Nervous Control, The Motor System (physiology) Flashcards
What are the three types of movements we make?
Reflex- e.g knee jerk
Voluntary- e.g playing piano
Rhythmic- e.g walking
Where does the highest control of movements reside?
In areas of association cortex and basal ganglia.
What is a reflex?
Rapid, automatic and predictable response to a specific stimuli.
What do we call the nerve pathway involved in a reflex action?
Reflex arc
What are the five components of the reflex arc?
-Sensory receptors
-Sensory neuron/afferent pathway
-Information processing in the CNS/ Integration centre.
-Motor neuron/ efferent pathway
-Effector
Briefly explain the events in a reflex arc(5)
- Arrival of stimulus and activation of receptor.
- Activation of sensory neuron.
- Information processing in CNS.
- Activation of motor neuron.
- Response by a peripheral effector.
Four types of classification by receptors
-By early development.
-By type of motor response.
-By complexity of neural circuit.
-By site of information processing.
What is the difference between the two types of reflexes, classified by development?
Innate reflexes
- They are formed before birth.
-Genetically programmed.
- E.g withdrawal, chewing.
Acquired reflexes
-They are rapid, automatic reflexes that are learned.
-Repetition enhances them.
-E.g braking a car during emergency.
What is the difference between the two types of reflexes, classified by the type of motor response?
Somatic reflexes
- Control skeletal muscle contraction.
Visceral reflexes
- Control contraction of other effectors.
-e.g. Smooth muscles, cardiac muscles, glands.
What is the difference between the two types of reflexes, according to complexity of neural circuit?
Monosynaptic reflex
-The sensory neuron synapses directly with the motor neuron.
-Rapid response
Polysynaptic reflex
-There is an interneuron btwn the sensory and motor neurons.
-Slow response
What is the difference between the two types of reflexes, according to the site of information processing?
Spinal reflexes
-Processing occurs in the spinal cord.
Cranial reflexes
-Processing occurs in the brain.
What are muscle Proprioceptors?
List and distinguish btwn the two types of them.
Muscle proprioceptors are receptors that monitor stretch in locomotory organs.
1. Muscle spindle- found in the muscles, they sense stretch and the speed of stretch.
2. Golgi tendon organ- found near the tendon, sense muscle tension/force.
Three elements of the muscle spindle
Intrafusal muscle fibres
Afferent fibres
Efferent fibres
Briefly explain the withdrawal reflex.
For an example let’s say you step onto a nail.
The stimulus is sensed by the nociceptors and send the signal to the sensory neuron.
Sensory neuron sends the signal to an interneuron in the spinal cord.
Interneuron sends the signal to the motor neuron.
Motor neuron sends the signal to the effector organ( leg) to contract and withdraw the leg.
Explain the crossed extensor reflex
Let’s say the leg that is stimulated by pain is the right leg.
Note that the effector in this leg will be the flexus contracting to remove the leg from the stimulus and the extensors are inhibited.
-The weight will move to the left leg.
-Hence, in the left leg the flexus will be inhibited and the extensors will contract.