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Medicine Term One > Sensory receptors > Flashcards

Sensory receptors Flashcards

1
Q

what are sensory receptors

A

are nerve endings, often with specialized non-neural structures

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2
Q

What do sensory receptors induce

A

convert different forms of energy into frequency of Action Potentials (APs)

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3
Q

what is a sensory modality

A

a type of stimulus activating a particular receptor

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4
Q

what is the type of energy a receptor normally responds to called

A

an adequate stimulus

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5
Q

What are Mechanoreceptors

A

stimulated by mechanical stimuli

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6
Q

what are the mechanoreceptors in joints and muscles that signal information related to body or limb position called

A

Proprioceptors

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7
Q

What are the receptors that respond to pain

A

Nociceptors

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8
Q

Damage to the nerve by stimuli activates a generator potential which in turn opens

A

ion channels causing ion flow across the membrane

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9
Q

an adequate stimulus causes a graded membrane potential change called

A

receptor potential

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10
Q

For action potential to be fired what needs to happen

A

receptor potential reaches threshold

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11
Q

frequency coding of stimulus intensity means

A

the larger the receptor potential the higher the frequency of APs in sensory neurone

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12
Q

Merkel receptors senses

A

pressure and texture

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13
Q

Pacinanan corpuscle sense

A

vibration

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14
Q

meissners corpuscle senses

A

flutter and stroking movement

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15
Q

ruffini corpuscle senses

A

skin stretching

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16
Q

Adaption of sensory nerves is

A

stimulus is enough to trigger an AP, but as stimulus continues generator potential decreases so mechanoreceptor only responds to onset of stimulus
ie stimulus there but you are no longer consciously aware

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17
Q

Rapidly/Moderately-adapting receptors are

A

Pacinian corpuscles and Meissner’s corpuscles

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18
Q

Slowly-adapting receptors are

A

Merkel’s discs and Ruffini endings

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19
Q

Why don’t Nociceptors adapt

A

important not to ignore painful stimuli

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20
Q

Whats is the structure of Pacinian corpuscles

A

a myelinated nerve with a naked nerve ending,

naked nerve ending enclosed by a connective tissue capsule of layered lamella

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21
Q

Describe how Pacinian corpuscles respond to stimuli

A 
mechanical stimulus deforms capsule 
nerve ending is stretched 
ion channels open 
Na+ enters local depolarisation 
generator potential reaches threshold 
APs fire at myelinated nerve 
detect stimulus ON
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22
Q

How does the Pacinian corpuscles show rapid adaptation

A

Due to fluid redistribution in the capsule, removes mechanical stretch of nerve ending, causing stimulus to disappear and AP stop firing

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23
Q

What can cause an AP to fire again in a Pacinian corpuscles after stimulus is applied

A

withdrawal of stimulus causes capsule to bring back and AP fired again

24
Q

What is necessary for quick adaptation in Pacinian corpuscles and enhance sensory function

A

the lamella

25
Q

what is the receptive field

A

a somatic sensory neuron is activated by stimuli in a specific area

26
Q

What are the two things that tell parts of the skin apart

A

receptive field size

neuronal convergence

27
Q

Neuronal convergence occurs when there is

A

sensory neutrons with neighbouring receptive fields

28
Q

what can neuronal convergence stimulate

A

large secondary receptive field

29
Q

relatively insensitive area indicated by

and example

A

So convergence and a large secondary receptive field

eg. fingers and lips

30
Q

What is acuity

A

The ability to locate a stimulus on the skin and differentiate it from another close by

31
Q

Example of low acuity is

A

two different points are stimulated but one signal is sent to the brain

32
Q

What is lateral inhibition

A

Central neurone inhibits surrounding neighbour pathways this pinpoints where stimulus is

33
Q

Inhibition of lateral neutrons enhances what

A

perception stimuli, awareness of where exactly stimuli is coming from

34
Q

All sensory information goes to the brain then is relayed through what to what

A

relayed through thalamus to somatosensory cortex

35
Q

What are the three things present and needed in proprioceptors

A

Muscle spindles
golgi tendon organs
joint receptors

36
Q

What monitors muscle length and rate of change, controlling reflects and voluntary movement

A

Muscle spindes

37
Q

Where are muscle spindles located

A

in the intrafusal of muscle fibres

38
Q

What do golgi tendons do

A

tension on tendons

39
Q

What is tension produced by

A

muscle contraction

40
Q

What is the 3 functions of proprioceptors

A

Provide sensory information for:
Voluntary movement
spinal chord reflexes
kinaesthesia

41
Q

What lies in parallel with muscle fibres

A

muscle spindles

42
Q

What innervates end of intrafusal muscle spindle

A

gamma motor neurons

43
Q

what innervates end of extrafusal muscle spindle

A

alpha motor neurons

44
Q

How do afferent neurones position themselves around the muscle spindle

A

they spiral around

45
Q

What motor neurone is smaller in diameter

A

gamma

46
Q

How are golgi tendons arranged

A

in series with muscle fibres

47
Q

When muscle contraction increases tension in golgi tendon sensory axon fires but why doesn’t sensory axon fire from muscle spindle

A

as activated muscle stays the same length therefore doesn’t activate muscle spindle

48
Q

Gamma motor invasion of the muscle spindles allows

A

brain to be informed about muscle length

prevents spindle fibres flopping, allows them to contract

49
Q

What happens to muscle spindles when muscles contracts and shortens

A

gamma motor neurons contract poles of muscle spindle, shortening to match the muscle fibre.

50
Q

Why does the muscle spindle need to contract

A

to allow information to be transmitted to the brain

51
Q

spindle sensitivity to stretch is maintained by

A

gamma motorneurons

52
Q

the work of alpha and gamma is called

A

co-activation

53
Q

What does co-activation allow

A

this restores tension and resets sensitivity of the central sensory part of intrafusal fibres, at a new muscle length

54
Q

What are the two kinds of intrafusal fibre

A

nuclear bag fibres

nuclear chain fibres

55
Q

Reflex contraction inhibited by

A

muscle spindles

56
Q

Muscle contraction stretches golgi tendon organ but if excess load is applied what happens

A

Goligi tendon reflex causes relaxation due to motor neurone being inhibited, thus protecting muscle

Medicine Term One (59 decks)

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