Bio 102 Lab 06, Nervous System and Sensory Reception (1)trnin PDF

Preview

Summary

Download Bio 102 Lab 06, Nervous System and Sensory Reception (1)trnin PDF

Description

Bio 102 Lab 06, Nervous System and Sensory Reception Copyright © 2020 by Mary Vander Maten, Jill Caporale, and Karla Henthorn

To submit, print pages , complete all lab activities and answer the review questions, scan your lab pages using the free phone app AdobeScan, and upload your PDF to Canvas. If you have a disability that makes it difficult to complete this lab, please contact your instructor. Please provide your instructor a copy of the Memorandum of Accommodation (MOA) from NVCC Disability Support Services.

OBJECTIVES After completing this lab, you should be able to: •

Label and identify the parts of a typical neuron.

•

Trace a reflex arc.

•

Be able to identify the form and function of white and grey matter in the brain and spinal cord.

•

Label designated parts of the eye.

•

Label designated parts of the ear.

•

Describe the results of sensory tests performed in the lab.

The basic conducting unit of the nervous system is the neuron. Neurons pick up information through dendrites and are capable of transmitting chemical information along the axon to other neurons, muscles, or glands through electrical conduction down the axon. In this lab we will investigate three types of neuronal transmission: 1. 2. 3.

Sensory neurons that transmit information from sense organ or receptors in eyes, ears, taste buds, olfactory organs, and sense receptors of the skin. Interneurons that make up most of the neurons in the brain and spinal cord. Motor neurons that transmit signals to muscles.

In addition to neurons, nervous tissue contains many supporting cells called glia. Glial cells have a number of different roles that support and protect the nervous system. One of the types of glial cells is the Schwann cell that wraps around the axon in motor neurons to make a protective layer, the myelin sheath.

1 Bio 102 Lab 06, Nervous System and Sensory Reception

Exercise A: Motor Neuron

2 Bio 102 Lab 06, Nervous System and Sensory Reception

3 Bio 102 Lab 06, Nervous System and Sensory Reception

Exercise B: Simple Reflex The patellar reflex, also known as the knee-jerk response, occurs when the patellar ligament, the ligament just under the knee bone, is stretched, resulting in an impulse that travels through the sensory neuron into the spinal cord and out to the motor neuron which triggers a contraction of the quadriceps muscle and causes an involuntary kick. Sit and relax your leg. Test that your leg is completely relaxed by gently swinging the leg to see that it moves freely. Once your leg is completely relaxed, find the gap just below the patella by feel. Then gently hit the patellar ligament with a gentle chop of your hand.

Your leg should respond with a kick,

Did the kick happen automatically?

yes Do you think the message needed to be transmitted to the brain for a response? no

4 Bio 102 Lab 06, Nervous System and Sensory Reception

Exercise C: Central Nervous System, White and Grey Matter The white matter appears white because it is lined with a myelin sheath. The myelin sheath cells have a higher fatty content, making the matter appear white, providing a sort of insulation, and facilitating a faster transmission of neurological impulses. Look at photographs of transverse section of the spinal cord. Identify the white and grey matter.

Is the white matter on the inside or outside? Outside

Is the grey matter on the inside or outside?

Inside 5 Bio 102 Lab 06, Nervous System and Sensory Reception

6 Bio 102 Lab 06, Nervous System and Sensory Reception

Look at a photograph of a brain section. Identify the white and grey matter.

Photo from Duke University

Is the white matter on the inside or outside? Outside Is the grey matter on the inside or outside Inside

7 Bio 102 Lab 06, Nervous System and Sensory Reception

Exercise D: Sensory Reception, Touch Receptors 1. Touch Receptors Examine a diagram of a cross-section of the skin and locate the touch receptors.

1) Which layer contains touch receptors called Pacinian corpuscles (hypodermis, dermis, or epidermis)? Hypodermis 2) Which layer contains touch receptors called Meissner corpuscles (hypodermis, dermis, or epidermis)? Dermis 3) By evaluating the location of the Pacinian and Meissner corpuscles, which type of receptor detects pressure and vibration? Pacinian 4) Which type of receptor detects light touch Meissner 2. Touch Sensitivity You will conduct what is referred to as a two-point touch test to determine sensitivity. This test is used by neurologists to determine how well a particular area of the skin is innervated. Set up the experiment as shown below.

