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77 Cards in this Set
- Front
- Back
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What is transduction?
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When a sensory receptor detects a stimulus and translates it to an action potential that can be sent to the CNS
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Where are special sensory receptors located?
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In the sense organs
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What happens if transduction does not occur?
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As far as your mind is concerned, the stimulus does not exist.
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What is receptor specificity?
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The characteristic sensitivity of a specific receptor
Ex. Touch receptor is very sensitive to pressure, but not to chemicals. Taste receptor is very sensitive to chemicals, but not to pressure. |
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What are the simplest receptors?
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Dendrites of sensory neurons, which are free nerve endings
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Where can you find free nerve endings?
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At the ends of dendrites
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Are free nerve endings protected by accessory structures?
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No.
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Do free nerve endings have a high receptor specificity?
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No. Free nerve endings can detect many things.
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What is defined as the following: an area monitored by a single receptor cell?
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Receptive field
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How big is a touch receptor on the general body surface?
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Around 2.5 (7 cm) inches in diameter
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If you have a large receptor field, how specific will the stimulus you receive be?
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Not that specific.
The smaller the receptor field, the more precise the information |
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How does transduction begin?
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When a stimulus changes the transmembrane potential of the receptor cell.
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What is a depolarizing receptor potential in a neural receptor called?
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Generator potential
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What is it called when a stimulus changes the transmembrane potential of the receptor cell?
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Receptor potential
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What are the 2 types of receptor potentials?
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Graded depolarization or a graded hyperpolarization
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How is the strength, duration, and variation of a stimulus conveyed to the brain?
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By the frequency and pattern of action potentials
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What is sensory coding?
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The translation of complex sensory information into meaningful patterns of action potentials.
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What system assists you in listening carefully?
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RAS (reticular activating system)
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Are there any proprioceptors in the visceral organs?
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No. Proprioreception is strictly somatic.
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What marks the difference between a somatic receptor and a visceral receptor?
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Their location
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Where does most of the body's sensory processing occur?
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Along the sensory pathways in the spinal cord or brain stem
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Describe the structure of nociceptors.
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Free nerve endings with large receptor fields
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What are the two types of axons that carry painful sensations?
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Type A and C fibers
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Which type of axon carries fast pain?
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Type A fibers
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What type of axon carries slow pain (burning and aching)?
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Type C fibers
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When will pain sensations stop?
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Only after tissue damage has ended
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Reducing the perception of pain involves inhibiting what parts 4 of the brain?
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Thalamus, lower brain stem, reticular formation, and spinal cord
Tip: TLRS |
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How can the level of pain felt by an individual be reduced?
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By the release of endorphins and enkephalins within the CNS
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Identify the function of the following neuromodulatorss: endorphins and enkephalins.
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Inhibits activity along pain pathways in the brain
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Where can endorphins and enkephalins be found?
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In the limbic system, hypothalamus, and reticular formation
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What 2 neurotransmitters may be released when the sensory neurons bring pain sensations to the CNS?
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Glutamate and/or substance P
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Are there more cold receptors or warm receptors?
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Three to four times more cold receptors
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Describe the structure of thermoreceptors.
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Free nerve endings located in the dermis, in skeletal muscles, in the liver, and in the hypothalamus
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Where are four places you can find thermoreceptors?
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In the dermis, in skeletal muscles, in the liver, and in the hypothalamus
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Where are most tactile receptors located?
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In the skin
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How many different types of tactile receptors are there?
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6 types
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What has happened when an arm or leg “falls asleep”?
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It is the result of pressure on a peripheral nerve.
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What is paresthesia?
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The presence of abnormal sensations, such as when your arm or leg "falls asleep".
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What do baroreceptors detect?
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Changes in pressure in an organ
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Do chemoreceptors of the general senses send info to the primary sensory cortex?
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No.
This is why we don't feel sodium entering our cells. |
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What kind of chemicals are chemoreceptors sensitve to?
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Water-soluble and lipid-soluble substances
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What are the three major somatic sensory pathways?
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(1) the posterior column pathway, (2) the spinothalamic pathway, and (3) the spinocerebellar pathway.
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Where is the cell body of a first-order general sensory neuron commonly located?
