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80 Cards in this Set
- Front
- Back
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What are sensory receptors? |
specialized cells that provide the central nervous system with information about conditions inside or outside the body |
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Where are general sensory receptors located?
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throughout the body
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Where do sensory pathways begin and end?
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they begin at peripheral receptors and end in the CNS, usually in the diencephalon or cerebral hemispheres |
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What is the information carried by a sensory pathway called?
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a sensation |
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What is perception?
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our concious awareness of a sensation |
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What is the relationship between a receptive field and localizing a stimulus?
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the larger the receptive field, the poorer your ability to localizee the stimulus |
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What is sensory modality?
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A unique sensation |
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What are the two classes of sensory modalities?
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1. general senses |
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What are the four steps in the process of sensory and motor pathways? |
1. stimulation |
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What are the simplest receptors? |
dendrites of sensory neurons
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Why do dendrites of sensory receptors exhibit little receptor specificity? |
they can be stimulated by a large variety of stimuli
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What alters the sensitivity and specificity of a free nerve ending?
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its location and presence of accessory structures
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What are the three sensory receptor locations? |
exteroceptors, interoceptors, proprioceptors
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Where are exteroceptors activating stimuli?
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at or near the body surface, external environment, touch, pressure, vibration, thermal, pain
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Where are interoceptors activating stimuli? |
in blood vessels, visceral organs, nervous system, internal environment, not consciously perceived, felt as pressure or pain
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Where are proprioceptors activating stimuli? |
in muscles, tendons, joints. could be body position, muscle length and tension, joint motion and position
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What are the five types of stimulus detected?
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mechanreceptors, thermoreceptors, nociceptors, chemoceptors, osmoreceptors
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How many different types of mechanoreceptors are there in the body? |
six
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Describe mechanoreceptors.
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detect mechanical pressure like touch, vibration, pressure, proprioception, blood vessels and organ stretch
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What do thermoreceptors detect |
changes in temp
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What type of receptrs are nociceptors?
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pain from physical or chemical damage to tissue
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What do chemoreceptors respond to? |
chemicals in body fluids
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What do osmoreceptors respond to?
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osmotic pressure of body fluids
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How can receptors for general senses be classified? |
by function and sensitivtiy |
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What are the two types of responses to stimulation? |
tonic or phasic |
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Compare tonic and phasic receptors. |
1. tonic receptors: are always active and producing action potentials. when the stimulus increases or decreases, the rate of action potential generation changes.
2. phasic receptors: are normally inactive but becomes active for a short time in response to changes in conditions they are monitoring |
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Compare peripheral and central adaptation. |
1. peripheral adaptation: level of receptor activity changes
2. central adaptation: occurs along sensory pathways in the CNS and involves inhibition of the nuclei on this pathway |
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What are the six different types of tactile receptors? |
1. free nerve endings |
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Where are free nerve endings found?
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everywhere in the skin and other tissues |
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What do free nerve endings detect?
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touch and pressue
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What type of tactile receptor respons to tickles, itches, and light touch? |
free nerve endings |
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What type of fiber does free nerve endings info travel on? |
Type C-unmyelinated
2 m/sec |
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Where are Meissners corpuscles found? |
nonhairy parts of the skin; abundant in fingertips and lips
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What do Meissners corpuscles detect? |
spatial locations of touch, movment of an object over an area, low frequency vibration
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Where are Merkel's discs found? |
Hairy and non-hairy parts of the skin
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Do Meissners corpuscles adapt quickly or slowly?
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quickly
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What do Merkels discs detect?
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sensations of continuous touch of objects against the skin
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Do Merkels discs adapt quickly or slowly?
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slowly
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What do Meissners and Merkels detect together? |
localizing touch sensations and determining an objects texture
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Where are root hair plexuses found |
the hair end organ
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What sensation is detected by a root hair plexus? |
initial body contact and subsequent movements
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Describe Ruffini's corpuscles structure.
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multibranched, encapsulated nerve endings
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Where are Ruffini's corpuscles located? |
deep layers of the skin and deeper internal tissues
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What sensation is detected by Ruffini's corpuscles?
