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List and describe the three types of viceral receptors.
- Chemoreceptors : Monitor O2, CO2, H+ levels in the blood.
- Baroreceptors : Stretch receptors in aortic arch and carotid sinuses of the carotid arteries that monitor blood pressure.
- Mechanoreceptors : measures amount of distension in the gastrointestinal tract.
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List and describe the two categories of sensory input from the somatosensory system.
- Somesthic : Receptors in the skin. (Nocioceptors)
- Proprioception : perception of the position of the limbs and the body.
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List the types of sensory input from the special sensory system.
- Vision
- Hearing
- Equilibrium
- Taste
- Smell
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What is modality?
The energy from a stimulus of which a neuron is most sensitive to.
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What is transduction?
- Conversion of one form of energy into another.
- Energy from sensory stimuli is converted into changes in membrane potential called receptor potentials or generator potentials.
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Describe receptor potentials.
Change in membrane potential in response to a stimulus acting on a sensory receptor. These graded potentials are caused by the opening and closing of ion channels. Can cause action potentials.
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What is adaptation?
Decrease in amplitude of receptor potential over time in presence of a constant stimulus.
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What is a sensory unit?
A single afferent neuron and all receptors (all the same type) associated with it.
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What is a receptive field?
Area over which an adequate stimulus can produce a response in the afferent neuron; corresponds to the region containing receptors for that afferent neuron.
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What are the three factors that code sensory information?
- Stimulus type
- Stimulus intensity ( Frequencing & Population Coding )
- Stimulus location ( Receptive field )
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Describe Population Coding.
- Also called recruitment coding.
- Stronger stimulus activates more receptors. ( Can be from the same or other afferent neurons)
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What is Acuity?
The precision with which the location of a stimulus is perceived.
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Describe lateral inhibition.
A stimulus that strongly excites receptors in a given location inhibits activity in the afferent pathways of other nearby receptors.
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What are the four types of Somesthetic sensory stimuli?
- Pressure
- Temperature
- Pain
- Proprioception
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What type of receptor detects pressure, force, or vibrations?
Mechanoreceptors
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What type of receptor detects chances in temperature?
Thermoreceptors
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What type of receptor detect tissue damaging stimuli?
Nocioceptors
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What type of receptors detect the bodys position in space?
Proprioceptors
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List the different types of rapidly and slow adapting mechanoreceptors.
- Rapidly adapting : Pacinian corpuscle, Meissner's corpuscle, Hair follicle receptor.
- Slow adapting : Free nerve endings, Merkel's disk, Ruffini's ending.
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Describe warm thermoreceptors.
- Free nerve endings
- Respond to temperatures from 30 - 45 C
- Increase frequency with increase temperature.
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Describe cold thermoreceptors.
- Possible free nerve endings.
- Respond to temperatures from 20 - 35 C.
- Increase frequency with decrease in temperature.
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Describe nocioceptors.
- Respond to tissue-damaging stimuli.
- Free nerve endings
- Classes : Mechanical ( Respond to intense mechanical stimuli) Thermal ( Respond to intense heat) Polymodal ( Respond to a variety of stimuli including inttense mechanical stimuli, heat, cold, and chemical.
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What are the pathways to Somatosensory cortex?
- Dorsal colum (medial lemniscal pathway)
- Spinothalamic tract
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What type of sensations travel through the Dorsal column-medial lemniscal pathway?
Touch, pressure, and proprioception
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What type of sensations travel through the spinothalamic tract?
Pain and temperature
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Activation of nocioceptors leads to what type of response?
Perception of pain, elicits autonomic responses, emotional responses, and reflective withdrawal from stimulus.
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Describe fast pain perception.
- Travel through A delta fibers
- Elicit a sharp pricking sensation
- Are well localized
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Describe slow pain perception.
- Travel through C fibers
- Elicit a dull aching
- Are poorly localized
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What neurotransmitter is released from A delta and C fiber pathways?
Substance P
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