Sensory Pathways Flashcards
Sensory receptors monitor what?
Monitor internal and external environment
Visceral sensory
Goes to brain stem and diencephalon
Somatic sensory
Goes to post central gyrus or appropriate cerebral hemisphere
Post central gyrus
Receives general senses
Temp, pain, touch, pressure, vibration, and body position
Sensation
Is when action potential arrives
The arrival of information
Perception
Is conscious awareness
Receptive fields
Monitored by receptor cell
Larger field- poorer ability to localize stimuli
Smaller field- more precise localization
Two types of receptors
Tonic receptors
Phasic receptors
Tonic receptors
Always active, show little peripheral adaptation, and are slow adapting
Ex. Pain
Phasic receptors
Not active, fast adapting
Ex. Smell
Adaptation
Receptor becomes numb to stimuli
Sensory receptor classification
Exteroceptors
Proprioceptors
Interoceptors
General sensory receptors
Nociceptors-pain
Thermoreceptors- temp
Mechanoreceptors- physical distortion
Chemoreceptors- chemical concentration
Nociceptors
Have free nerve endings and large receptive fields
Sensitive to temp, chemicals, and mechanical damage.
Type A fibers
Carry painful sensation Myelinated, fast pain, and conscious
Type C fibers
Carry painful sensations, slow pain, you are aware but only have general idea of location
Thermoreptors
Location
Free nerve endings
Located in dermis, skeletal muscle, liver, and hypothalamus
Mechanoreceptors
Sensitive to distortion of plasma membrane
3 types of mechanoreceptors
Tactile- sensation for touch, pressure, vibration
Barorecptors- detect pressure in Blood vessels
Proprioceptors- monitor position of joints, tension in tendons and ligaments, muscle contraction.
First order neuron
Delivers sensation to CNS
Located in dorsal root ganglion
Second order neuron
Interneuron located in brain stem or spinal cord
Third order neuron
Located in thalamus
Only synapses if sensation reaches our awareness
Somatic sensory pathways
Spinothalamic pathway
Posterior column pathway
Spinocerebellar pathway
Spinothalamic pathway
Provides conscious sensation poorly localized (crude) touch pressure pain and temp
Ascending
Posterior column pathway
Carriers sensations of highly localized (fine) touch, pressure, vibration, and proprioception
Spinocerebellar pathway
Sends info to cerebellum
Proprioceptive- positions of skeletal muscles, tendons, and joints
2 spinal tracts of
Posterior Column pathway
Fasciculus gracilis— inferior part of body
Fasciculus cuneatus—superior part of the body
Nerves that carry visceral sensory info
Cranial nerves 5,7,9,10
Delivered to solitary nucleus
Somatic motor pathways always involve 2 motor neurons
Upper motor neuron—pre central gyrus
Lower motor neuron—anterior horn opposite side in brain stem or spinal cord
Chemoreceptors
Located in carotid bodies and aortic bodies
Monitor ph of CO2, hydrogen ions, and oxygen
Corticospinal pathway
Begins at pyramidal cells in pre central gyrus and descends down spinal cord
Conscious
Corticobular
Synapse on motor neuron in cranial nerves 3,4,5,6,7,9,11,12
Move eye, jaw, face, neck, pharynx
Cross at brain stem and end on opposite side
3 types of medial pathway
Vestibulospinal
Tectospinal
Reticulospinal
Lateral pathway
Control muscle tone and precise movement in distal limbs
Midbrain cross then descend to cervical spinal cord
Ex rubrospinal tract
