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chemoreceptors
respond to changes in the chemical concentrations of body fluids, ingested materials, and the outside medium
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pain receptors (nociceptors)
respond to tissue damage
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thermoreceptors
respond to changes in the external and internal temperatures
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photoreceptors
respond to the presence of and changes in electromagnetic radiation, particularly visible light
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mechanoreceptors
respond to changes in touch and pressure
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sensation (perception)
occurs when the brain receives information from sensory cells and interprets them
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projection
the brain projects the sensation back to the apparent source
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basic conduction of nerve impulses
some cells of the central nervous system (brain and spinal cord) integrate the information sent from sensory cells in the sense organs, and send signals to the cells that elicit some response to the stimulus (the effector organs, muscles and glands)
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reflex
an unconscious response to a stimulus, usually involving no more than a few neurons
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relex arc
- simplest response
- can remove the body part from danger much more rapidly
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reflex arc steps
a sensory cell, after detecting a stimulus, sends a signal to an internueron in the spinal cord, which sends a signal to the motor neuron, which stimulates the effector organ
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interneurons
- make the command decisions for the motor neuron in a reflex arc
- faster than the brain sending a motor signal back down the spinal cord
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rods
- sensitive to black and white vision
- detect the presence of fewer photons (light)
- predominate peripheral portions of the eye
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cones
- see different colors
- predominate the fovea
- color blind people may be missing or have insufficient numbers of types of cone cells
- three populations - sensitive to blue light, green light, and red light
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The most common color-blindness is due to...
... a deficiency of red and green cones.
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One possible hypothesis that can be testes is that a person who is right-handed is right-eye dominant, and a person who is left-handed is left-hand dominant. The data can be analyzed by using a special kind of chi-square analysis...
... a R x C contigency test.
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near point
- the shortest distance that an object is in sharp focus
- the closer the distance, the greater the ability of your eyes to focus on objects at various distances
- this distance inscreases with age
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In order to discriminate two points pressing in on our skin...
... we have to have two different receptors sending two different signals, which the brain interprets as two points.
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sensory adaptation
the initial pressure sensation with eventually disappear
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referred pain
a phenomenon in which the experience of a mild discomfort on one body part, the pain appears to be located elsewhere
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olfaction
- the sense of smelling
- where molecules of the substance you are detecting interact with olfactory receptor cells
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olfactory receptor cells
neurons that have sensory hairs, which are long cilia that protrude out of the cell and into a layer of mucus
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The perception of chemicals is created by...
... smell and taste (olfaction and gustation, respectively) working together.
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taste buds
- barrel-shaped structures in stratified squamous epithelium, located primarily on the sides of the various papillae of your tongue
- respond to chemicals that have been dissolved in saliva
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