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adaptation
________ is desensitization, the process by which receptors show a progressive decrease in sensitivity.
receptive fields
The ________ are the regions in which a stimulus will alter a sensory neuron's fighting rate.
Stimulus intensity
________ can be encoded by the number and threshold of activated cells.
Meissner
_______ and Pacinian corpuscles are phasic receptors; they respond immediately but stop responding unless there is a change in the stimulus.
S1 cells
________ are arranged as a map of the body; a sensory homunculus.
physical event
A(n) ________ that triggers a sensory response.
association areas
they hold polymodal neurons that hold different neurons and allow them to interact.
Mechanoreceptors
they detect mechanical sensations: differences in pressure.
receptor cells
Molecules that can bind to hormones, drugs, and antigens.
receptor cells
Can sense some stimuli, but not others. Specialized.
stimulus
A physical event that triggers a sensory response.
labeled lines
Tiny receptors all over the body, how the body senses touch
receptor cells
They sort of act as filters, ignoring background noise and converting the stimuli into electrical signals.
labeled lines
We have very distinct ___________, and each sensory receptor has its own pathway up to the brain
Pacinian corpuscles
Skin receptors that respond to vibration and pressure. Located deep in the skin, in the hypodermis layer. Since it's deeper, it needs stronger stimuli like a push or poke
Maisner's corpuscles
Perceives the form of objects that we touch. More sensitive, on the top layer of skin. Responsible for light touch, aware when you brush lightly against something or when you put on a light t-shirt. They need constantly changing stimuli to make you aware of sensations.
receptor cells
Converts energy into a change in the electrical potential across its membrane.
Merkel’s discs
Specialized skin cells, respond to indentations of the skin like poking. Adapts slowly to pressure, record sustained pressure, aka stimuli that are present for longer. More sensitive to touch, at the base of the epidermis but still near the top layer of skin.
Ruffini’s corpuscles
Perceive stretching of the skin when we move. Near the bottom layer of the skin.
Free nerve endings
2 different types, thermoreceptors and nociceptors.
free nerve endings
Thermoreceptors have 2 different types of _______ for perceiving hot and cold.
95, 77, 41
Cold receptors kick in when the temp is under ______ degrees, most stimulated at ______, and turn off at ______ degrees.
86, 113
Hot receptors perceive above _____ degrees, most stimulated at _____ degrees but beyond that pain receptors will take over in order for damage to be avoided to skin.
stimulus
The location of a _____ is determined based on a map-like representation of the position of the activated receptors.
specificity
When poking close spots together without looking, it feels like one poke; when they go farther apart, we notice them as two spots. In order to get ______ in a receptive field, anything outside of the field is inhibited and doesn't fire so that you know exactly where a stimulus was touching you.
sensory adaptation
Stimulus intensity can be encoded by the number and threshold of activated cells. If there are a lot, you’re aware of them. With higher intensities, other sensory neurons are recruited.
adaptation
We can't perceive everything that we are sensing all the time. _____ is desensitization, the process by which receptors show a progressive decrease in sensitivity.
phasic receptors
The type of receptors that adapt very quickly to the stimulus. Decreases the frequency of action potentials firing. The stimuli are still there, but we stop firing because it is not important.
phasic receptors
Lets us know when there are changes in sensory stimuli, gives us the ability to stop paying attention to constant stimuli like temperature or smells.
tonic receptors
Keeps constant the frequency of action potentials firing.
nociceptors
What type of nerve endings are used for pain detection?
accurate
Sensory systems often shift away from _____ portrayals of reality in order to function; otherwise, you’re overloaded. Noting changes can be more important than exactness.
Central modulation of sensory modulation
When your brain is actively focusing on certain inputs and ignoring others. The cortex and the thalamus are involved in this.
Somatosensory system
We have distinct pathways from sensory receptors that lead from the periphery to the central nervous system.
Dorsal column system
Responsible for delivering touch information. Receptors send axons via the dorsal spinal cord to synapse onto neurons in the brainstem. Once in the brainstem, they cross the midline and go to the thalamus.
primary sensory cortex
One exists for each modality
nonprimary sensory cortex
Receives direct projections from the primary sensory cortex for that modality
Primary somatosensory cortex (S1)
In the postcentral gyrus. On each hemisphere of the brain that processes touch information from the opposite side of the body.
Primary somatosensory cortex (S1)
Arranged as a map of the body, a sensory homunculus. We have receptors that help us perceive information, but one type is almost never activated alone; things work in tandem.
sensory homunculus
the imaginary map of neurological connections based on sensory processing
association area
cortical areas that are neither motor or sensory but are thought to be involved in higher processing of information
A delta fiber
Thick and large, myelinated (coated with myelin) axons that register pain. Conducts quickly.
C fiber
Thin and small unmyelinated axons that conduct more slowly. Produces pain.
Anterolateral system (spinothalamic system)
An ascending somatosensorial tract that carries pain and temperature information from the skin to the brain.
Substance P
Peptide that boosts pain signals.
axons
Nerve fibers send _____ into the dorsal horns of the spinal cord.
glutamate
an excitatory substance that is released alongside substance P to boost pain signals and remodel neurons.
cingulate
Pain information is integrated into the _____ cortex.
analgesia
absence of the sense of pain without loss of consciousness
afferent nerves
the axons carried by a sensory nerve that relay sensory information from sensory receptors to regions of the brain. Afferent projections arrive at a particular brain region.
the spinal cord contains a neurological 'gate' that either blocks pain signals or allows them to continue on to the brain
gate control theory
motor plan
a set of muscle commands that we establish before a behavior happens
hierarchy of motor control
Skeletal system and attached muscles determine movements
Spinal cord controls skeletal muscles
The brain stem integrates motor commands
Primary motor cortex initiates commands
Nonprimary cortex is an additional source for commands
Cerebellum and basal ganglia modulate activities via thalamus
synergists
Muscles that act together to move a limb are _____
McGill pain questionnaire aspects of pain
Sensory/discriminative
Motivational/affective
Cognitive/evaluative
Antagonistic muscles
when one muscle contracts, the other stretches
striate muscle
Striped muscles in the skeleton, given appearance by myosin and actin
Most muscles contain a mix of ____ and _____ fibers
fast twitch and slow twitch fibers
fast twitch fibers
contract rapidly but fatigue easily
slow twitch fibers
contract slowly but fatigue slowly
motoneurons
In the spinal cord and brain stem, send action potentials down axons to innervate muscles
motor unit
motor neurons axon and all of its target fibers
motor neuron
_____ are the most common way the brain and spinal cord control muscles
proprioception
the ability to sense the position and location and orientation and movement of the body and its parts
two
How many kinds of proprioceptors?
muscle spindle
A _____ is a capsule that is buried in other muscle fibers. Detects changes in muscle length. A type of proprioception.
golgi tendon organ
Provides us with sensory signals that monitors the force that is generated by a contracting muscle. A type of proprioception.
pyramidal system
Conscious control of muscles from the cerebral cortex to the muscles of the body and face.
hand and jaws
Which two areas take up the most space in the primary motor cortex?
extrapyramidal system
Originate in the brainstem, carrying motor fibers to the spinal cord. They are responsible for the unconscious, reflexive or responsive control of musculature like muscle tone and balance.
somatosensory
the senses of the body
tracts
collections of axons
Note
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