WEEK 3 ASSIGNMENT 1: REFLEXES Submission Instructions Please complete your answers to the lab questions on this form. Please complete your answers, and SAVE the file in a location which you will be able to find again. Then, attach and submit the completed form to the Week 3 Laboratory dropbox in the Ashford University classroom. Post-Lab Questions 1. What is the pupillary response of the right eye when a light was shone into the pupil? 2. What is the consensual response? (The response of the left eye). 3. What branch of the nervous system controls this response? 4. Can this response be inhibited? 5. Define what a reflex is. 6. Name five essential components of a reflex arc. © eScience Labs, 2013 WEEK 3 ASSIGNMENT 2: TESTING CRANIAL NERVE FUNCTIONS Result Tables Table 2: Cranial Nerve Function Testing Cranial Nerve Test Result Post-Lab Questions 1. What do your cranial nerve test results tell you? 2. When might these tests be used in a clinical setting? 3. What cranial nerve may not be functioning properly if a patient cannot detect taste on the anterior tongue? 4. What cranial nerve may not be functioning properly if a patient can move his/her eyes medial, superior, and inferior, but not lateral? © eScience Labs, 2013 WEEK 3 ASSIGNMENT 3: TESTING TOUCH, TEMPERATURE, AND PAIN Result Tables Table 3: Blind Coin Differentiation Coin Observation Guess Quarter Dime Nickel Penny Post-Lab Questions 1. Describe the difference between the four US coins. 2. Was the participant able to distinguish between these coins? 3. Which coin was the easiest to identify by touch? Which was the most difficult to distinguish by touch? 4. Why is the detection of temperature important to maintaining overall health? 5. Did the participant notice any difference between the amounts of pain reception in the different areas tested? © eScience Labs, 2013 © eScience Labs, 2013 WEEK 3 ASSIGNMENT 1: REFLEXES Nerve impulses travel through the nervous system via nerve pathways. A reflex is a rapid, involuntary response to a stimulus which occur over pathways called reflex arcs. Materials You must provide the following items to complete your experiment: • Participant • Flashlight Procedure 1. Before you begin the experiment, review the reflex arc animation in the Nervous System section of the eScience Labs Student Portal. 2. Find an area with dim lighting to conduct this experiment. 3. Stand next to the participant and instruct him/her to focus on a distant object. 4. Quickly shine the light into the right eye. 5. Wait 30 seconds and repeat the procedure with the left eye. Examine the response of the left eye. WEEK 3 ASSIGNMENT 2: TESTING CRANIAL NERVE FUNCTIONS Twelve pairs of nerves arise from the inferior area of the brain. The cranial nerves are numbered from I to XII indicating the order in which they originate from front to back. Each cranial nerve has a distinct function. This may be sensory, motor or both. Materials You must provide the following items to complete your experiment: • Participant • Various Materials (depending on test performed) Procedure 1. Review the cranial nerve information on the following page. This table describes the function and functional test used to examine each cranial nerve. 2. Pick three cranial nerves that can be tested independently of each other. Identify these nerves in Table 2. 3. Perform the test for each of the nerves you selected. Record the test you performed in Table 2. 4. Record the results of each test in Table 2. WEEK 3 ASSIGNMENT 3: TESTING TOUCH, TEMPERATURE, AND PAIN PERCEPTION PROCEDURE Receptors located throughout the integumentary system aid in our sensation of touch, temperature and pain. In this assignment you will test sensitivities to several stimuli. Materials You must provide the following items to complete your experiment: • Coins: Quarter, Dime, Nickel, and a Penny • Participant • Warm and Cold Water Baths • Needle or Pin Procedure Part 1 1. Place one of each type of coin (a quarter, dime, nickel and a penny) on a flat surface. 2. Instruct the participant to close his/her eyes. 3. Hand each coin separately to the participant and ask him/her to determine the relative diameter, the presences or absences of serrations and the thickness. 4. Record any observations in Table 3. Part 2 5. Prepare a warm and a cold water bath. 6. Instruct the participant to close their eyes. 7. Place participant’s hands in each of the two water baths. 8. Record any observations in Table 3. Part 3 9. Instruct the participant to close his/her eyes. 10. Gently press needle against the participant’s palm, fingertip and forearm. 