Nervous System 5 Flashcards
_____ Pathways into the CNS Enters the spinal cord via the posterior/dorsal roots
Afferent
_____ are Receptors and neurons in the CNS are dedicated to carrying particular sensory information.
Labeled Lines:
Which order neuron of afferent pathways always synapse in thalamus?
2nd order neuron
Which afferent pathway deals with touch, pressure, propriotion, and vibration?
Dorsal column
Which afferent pathway deals with pain and temp?
Spinothalamic
____ receptors are activated by compression/stretch; Includes receptors in skin, muscle spindles, hearing, equilibrium, arterial pressure, etc.
Mechanoreceptors
______ receptors are activated by ligands, Includes receptors for taste, smell, arterial oxygen, osmolarity, blood gas, blood glucose, etc.
Chemoreceptors
____ receptors are activated by cold/warm
Thermoreceptors
____ receptors are activated by damage/pain
Nociceptors
The particular form of energy to which a receptor is most sensitive is called its ______ ; Receptors do respond to forms of energy, but the threshold for these nonspecific responses is much higher.
adequate stimulus
Activation of any sensory receptor changes membrane potential (transduction) and produces what is called a ______ (a graded potential).
receptor potential
Increases in stimulus strength will increase the _____ of receptor potentials, but this is not a direct (linear) relationship.
amplitude
The intensity (or strength) of stimulus perception is determined by what 2 things?
Frequency of APs (temporal summation) and Total number of receptors activated (spatial summation)
A Stronger stimulus intensity produces a ____ Receptor (Graded) Potential, ____ Actions Potentials (Temporal Summation) and causes _____ neurotransmitter release into the synapse.
Larger, More, More
If a stimulus of constant strength is maintained on a sensory receptor, the frequency of the action potentials in its sensory nerve declines over time.
Perceptual Threshold
_____ can occur at the receptor or in the neuron. In response to continual, high impulse sensory stimuli, the response of almost all receptors decreases, but to varying degrees.
Adaptation
Decrease in amplitude of receptor potential over time in the presence of a constant stimulus; leads to corresponding decrease in frequency of APs and decreases perception of stimulus
Receptor adaptation
Tonic receptors help differentiate stimulus ___
intensity
Phasic receptors help differentiate stimulus ____
Duration
A precise modality activates specific receptors and postsynaptic cells. This information continues on a predicted pathway such that particular kinds of information are conveyed via specific nerve fibers to specific regions of the CNS that are programmed for perception of that modality.
Labeled Line Principle
______ correlates the anatomical regions of the CNS with where interpretation and awareness of sensations are perceived.
Homunculus
Region where a single fiber’s afferent receptors (primarily on dendrites) are located.
Receptive Field:
OVerlap of adjacent neurons _____ localization ability
Improves
____ is the precision with which a stimulus is perceived
Acuity
Improves discrimination ;Sensory stimulation of a single point on the skin can elicit excitation in one tract of post-synaptic cells while simultaneously inhibiting lateral neurons; occurs throughout the CNS and is advantageous since it diminishes lateral spread of an excitatory signal and increases degree of contrasts in the sensory pattern perceived in the cortex. This inhibition occurs at each synapse: (1) medulla, (2) thalamus and (3) cerebral cortex
Lateral inhibition
Which sensation do you perceive first vibration or touch?
Vibration
____ receptors include TACTILE and POSITION sensations that are stimulated by mechanical displacement of some tissues in the body.
Mechanoreceptors
_____ mechanoreceptors Touch sensations from stimulation of tactile receptors in the skin or tissues beneath the skin; Pressure sensations from deformation of deeper tissues; Vibration sensations from rapidly repetitive sensory signals.
Tactile
_____ mechanoreceptors Static position sense is conscious perception of orientation of different parts of the body with respect to one another; Rate of movement sense is also called kinesthesia or dynamic proprioception.
Position
_____ receptors are sensitive to pressure, touch, and vibration so mechanical stimuli are responsible for their activation.
Mechanoreceptors
Detect touch & pressure (temp. & pain)b.In skin, cornea, dental pulp, GI tract; Slow adaptation/ Tonic
Free Nerve Endings
Which mechanoreceptors Detect deep pressure, vibrationb.In subcutaneous tissue, viscera, jointsc.Rapid adaptation/Phasic
Pacinian Corpuscles
Higher frequency vibration is sensed by which mechanoreceptors?
Pacinian Corpuscles
Lower frequency vibration is sensed by which mechanoreceptors?
Meissner’s Corpuscles
Which ascending spinal pathway detects vibration?
Dorsal column
Which mechanoreceptors Detect light touch, pressure, vibration; Localization; Found on glabrous skin; Rapid adaptation/Phasic
Meissner’s Corpuscles
Which mechanoreceptors Localize continuous pressure and sensing an object’s texture; All skin; Slow adaptation/Tonic
Merkel’s Disks
Which mechanoreceptors are Sensitive to stretch or indentation; proprioceptionb.Deep layers of skin, joints, surrounding tooth roots; Slow adaptation/Tonic
Ruffini’s Endings
Which mechanoreceptors Hair Movement b.Base of hair follicle c.Rapid Adaptation/Phasic
Hair End-Organ
The _____ is an ascending bundle of heavily myelinated axons that cross over in the medulla. in the dorsal pathway
medial lemniscus
The The second order neuron crosses over in the _____ and synapses w/ 3rd order in _______
medulla oblongata; thalamus
What size nerve fibers are associated w dorsal column pathway?
A beta fibers
The ___ pathway deals with touch, pressure, and vibration
Dorsal column pathway
The ____ pathways senses Pain, Thermoreceptors, Crude Tactile, Tickle, Itch and Sexual Sensations
Spinothalamic
What size nerve fibers are involved in the spinothalamic pathways?
A delta and C fibers
Where does the 2nd order neuron decussate in spinothalamic pathway?
Spinal cord
With a UNILATERAL lesion of the spinal cord, one would expect to lose _____ lateral touch/pressure & _____ lateral pain/temperature sensations below the injury level.
Ipsilateral; contralateral
Receptors for ____ include photoreceptors, touch and pressure receptors in skin, joints, and ligaments, skeletal muscle receptors (muscle spindles and golgi tendon organs), and vestibular receptors; used for awareness of body’s position in space
Proprioception
______ mechanoreceptors areMostly complex Ruffini-like receptors; also free nerve endings. Axons are large & myelinated. 3.Adaptation is both slow and fast Location of receptors allow them to respond to any forces applied to the crown of the teeth (when biting and chewing)
Periodontal
Brisk tap on tooth ____ jaw closing muscles (ex. jaw opens to prevent damage)
inhibits
Weak tap on tooth ____ jaw closing muscles (ex. to hold onto food and adjust chewing force)
activates
