Topic 5: Nervous System 3 - Integration and Control - Spinal Cord Flashcards
What does the sensory (afferent) division do?
- inputs info to brain and spinal cord (control centres)
What does the brain and spinal cord do?
- integrates info and controls effectors through motor (efferent) division (output)
Which is responsible for reflexes: The brain or spinal cord?
- spinal cord
What are reflexes? (2)
- rapid automatic responses to stimuli
- usually protective
What do reflexes need? (2)
- stimulus always cause the same motor response
- involves 2 or more neurons
The reflex pathway or arc is a pathway of _____
impulses
Reflex pathway diagram
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How are reflexes categorized? (3)
- Effector
- Which side of the body the sensory and motor neurons are located
- Number of Synapses (and neurons) in arc
What are the effectors in a reflex for somatic reflex?
skeletal muscle
What are the effectors in a reflex for visceral (autonomic) reflex? (3)
- smooth, cardiac muscle
- glands
reflexes are categorized based on which side of the body the sensory and motor neurons are. What is an ipsilateral reflex?
- sensory and motor neuron on same side
reflexes are categorized based on which side of the body the sensory and motor neurons are. What is contralateral reflex?
- sensory and motor neuron on opposite sides
Reflexes are categorized based of number of synapses and neurons in the arc. What is a monosynaptic reflex?
one synapse between 1 sensory and 1 motor neuron
Reflexes are categorized based of number of synapses and neurons in the arc. What is a polysynaptic reflex?
- 2+ synapses between 3+ neurons
What are 4 examples of SOMATIC spinal reflexes? (3)
- stretch reflex
- Flexor (withdrawal) reflex
- Crossed extensor reflex
Give an example of a stretch reflex. Then, name the
a) stimulus
b) receptor
c) effector
4) type of reflex
- knee jerk reflex where extensor muscle contracts
a) stimulus is tapping patellar ligament, which stretches the quadricep femoris muscle
b) receptor = muscle spindle (in quad)
c) effetor = skeletal muscle (quad) which contracts
d) ipsilateral and monosynaptic
Give an example of a flexor (withdrawal) reflex. Then, name the
a) stimulus
b) receptor
c) effector
4) type of reflex
- in leg
a) stimulus is stepping on a nail
b) receptor = touch, pressure, pain
c) effector is hamstrings (flexors) which contracts
d) ipsilateral and polysynaptic
Give an example of a crossed extensor reflex. Then, name the
a) stimulus
b) receptor
c) effector
4) type of reflex
- ex in leg
a) stimulus is stepping on a nail
b) receptor = touch, pressure, pain
c) effector = quad fem in opposite leg (extensor) which contracts
d) contralateral and polysynaptic
What is the purpose of a crossed extensor reflex in the leg?
keeps you from falling down when withdrawal (flexor) reflex occurs
Somatic spinal reflexes also include reciprocal inhibition. What is that? (2)
-muscle (or group) contracts (AGONIST)
- at the same time, antagonist is prevented from contracting due to inhibitory interneurons firing
What is an example of reciprocal inhibition? (3)
- in stretch reflex
- quadriceps femoris (agonist) contracts
- hamstrings (antagonists) contraction inhibited
Give an example of an autonomic Spinal reflex, and name
a) stimulus
b) receptor
c) division of NS and location
d) effector
- Micturition reflex in urinary bladder
a) stimulus is stretch of bladder
b) receptor - stretch receptors in bladder wall
c) CNS in sacral segment of spinal cord (PSNS)
d) effector = detrusor muscle (wall of bladder) which contracts and internal urethral sphincter opens (both are smooth muscle)
