Discussion: Nervous System & Sensory Reception

BIOLOGY 21 ON-LINE LAB 4: NERVOUS SYSTEM & SENSORY RECEPTION This week, we will examine the nervous system and sensory reception. The nervous system is responsible for emotions, cognition (thinking), movement and sensations (awareness of a stimulus). To understand how the nervous system operates, you must know some basic anatomy of sensory organs and some neuroanatomy (anatomy of the brain and spinal cord). Materials needed for this week’s lab: From the Bio 21 packet: blind spot card, large paper clip, and paper ruler. From home: timer (kitchen timer or timer on your phone); optional: small flashlight (or light on your phone). ACTIVITY 1: ORGANIZATION OF THE NERVOUS SYSTEM Refer to Chapter 11 in your textbook and answer the questions below. (Hint: Figure 11.1 is very helpful here.) 1. What are the two major divisions of the nervous system? a. ___________________________________ b. __________________________________ 2. What are the two key anatomical structures of the central nervous system? a. ___________________________________ b. __________________________________ 3. What are the two main divisions of the peripheral nervous system? a. ___________________________________ b. __________________________________ 4. The motor (output) division of the PNS is further subdivided into what two divisions? a. ___________________________________ b. __________________________________ 5. The autonomic division of the PNS is still further subdivided. What are these two divisions? a. ___________________________________ b. __________________________________ Human Biology: Lab 4 MORE 4.1 ACTIVITY 2: THE BRAIN UP CLOSE Using Figure 11.15 in your textbook, label the different parts of the brain below. The figure on the left shows the external anatomy of the brain.

The figure on the right is a cross section of the brain showing interior features. www.turbosquid.com/3d-models/3d-human-brain/1135663 © 2017 Pearson Education, Inc. Using information in Chapter 11 of your textbook and healthline.com, identify the functions of the following parts: Part Function Cerebrum Cerebellum Corpus Callosum Thalamus Medulla oblongata 4.2 Human Biology: Lab 4 ACTIVITY 3: REFLEXES Reflexes are unconscious responses to a stimulus. The response is stereotyped (always the same) and involuntary (without awareness). The response does not require information from higher brain centers (that is, information from the cerebrum). When a stimulus is received (for example, you accidentally cut your finger), a reflex action occurs (you pull your hand back). Go to https://www.youtube.com/watch?v=c-dD0N53QRg (also on Canvas under Lab 4) for a 2 minute video demonstrating a specific stretch reflex – the knee jerk or patellar reflex. Note: the narrator’s voice is fast in this video. Remember, you can change Youtube settings to slow down the playback speed and/or show subtitles. Discussion: Nervous System & Sensory Reception

Click on the small gear symbol to bring up the Settings menu to make adjustments. Answer the following as you view this video. 1. What tendon is your doctor tapping just below your knee cap (patella) to test the knee jerk reflex? ____________ What happens when this tendon is tapped? ____________________? 2. The knee jerk reflex is a simple reflex arc that occurs at the level of the spinal cord (meaning, the brain is not involved). When the patellar tendon is tapped, muscle spindles in the quadriceps stimulate what kind of neurons? ________________________. Where do these neurons go? __________________________ What type of neurons do they communicate with (“synapse”)? _______________________. Then what happens? ________________________________________________________. 3. Label the neurons in A and B in the diagram below to show the neural pathway from the knee to the spinal cord and back to the knee. A 4. Finally, what type of “interneuron” tells the B hamstring muscle to relax so that the quadriceps muscle can contract unopposed? _____________________________. 5. Think back to Activity 6 in Lab 3. The quadriceps and hamstrings are an example of an antagonistic pair of muscles. What does this mean? _______________________________ ________________________________________________________________________ ________________________________________________________________________ Human Biology: Lab 4 4.3 ACTIVITY 4: REACTION TIME This fun demonstration allows you to appreciate the speed of your nervous system. During this exercise, think about the amount of time it takes your cerebrum to send information to the spinal cord and then on to your hand… Go to faculty.washington.edu/chudler/java/reacttime.html (also on Canvas under Lab 4). You will do this “experiment” a total of 7 times. An experiment consists of 5 reaction times; the game reports your average for these 5 reaction times (along with total time). The first experiment is a “throw away” so you can familiarize yourself with how this works. Then do the experiment 3 times with your right hand, and 3 times with your left hand. Follow the instructions on the webpage. Note: the New Experiment button may or may not work for you. Paste in the url again and the page will reset. How did you do? Report your average time for an experiment of 5 reaction times. Repeat the experiment two more times to see if you improve or stay the same. Average time Right hand Average time Left hand Experiment 1 Experiment 2 Experiment 3 1. Did you improve with time? ____________________ 2. Did you do better, worse or about the same with your dominant hand? (That is, the hand you write with.) _____________________________. Since these experiments are testing a voluntary response, you might expect to see better results with your dominant (i.e. “more coordinated” hand). ACTIVITY 5: A NERVOUS EXPERIMENT (Brittany Sanner, Arizona State University) The nervous system is essential in relaying information about our environment to the brain, and the brain’s “decision” back to the body. But some areas of the body are more sensitive to stimulation than others. Discussion: Nervous System & Sensory Reception