11. Record any observations. Week 3 Lab Exercise (Introduction) Introduction The nervous system carries a large responsibility for maintaining the homeostasis within the body. It is the master control and communication center of the body. The nervous system allows the body to interpret, integrate, and react to the surrounding environment as well as the internal stimuli occurring simultaneously throughout the body. Voluntary actions such as writing, reading, or running, as well as involuntary actions such as the heart pumping blood through the body, the pancreas releasing enzymes, or the gut digesting food are monitored by this complex system. The importance of a properly functioning nervous system can be realized simply by considering how well protected the brain and spinal cord are. Disruptions to the nervous system could result from structural abnormalities, biochemical imbalances, neuronal damage, and microbial infections. Figure 1: Neurons are located all across the body, and allow impulses to travel from receptor cells to the central nervous system. The three main responsibilities of the nervous system are sensory input (for stimuli inside and external to the body), integration of sensory input, and a motor response by activating effector organs. To accomplish these substantial tasks, the nervous system is organized into two distinct sub-systems: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS includes the brain and the spinal cord.Nervous tissue that resides outside of the brain and spinal cord are included in the PNS. The PNS carries neural impulses to and from the brain. Figure 2: The brain, superior view. Note the areas that correspond to hearing and vision in addition to language and writing. The right and left cerebral hemispheres are connected by the corpus callosum (visible in a sagittal view), allowing them to coordinate actions. The Brain The master control center for the nervous system is the brain. This organ enables voluntary movements, interpretation and integration of sensation, consciousness, and cognitive function. Anatomically, the brain can be divided into several different structures and areas which perform specific functions (Figure 2 and Table 1). The brain is protected by the skull, a specialized covering called the meninges and cerebrospinal fluid. The Spinal Cord The spinal cord is a two-way impulse conduction pathway and a reflex center. It serves two main functions: the transmission of nerve impulses and spinal reflexes. It resides within the vertebral column and is protected by meninges and cerebrospinal fluid. Spinal nerves emerge from the spinal cord in pairs, one extending from each side. Thirty-one pairs of spinal nerve roots can be identified along the length of the spinal cord. Virtual Learning: Reflex Arc When examining a cross-section of the spinal cord (Figure 3), the central gray matter of the spinal cord appears H-shaped surrounded by white matter. The anterior horns of this gray matter are composed mainly of somatic motor neurons while the posterior horns contain visceral motor neurons and posterior horns contain interneurons that synapse with sensory neurons. Two major roots, or branches of the spinal nerve that connect to the spinal cord, are present in the spinal cord: ventral and dorsal roots. Ventral roots enter the ventral side of the spinal cord, and contain motor nerve axons responsible for transmitting impulses to skeletal muscles. Dorsal roots enter the dorsal side of the spinal cord, and contain sensory nerve fibers that relay impulses from peripheral regions of the body to the spinal cord. Dorsal root ganglions are clusters of sensory nerve cell bodies that reside on the dorsal root. Figure 3: The spinal cord. Virtual Learning: The 12 Cranial Nerves Neurons and Glial Cells There are two principle cell types within the nervous tissue. Neurons are the excitable cells that transmit electric impulses, while glial cells surround and wrap neurons to aid in their functionality. Neurons are the structural units of the nervous system. They are composed of a body containing the nucleus, an axon which arises from the axon hillock of the cell body, and dendrites and their plasma membrane function in electrical signaling.Neurons can be classified structurally into the following groups based on the number of processes that extend from the cell body: multipolar (the majority of neurons in the body), bipolar (sensory neurons found in the special senses), and unipolar (located in the CNS). Figure 4: Multipolar neuron. In addition to the above receptors, the nervous system also features many specialized functions which rely on organs and cells with precise locations and utility. These functions are often referred to as the five senses, or specialized senses. These senses are vision, hearing, balance, taste and smell. Consider the importance of these senses for the well-being of an individual. Taste, for example, allows one to detect bitter and possibly poisonous substances in addition to enhancing ingestion of needed nutrients. Virtual