Chapter 15 Sensory Pathways & SNS

Lamellar corpuscles

sensitive to deep pressure and vibration.

Afferent division

somatic and visceral sensory pathways bring info.

Efferent division

somatic and visceral motor commands from motor cortex in brain.

General senses

Widely distributed over body and more externally than internally.

Free nerve endings

Sensitive to touch and pressure.

Tactile corpuscles

perceive sensations of fine touch, pressure, and low- frequency vibration.

Lateral pathway helps?

control distal limb muscles that perform precise movements.

Chemoreceptors

respond to water and lipid soluble substances that are dissolved in body fluids (example: blood O2 & CO2)

Perception

conscious awareness of a sensation (processing)

Spinothalamic Pathway

Carry sensations of crude touch, pressure, pain, and temperature.

Bulbous corpuscles

Sensitive to pressure and distortion of skin.

Tactile discs

Fine touch and pressure receptors.

Tactile receptors

touch, vibrations, and pressure.

Somatic nervous system

control contractions of skeletal muscles.

Crude touch

large receptive fields, less sensitive.

single dendrite

A(n) ________ lies within a series of concentric layers of collagen fibers.

Transduction

conversion arriving stimuli into action potential by sensory receptor.

Corticobulbar tracts

allow conscious movement of eyes, jaw, face, and some muscle in neck and pharynx.

Anterior corticospinal tracts

contains axons that cross over in anterior white commissure.

abdominopelvic cavities

Interorceptors detect stimuli for viscera in thoracic and ________.

Lateral corticospinal tracts

contains axons that decussate at pyramids.

Fine touch

narrow receptive fields, sensitive.

Tonic receptors

always active, slow- adapting receptors.

Medial pathway helps

________ control movements of trunk and proximal limb muscles.

Phantom Limb Syndrome

sensory neuron or interneuron activity without limb causing perceived pain.

Spinocerebellar Pathway

conveys info about positions of muscles, tendons, and joints from spinal cord to cerebellum and this info does not reach our awareness.

Sensory homunculus

functional map of primary somatosensory cortex.

Corticospinal tracts

visible along anterior surface of medulla oblongata as a pair of thick bands called pyramids.

Adaptation

reduction of receptor sensitivity due to constant stimuli.

Phasic receptors

normally inactive, fast- adapting receptors.

Sensory pathways

sensory information travels from receptors to CNS

Sensory receptors

detect incoming stimuli, can be specialized cells or cell processes, action potentials are sent along sensory pathways

Receptive field

size is inversely related

Transduction

conversion arriving stimuli into action potential by sensory receptor

Sensation

arriving info to cortex(input)

Perception

conscious awareness of a sensation(processing)

Afferent division

somatic and visceral sensory pathways bring info

Efferent division

somatic and visceral motor commands from motor cortex in brain

General senses

Widely distributed over body and more externally than internally

Labeled line

path of incoming stimuli to CNS

Adaptation

reduction of receptor sensitivity due to constant stimuli

Tonic receptors

always active, slow-adapting receptors

Phasic receptors

normally inactive, fast-adapting receptors

Phantom Limb Syndrome

sensory neuron or interneuron activity without limb causing perceived pain

Referred Pain

sensation shares spinal pathway leading to 1 sensory cortex in the brain

Fine touch

narrow receptive fields, sensitive

Crude touch

large receptive fields, less sensitive

Free nerve endings

Sensitive to touch and pressure

Root hair plexus nerve endings

monitor distortions and movements wherever hairs are located

Tactile discs

Fine touch and pressure receptors

Bulbous corpuscles

Sensitive to pressure and distortion of skin

Lamellar corpuscles

sensitive to deep pressure and vibration

Tactile corpuscles

perceive sensations of fine touch, pressure, and low-frequency vibration

Baroreceptors

detect pressure changes

Proprioceptors

monitor positions

Tactile receptors

touch, vibrations, and pressure

Spinothalamic Pathway

Carry sensations of crude touch, pressure, pain, and temperature

Sensory homunculus

functional map of primary somatosensory cortex

Spinocerebellar Pathway

conveys info about positions of muscles, tendons, and joints from spinal cord to cerebellum and this info does not reach our awareness

sensory info from mouth, palate, pharynx, larynx, trachea, esophagus carried by cranial nerves

V, VII, IX, and X

Somatic motor pathways

carries motor commands from motor cortex to brain stem or spinal cord and then to PNS

Upper motor neuron

neuron cell body lies in a CNS processing center

Lower motor neuron

neuron cell body lies in a nucleus of brainstem or spinal cords, axons extends outside CNS

Somatic nervous system

control contractions of skeletal muscles

Corticospinal pathway

from the cortex down to spinal cord