This activity will take you through investigating this phenomenon. First, think about how sensitive your fingertips, arm and back are. Write down a hypothesis here to predict what will happen if you poke these three areas with a paperclip. Hypotheses can be very simple. For example, I expect that __________________________ will be the most sensitive to stimulation because ______________________________. 4.4 Human Biology: Lab 4 Make your ‘nerve tester.’ Using the large paperclip in your Bio 21 packet, open the “arms” of the paperclip to make a lopsided square; adjust the ends so that you have a 4 cm gap (with each side being about 4 cm long. Use ruler included in your lab kit to measure. Collect data. Start by touching both ends of the paper clip to your fingertip (you don’t need to stab yourself – just a gentle touch is fine; see picture below). If you feel both ends of the paperclip, record this in the table below as a “2”. If you feel only one end, record as a “1”. (This first data point should be entered in the column “Fingertip” and the row “4 cm”.) Do the same thing (with the paperclip still opened at 4 cm) on your arm and shoulder (see figure below), but record these data point in the 3rd and 4th column of the table, respectively). Next, push the paper clip ends ½ centimeter closer, and poke yourself again on the fingertip, arm and shoulder. Record your data in the row in the table marked 3.5 cm. Repeat pushing the paper clip closer and closer at ½ centimeter intervals until you complete the table. Distance between paperclip ends Fingertip Upper arm Back 4 cm 3.5 cm 3.0 cm 2.5 cm 2.0 cm 1.5 cm 1.0 cm 0.5 cm End touching Key: 2 = felt both ends of the paperclip; 1 = felt only one end of the paperclip. Human Biology: Lab 4 4.5 1. Look at the direction of the nerves shown in the image on the right. Nerves run up and down the body and rarely side to side. Nerves can only send one signal at a time. Knowing this, why might you have felt both ends of the paper clip versus only one end? ________________ _______________________________________________________ _______________________________________________________ 2. What part of the body was the least sensitive?_________________ 3. What part of the body was the most sensitive? ________________ 4. Do your observations (data) support your hypothesis? __________ 5. Nature rarely wastes resources on something that is not needed for survival and reproduction. Thinking about adaptations, why would some parts of your body benefit from extra nerve supply? www.khanacademy.org/ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ ACTIVITY 6: EYES & EARS Below are illustrations of human ears and eyes. Using Chapter 12 in your textbook, identify the different parts of the eye and ear indicated on the diagrams, and then list their functions. Illustration by Fitz Vo by permission. 4.6 Human Biology: Lab 4 Part of the Eye Function Cornea Retina Lens Pupil Fovea (not shown on the diagram above) 1. What part of the eye is affected by “Lasik” surgery? (go to Google for help if necessary!) Illustration by Fitz Vo by permission. Parts of the Ear Function Pinna Tympanic Membrane Malleus, Incus, and Stapes Cochlea Auditory Canal Eustachian Tube 2. What is the scientific name for the ear drum?____________________________________ Human Biology: Lab 4 4.7 ACTIVITY 7: PUPILLARY REFLEX (OPTIONAL) The pupillary reflex causes your pupils (the opening of the eye) to dilate or constrict to accommodate the amount of light that enters the eye. This reflex is involuntary. You will need a flashlight (or use the flashlight on your phone) and a person to help you with this. a. Shine the flashlight into one of your helper’s eyes and observe the response. b. Turn the flashlight off and observe the response. c. Ask your helper if he or she was aware of the pupil’s response. d. Now reverse roles and repeat. Answer the following questions about the pupillary reflex. 1.Discussion: Nervous System & Sensory Reception

