortex
110
describe the posterior trigeminothalamic pathway
- sensory neuron project into the brainstem via the trigeminal nerve
- cell body of trigeminal afferents in the trigeminal ganglia
- axon projects into the brainstem where it synapses with the second order sensory neuron
- crosses to the opposite side and projects into the thalamus where it connects with the tertiary neuron
- crosses to the cortex and terminates here
111
describe the spinothalamic pathway
- free nerve endings coalsce to form an axon
- projects via peripheral nerve into the spinal cord
- into the dorsal horn of the spinal cord
- synapse with second order sensory neuron
- sends an axon to the opposite side of the body at the same segmental level
- then is ascends the spinal cord to the thalamus
- via a white matter bundle
- to synapse with tertiary sensory neuron in thalamus
- to go to cerebral cortex
- perception received
112
what is the anterior trigeminothalamic pathway describing
pain in the face
113
what is the dorsal trigeminothalamic pathway describing
somatic mechanoreception ie general sensation in the face
114
what is the spinothalamic pathway describing
somatic nociception ie pain
115
what is the dorsal column medial lemniscal pathway describing
somatic mechanoreception - general sensation
116
what is sensation
the process of sensing our environment by activation of sensory receptors and associated sensory pathways
117
what are some different sensations
touch
taste
sight
smell
118
what is perception
this is the interepration of sensory input, and requires a high degree of cortical processing
119
what is stereognosis
mental perception of objects referenced by touch - it is our ability to generate a mental perception of objects from touch stimuli only
120
what is involved in the cortical processing of stereognosis
- integration of information on several aspects of touch like texture, weight and size
- ability to retrieve previous experiences
- generate a 3D mental image without having seen the object
121
what is stimulating in the sensory cortex during stereognosis
hippocampus
basal ganglia
motor cortex
122
what is proprioception
this is the sense of self movement and body position, otherwise known as kinesthesia
123
describe the integration of mechanosensory input in kinesthesia
- balance organs in the inner ear
- muscle receptors and joint receptors
- mechanoreceptors
- periodontal receptors
124
what are the balance organs in the inner ear
utricle
saccule
semi circular canals
125
why are muscle receptors and joint receptors used during kinesthesia
for muscle length and tension
joint position
126
how are axon fibres classified
according to their:
- myelination
- diameter
- conduction velocity
- sensory modality