8 Bio 102 Lab 06, Nervous System and Sensory Reception

Insert two pins in cardboard and gently touch the areas listed. Start so that you feel two pin points. Reduce the distance between the pins until you only feel one point. Record in the table below the smallest distance that two points were able to be perceived. Fingertip: ___4_ mm Back of hand: _6__mm What does the two-point discrimination test tell us about the sensitivity of the skin in that area? That the fingertips are more sensitive than the back of our hands. Our fingertips most likely contain more Meissner receptors, and the back of our hands contain more Pacinian receptors. How do you think this relates to the number, density, and type of touch receptors in that Through evolution, we adapted more sensitive receptors on our fingertips than the back of our hands because we are feeling more things with our fingertips than the back of our hands.

Exercise E: Sensory Reception, Vision, Hearing, Taste, and Smell The purpose of the eye is to bring in light and focus those light rays onto the retina at the back of the eyeball. Receptors in the retina send messages to the brain via the optic nerve. Rods are receptors that are stimulated by low light and therefore allow you to see at night. There are also three different types of cones that are sensitive at different wavelengths, thus allowing you to see color. The area containing the greatest density of cones is the fovea, and is directly in line with the center of the pupil. There are also photosensitive cells in the eye that do not aid in vision, but are rather thought to contribute to circadian rhythm—your sleep-wake cycle. 1. Eye Anatomy Identify the parts of the eye listed below: Use the diagram from your text (Campbell: Biology in Focus, 3rd edition, page 818).

9 Bio 102 Lab 06, Nervous System and Sensory Reception

10 Bio 102 Lab 06, Nervous System and Sensory Reception

2. Vision Tests A. Near point Hold a book in front of your face, and slowly bring it closer to your eyes. It will get blurry close to your eyes. Find the closest distance still in focus and have your partner measure the distance from your eyes to the book. Near point distance in cm: 10 How does near point discrimination change as a person ages? The near point decreases with age because the lens inside the eye becomes less flexible B. Blind spot This test tests for the “blind” spot in each eye where the retina has no receptors due to the presence of the optic nerve.

X

O

Close or cover your left eye. Stare at the X with your right eye with the screen very close to your face. Slowly move away from the screen and continue to stare at the X. When you notice the O disappear, you have found the blind spot in that eye. Repeat with the left eye (close or cover your right eye). Why are there no receptors in the blind spot of the retina?

11 Bio 102 Lab 06, Nervous System and Sensory Reception

Your blind spot is the location of where your optic nerve and retina connect. There are no receptors there. C. Afterimage When an image remains on the retina after the object is removed, that image is called an afterimage. If you saw a flash of bright light and then close your eyes and the image still remains it is probably because the photochemical response has continued even though the light no longer shines. This is a positive afterimage. If you stare at an image and fatigue the cones and rods in an area of the retina, you may also see an image beyond the source of the stimuli. This is referred to as a negative afterimage. To create a negative afterimage, rest your elbows on the table about two feet apart and hold your head steady using your hands cradled around the side of your face. Stare at the image for one minute without moving your head or eyes. Then shift your gaze to the plain white area next to the image.

www.Wikipedia.org

Scroll down on this Wikipedia page and watch the video to observe an illusion sometimes called a “motion aftereffect:” https://en.wikipedia.org/wiki/Afterimage

A similar video, with a little extra twist, is found here: https://www.youtube.com/watch?v=LFqnyeufcjs

12 Bio 102 Lab 06, Nervous System and Sensory Reception

D. Astigmatism, Color Vision, and Visual Acuity Test your vision with interactive eye tests for visual acuity, astigmatism, and color vision at https://www.essilor.com/en/vision-tests/test-your-vision/ . Astigmatism: Do you already know you have astigmatism? NO According to this test, do you have astigmatism? If so, in which eye(s)? I do not Color Vision: Sometimes an individual is born with a defect of certain cones (photoreceptors for color vision). This may result in difficulty differentiating colors, particularly red and green. Do you already know you are colorblind? no According to this test, do you have colorblindness? No The test shows 6 colored pictures. How many did you identify correctly? all six of them Visual Acuity: According to this test, does your left or right eye have greater acuity or do both eyes have equal visual acuity? Right According to the test, what was your rating of visual acuity? ☹, �, or � Eye Chart Repeat the test of visual acuity using an eye chart. Follow the instructions for downloading, printing, and using the eye chart at https://visionsource.com/patients/free-eye-chart-download/ Stand 10 feet from the chart. Cover one eye to determine how far down the chart you can read. Repeat with the other eye. What is your left eye acuity? 20/40 Right eye acuity? 20/40 What is your vision with both eyes open?

