General Sensory Mechanisms (Lec 3) Flashcards
This type of receptor deals with receiving skin tactile sensibilities, deep tissue sensibilities, hearing, equilibrium and arterial pressure
Mechanorecptors
Nociceptors have free nerve endings that respond to ___
pain
This type of receptor includes rods and cones of the eye for vision
electromagnetic receptor
Taste, smell, arterial oxygen, osmolarity, blood carbon dioxide, blood glucose deal with this type of receptor
chemoreceptor
What is modality?
refers to each of the principal types of sensation
What is the labeled line principle?
refers to the specificity of nerve fibers for transmitting only one modality of sensation
What are the four mechanisms of stimulation for receptors?
mechanical deformation, application of a chemical, temperature change, and electromagnetic radiation
What are some of the characteristics of tonic receptors?
slow adapting, detect continuous stimulus strength, transmit impulses as long as stimulus is present
Muscle spindles, Golgi tendon organs, macula and vestibular receptors, baroreceptors, and chemoreceptors are all types of what kind of receptor?
Tonic receptor
Rapidly adapting, do not transmit continuous signal, stimulated only when stimulus strength changes, transmit information regarding rate of change are all characteristics of what type of receptor?
Phasic receptor
What are the two types of nerve fibers?
Type A (large and medium sized myelinated fibers of spinal nerves) Type C (small, unmyelinated fibers)
What type of nerve fibers make up more than half of all sensory fibers in most peripheral nerves and all postganglionic autonomic fibers?
Type C
Describe Group Ia nerve fibers
fibers from annulospiral endings of muscle spindles
Describe Group Ib nerve fibers
fibers from Golgi tendon organs
Describe Group II nerve fibers
cutaneous tactile receptors and flower-spray
Describe Group III nerve fibers
carry temperature, crude touch, and pricking pain
Describe Group IV nerve fibers
carry pain, itch temperature, and crude touch
How does spatial summation work?
increasing signal strength by using progressively greater number of fibers
How does temporal summation work?
increasing signal strength by increasing frequency of nerve impulses in each fiber
Diverging neuronal pathways result in ____
amplification of initial signal and may allow transmission of original signal to separate areas
Converging neuronal pathways allow for ____
multiple input fibers to converge onto a single output neuron
What causes a reverberatory circuit?
positive feedback within neuronal circuit
True or False?
a reverberatory circuit may be stimulated once but discharge repetitively for a long time
true
What do somatic senses do and what are some types?
collect sensory information from all over the body
examples: mechanoreceptive, thermoreceptive, pain
Vision, hearing, smell, taste, and equilibrium are examples of
special senses
Proprioceptive sensations refer to ___
physical state of body
examples: position sensations, muscle and tendon sensations, pressure sensations, equilibrium
What are examples of deep sensations?
deep pressure, pain, and vibrations
What are three physiological types of somatic senses?
mechanoreceptive somatic senses, thermoreceptive senses, and pain
Describe primary sensory neurons
from external receptors, travel through dorsal roots of spinal cord
Describe secondary neurons
make up tracts in spinal cord and brainstem
Describe tertiary neurons
from thalamus to primary sensory cortex, travel through internal capsule
Spinothalamic and Medial Lemniscal systems are for
concious perception
Spinocerebellar, spino-olivary, spinotectal, and spinoreticular are for
unconscious perception
What type of information does the lateral spinothalamic tract carry?
carries pain and temperature
What type of information does the anterior spinothalamic tract carry?
carries light and touch, pressure, tickle, and itch
What type of information does the medial lemniscus system carry?
carries sensations for two-point sensation (fine touch), pressure, and vibration
Where do fibers of fasciculus gracilis synapse compared to fibers of fasciculus cuneatus?
fasciculus gracilis: nucleus gracilis (sensations from below mid thoracic level)
fasciculus cuneatus: nucleus cuneatus (sensations above mid thoracic level)
Where do secondary fibers in the medial lemniscus system ascend to?
ascend to synapse in VPL of thalamus
Where do tertiary fibers in the medial lemniscus system ascend to?
ascend through internal capsule to primary sensory cortex
What area of the neuronal pool includes all of the output fibers stimulated by the incoming fiber?
Discharge zone
What is the name of the location in the neuronal pool where neurons further from the discharge zone are facilitated but not excited?
Facilitated zone
In the lateral spinothalamic trunk, secondary fibers are joined in brain stem by fibers of what other tract? What do they carry?
Trigeminothalamic, pain from face and teeth
What physiological feelings do secondary fibers stimulate?
Wakefulness and consciousness
In regards to the lateral spinothalamic tract, where do tertiary fibers synapse?
Postcentral gyrus: somatic sensory areas 1 2 3
