Sensory Receptors 2 Flashcards
What is a proprioreceptor?
A proprioreceptor is a mechanoreceptor that signals the bodies or limbs position
What are examples of proprioreceptors?
Examples of proprioreceptors are:
Muscle spindle
Golgi tendon organs
Joint receptors
What does the muscle spindle do?
The muscle spindle monitors the muscle length and rate of change of muscle length
Controls reflexes and voluntary movement
What does the golgi tendon organ do?
The golgi tendon organ monitors the tension on a tendon
What does a joint receptor do?
A joint receptor monitors the joint angle, rate of angular movement and the tension on the joint
What are the three things that proprioreceptors do?
Allow the brain to control voluntary movement by sending sensory information
Muscle spindle and golgi tendon organs give sensory information that drives spinal cord reflex
Percieve limb and body position and movement in space (kinaesthesia)
What is the muscle spindle composed of?
The muscle spindle is composed of intrafusal and intrafusal muscle fibres
What are the intrafusal muscle fibres contained in?
Intrafusal muscle fibres are contained in a capsule and have their own sensory and motor innervations
Lie parralel to muscle fibre
How do intrafusal muscles lie in relation to the muscle fibres?
Lies parralel
What does the alpha motor neuron do?
The alpha motor neuron goes to the extrafusal muscle fibre and makes it contract
What does the gamma motor neuron do?
The gamma motor neuron goes to the intrafusal muscle fibre at each end
What are the two types of intrafusal fibres?
The two types of intrafusal fibres are:
Nuclear bag fibre
Nuclear chain fibre
What are nuclear bag fibres?
Nuclear bag fibres are bag shaped with nuclei collected together
What are nuclear chain fibres?
Nuclear chain fibres are nuclei lined up in a chain
Are muscle fibres multi or mono nucleic?
Muscle fibres are multinucleic
What does a diagram showing the contractile and non contractile end of a muscle fibre look like?
What are the two ends of a intrafusal muscle fibre innervated by?
Gamma fibres
What part of the intrafusal muscle fibre contracts?
The ends, not the middle
What are annulospiral endings?
Primary endings from type I alpha afferent nerves wrap around centre of the intrafusal fibre
What are flower spray endings?
Secondary endings from type II afferent
What happens when the gamma fibre fires?
Ends contract and shorten
Middle stretches
What stimulates the spindle stretch receptors?
The muscle stretching
What happens when a stretch stimulates the spindle stretch receptors?
- Stretch sensitive ion channels open
- Causes generator potential
- Causes action potential
What does the resting action potential depend on during a stretch?
The length Lo
What does the action potential frequency depend on during a stretch?
The velocity of the stretch from L0 to L1
What happens to the action potential frequency after the stretch?
After a stretch the action potential frequency is at a new steady state (L1 > L0)
What is joint movement organised by?
Joint movement is organised by groups of muscles working opposite to each other
What is a relationship around a joint between the agonist and the antagonist?
When the agonist contracts the antagonist relaxes
What does contracting a muscle mean?
Shortening the muscle
What does the golgi tendon organ do (GTO)?
The golgi tendon organ monitors muscle tension
What is the relationship between the golgi tendon organ and the tendon?
Nerves endings of the golgi tendon organ mingle with tendon bundle at the end of the muscle, so they monitor the stretch of the tendon
How do passive stretches affact the tendon?
Passive stretches do not effect the tendon much unlike muscle spindle because they are inelastic
How do muscles develop tension?
By contracting to stretch the tendon
What happens to the tension in a tendon when a muscle fibre contracts?
It increases the tension
How does the muscle spindle and the golgi tendon organ lie in relation to the extrafusal muscle fibre?
Muscle spindle lies parralel and the golgi tendon organ lies in series
What is the function of the gamma motor neuron?
Contract the poles of the muscle spindle so it matches the muscle
Where do the alpha and gamma neurons connect to?
Alpha goes to the muscle
Gamma goes to the muscle spindle
What happens to the gamma motor neuron when the alpha is activated?
Alpha is activated to cause contraction
Gamma is activated in parralel to maintain spindle selectivity (tension matches new muscle length)
What is an example of proprioreceptors acting autonomically?
Controlling movement such as the spinal cord reflex
