Senses+MC

Senses SCI Human Biology - 1 Assigned: 10/16 Due: 10/17 14.1

-Sensory Receptors are dendrites specialized to detect certain types of stimuli (sing.,stimulus). - They are sensory receptors that detect stimuli from outside the body, such as those that result in taste, smell, vision, hearing, and equilibrium. Those in the eyes and ears are not directly involved in homeostasis and continually send messages to the central nervous system regarding environmental conditions. Examples are taste cells, olfactory cells, rod cells and cone cells in retina, hair cells in spiral organ, hair cells in semicircular canals, and hair cells in vestibule. - They receive stimuli from inside the body. For example, among interoceptors, pressoreceptors respond to changes in the blood pressue, osmoreceptors detect changes in the water-salt balance, and chemoreceptors monitor the pH of the blood. When blood pressure rises, pressoreceptors signal a regulatory center in the brain, which sends out nerve impulses to the arterial walls, causing them to relax; the blood pressure then falls. -Exteroceptors such as those in the eyes and ears are not directly involved in homeostasis and continually send messages to the central nervous system regarding environmental conditions. -chemoreceptors respond to chemical substances in the immediate vicinity. Taste and smell detect external stimuli, utilize chemoreceptors; but so do various other organs that are sensitive to internal stimuli. Chemoreceptors that monitor blood pH are located in the carotid arteries and aorta. If the pH lowers, the breathing rate increases. AS more carbon dioxide is expired, the blood pH rises. Examples are taste cells and olfactory cells. -Pain receptors are a type of chemoreceptor. They are naked dendrites that respond to chemicals released by damaged tissues. Pain receptors are protective because they alert us to possible danger. For example, without the pain of appendicitis, we might never seek the medical help needed to avoid a ruptured appendix. They are also called nociceptors. -photoreceptors respond to light energy. Our eyes contain photoreceptors that are sensitive to light rays and thereby provide us with a sense of vision. Stimulation of the photoreceptors known as rod cells results in black-and-white vision, while stimulation of the photoreceptors known as cone cells results in color vision. The sights @ the amusement park, including colorful balloons, spinning rides, and rings being tossed, would have stimulated the boys’ photreceptors. Examples are rod cells and cone cells in retina. -mechanoreceptors are stimulated by mechanical forces, which most often result in pressure of some sort. Mechanoreceptors are responding to fluid-borne pressure waves when we detect changes in gravity and motion, helping us keep our balance. The sense of touch depends on pressure receptors that are sensitive to either strong or slight pressures. Examples are hair cells in spiral organ, hair cells in semicircular canals, and hair cells in vestibule (sound waves, motion, and gravity). - thermoreceptors located in the hypothalamus and skin are stimulated by changes in temperature. Those that respond when temperatures rise are called warmth receptors, and those that respond when temperatures lower are called cold receptors. The heat of the sun would have activated the thermoreceptors of the boys, and the rise in their body temperature would most likely have had them seeking some shade. -Sense of taste= In adult humans, approximately 3,000 taste buds are located primarily on the tongue. Many taste buds lie along the walls of the papillae, the small elevations on the tongue that are visible to the naked eye. Isolated taste buds are also present on the hard palate, the pharynx, and the epiglottis. There are at least four primary types of taste: sweet, sour, salty, and bitter. A fifth taste, called umami may exist for certain flavors of cheese, beef broth, and some seafood. Taste buds for each of these tastes are located throughout the tongue, although certain regions may be most sensitive to particular tastes: The tip of the tongue is most sensitive to sweet tastes, making it especially pleasurable to lick an ice cream cone. The margins of the tongue are most sensitive to salty and sour tastes; and the rear of the tongue to bitter tastes. Taste buds also open at a taste pore. They have supporting cells and a number of elongated taste cells that end in microvilli. Since we can respond to a range of sweet, sour, salty, and bitter tastes, the brain appears to survey the overall pattern of incoming sensory impulses and to take a “weighted average” of their taste messages as the perceived taste.
 * Define sensory receptors. 274
 * Give examples of exteroceptors. 274
 * Give examples of interoceptors. 274
 * Which type of receptors only detect information and send information to the brain but do not regulate the body's homeostasis. 274
 * Describe (in detail) and give examples of each of the following receptor types...(274)
 * Explain in a five point paragraph the sense of taste (278), smell (278) or vision (280).