Reflexes Flashcards
What are the 2 classifications of reflexes?
Somatic (muscle) or autonomic (saliva).
What is the orderly sequence of events which reflexes are involved with?
Reflex Arc
What are the two types of reflexes (synaptic)?
Monosynaptic or polysynaptic.
What is a reflex?
A reflex is an involuntary stereotyped coordinated response to a stimulus.
What is the result when a muscle is stretched?
Reflex contraction, muscle ‘fights back’
What do these correlate to?
(a) Sensory receptor
(b) Afferent nerve fibre
(c) Synapse
(a) Muscle spindle
(b) IA afferents
(c) Spinal cord
What do these correlate to?
(d) Motor fibers
(e) Effector organ contracts
(d) alpha motor neuron
(e) Skeletal muscle
What is a reflex an example of?
Negative feedback
What does a mechanoreceptor respond to ?
A mechanoreceptor responds to stretch, and therefore responds to length changes in the muscle.
What are mechanoreceptors composed of?
Of Intrafusal and muscle fibers which lie parallel to EXTRAFUSAL FIBERS.
What are the two components at the centre and poles of the intrafusal fibers?
They have non-contractile centres and some contractile tissue at either end (poles.
What are the 2 types of intrafusal fibers?
Nuclear Bag (jumbled) Nuclear Chain (tidy, rolls)
What is spinal innervation - motor innervation? (DEFINITION)
This is when gamma (y) motor neurons innervate intrafusal fibers of the muscle spindle.
What nerve endings does sensory innervation involve?
Primary, annulospiral nerve endings, which are Type 1a afferents - detect amount of muscle stretch
What are two characteristics about primary, annulospiral nerve endings which are type 1a afferents. Speed and size?
They are rapidly conducting myelinating neurons.
They are larger than Type II
What are three characteristics (speed, covering, response) of secondary flower spray endings , what type are they?
These type two afferent; secondary flower spray endings are static in response, myelinated and are SLOWER conducting neurons in comparison to type 1a.
What do primary annulospiral nerve endings mainly innervate(intrafusal fibers)?
BOTH (I) nuclear bag and chain fibers - type II mainly CHAIN FIBERS
What is an example of how the postsynaptic reflex is activated?
Activated in response to a painful stimulus - therefore; a protective reflex.
Very rapid response.
What reflex supports the body weight against gravity as you move away from the stimulus that triggered the polysynaptic reflex?
The crossed extensor reflex.
Where does the golgi tendon organ reflex arc lie?
Mechanoreceptor
It lies at the junction between tendon and muscle.
It is very sensitive to muscle tension.
Tendon detects tension
Where do GTO lie in correlation with the muscle?
In series.
What innervates the GTO collagen of tendon?
The nerve terminals
How is sensory information sent in the GTO reflex arc? Describe the size of these fibers?
Sensory information is sent via the 1b afferents.
These have a large diameter and are rapidly conducting fibers
During muscle contraction for example biceps muscle when holding an object what does the GTO detect?Where is this information sent to and what happens?
It detects tension in contracting muscle.
Sensory information is carried into the spinal cord.
Here is where it then synapses with an interneuron.
