BGYB30H3 Lecture 11 Notes Sensory 2-Oct 15

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11 Aug 2010
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BGYB30H3 Lecture 11 Notes
-special senses are conscious and cause voluntary responses (vision, taste, hearing, smell, and
equilibrium)
-somatic senses can either be conscious or unconscious senses causing a response (pain, touch,
proprioception, blood pH, blood pressure, temperature)
-blood pH and pressure are unconscious senses
-sensory systems are activated by physical and sometimes chemical energy
-changes in membrane potential are known as generator/receptor potentials, which are the
same as graded potentials
-integration of a signal in the CNS is through somatosensory cortex (conscious) or spinal cord
(unconscious)
-simple receptor neuron has free nerve endings that come in contact with stimulus (can be
myelinated or unmyelinated)
-complex receptor neuron has connective tissue that covers nerve endings and are always
myelinated
-special senses receptor neuron have a receptor cell that synapses onto the sensory neuron
and are always myelinated
-stimulus hits receptor cell which releases neurotransmitters onto sensory neuron
-chemical stimuli such as taste, smell, oxygen and glucose activate chemoreceptors
-mechanical stimulus such as pressure (baroreceptors), vibration (osmoreceptors) and
acceleration/gravity (proprioception) and sound activate mechanoreceptors
-nocioreceptors respond to pain stimuli
-an adequate stimulus is the form of energy to which that receptor is most responsive to
-CNS integrates sensory info in three ways (olfaction, sensory receptors, and equilibrium)
-olfactory system receives info and relays it through the olfactory bulb to the olfactory cortex
-sensory receptors respond to all stimuli
-equilibrium info is inputed from the inner ear to the cerebellum and not through the
thalamus
-somatic and vision sensory neurons have receptive fields
-receptive fields may overlap to cause variable sensitivities
-convergence of receptive fields decreases sensitivity of primary stimulus
-two or more primary sensory neurons synapse onto a secondary sensory neuron
-in two point discrimination, the outcome is that the receptive field can be detected for one
primary sensory neuron
-ear is sensitive to different frequencies of sound waves
-the timing of stimulation is used to compute the location of a stimulus
-time difference is registered in the auditory cortex of both sides of the brain
-neuron activation is proportional to the stimulus
-in lateral inhibition a secondary neuron that is closest to the stimulus inhibits adjacent
neurons to cause enhanced awareness of location
-lateral inhibition prevents interference caused by adjacent neurons that respond as well
-stimuli modality, location, intensity, and duration are properties of stimuli that the CNS
distinguishes
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