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In a dorsal root ganglion or cranial nerve ganglion
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In order for a sensation to reach our awareness, where does it have to synapse?
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In the thalamus with a third-order neuron
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What kind of neuron is a second-order neuron?
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Interneuron
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What kind of sensations does the posterior column pathway carry?
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Sensations of highly localized (“fine”) touch, pressure, vibration, and proprioception
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What pathway is also known as the dorsal column/medial lemniscus?
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Posterior column pathway
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Where does the posterior column pathway begin and end?
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Begins at a peripheral receptor and ends at the primary sensory cortex of the cerebral hemispheres
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What are the spinal tracts involved with the posterior column pathway?
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Fasciculus gracilis and fasciculus cuneatus
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Where is the fasciculus gracilis and the fasciculus cuneatus located?
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On both sides of the posterior median sulcus, with the fasciculus gracilis being more medial
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When information reaches the ventral nuclei of the thalamus via the posterior column pathway, how is it sorted?
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1) the nature of the stimulus
(2) the region of the body involved |
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What kind of sensations does the anterior spinothalamic pathway carry?
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Crude touch and pressure to the primary sensory cortex on the opposite side of the body
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What kind of sensations does the lateral spinothalamic pathway carry?
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Pain and temperature to the primary sensory cortex on the opposite side of the body
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The size of an area in the sensory cortex is dependent upon what info?
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The number of sensory receptors at that specific part of the body.
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Describe the action of the first and second-order neurons of the spinothalamic pathway.
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Axons of first-order sensory neurons enter the spinal cord and synapse on second-order neurons within the posterior gray horns
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Where do the two spinothalamic tracts end?
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At third-order neurons in the ventral nucleus group of the thalamus
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After the sensations of the spinothalamic pathway have been sorted and processed in the ventral nucleus group of the thalamus, where do they go?
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Primary sensory cortex
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What is referred pain?
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Pain sensations from visceral organs are often perceived as involving specific regions of the body surface
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Does information from the spinocerebellar pathway ever reach our awareness?
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No.
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What kind of information does the spinocerebellar pathway carry?
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Proprioceptive information about the position of skeletal muscles, tendons, and joints
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Describe the action of the first and second-order neurons of the spinocerebellar pathway.
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First-order sensory neurons synapse on interneurons in the dorsal gray horns of the spinal cord; second-order neurons ascend into one of the other tracts
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What are the two tracts of the spinocerebellar pathway?
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The posterior and anterior spinocerebellar pathway
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In which tract does a "double cross" of axons occur?
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Anterior spinocerebellar tract
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Where does information carried by the spinocerebellar pathway ultimately arrive?
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At the Purkinje cells of the cerebellar cortex
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Which pathway detects proprioreception?
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Spinocerebellar pathway
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Where is the solitary nucleus located?
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In the medulla oblongata
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What is the major processing and sorting center for visceral sensory information?
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The solitary nucleus in the medullla oblongata
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Which spinal nerves carry visceral sensory information provided by receptors in organs located between the diaphragm and the pelvic cavity?
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T1-L2
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Which spinal nerves carry visceral sensory information provided by receptors in organs in the inferior portion of the pelvic cavity and most of the things below it?
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S2-S4
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Where can you find the cell body of an upper motor neuron?
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In a CNS processing center
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Where can you find the cell body of a lower motor neuron?
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In a nucleus of the brain stem or spinal cord
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Activity in the upper motor neuron causes what action(s) to a lower motor neuron?
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It may facilitate or inhibit the lower motor neuron.
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What is the result when there is damage to a lower motor neuron?
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Eliminates the voluntary and reflex control over the innervated motor unit
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What are the 3 descending motor pathways that control skeletal muscles?
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The corticospinal pathway, the medial pathway, and the lateral pathway
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Why is the corticospinal pathway also known as the pyramidal system?
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Because the system begins with the pyramidal cells of the cerebral cortex
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What is the purpose of the corticospinal pathway?
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Voluntary control over skeletal muscles
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What are the three pairs of descending tracts in the corticospinal pathway?
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(1) the corticobulbar tracts, (2) the lateral corticospinal tracts, and (3) the anterior corticospinal tracts
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