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BISC 104 Lab Assignment Senses

BISC 104 Lab Assignment Senses - SENSATION Our information...

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SENSATION Our information about the world around us is obtained through the stimulation of sensory nerves in the peripheral nervous system, which relay this information to the brain. The brain is able to build a picture from these signals, and our perception of the world is shaped by this input combined with experience. Changes in the environment cause sensory receptors that are specialized for a specific modality (which sense) to trigger the depolarization of sensory nerve endings and the firing of neurons for different types of stimuli . Chemical stimuli: taste, smell Mechanical stimuli: pressure, sound, touch, vibration, gravity Electromagnetic stimuli: light, heat A. GENERAL PROPERTIES OF SENSORY NEURONS 1. Receptors as Transducers All receptors act like transducers, in other words, they convert one type of energy into another (like some of the equipment you use in your laboratory). Each sensory organ contains primary sensory receptor cells. These cells have specialized endings that detect small changes in a given stimuli that cause the cell to create electrical potentials that usually generate an action potential. After several synapses, the signals are eventually passed to the cerebral cortex, which is when we may become conscious of the sensation, or in other words, we perceive the sensation. However, once sensation reaches this level, the actual sensation has been processed by the CNS, and often modified by our attention and previous experience. Specialized sensory receptors exist for the various senses in each sense organ: Smell: olfactory receptors in the epithelium of the nose Taste: taste receptor cells on the tongue Touch: touch and temperature nerve endings in the skin Hearing: hair cells in the organ of Corti in the inner ear Vision: rods and cones in the retina of the eye Balance: hair cells in the vestibular apparatus of the inner ear Name some things you can sense that are not mentioned above. 2. Receptive Fields Usually a sensory cell can detect only a small portion of the full range of possible stimuli that your whole sensory system can detect. This limited range of stimuli fall within that cell’s receptive field. Every sensory cell, no matter at what level of the nervous system, has a receptive field, but for various reasons, the size of these receptive fields may vary by a great deal. What properties would be exhibited by a receptive field of the following primary sensory neuron? Touch, Sight, Sound, Motion
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3. Adaptation Many receptors adapt to a static situation. This makes us better at detecting new or perhaps more behaviorally relevant stimuli. Most of our sensory systems are better at detecting changes in our environment or ourselves than at detecting steady-state stimuli. For instance, you’re much better at spotting a moving deer on the roadside than a completely still one. Another example is what you experience when you’re driving through a tunnel. The lighting in a tunnel doesn’t change with the time of day. However, when you
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BISC 104 Lab Assignment Senses - SENSATION Our information...

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