Sensory receptors

Question 1

what are sensory receptors

Answer 1

are nerve endings, often with specialized non-neural structures

Question 2

What do sensory receptors induce

Answer 2

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

Question 3

what is a sensory modality

Answer 3

a type of stimulus activating a particular receptor

Question 4

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

Answer 4

an adequate stimulus

Question 5

What are Mechanoreceptors

Answer 5

stimulated by mechanical stimuli

Question 6

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

Answer 6

Proprioceptors

Question 7

What are the receptors that respond to pain

Answer 7

Nociceptors

Question 8

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

Answer 8

ion channels causing ion flow across the membrane

Question 9

an adequate stimulus causes a graded membrane potential change called

Answer 9

receptor potential

Question 10

For action potential to be fired what needs to happen

Answer 10

receptor potential reaches threshold

Question 11

frequency coding of stimulus intensity means

Answer 11

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

Question 12

Merkel receptors senses

Answer 12

pressure and texture

Question 13

Pacinanan corpuscle sense

Answer 13

vibration

Question 14

meissners corpuscle senses

Answer 14

flutter and stroking movement

Question 15

ruffini corpuscle senses

Answer 15

skin stretching

Question 16

Adaption of sensory nerves is

Answer 16

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

Question 17

Rapidly/Moderately-adapting receptors are

Answer 17

Pacinian corpuscles and Meissner’s corpuscles

Question 18

Slowly-adapting receptors are

Answer 18

Merkel’s discs and Ruffini endings

Question 19

Why don’t Nociceptors adapt

Answer 19

important not to ignore painful stimuli

Question 20

Whats is the structure of Pacinian corpuscles

Answer 20

a myelinated nerve with a naked nerve ending,

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

Question 21

Describe how Pacinian corpuscles respond to stimuli

Answer 21

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

Question 22

How does the Pacinian corpuscles show rapid adaptation

Answer 22

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

Question 23

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

Answer 23

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

Question 24

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

Answer 24

the lamella

Question 25

what is the receptive field

Answer 25

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

Question 26

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

Answer 26

receptive field size | neuronal convergence

Question 27

Neuronal convergence occurs when there is

Answer 27

sensory neutrons with neighbouring receptive fields

Question 28

what can neuronal convergence stimulate

Answer 28

large secondary receptive field

Question 29

relatively insensitive area indicated by | and example

Answer 29

So convergence and a large secondary receptive field | eg. fingers and lips

Question 30

What is acuity

Answer 30

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

Question 31

Example of low acuity is

Answer 31

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

Question 32

What is lateral inhibition

Answer 32

Central neurone inhibits surrounding neighbour pathways this pinpoints where stimulus is

Question 33

Inhibition of lateral neutrons enhances what

Answer 33

perception stimuli, awareness of where exactly stimuli is coming from

Question 34

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

Answer 34

relayed through thalamus to somatosensory cortex

Question 35

What are the three things present and needed in proprioceptors

Answer 35

Muscle spindles golgi tendon organs joint receptors

Question 36

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

Answer 36

Muscle spindes

Question 37

Where are muscle spindles located

Answer 37

in the intrafusal of muscle fibres

Question 38

What do golgi tendons do

Answer 38

tension on tendons

Question 39

What is tension produced by

Answer 39

muscle contraction

Question 40

What is the 3 functions of proprioceptors

Answer 40

Provide sensory information for: Voluntary movement spinal chord reflexes kinaesthesia

Question 41

What lies in parallel with muscle fibres

Answer 41

muscle spindles

Question 42

What innervates end of intrafusal muscle spindle

Answer 42

gamma motor neurons

Question 43

what innervates end of extrafusal muscle spindle

Answer 43

alpha motor neurons

Question 44

How do afferent neurones position themselves around the muscle spindle

Answer 44

they spiral around

Question 45

What motor neurone is smaller in diameter

Answer 45

gamma

Question 46

How are golgi tendons arranged

Answer 46

in series with muscle fibres

Question 47

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

Answer 47

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

Question 48

Gamma motor invasion of the muscle spindles allows

Answer 48

brain to be informed about muscle length | prevents spindle fibres flopping, allows them to contract

Question 49

What happens to muscle spindles when muscles contracts and shortens

Answer 49

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

Question 50

Why does the muscle spindle need to contract

Answer 50

to allow information to be transmitted to the brain

Question 51

spindle sensitivity to stretch is maintained by

Answer 51

gamma motorneurons

Question 52

the work of alpha and gamma is called

Answer 52

co-activation

Question 53

What does co-activation allow

Answer 53

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

Question 54

What are the two kinds of intrafusal fibre

Answer 54

nuclear bag fibres | nuclear chain fibres

Question 55

Reflex contraction inhibited by

Answer 55

muscle spindles

Question 56

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

Answer 56

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