| ACT #5: Sensory Perception
�Different Strokes for Different Folks� (pg.508-509 text). (A) What is the difference between perception and sensation? (B) What kind of sensory receptors are there? (There are six of them listed in our text.) What do each of the receptors detect? (C) Are all receptors found in equal quantities in all areas of your body? Give me two examples when this isn�t true. (D) Are heat and cold receptors equally sensitive over all parts of your body? Think about when you are swimming- does the cold water bother all of your body or only certain parts? ACT #6: Regions of taste Pg. 517 text book (A) We use chemoreceptors in our mouth, tongue, and throat to detect taste. The nerve impulse pathway starts with the chemoreceptors, where chemicals from things we�ve placed in our mouths are dissolved in the fluid in our mouth. The sensory input (stimulus) travels from the receptors (by sensory neurons) to the brain, where perception of the stimulus is matched with our stored memories. Interneurons from our brain sends a signal (by motor neurons) to our glands to release certain digestive juices and to our muscles in the head region to begin the process of physically breaking down food items. Please sketch Figure 31.14 pg. 517 of the tongue. Include and section of the tongue figure 31.14 (c) and label the taste bud (where chemoreceptors are located) and sensory nerve. (B) Let�s try our Bio �taste-test�. Add a �splash� (just a little bit) of each solution in different cups: lemon juice, tonic water, salt water, and sugar water. Make sure you label the cups. Dry your tongue with a dry paper towel. Using a spoon, drip several drops of one solution onto a toothpick. Touch it to different areas of your tongue to determine where you taste this substance. Label a section of your tongue (that you sketched above) that distinguishes the �flavor�. Try it for all four solutions. (C) Questions: 1) What are taste buds are how many do we (humans) typically have? 2) What five flavors can people generally tell apart? 3) Why is a sucker (lollipop) sweeter when you lick it that when you chew it? ACT #7: How we see The eye is very much like a camera. It has a lens, a method of opening and closing the lens to varying amounts of light, and a way of focusing the lens on things that are very close or very far way. Instead of film (or digital image saved on a flash card), the image that the eye �sees� is received by the inner lining of the eye. This structure is called the retina. The retina is less than 1/80 of an inch thick. It is composed of 7 layers of cells that include receptors and nerve fibers. The receptors are stimulated by light and are called PHOTORECEPTORS. The photoreceptors consist of CONES and RODS. (A) Find out how cones and rods are different. Pg. 516 text. More than � million nerve fibers lead from the surface of the retina to a large cranial nerve called the optic nerve. There are no rods or cones where the optic nerve joins the retina so no vision is possible in this area. This area is the �blind spot�. (B) Why don�t we see colors very well at night? (C) What structures are responsible for color vision? We will look at the structure of the eye with our sheep�s eye dissection. We will also take a look at the blind spot and colorblindness later. |