Senses 1 Flashcards

(48 cards)

1
Q

what are sense organs?

A

structures containing receptors and interneurons that are specialised for detecting and processing particular types of stimuli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

mechanical modalities

A

touch

pain

hearing

vestibular

joint

muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

visual modalities

A

seeing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

thermal modalities

A

cold

warmth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

chemical modalities

A

smell

taste

common chemical

vomeronasal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

electrical modalities

A

electroreception

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

touch

A

contact with/deformation of body surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

pain

A

tissue damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

hearing

A

sound vibrations in air/water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

vestibular

A

head movement and orientation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

joint

A

position and movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

muscle

A

tension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

seeing

A

visible radiant energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

cold

A

decrease in skin temp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

warmth

A

increase in skin temp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

smell

A

odorous substances dissolved in air/water in nasal cavity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

taste

A

substances in contact with tongue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

common chemical

A

changes in CO2, pH, osmotic pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

vomeronasal

A

pheromones in air/water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

electroreception

A

diffs in density of electrical currents

21
Q

what are receptor neurons?

A

are specialised to detect internal and external stimuli of a particular sensory modality, especially when stimuli change

act as filter for stimulus information, transforming stimulus energy in neural signals that are transmitted to sensory interneurons

22
Q

coding in diff sensory modalities

A

all neurons share the same vocabulary of neural signals.

23
Q

first stage in processing sensory info

A

receptor neuron

all in PNS – send info to CNS

taste receptors and sensory interneurons in the tongue

photoreceptor and sensory interneurons in the eye

hair cells and sensory interneurons in the ear

Pacinian corpuscle in the skin

don’t have axons that enter CNS

Olfactory receptor in the nose

sensory receptors and interneurons from each sensory modality project to segregated areas or layers within an area of the brain

24
Q

what other senses do animals rely on?

A

magneto-reception (e.g. birds, reptiles)

polarisation vision (e.g. insects)

electro-sensation (e.g. eels, teleost fish)

echolocation hearing (e.g. bats, whales)

such additional senses require adaptations at the level of receptor neurons and/or in the processing sensory pathways and brain areas

25
what are sensory systems?
good examples to demonstrate some of the known fundamental principles of brain organisation and neural network functions.
26
what are mechanoreceptors?
touch and pain: Diverse receptors in the skin and body posture control: Propioreceptors in the body (muscles, joints) hearing: Hair cells in the inner ear balance control: Vestibular receptors in the vestibular apparatus
27
receptive field of a receptor neuron
receptive field is the region in space in which stimuli affect that neuron’s firing rate
28
small receptive fields
in touch-sensitive receptors: Free nerve endings, Merkel’s disc and Meissner’s corpuscle sense innervate the surface of the skin and are sensitive to stimuli in small areas of the skin
29
large/wide receptive fields
Pacinian corpuscles and Ruffini’s endings innervate deeper layers of the skin and are sensitive to stimuli over a larger areas of the skin
30
receptors that transmit signals from skin to spinal cord
Pacinian corpuscle (in skin, muscles – detecting vibration and pressure) is a unipolar cell that extends one branch of its axon to skin and other to spinal cord afferent projections form the dorsal root (spinal) nerve and the cell bodies are part of the dorsal root (spinal) ganglion.
31
mechanically-gated ion channels
vibration or pressure on skin deforms the corpuscle and stretches the tip of the axon opening mechanically-gated ion channels. note the concentric layers of tissue (like in an onion) around the axon tip that amplify the signal
32
receptors with a graded potential
similar to the dendrites of a postsynaptic neuron, receptors respond to stimulation with a graded potential, the receptor potential spiking receptor neurons convert the receptor potential into spikes
33
response thresholds in receptor neurons
receptors respond to a stimulus within a range of stimulus intensities. different types of receptor neurons vary in their response thresholds for the same type of stimulus. response rates for three different hypothetical types of receptor neurons with different response thresholds. low threshold fires no matter what others need a stronger stimulus
34
filtering and coding sensory info
sensory systems can combine receptor neurons with different sensitivities (=different thresholds). this is useful for extending the range of intensities for which they jointly can respond and for distinguishing between different stimuli, if using a combinatorial code.
35
receptor adaptation: adjustment of thresholds over time
receptors can adapt (to certain extent) their threshold, if the prevailing range of stimulus intensities changes, to optimise coding of the stimulus. move threshold to experience lower freq if continuously experiencing lower thresholds and vice versa for high
36
adjustment of receptor response over duration of stimulus
a single stimulus is usually not enough to shift the sensitivity of the receptor neuron (response threshold) after a short break a second stimulus of the same intensity will elicit the same response.
37
slow adapting and small receptive field receptors
Merkel's disc - sensing texture
38
slow adapting and large receptive field receptors
Ruffini's ending - sustained contact
39
fast adapting and small receptive field receptors
Messiner's corpuscle - vibration
40
fast adapting and large receptive field receptors
Pacinian corpuscle - initial contact
41
sensory pathways
segregated projections to different areas of brainstem, thalamus and cortex (labeled-line principle). where possible, information about the spatial location of stimuli is preserved by separating projections that come from receptors in different locations. it is important to know where stimulation occurred in the body (e.g. whether the hand or back was touched) or relative to the body (e.g. whether wind blows into the face or neck).
42
receptive fields of neurons
receptive fields can be mapped for neurons in the sensory pathway
43
cortical encoding in form of somatotopic maps
primary somatosensory cortex is located in the postcentral gyrus in the parietal lobe of the human brain. Brodman areas 1,2 and 3a,b adjacent regions on body are generally encoded in adjacent regions in cortex (with some curious exceptions)
44
sensory segregation in cortical somatotopic maps
fast adapting signals (from Meissner’s and Pacinian corpuscles) and slow adapting signals (from Merkel’s disks and Ruffini’s endings) remain segregated in cortex information from different skin receptor types is projected into the different Brodman areas organisation of neurons in columns and layers in the primary somatosensory cortex.
45
experience dependent plastic reorganisation of cortical maps
can be very plastic cortical representations can change with use Owl monkey trained for several months at task using fingers 2-4
46
suppressing sensory input
just as nerve cells need to be inhibited, receptors and the signals they convey also need to be ‘switched off’ at times often suppression involves accessory organs. Such structures reduce the intensity or alter the stimulus before it reaches the receptor e.g. Eyelids, muscles in ear or it can be via top-down processes e.g. brain stem sends messages to receptor cells in the ear to selectively dampen sounds
47
phasic receptors
receptors that show fast loss of response shortly after onset of stimulation
48
tonic receptors
receptors show a slow loss of response