Receptors Flashcards
What is a proprioreceptor?
Mechanoreceptors that signal body or limb position
What do muscle spindles monitor?
Muscle length and the rate of change of muscle length
What do golgi tendon organs monitor?
Tension on tendons
What do joint receptors do?
Monitor joint angle, rate of angular movement
What do the 3 proprioreceptors do?
Sed sensory info to the brain to control
Muscle spindles and golgi provide sensory info for spinal cord reflexes
Provide sensory info to percieve limb position and movement in space
Where do muscle spindles lie parallel with?
Muscle fibres
What do golgi tendon organs do?
Monitor muscle tension
Are tendon elastic?
No fairly inelastic
What are the nerve endings in cutaneous sensory receptors protected by?
A capsule
What fibres is skeletal muscle made up of?
Intrafusal
Extrafusal
What are extrafusal muscle fibres?
Regular muscle fibres
What forms muscle spindles?
Intrafusal fibres with their specialised motor and sensory innervation
What are the end of golgi tendon organs intermingled with?
Tendons
Since tendons are inelastic what must the muscle develop?
Tension to stretch them
What are sensory receptors?
Nerve endings with specialised non-neural structures
What do the sensory receptors convert what to?
Different forms of energy to AP
What is an aqequate stimulus?
Type of energy a receptor will respond to
What do nocieceptors respond to?
Pain
What do thermreceptors respond to?
Warm and cold
What do chemoreceptors detect?
Chemical changes
What do photoreceptors detect?
Particular wavelengths of light
What are mechanoreceptors stimulated by?
Mechanical stimuli
What do proprioreceptors signal info about?
Body or limb position
What do all sensory receptors involve the opening and closing of?
Ion channels
What does an adequate stimuli cause?
Receptor potential or generator potential
The stronger the stimulus the more what?
AP fired
The larger the stimulus the larger the receptor potential the higher the what?
The higher the frequency of AP in a sensory nerve
What is adptation?
When the receptor adapts to a maintained stimulus (i.e putting on clothes) and only changes signal at the onset of the stimulation
What receptor do not show adaptability?
Nocireceptors
Why do nocireceptor never adapt?
Because it is important to always feel painful stimuli
What is the best understood mechnoreceptor?
The pacinian corpuscle
What does the pacinian corpuscle show?
Rapid adaptation
What can neurons with neighbouring neurons exhibit?
Neuronal convergence
What does convergence allow?
Simultaneous sub-threshold to form a large secondary receptive field and initiate an AP
What does convergence indicated?
A relatively insensitive area
If there is low acuity what is there alot of going on?
Convergence
If there is high acuity is there alot of convergence?
No
What is acuity?
The ability to located stimulus on the skin and differentiate it from another closeby
Where does all our sensory info go?
To our brain
What does lateral inhibition do?
Inhibits the surrounding neurons to produce high acuity
What are the 2 types of intrafusal fibre?
Nuclear bag fibres
Nuclear chain fibres
What are the sarcomeres at the end of muscle spindles controlled by?
Gamma motoneurones
What innervate intrafusal fibres?
y motoneurones
What innervate extrafusal muscle fibres?
Alpha motoneurones
What stimulates the spindle stretch receptors?
Muscle stretch
When the agonist muscle contracts what happens to the muscle spindles?
They contract also
When the agonist muscle and spindle contracts what happens to the antagonist muscle?
It lengthens and those muscle spindles increase their outflow of AP
What is the role of the gamma MN?
To maintain muscle spindle sensitivity
What does the muscle spindle cause?
Contraction of the muscle
What does the Golgi tendon organ cause?
The relaxation of the muscle
When both the a and y motor neurones fire What happens?
Both the muscle and muscle spindle shorten
