Senses+MV

Molly Vaughn

14.1 Define sensory receptors. 274 - Sensory receptors are dendrites specialized to defect certain types of stimuli. Sensory receptors in humans can be classified into just four categories: chemoreceptors, photoreceptors, mechanoreceptors, and thermoreceptors.

Give examples of exteroceptors. 274 - Exteroceptors are sensory receptors that detect stimuli from outside the body, such as those that result in taste, smell, vision, hearing, and equilibrium.

Give examples of interoceptors. 274 - Interoceptors receive stimuli from inside the body. For example, among interoceptors, pressoreceptors respond to changes in blood pressure, osmoreceptors monitor the pH of the blood.

Which type of receptors only detect information and send information to the brain but do not regulate the body's homeostasis. 274 - Exteroceptors

Describe (in detail) and give examples of each of the following receptor types...(274) Chemoreceptors: Chemoreceptors respond to chemical substances in the immediate vicinity. They indicate taste, and smell, which detect external stimuli, utilize chemoreceptors; but so do various other organs that are sensitive to inter 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.

Pain receptors: 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.

Photoreceptors: 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 result in black-and-white vision, while stimulation of the photoreceptors known as cone cells result in color vision. The sights at the amusement park, including colorful balloons, spinning rides, and rings being tossed, would have stimulated the boys’ photoreceptors.

Mechanoreceptors: Mechanoreceptors are stimulated by mechanical forces, which most often result in pressure of some sort. When we hear, airborne sound waves are converted to fluid-borne pressure waves that can be detected by mechanoreceptors in he inner ear. The boys at the park would have heard people yelling and screaming, music playing, bells ringing, and popcorn popping, for example. Mechanoreceptors are responding to fluid-borne pressure waves when we detect changes in gravity and motions, helping us keep our balance. These receptors are in the vestibule and semicircular canals of the inner ear, respectively. The “Twisted Tornado” tested the ability of the boys to maintain their balance, despite the ordeals of their ride. The sense of touch depends on pressure receptors that are sensitive to either strong or slight pressures. Pressoreceptors located in certain arteries detect changes in blood pressure, and stretch receptors in the lungs detect the degree of lung inflation. Proprioceptors, which respond to the stretching of muscle fibers, tendons, joints, and ligaments, make us aware of the position of our limbs.

Thermoreceptors: 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 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.

Explain in a five-point paragraph the sense of taste (278), smell (278) or vision (280). - 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. 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 sensitive to particular tastes: The tip of the tongue is most sensitive to sweet tastes, making it especially pleasurable to like 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 open at a taste pore. They have supporting cells and a number of elongated taste cells that end in microvilli. When molecules bind to receptor proteins of the microvilli, nerve impulses are generated in sensory nerve fibers that go to the brain. When they reach the gustatory cortex, they are interpreted as particular tastes. 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. Again, we can note that even though our senses depend on sensory receptors, the cortex integrates the incoming information and gives us our sensations.