Sensory And Motor Pathways Flashcards
Special senses
Senses with receptors that are stimulate specific sensory organs.
This includes vision (eye), hearing(ear), smell (nose) and taste (tongue)
Processes of sensation
- Stimulation: when something touches the receptor(a change in the environment)
- Transduction: converting one energy to the other
- Conduction: the action potential moves along the neuron(could be myelinated or unmyelinated)
- Translation: translates the impulse into a sensation
Unencapsulated nerve endings
Bare dent rites of first-order sensory neurons
Encapsulated nerve endings
Dentrites of first-order sensory neurons enclosed in a connective tissue capsule
Sensory receptor cells
Highly specialized separate cells that synapse with a first-order sensory neuron
General senses
Senses with receptors spread throughout the body.
Provide information about touch, pressure, itch, vibration, temperature, proprioception and pain
Exteroreceptor
Located at or near the body surface
Interoreceptor
Located in blood vessels, organs and the nervous system
Proprioreceptor
Tells us where we are
Located in muscles
Mechanoreceptor
Detects mechanical stimuli
Thermoreceptor
Detects changes in temperature
Nociceptor
Responds to painful stimuli
Photoreceptor
Detects light
Chemoreceptor
Detects chemicals in the mouth, nose, and body fluids
Osmoreceptor
Detects change in osmotic pressure
Somatic sensations
Come from stimulation of sensory receptor embedded in the skin
Tactile sensations
Touch, pressure, vibration, itch, tickle
Thermal sensations
Cold and warm
Proprioceptive sensations
Kinesthesia and weight discrimination
Somatic pain reception
Location: nearly every body tissue and respond to many stimuli: pressure, temperature
Pain receptors slowly adapt to the stimuli
Somatic sensory pathways
Conduct sensory information from somatic receptors to the primary somatosensory area of the cerebral cortex
Decussation
The pathways cross from one side of the CNS to the other at some point along their journey
Relay
The pathways consist of a chain of 3 neurons.
First order neuron
Conduct information from somatic sensory receptors to second order neurons.
Located in dorsal root ganglia
Second order neurons
Type of inter neuron
Conduct sensory information from first order neurons to third order neurons.
Located in brain stem or spinal cord
Third order neurons
Type of interneuron
Conduct sensory information from second order neuron to neurons making up primary somatosensory area of the cerebral cortex
Located in the thalamus
Symmetry
All pathways are paired symmetrically with a member of the pair present on each side of the spinal cord and brain
Features of somatic sensory pathway
- Decussation
- Relay
- Symmetry
- Somatotopy
The Somatic Sensory Pathways
Medial lemniscus pathway
Spinothalamic pathway
Trigeminothalamic pathway
Somatic motor pathway
Conduct motor information from cerebral cortex and brain stem to skeletal muscle
Direct motor pathways
Convey muscles from the cerebral cortex that result in precise voluntary muscle movements
The Direct Motor Pathways
Lateral corticospinal tract
Anterior corticospinal tract
Corticobulbar tract
Promotes voluntary movements of the head and neck to coordinate precise voluntary movements
Includes: eyes, tongue, neck
Has 2 neurons
