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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.
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.
List the types of sensory input from the special sensory system.
What is modality?
The energy from a stimulus of which a neuron is most sensitive to.
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.
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.
What is adaptation?
Decrease in amplitude of receptor potential over time in presence of a constant stimulus.
What is a sensory unit?
A single afferent neuron and all receptors (all the same type) associated with it.
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.
What are the three factors that code sensory information?
- Stimulus type
- Stimulus intensity ( Frequencing & Population Coding )
- Stimulus location ( Receptive field )
Describe Population Coding.
- Also called recruitment coding.
- Stronger stimulus activates more receptors. ( Can be from the same or other afferent neurons)
What is Acuity?
The precision with which the location of a stimulus is perceived.
Describe lateral inhibition.
A stimulus that strongly excites receptors in a given location inhibits activity in the afferent pathways of other nearby receptors.
What are the four types of Somesthetic sensory stimuli?
What type of receptor detects pressure, force, or vibrations?
What type of receptor detects chances in temperature?
What type of receptor detect tissue damaging stimuli?
What type of receptors detect the bodys position in space?
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.
Describe warm thermoreceptors.
- Free nerve endings
- Respond to temperatures from 30 - 45 C
- Increase frequency with increase temperature.
Describe cold thermoreceptors.
- Possible free nerve endings.
- Respond to temperatures from 20 - 35 C.
- Increase frequency with decrease in temperature.
- 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.
What are the pathways to Somatosensory cortex?
- Dorsal colum (medial lemniscal pathway)
- Spinothalamic tract
What type of sensations travel through the Dorsal column-medial lemniscal pathway?
Touch, pressure, and proprioception
What type of sensations travel through the spinothalamic tract?
Pain and temperature
Activation of nocioceptors leads to what type of response?
Perception of pain, elicits autonomic responses, emotional responses, and reflective withdrawal from stimulus.
Describe fast pain perception.
- Travel through A delta fibers
- Elicit a sharp pricking sensation
- Are well localized
Describe slow pain perception.
- Travel through C fibers
- Elicit a dull aching
- Are poorly localized
What neurotransmitter is released from A delta and C fiber pathways?