13 Bio 102 Lab 06, Nervous System and Sensory Reception

3. Ear Anatomy The outer ear gathers sound waves and directs them into the ear canal. The tympanic membrane (ear drum) vibrates, causing small ear bones to vibrate and transmit the sound to the cochlea. These vibrations travel through the fluid-filled cochlea, where receptors take the messages to the brain via the auditory nerve. Identify the parts of the ear listed below. Use the diagram from your text (Campbell: Biology in Focus, 3rd edition, page 815).

•

stapes

•

external auditory canal

•

semicircular canals

•

cochlea

•

incus

•

pinna (external ear)

•

malleus

•

tympanic membrane

•

inner ear

•

middle ear

•

auditory tube (Eustachian)

•

auditory nerve

14 Bio 102 Lab 06, Nervous System and Sensory Reception

4. Taste A. Map the area(s) of your tongue that can taste saltiness and sweetness. Sweetness: Mix 1 teaspoon of sugar in ¼ cup of water. Use a cotton swab dipped in the sugar water and then touched to a paper towel (to remove excess liquid). Touch the swab lightly to the left or right side of your tongue of your tongue. Do you taste the sweet flavor? Wait a minute and then repeat for the other areas of your tongue (back, center, tip), waiting a minute in between the tests of each tongue region. Mark the diagram to show which areas allow taste reception of sweetness. Saltiness: Mix 1 teaspoon of salt in ¼ cup water (some of the salt may not dissolve). Use a clean cotton swab to repeat the process of testing the different areas of your tongue. Mark the diagram to show which areas allow taste reception of saltiness.

15 Bio 102 Lab 06, Nervous System and Sensory Reception

Back of the tongue - Bitter Sides of the tongue - Salty Middle of the tongue Umami

16 Bio 102 Lab 06, Nervous System and Sensory Reception

17 Bio 102 Lab 06, Nervous System and Sensory Reception

18 Bio 102 Lab 06, Nervous System and Sensory Reception

Review Questions 1. How do Schwann cells speed nerve impulses? Schwann cell form a myelin sheath around nerve cell. Myelin formation is not continuous around the axon. Its discontinuous so there is a formation of a node. So in case of myelinated nerve fibers, nerve impulses jump from one node to another. 2. Which part of the neuron conveys impulses away from that neuron? Axon 3. Why do nerve tracts appear white? The myelin sheath is white. 4. What kind of touch do Pacinian corpuscles detect? Deep pressure touches and vibration. 5. How does touch sensitivity correlate to number of touch receptors? The area with greater density of touch receptors is more sensitive to touch than lower density touch receptors area. 6. What is astigmatism and how can it be corrected? Astigmatism is a condition of eyes which occurs when cornea or lens is curved more steeply in one direction than in another. It can be corrected with using spectacles or contact lenses. Another way to correct is refractive surgery using lasers. 7. Describe the location of the blind spot and explain why that portion of an image hitting this area of the eye does not convey information to the brain. Because this is where the optic nerve and the retina connect. There are no light receptors there. It located on the back of the reitina.

Bio 102 Lab 06, Nervous System and Sensory Reception 19 Bio 102 Lab 06, Nervous System and Sensory Reception

8. What causes negative afterimages and what is unique about colors in a negative afterimage? Negative after images are caused when eyes photoreceptors are prone to over stimulation and lose sensitivity. Negative afterimages exhibit colors complementary to the stimulus or on prolonged stimulus. 9. Sound waves hit the ear and sound vibrations cause other structures to vibrate. Number these structures in order of movement/stimulation: 2 malleous (hammer) 5 cochlear fluid 3 incus (anvil) 1 tympanic membrane 4 stapes (stirrup) 6 receptor cell 11. If a person has a car accident that injures their face, the sense of smell may be lost. How does this affect taste? If the person loses their smell, then the taste receptors become more active as a result, the tasting capabilities are enhanced.

20 Bio 102 Lab 06, Nervous System and Sensory Reception...