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deep pressure
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Do Ruffinis corpuscles adapt very quickly or very slowly? |
very slowly
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Do root hair plexuses adapt very quickly or very slowly
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very quickly
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Where are pacinian corpuscles located? |
immediately beneath the skin
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What type of stimulation do pacinian corpuscles detect?
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rapid local compression; pulsing or high frequency vibrating stimuli
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What type of fibers do meissners, merkels, ruffinis, and pacinian travel?
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AB fibers
30-70 m/sec |
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What are the three sets of neurons along the somatic sensory pathways? |
first order, second order, and third order |
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Where do first order neurons originate and synapse? |
First Order Neurons originate in somatic receptors into the brain stem or spinal cord |
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Where are second order neurons located? |
Second Order Neurons are located from the brain stem and spinal cord to the thalamus for conscious awareness |
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What happens to the axons in the brain stem or spinal cord before they ascend to the hypothalamus? |
they cross over to the other side |
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Where are third order neurons located?
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Third Order Neurons are located at the synapse with second order neurons in the thalamus to the primary somatosensory area of the cortex on the same side |
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Impulses headed for the cortex travel along what two pathways? |
1. posterior column or 2. spinothalamic pathway |
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Impulses headed for the cerebellum travel along what pathway? |
the spinocerebellar pathway |
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Is the anterior or posterior spinocerebellar tract responsible for axons that have crossed over from the other side of the spinal cord? |
anterior tract |
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What type of sensations does the posterior column pathway carry to the cerebral cortex? |
fine touch, vibration, pressure, and proprioception
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Describe the pathway of an action potential in the posterior column pathway. |
first order neuron travels up the spinal cord, synapses with second order neuron, crosses over to opposite medial lemniscus, synapes with third order neuron in the ventral nuclei of the thalamus, third order neuron brings information to the primary sensory cortex |
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Where does the sensory information decussate in a posterior column pathway? |
the medulla oblongata
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What types of sensations does the spinothalamic pathway take to the primary sensory cortex? |
localized crude touch, pressure, pain, and temperature |
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What are the two tracts of the spinothalamic pathway? |
1. anterior & 2. lateral |
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What sensations does the anterior spinothalamic tract of the spinothalamic pathway carry? |
crude touch and pressure |
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What sensations does the lateral spinothalamic tracts of the spinothalamic pathway carry? |
pain and temperature
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In the spinocerebellar pathway, when does information coross over? |
ONLY if the information comes from the RIGHT side |
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What type of information does the cerebellum recieve from the spinocerebellar pathway? |
proprioceptive input from Golgi tendon organs, muscle spindles, and joint capsules
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How many synapses are there in the spinocerebellar pathway?
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one
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How many motor neurons does the somatic motor pathways always involve?
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at least two
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Where does an upper motor neuron's cell body lie?
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in a CNS processing center
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Where does a lower motor neurons cell body lie?
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in the nucleus of the brain stem or spinal cord |
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What pathway provides voluntary control over skeletal muscles? |
corticospinal
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What are the nuclei of the medial pathway?
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superior and inferior colliculi, reticular formation, vestibular nucleus
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What are the nuclie of lateral pathway?
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the red nuclei
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what does the lateral pathway help control?
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the distal lim muscles that perform more precise movements
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What does the medial pathway help control?
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gross movements of the trunk and proximal limb muscles
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What is the relationship between the distance of a motor center from the cortex to the complexity and variability of the motor activities there?
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the closer a motor center is to the cerebral cortex, the more complex and variable the motor activities will be
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What happen when you make a conscious decision to perform a specific movement?
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information is relayed from the frontal lobes to the motor association areas, then these areas relay the information to the cerebellum and basal nuclei
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What happens once the movemtn begins?
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th emoter association areas send instructions to the primary motor cortex
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What is referred pain?
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the sensation of pain in a part of the body other than its actual source
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What does the SNS provide?
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conscious and subconscious control over the skeletal muscles of the body
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