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
Q

What structure focuses visual images onto the retina?

A

the lense

26
Q

what is accommodation? what structure aids in accomodation?

A

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
Q

how does accommodation occur?

A

muscles relaxed- fibers tense and lens flattens to see far

muscles contracted- fibers relax and lens rounds to see close

28
Q

What is Myopia?

A

Nearsightedness- light rays focus in front of the retina making it hard to see far away
-corrected with concave lense

29
Q

What is hyperopia?

A

Farsighted-Light rays focus behind the retina making it hard to see up close
-corrected with convex lens

30
Q

what is presbyyopia?

A

loss of elasticity in the lens
-inability to accommodate for near vision
- >40 years

31
Q

what is an astigmatism?

A

Surface of lens / cornea not smoothly spherical
-results in distorted images

32
Q

what is glaucoma?

A

damage to the retina due to increased ocular pressure

33
Q

what are cataracts?

A

clouding of the lens
-usually due to degradation of protein which form a cloud over the lens

34
Q

what is the binocular zone of vision?

A

Where the left and right visual fields overlap

35
Q

where do photoreceptors pass sensory information to?

A

Bipolar cells thich pass info to to the ganglion cells

36
Q

what are rods?

A

Photoreceptors that function in low light conditions

37
Q

what wavelength are photoreceptors sensitive to?

A

400nm - 750nm

37
Q

What are cones?

A

Photoreceptors that function best in bright light.
-colour vision

37
Q

How does phototransduction occur?

A
  1. Activation of rhodopsin
  2. Activation of G-protein
  3. Activation of phosphodiesterase
  4. Hydrolysis of cGMP
  5. Closure of ion channels
38
Q

Can photoreceptors and bipolar cells generate AP? where is the AP generated?

A

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
Q

Is glutamate inhibitory or excitatory for ON bipolar cells?

A

Inhibitory
-metabotropic receptors

40
Q

Is glutamate inhibitory or excitatory for OFF bipolar cells?

A

Excitatory
-ionotropic receptors

41
Q

True or false:

Photoreceptors are depolarized in both ON and OFF pathways in the absence of light

A

TRUE

42
Q

what happens to glutamate release in the light? what does this result in?

A

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
Q

what is the purpose of the ON and OFF pathways?

A

It acts as lateral inhibition to improve image resolution on the retina
-improves the brain’s ability to perceive contrast at edges / borders

44
Q

where are optical signals sent prior to reaching the occipital lobe?

A

Thalamus

45
Q

what structures are a part of the ear?

A

Pinna, ear canal, tympanic membrane, malleus, incus, stapes, oval window (stapes inside) , semicircular canal, cochlea, nerve (vestibulocochlear), eustachian tube

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46
Q

what structures make up the inner ear and cochlea?

A

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
Q

how does sound travel through the ear?

A

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
Q

what essential organ does the cochlea contain?

A

Organ of corti

49
Q

what is the purpose of hair cells in the auditory system? what channels are responsible for depolarization?

A

They release NT

K+ channels; there are no Na+ channels

50
Q

Where do primary sensory neurons send info to?

A

The medulla oblongata in the brainstem

51
Q

where do secondary sensory neurons send info to? where do they synapse?

A

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
Q

can localization of a sound be achieved through input from a singular ear?

A

No, localization requires simultaneous input from both ears

53
Q

what is conductive hearing loss?

A

No transmission through external or middle of the ear

-ear wax

54
Q

what is central hearing loss?

A

Damage to neural pathways between ear and cerebral cortex / cerebra cortex (uncommon, stroke)

54
Q

what 2 devices are used to restore hearing loss? how do they differ?

A

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
Q

what is sensorineural hearing loss?

A

damage to inner ear structures

most common; old age, damage to hair cells / loud noises (irreversible)