Glossary
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- Adaptation
- the decrease in the activity of first order neurons in response to a constant stimulus
- Ascending pathway
- fiber structure that relays sensory information from the periphery through the spinal cord and brain stem to other structures of the brain
- Association area
- region of cortex connected to a primary sensory cortical area that further processes the information to generate more complex sensory perceptions
- Chemoreceptor
- sensory receptor cell that is sensitive to chemical stimuli, such as in taste, smell, or pain
- Contralateral
- word meaning "on the opposite side," as in axons that cross the midline in a fiber tract
- Corticobulbar tract
- connection between the cortex and the brain stem responsible for generating movement
- Corticospinal tract
- connection between the cortex and the spinal cord responsible for generating movement
- Crossed flexor
- extensor reflex occurs in regards to a painful or destructive stimulus that occurs on a weight bearing body part; in order to retract from the painful stimulus in a flexing motion the other limb must be extended to bear the full body weight
- Decussate
- to cross the midline, as in fibers that project from one side of the body to the other
- Diencephalon
- a portion of the brain containing the thalamus and hypothalamus
- Dorsal column system
- ascending tract of the spinal cord associated with fine touch and proprioceptive sensations
- encapsulated ending
- configuration of a sensory receptor neuron with dendrites surrounded by specialized structures to aid in transduction of a particular type of sensation, such as the lamellated corpuscles in the deep dermis and subcutaneous tissue
- Exteroceptor
- sensory receptor that is positioned to interpret stimuli from the external environment, such as photoreceptors in the eye or somatosensory receptors in the skin
- First order neuron
- neuron that extends from the sensory receptor to the posterior grey horn of the spinal cord; is named as such because it is the first neuron to carry that particular sensory information
- Free nerve ending
- configuration of a sensory receptor neuron with dendrites in the connective tissue of the organ, such as in the dermis of the skin, that are most often sensitive to chemical, thermal, and mechanical stimuli
- General sense
- any sensory system that is distributed throughout the body and incorporated into organs of multiple other systems, such as the walls of the digestive organs or the skin
- Generator potential
- a graded potential produced in a receptor that is part of the sensory neuron in response to a stimulus
- Hypothalamus
- a portion of the diencephalon that communicates with the limbic system and has both somatic and autonomic functions
- Interoceptor
- sensory receptor that is positioned to interpret stimuli from internal organs, such as stretch receptors in the wall of blood vessels
- Ipsilateral
- word meaning on the same side, as in axons that do not cross the midline in a fiber tract
- Kehr sign
- the presentation of pain in the left shoulder, chest, and neck regions following rupture of the spleen
- Lamellated corpuscle
- also known as Pacinian corpuscles, are receptors in the skin that respond to deep pressure or vibration
- Lower motor neuron
- also known as the terminal neuron, extend from the ventral grey horn of the spinal cord to the skeletal muscle effector and stimulate the muscle directly
- Mechanoreceptor
- receptor cell that transduces mechanical stimuli into an electrochemical signal
- Medial lemniscus
- fiber tract of the dorsal column system that extends from the nuclei gracilis and cuneatus to the thalamus, and decussates
- Merkel's disc (cell)
- a specialized receptor cell that detects mechanical stimuli in the epidermis of the skin
- Motor homunculus
- a topographical representation of a body within the primary motor cortex that demonstrates correspondence between neuronal processing and motor control
- Motor unit
- one motor neuron and all of the muscle cells/fibers that the neuron innervates, can be large or small depending on the amount of control needed over the resulting movement
- Multimodal integration area
- region of the cerebral cortex in which information from more than one sensory modality is processed to arrive at higher level cortical functions such as memory, learning, or cognition
- Muscle spindle
- stretch receptors in skeletal muscles that are stimulated by muscle stretch and act to prevent muscle tearing and over-contraction
- Nociceptor
- receptor cell that senses pain stimuli
- Osmoreceptor
- receptor cell that senses differences in the concentrations of bodily fluids on the basis of osmotic pressure
- Premotor cortex
- cortical area anterior to the primary motor cortex that is responsible for planning movements
- Primary motor cortex
- region of the cerebral cortex that aids in planning and initiating skeletal muscle movements
- Primary sensory cortex
- region of the cerebral cortex that initially receives sensory input from an ascending pathway from the thalamus and begins the processing that will result in conscious perception of that modality
- Proprioceptor
- receptor cell that senses changes in the position and kinesthetic aspects of the body
- Receptor potential
- a graded potential produced in a standalone receptor cell in response to a stimulus
- Referred pain
- irregular pattern of projection of conscious perception of visceral sensations
- Reflex
- response to a stimulus that occurs without conscious thought, the integrating center is the spinal cord instead of the cerebral cortex
- Ruffini corpuscles
- also known as bulbous corpuscles, are receptors in the skin activated by stretch
- Second order neuron
- neuron that extends from the posterior grey horn to the thalamus decussating at the medulla or spinal cord; is named as such because it is the second neuron to carry that particular sensory information
- Sensation
- a perception or feeling that results from a stimulus
- Sensory homunculus
- topographic representation of the body within the somatosensory cortex demonstrating the correspondence between neurons processing stimuli and sensitivity
- Sensory modality
- a particular system for interpreting and perceiving environmental stimuli by the nervous system
- Sensory receptors
- cells or structures that detect sensations
- Somatosensation
- general sense associated with modalities lumped together as touch
- Special sense
- any sensory system associated with a specific organ structure, namely smell, taste, sight, hearing, and balance
- Spinothalamic tract
- ascending tract of the spinal cord associated with pain and temperature sensations
- Stretch reflex
- response to activation of the muscle spindle stretch receptor that causes contraction of the muscle to maintain a constant length
- Supplemental motor area
- cortical area anterior to the primary motor cortex that is responsible for planning movements
- Tactile corpuscles
- also known as Meissner corpuscles, are encapsulated receptors in the skin that respond to light touch
- Tendon organ
- receptors located in tendons that respond to stretch
- Thalamus
- a portion of the diencephalon that serves as a relay for communication between the cerebrum and rest of the nervous system
- Thermoreceptor
- sensory receptor specialized for temperature stimuli
- Third order neuron
- a neuron that extends from the thalamus to the primary sensory cortex in the parietal lobe; is named as such because it is the third neuron to carry that particular sensory information
- Upper motor neuron
- neuron that extends from the primary motor cortex of the cerebrum down to the ventral grey horn at the appropriate level of the spinal cord
- Withdrawl reflex
- retracting the affected pat of the body in response to a painful or destructive stimulus
Grant and Other Information
Except where otherwise noted, this work by The Community College Consortium for Bioscience Credentials is licensed under a Creative Commons Attribution 4.0 International License.
Text from BioBook licensed under CC BY NC SA and Boundless Biology Open Textbook licensed under CC BY SA.
Other text from OpenStaxCollege licensed under CC BY 3.0. Modified by Alice Rudolph, M.A., Michael Ayers, M.S. and Andrea Doub, M.S. for c3bc.
Instructional Design by Courtney A. Harrington, Ph.D., Helen Dollyhite, M.A. and Caroline Smith, M.A. for c3bc.
Media by Brittany Clark, Jose DeCastro, Jordan Campbell and Antonio Davis for c3bc.
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