Spinal Cord Reflexes Flashcards
What are Reflexes?
Automatic Response to sensory stimuli
What are the characteristics of reflexes?
Homeostatic responses
Rapid Unconscious (involuntary)
Unlearned S
terotyped (same in every body)
What autonomic (visceral) reflexes
- effector is smooth muscle, cardiac muscle, or glands - generally not consciously perceived
What are somatic reflexes?
- Effector is skeletal muscle
- Consciously perceived
Pupillary light Reflex What type of reflex is this?
Autonomic reflex
Cough Reflex
What type of reflex is this?
Mixed reflex (both autonomic and somatic)
Withdrawal Reflex
What type of reflex is this?
Somatic Reflex
What are somatic reflex modified by?
By higher brain center
- fundamental circuit for movement (involuntary and voluntary)
- Provide the building blocks for complex, voluntary behaviors
- are coordinated and modulated by the cortex and brainstem
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Stretch reflex, withdrawal reflex, crossed extensor reflex, and plantar response are examples of what type of reflex?
Somatic reflex
Stretch Reflex (myotatic)
Also called, deep tendon reflex or monosynaptic reflex Knee Jerk Reflex
- Sensory receptor - muscle spindle
- Sensory neuron- cell body in DRG - Type 1a fiber
- Central integration: 1 synapse: 1a to Aa
- Efferent Neuron: A- motor neuron
- Effector organ: skeletal m.
These two reflexes are coupled
Withdrawal Reflex (Flexor) AND Crossed-Extensor Reflex
Plantar (Babincki) Reflex
changes with development
What are the components of the reflex are?
- Sensory Receptor
- Afferent (Sensory) Neuron
- Central Integrator (spinal cord and synapse)
- Efferent Neuron (motor neuron)
- Effector Organ
Sensory Receptor
structures that detect and respond to sensory stimuli
Afferent (sensory) neuron
conducts impulse from sensory receptor to CNS
Central Integrator
Monosynaptic (direct contact between afferent and efferent neuron; no interneurons) vs polysynaptic
Efferent neuron
transmitter of impulse from integrating center to effector
Somatic reflexes is always going to involve the motor neuron
Effector organ
muscle or gland which responds to the effector
Myotatic units are activated by ?
Activated by Spinal Reflexes Myototic units are a group Agonist and antagonist muscle from common spinal reflex response, function together
How do agonist muscles behave?
In parallel
How do Muscles around a joint behave?
In concert
What establishes a strong neural linkage between muscles acting around a joint so that muscle do not act independent of each other?
Divergent connection of spindle afferents
What is Reciprocal Inhibition?
Even though the main arc in monosynaptic, you will have a disynaptic unit that synapses with a inhibitory intermotornueron in spinal cord and then makes a synapse with the alpha motor neuron and goes to the antagonist muscle

