Sensory physiology Flashcards

1
Q

What 2 kinds of sensory neurons are there?

A

1) sensory receptors attached to neurons

2) Receptor cell as a separate entity

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2
Q

What are receptor potentials?

A

graded potentials that initiate AP (allow the passage of ions in order to change membrane potential)

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3
Q

What are transductions?

A

Transmission of stimulus through an axon

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4
Q

what are the major types of receptors?

A

Chemo
Mechano
Photo
Thermo
Noci-pain

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5
Q

What are the 4 properties of all stimuli?

A

Modality (type of stimulus) , Location, Intensity and Duration

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6
Q

what does adequate stimulus mean?

A

The perception of a receptor to other stimuli

ex) when feeling heat it activates thermoreceptors, however, if hot enough it will also activate nociceptors

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7
Q

how does the size of the receptive field affect perception of a stimulus?

A

smaller and more numerous receptive fields increase sensitivity in a region

larger receptive fields are seen in less sensitive areas

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8
Q

explain the concept of lateral inhibition

A

Lateral inhibition occurs when a secondary neuron inhibits its lateral neurons, preventing them from sending stimuli to the lateral tertiary neurons

-this allows the brain to localize sensory input

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9
Q

what are the 2 properties of a stimulus?

A

Intensity
-population coding (number of receptors activated)
-frequency coding (frequency of AP)

Duration (duration of AP)
-Tonic receptors
-Phasic receptors

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10
Q

what is a phasic receptor?

A

a rapidly adapting receptor where signals come and go
-thermoreceptor
-chemoreceptor

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11
Q

what is a tonic receptor?

A

a slowly acting receptor in which signals are constantly sent (needed for survival)
-nociceptors
-proprioception

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12
Q
A

Tonic

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13
Q

what are somatic receptors?

A

variety of sensory receptors from the skin, skeletal muscles, bones, tendons, and joints

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14
Q

What is the Meissner’s Corpuscle receptor?

A

(A)
-rapidly adapting mechanoreceptor
-sensitive to touch / pressure
-located in dermis

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15
Q

What is the merkel’s Corpuscle receptor?

A

(B)
-slowly adapting mechanoreceptor
-located in the dermis
-sensitive to touch /pressure
-usually for grip

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16
Q

What is the free neuron ending receptor?

A

(C)
-slowly adapting nociceptor, itch, thermo and mechanoreceptor
-mostly located in the dermis

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17
Q

What is the Pacinian Corpuscle receptor?

A

(D)
-rapidly adapting mechanoreceptor
-sensitive to vibration and deep pressure

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18
Q

What is the Ruffini Corpuscle receptor?

A

(E)
-slowly adapting mechanoreceptor
-sensitive to stretching of skin

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19
Q

what 2 things does visual perception require?

A

-an organ (the eye)
-neural pathways

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20
Q

name the parts of the eye

A

PISCAL

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21
Q

what is the optic disk?

A

the blind spot where neurons join to the optic nerve

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22
Q

what is the macula?

A

the round area at the center of the retina
-contains the fovea

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23
Q

what is the fovea?

A

Fovea is the region of sharpest vision
-highest [photoreceptors]

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24
Q

what structure in the eye is responsible for refraction?

A

The cornea

25
What structure focuses visual images onto the retina?
the lense
26
what is accommodation? what structure aids in accomodation?
The process where the eye adjusts the shape of lens to keep objects in focus Zonular fibers -attach the lens to the eye muscles
27
how does accommodation occur?
muscles relaxed- fibers tense and lens flattens to see far muscles contracted- fibers relax and lens rounds to see close
28
What is Myopia?
Nearsightedness- light rays focus in front of the retina making it hard to see far away -corrected with concave lense
29
What is hyperopia?
Farsighted-Light rays focus behind the retina making it hard to see up close -corrected with convex lens
30
what is presbyyopia?
loss of elasticity in the lens -inability to accommodate for near vision - >40 years
31
what is an astigmatism?
Surface of lens / cornea not smoothly spherical -results in distorted images
32
what is glaucoma?
damage to the retina due to increased ocular pressure
33
what are cataracts?
clouding of the lens -usually due to degradation of protein which form a cloud over the lens
34
what is the binocular zone of vision?
Where the left and right visual fields overlap
35
where do photoreceptors pass sensory information to?
Bipolar cells thich pass info to to the ganglion cells
36
what are rods?
Photoreceptors that function in low light conditions
37
what wavelength are photoreceptors sensitive to?
400nm - 750nm
37
What are cones?
Photoreceptors that function best in bright light. -colour vision
37
How does phototransduction occur?
1. Activation of rhodopsin 2. Activation of G-protein 3. Activation of phosphodiesterase 4. Hydrolysis of cGMP 5. Closure of ion channels
38
Can photoreceptors and bipolar cells generate AP? where is the AP generated?
No they produce graded potentials due to a lack of voltage gated channels AP are generated in ganglion which are the first cells in the pathway
39
Is glutamate inhibitory or excitatory for ON bipolar cells?
Inhibitory -metabotropic receptors
40
Is glutamate inhibitory or excitatory for OFF bipolar cells?
Excitatory -ionotropic receptors
41
True or false: Photoreceptors are depolarized in both ON and OFF pathways in the absence of light
TRUE
42
what happens to glutamate release in the light? what does this result in?
release from photoreceptors declines results in the depolarization of ON cells and hyperpolarization of OFF cells -excitatory NT released to ON bipolar cells which depolarize onto ganglion increasing frequency of AP propagation to the brain
43
what is the purpose of the ON and OFF pathways?
It acts as lateral inhibition to improve image resolution on the retina -improves the brain's ability to perceive contrast at edges / borders
44
where are optical signals sent prior to reaching the occipital lobe?
Thalamus
45
what structures are a part of the ear?
Pinna, ear canal, tympanic membrane, malleus, incus, stapes, oval window (stapes inside) , semicircular canal, cochlea, nerve (vestibulocochlear), eustachian tube Pamela Eats Tomatoes that MISs Olsen Sells Cheaply, Never Expensive
46
what structures make up the inner ear and cochlea?
ear canal tympanic membrane malleus, incus, stapes (at oval window) round window middle ear cavity cochlea, cochlear duct basilar membrane scala vestibuli scala tympani
47
how does sound travel through the ear?
1) soundwaves travel to tympanic membrane 2) malleus, incus and stapes move 3) membrane in oval window moves 4) waves travel through scala vestibuli and return back to oval window through scala tympani 5) membrane in round window moves
48
what essential organ does the cochlea contain?
Organ of corti
49
what is the purpose of hair cells in the auditory system? what channels are responsible for depolarization?
They release NT K+ channels; there are no Na+ channels
50
Where do primary sensory neurons send info to?
The medulla oblongata in the brainstem
51
where do secondary sensory neurons send info to? where do they synapse?
Information is projected to both sides of the brain so both sides get signals from both ears synapse occurs in the nuclei of the midbrain and thalamus prior to being sent to the auditory cortex
52
can localization of a sound be achieved through input from a singular ear?
No, localization requires simultaneous input from both ears
53
what is conductive hearing loss?
No transmission through external or middle of the ear -ear wax
54
what is central hearing loss?
Damage to neural pathways between ear and cerebral cortex / cerebra cortex (uncommon, stroke)
54
what 2 devices are used to restore hearing loss? how do they differ?
Hearing aid- amplifier placed in the auditory canal (activates existing auditory machinery) Cochlear implant- externally located audio sensor that sends stimulus directly to cochlear nerve
54
what is sensorineural hearing loss?
damage to inner ear structures most common; old age, damage to hair cells / loud noises (irreversible)