Biology 30 Notes

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The senses transmit sensory information’s, in the form of electrochemical impulses, to the brain. Different forms of energy stimulate the sensory receptors – the nerve endings and cells that detect sensory information. The sensory receptors then initiate neural impulses. Sensation occurs when the neural impulses arrive at the cerebral cortex. Neural impulses that begin in the optic nerve are sent to the visual areas of the cerebral cortex, and we see objects. Each person’s unique perception results from how the cerebral cortex interprets the meaning of the sensory information.

Sensory adaptation: brain filters out redundant, insignificant information. Example: when you no longer the ticking of a clock or the feel of clothes on your skin. The senses detect a significant change in external or internal conditions, and the body readjusts. In order to process sensory information quickly, the brain parallels or splits up this input to carious areas of the brain, and forma a neural multi-tasking.

Sensory receptors are specialized cells or neuron endings that detect specific stimuli. Human sensory receptors can be classified into four categories: photoreceptors, chemoreceptors, mechanoreceptors, and thermoreceptors. Each receptor is able to transduce or convert one form of energy from a specific stimulus into electrochemical energy, which can be processes by the nervous system.

Light energy stimulates photoreceptors. Our eyes contain photoreceptors, called rods and cones that absorb light and allow us to sense different levels of light and shades of color. Certain chemicals stimulate chemoreceptors. The tongue contains taste buds that detect various particles in the food we eat. The nose has olfactory cells that detect odors in the air. Other chemoreceptors detect changes in the internal environment. Mechanoreceptors respond to mechanical forces from some form of pressure. Example: hair cells in the inner ear are activated when sound waves cause parts of...
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