Learning: The Sense of Hearing Vision and the Eye Vision is dependent on the ability to respond to external stimuli; as well as the interaction between the CNS and the eye. Light-sensitive cells found on the surface of the retina field optical images, which can be translated into a meaningful picture through the nervous system. Virtual Learning: The Sense of Sight The eye is a spherical, approximately 2.3 cm in diameter, structure housed in the orbital sockets of the skull (Figure 5). The majority of the eye consists of two fluids: aqueous humor and vitreous humor. Aqueous humor fills the empty space between the cornea and the iris, as well as the iris and the lens. This fluid is clear, and water like in viscosity. It enhances vision by providing shape, structure, and nutrients to the eye. Vitreous humor fills the primary cavity of the eye. It is a gel-like substance estimated to be composed of approximately 99% water. This fluid provides structure and support, but does not offer nutritional value. Figure 5: Eye anatomy. Three primary layers are responsible for the majority of eye function. The first layer consists of the sclera and the cornea. The sclera is a thin membrane which encloses and protects the eyeball. This membrane contributes to the firm, white component of the eye. The cornea is located within the sclera, but is only present near the front (outward facing) region of the eye. The cornea projects slightly outward, and is a very delicate membrane which allows light rays to pass into the eye. The second layer consists of the choroid, the ciliary body, and the iris. The choroid is enriched with blood vessels which nourish the eye with oxygen, zinc, and other nutrients. The iris forms a round, pigmented layer beneath the cornea and accounts for eye color. The “opening” near the center of the iris is called the pupil. The pupil is a dark aperture which can contract or dilate to control the amount of light entering the interior of the eye. This function is useful when the amount of light available is insufficient (e.g., at night) or excessive (e.g., bright lights). The retina sits beneath the choroid, comprising the third layer. This layer includes an outer layer of rods and cones, a middle layer of bipolar neurons, and an inner layer of ganglion cells. Combined, these three layers of the retina exhibit the neural component of vision. Rods and cones are specialized photoreceptors which translate light waves into electrical signals (neural impulses). Axons of the ganglion cells form the optic nerve, which carries neural impulses to the brain. In this way, the optic nerve is considered part of the eye as well as part of the brain. The brain then interprets the impulses delivered by the optic nerve into a meaningful image. Hearing and the Ear Hearing is another one of the five senses. Similar to vision, hearing is dependent on coordination with the CNS; and, similar to the eye, the ear has three primary layers. Hearing is also very specialized as the brain must isolate different sounds using pitch, intensity, and timbre. However, the ability to hear something requires the nervous system to transform sound waves into a meaningful noise. The first layer is called the external ear. The external layer includes the pinna (the ear), external auditory meatus (ear canal), and tympanic membrane (ear drum). The pinna is the visible, skin-covered portion of the cartilage which projects on the outside of the head. This layer is responsible for collecting sound waves from the external environment and funneling them into the external auditory meatus. The pinna also filters certain sound waves prior to entering the external auditory meatus, resulting in a narrowed range of sound waves which can be used for hearing.The remaining sound waves cause the tympanic membrane to vibrate according to the frequency of the sound waves. The vibration of the tympanic membrane sets off a domino effect of vibrations, beginning with the bones of the middle ear. These bones, termed the incus, stapes, and the malleus, vibrate at the same frequency of the tympanic membrane. This vibration causes a feature on the stapes called the oval window to vibrate and trigger vibrations throughout the inner ear fluid. The inner ear is primarily composed of the cochlea, a coiled tube which is often described as looking like a snail shell. The cochlea is dependent on the Organ of Corti, which contains auditory sensory receptor cells. Every receptor cell is married to a hair cell which is able to open and trigger a series of electrochemical interactions which eventually reaches the primary auditory cortex located in the superior temporal gyrus. Here, sounds can be processed and hearing results. Figure 6: Ear anatomy. Virtual Learning: Ear Anatomy
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