KIN 103 (Chp: 13) Flashcards
What is a reflex?
A reflex is an involuntary response to the activation of a sensory receptor.
Monosynaptic reflexes
Monosynaptic reflexes- a single synapse between afferent and efferent neurons.
Polysynaptic reflexes
Polysynaptic reflexes- two or more synapses in the CNS
Proprioceptors
are located in skeletal muscles, joints, ligaments and the skin (muscle spindles, Golgi tendon organs, joint receptors, cutaneous receptors)
“proprius”- latin for “ones own”
Alpha motor neurons are always what?
Somatic motor neurons carry output signal (Alpha motor neurons)- always excitatory
Muscle spindles (What do they do?)
Muscle spindles provide information about static muscle length (position) and the rate of change of muscle length (velocity, acceleration).
Extrafusal muscle layer (What is it made of)
- Extrafusal muscle fibers
- Alpha motor neurons (invertebrates exfsal)
Intrafusal muscle layer (what is it made of)
- Intrafusal muscle fibers
- Gamma motor neurons (control from CNS)
(It is also found in muscle spindles)
Muscle spindles (Tonic firing)
- extrafusal muscle fibers are at rest
- sensory neuron is tonically active
- spinal cord integrates function
- alpha motor neurons to extrafusal fibers receive tonic input from muscle spindles
- extrafusal fibers maintain a certain level of tension even at rest
Muscle spindle reflex (What is it?)
The addition of a load stretches the muscle and the spindles creating a contraction
Muscle spindle reflex (What kind of loop is it?
The stretch reflex is a negative feedback loop that helps overcome unexpected disturbances and bring the limb back into position.
The muscle spindle reflex (when the muscle contracts what happens to the afferent signal?)
- the firing rate of the afferent neuron will decrease therefore causing negative feedback to occur
Alpha-gamma co-activation (What is it?)
Alpha-gamma co-activation maintains the sensitivity of the spindle when the muscle shortens voluntarily and the spindle might otherwise fall slack and become unresponsive to externally applied stretches.
Microneurography (What is it?
Using microneurography you can record action potentials as they travel along single human axons.
Patellar tendon reflex (What is it?)
- a monosynaptic stretch reflex
- accompanied by reciprocal inhibition of the antagonistic muscle.
Golgi tendon organs (What do they do?)
- Are located in the musculotendinous junction
- Golgi tendon organs discharge during contractions and provide information about contraction force
- Information from Golgi tendon organs is integrated in the CNS to help control movement
Cutaneous mechanoreceptors (What are they?)
Cutaneous mechanoreceptors provide information about tactile stimuli and limb movement.
Flexion and crossed extensor reflexes (What are they?)
essentially that when someone steps on something there will be a reflex that reaches the spinal cord only to activate an inverse response that pulls the individual away from the painful stimulus
Kinesthesia (What is it?)
Kinesthesia: the ability to consciously perceive the position and movement of the body segments without the aid of vision.
- Thought that muscle spindles are the cause of this
Muscle spindles and vibration
- Muscle spindles are highly sensitive to vibration
Illusions of movement- vibrate tendon on one side, subject matches any perceived movement with opposite limb
Reflex (characteristics)
stimulus: external sensory receptors
complexity: least complex