When the light was shined in your helper’s eyes, did the pupil get larger or smaller? 2. When you turned off the light (after shining it in the helper’s eyes), did you’re the pupils of your helper get larger or smaller? 3. Was your helper aware of the pupil changing size? 4. Why does the pupil size change with the amount of light? ACTIVITY 8: BLIND SPOT We have a blind spot in our field of vision because there is an area in the back of the eye where the optic nerve and blood vessels enter/exit the eyeball. Being a hole, there can naturally be no photoreceptors present, which is what we require to see. This activity will allow you to “see” for yourself your blind spot. You received a card in your Bio 21 packet with a dot and a + on it. www.moorfields.nhs.uk/co ntent/anatomy-eye a. Cover your right eye with your right hand. Hold the card in your left hand at eye level about a foot away from your face. b. With your left eye, look at the +. Move the card very slowly back and forth until the dot disappears. The dot will only disappear at a very precise spot and only for a few seconds if you keep moving the card. Here’s a very short Youtube showing this procedure: https://www.youtube.com/watch?v=QXzgokis33I 1. About how far from the tip of your nose does the dot disappear?_____________________ 2. Why does the dot disappear? _______________________________________________ 4.8 Human Biology: Lab 4 ACTIVITY 9: SPINAL NERVES, EYES AND EARS WORKING TOGETHER Our sense of balance relies on information (cues) from the ears and the eyes. The cerebellum uses this information to help us keep our balance. If both of these cues are missing, we have difficulty keeping our balance. Try the following: Use a timer to record accurate time. a. Stand with both feet together. b. Lift one foot 6 inches off the floor, bending your knee at a 45-degree angle. If you’re righthanded, lift your left leg. If you are left-handed, lift your right leg. Don’t move your foot. c. Start the timer (it helps if you can find someone to do this for you!). Record in the table below how long you can maintain your balance. Now try this: a. Stand with both feet together. b. Close your eyes and lift one foot 6 inches off the floor, bend your knee at a 45-degree angle. If you’re right-handed, lift your left leDiscussion: Nervous System & Sensory Receptiong.  Discussion: Nervous System & Sensory Reception

If you’re left-handed, lift your right leg. c. Start the timer (this time it really helps having someone to do this for you!). Record how long you can maintain your balance in the table below. Note: The older you are, the harder it will be for you to keep your balance because information from the neurons travels at slower rate with age. Balance Time With Eyes Open With Eyes Closed Human Biology: Lab 4 MORE 4.9 ACTIVITY 10: HEARING EDUCATION AND AWARENESS FOR ROCKERS (H.E.A.R.) Recall the last time you went to a club or a concert. If you experienced ringing in your ears – either during or after – your ears sustained hearing damage. According to the H.E.A.R. website, “Damage from loud sound can occur from playing music, attending concerts, dance clubs, raves, using stereo earphones, playing amplified systems too loudly, or other noisy activities.” And if you think the government is looking out for you while you have fun, you’re mistaken. OSHA (Occupational Safety and Health Administration) only protects you on the job. (Although there is a notable exception – San Francisco has an “Earplug Ordinance” for San Francisco clubs.) Promoters, club managers and owners, and musicians routinely determine the loudness of music at concerts and clubs. And if you think their choices are informed and wise, you’d be mistaken there, too.

Keep in mind that the phenomenon of loud music isn’t that old – maybe three or four decades. We’re now finding all too often (and too late) that loud music causes hearing damage, loss, and deafness. This week we’re pointing you to a website created by musicians for music fans, DJs, sound engineers, and other musicians. Go to the links below (also on Canvas under Lab 4) and answer the following. www.hearnet.com/at_risk/risk_tinnitus.shtml 1. What is tinnitus? 2. What things aggravate tinnitus? 3. What should you do if you experience tinnitus? www.hearnet.com/at_risk/risk_aboutloss.shtml 4. At a typical rock concert where the music is between 110 and 120 dB, how long can you listen (with unprotected ears) before sustaining hearing damage and/or loss? www.hearnet.com/at_risk/risk_at_risk1.shtml 5. List three precautions you can take to protect your hearing at concerts and clubs? a. b. c. 6. List two precautions concert venues and clubs can take to protect patrons’ hearing? a. b. 4.10 Human Biology: Lab 4 …