(Lesson 18) Chapter 13: Spinal reflexes Flashcards
KNOW FOR EXAM
What are spinal nerves controlled by?
ONLY the spinal cord
Which type of segments can be found w/ spinal reflexes?
Involves
1. Single segments
2. Multiple segments
Spinal reflexes are which type of response?
- Rapid
- Automatic nerve response
How are spinal nerves triggered?
By a specfiic stimuli
What are reflexes coordinated with?
With the spinal cord
What is responsible for coordinating the nerves w/ the spinal cord?
- Interconnected sensory neurons
- Motor neurons
- Interneurons
What are the different types of reflexes that can be produced?
- Simple reflexes
- Complex reflexes
How do nerves help preserve homeostasis?
By making rapid adjustments w/ the organs or organ sys.
Do nerve reaction alter depending on what stimulus them?
Each time a particular reflex is activated, it produces the SAME motor response
Explain what are neural reflexes.
- Rapid automatic response to specific stimuli
- Building block of neural function
1 neural reflex = 1 motor resp.
Why are reflex arcs important for the N.S.?
They are the nerve pathway involved in reflex action
What are the structures of the reflex arc?
Begins @ Receptor of sensory neuron
Ends @ effector of motor neuron
To which response does a reflex arc respond to?
Negative feedback
(pressure or pain)
What are the 5 steps in a neural reflex?
Step 1: Arrival of stimulus activation of receptor
Step 2: Activation of sensory neuron
Step 3: Info processing of postsynaptic cell
Step 4: Activation of motor neuron
Step 5: Response of peripheral effector.
What are the 4 classifications of reflexes?
- Development
- Type of response
- Complexity of motor circuit
- Site of info process
Explain how the development of reflexes works?
There are two types of reflexes
1. Innate (born with)
2. Acquired (taught/learned)
What’s the difference between innate and acquired reflexes?
Our innate reflexes are the ones we are born with, whereas our acquired reflexes are the ones we’re born with
What are motor responses?
They consist of
1. Somatic reflexes
2. visceral reflexes
Define somatic reflexes
Involuntary control of nervous system
1. Superficial reflexes of skin
2. Stretch of deep tendon
Define visceral reflexes
Autonomic reflexes
Control systems other than muscular system
What makes up the complexity of neural circuit?
- Monosynaptic reflex
- Polysynaptic reflexes
Monosynaptic reflexes
Sensory neuron synapses directly onto motor neuron.
Polysynaptic reflexes
At least one interneuron between sensory neuron & motor neuron.
What are the sites of information processing?
- Spinal reflexes
- Cranial reflexes
What are the intersegmental reflex arcs
- Most complex spinal reflex
- Many segment interactions
- Produce highly volume variable motor response
NOTE:
More synapases = slower reaction
Note:
Monosynaptic= most simple reflex
Monosynaptic reflex
- a stretch reflex
! Have atleast 1 delay between sensory input and motor input. - Completed in 20-40 msec
- Receptor is muscle spindle
What are the muscle spindles responsible for?
They’re in charge of monitoring the stretching of the muscle
What are the receptors in stretch reflex?
Bundles of small, specialized
intrafusal muscle fibers
Intrafusal muscle fibers
(Small)
Skeletal muscle fibers that serve as specialized sensory organs (proprioceptors)
Detects amount and rate of change in muscle.
Extrafusal muscle
(Large)
- Large skeletal muscle
- Maintain tone & contract muscle
- Contracts when stimulated @ greater lvls
The extrafusal muscle is the ___________ layer
spindle layer
What is the sensory region?
Central region w/ intrafusal fibers wound w/ dendrites
Detects the stretch of intrafusal muscle
How does the sensory neuron axon enter the CNS?
The sensory neuron axon enters via dorsal root.
Explain how do sensory neuron axons synapse?
They synapse onto motor neurons (Gamma)
in anterior gray horn of spinal cord
What form of reflexes do sensory neuroyaxons release?
Monosynaptic reflexes
What are gamma efferents?
- Axons of the gamma motor neurons
- Complex reflex arcs
- Important in voluntary muscle contraction
How do gamma efferents contribute to completing the reflex arc?
Synapses back intrafusal fibers fibers to contract
Explain why gamma efferents are important for voluntary muscle contraction.
Allow CNS to adjust sensitivity of muscle sprindles bc of gamma efferents w/o trigger reflexes.
When does the initiation of stretch reflexes occur?
Postural reflexes are important for?
How do stretched muscle receptors?
Stretch reflexes?
What are polysynaptic reflexes?
What does the tendon reflex monitor?
What type receptors are tendon reflexes?
Sensory receptors
The tendon reflex is responsible for protecting the muscles in which form?
Withdrawal reflexes are responsible for?
What is an example of withdrawal reflexes?
What determines how the withdrawal reflexes reacts?
Required for flexor reflex to work?
Reciprocal inhibition
Why is reciprocal inhibition necessary for flexor reflexes to function properly?
What will happen if inhibition does not occur
What are additional reflex arcs?
Where do Ipsilateral reflexes occur?
What is an example of an ipsilateral reflex arc?
Where do crossed extensor reflexes occur?
With what other reflexes do crossed extensors work w/?
Example of crossed extensor reflexes coordinating w/ flexor reflex.
What are the 5 characteristics of polysynaptic reflexes?
What are pools of interneurons important for polysynaptic reflexes
Why are flexes not always automatic?
Voluntary movements & reflex motor patterns?
How do automatic reflexes work?
What are the examples of automatic reflexes?
- Running
- Jumping
- Walking
What are the reinforcement of spinal reflexes?
What are other examples of reinforcement of spinal reflexes?
How do higher centers inhibit spinal reflexes?
Babinski reflexes in infants?
This would be + Babinski reflex
What is the difference of + babinski reflex in adults
May indicate CNS damage in adults if toes fans when toes are stimulated.
- babinski reflex in adults
Normal for adults
-when stimulated curling of toes occur.
