Sensory Receptors Flashcards
What are the 3 types of sensory receptors
Mechanoreceptors = mechanical stimuli Propriocetors = mechanorceptors in joint and muscle Nocireceptors = respond to painful stimuli
What is the definition of sensory modality
The stimulus type which activates a particular receptor. Example is vibration, pressure, pain
Define adequate stimulus
Form of energy to which a receptor normally responds
What is the adequate stimulus for mechanoreceptors
Membrane deformation which leads to activation of stretch sensitive ion channels
What is the point called which it depolarisation reaches will lead to AP firing in mechanoreceptor
First node of ranvier
Increasing stimulus intensity creates a larger receptor potential which leads to what
High frequency of AP
What nerve receptors don’t adapt
Nocireceptors
Name a receptor which is slowly adapting
Merkels discs
Name a receptor which is fast adapting
Pacinian and meissnes corpuscles
The capsule of pacinian corpuscle is full of connective tissue, what is the name of the layer called
Lamellae
How does pacinian corpuscles adapt so quickly
Fluid is rapidly redistributed within capsule lamellae minimising downward deformation stopping AP
What is the area where a somatic sensory neutron is activated
Respective area
Name the test which tests our ability to tell 2 points of pressure on the skin
Two point dscrimination test
What factors determines the two point discrimination tedt
Respective field size and neuronal convergence
The larger a receptive field and the more convergence will lead to sensitive skin
No you dumb bitch, less sensitive
What method is used to increase specificity of location
Lateral inhibition
Describe the track sensory info goes to
Sensory nerve, spinal chord, thalamus then somatosensory cortex
What do the proprioreceptors do
They are mechanorecetors which signal the body or limb position
Muscle spindles, Golgi tendon organs and joint r captors ar examples of what
Propioreceotors
Are most contractile skeletal muscle extra fusal muscle or intrafusal muscle fibres
Extrafusal, inteafusal is muscle fibres which have th rthe own sensory and motor information which is only. A few
Of the alpha and gamma axons, which go into extrafusla, and intrafusal
Extrafusal is alpha
Intrafusal is gamma
Does the centre of intrafusal fibres contain sarcomeres
No only the ends
Gamma motor neurone causes what to contact
Ends of the sarcomere to contract result in in stretching of the centre
In intrafusal fibres, what causes AP firing
Gamma neurones cause contraction of sarcomeres, the stretching of the centre and which results in opening of ion channels causing AP in 1a afferent
What is the Golgi tendon fibre afferent called
1b
Golgi tendon lie in paralell while muscle spindles lies in series
False of course
What will fire in isometric muscle contraction, 1b or 1a
Activation of GTO therefore 1b, as length doesn’t change 1a in muscle spindles is not fired
The gamma axon is responsible for keeping the muscle spindles active, true or false
True, shortening of the spindle to match that of the muscle.
What does information does the 1a send to the Brian
Sends reports of the muscle shortening
In stretch reflex, the efferent goes to the antagonist muscle causing relaxation. What is this called
Reciprocal inhibition
When reacting to pain receptor, what is the reflex which is responible for this
Flexor reflex
Pain causes the flexor reflex to be engaged. Therefore describe the activation and inhibition of the extensor and flexor muscle on stimulated and opposite leg
Extensor inhibited STIM
Flexor activated STIM
opposite for unhurt leg
What happenes when the GTO reflex is activated, what is the function
Load is dropped, to protect the muscle
The alpha neurones integrate 10000 of signals which are excitery and inhibitory. Net effect is measure,what is this called
Summated
If your carrying carrying a baby, how is the GTO overridden
Descending voluntary excitation of alpha motor neurone overrides the inhibition from the GTO
What is the neurologist test to determine if an anxouis patient is causing descending inhibition hyperpolsrising alpha neurone
Jendrassik maneovre
What is the clinical relevance of reflexes
Important to assess the integrity of the whole SC circuit
Can help with spinal level localisation of a problem
Describe facilitation
Enhances effectiveness of sensory input. When activation occurs near by leading to activation of other neurones, see book
