anatomy and physiology of sensory system ppt

The inner ear contains the cochlea and vestibule, which are responsible for audition and equilibrium, respectively. Light touch is transduced by the encapsulated endings known as tactile (Meissner) corpuscles. Raised bumps called papillae (singular = papilla) contain the structures for gustatory transduction. A sound wave causes the tympanic membrane to vibrate. For this reason, capsaicin can be used as a topical analgesic, such as in products such as Icy Hot. Rod outer segments are long columnar shapes with stacks of membrane-bound discs that contain the rhodopsin pigment. Also located in the dermis of the skin are lamellated corpuscles, neurons with encapsulated nerve endings that respond to pressure and touch. The main sensory modalities can be described on the basis of how each is transduced. shape of the eye. Concentration 1: _____________ Concentration 2: _____________ Concentration 3: _____________ Concentration 4: _____________ Concentration 5: _____________. Light with a wavelength of 380 nm is blue whereas light with a wavelength of 720 nm is dark red. Using a tuning fork, have a subject sit with their eyes closed. The types of nerve endings, their locations, and the stimuli they transduce are presented in Table 14.1. The macula is composed of hair cells surrounded by support cells. Non-tasters can taste food, but they are not as sensitive to certain tastes, such as bitterness. Possible cuts include: To be able to best see the eyes structures, you should work very carefully. The cochlear duct contains several organs of Corti, which transduce the wave motion of the two scala into neural signals. These odorant molecules bind to proteins that keep them dissolved in the mucus and help transport them to the olfactory dendrites. Choroid body muscles surround the lens. These ganglia are located within the spiral-shaped cochlea of the inner ear. Eyelid. Other somatosensory receptors are found in the joints and muscles. The neurons can then communicate with other neurons in the nervous system via synapses and networks to coordinate responses. Light striking photoreceptor neurons activate networks of retinal neurons. Plate #: _______________ Image that you see: _____________. Our mission is to improve educational access and learning for everyone. Anatomy & Physiology Lecture 2301 (Martini text-Pearson) (2301 13978) Course Materials; Pearson PowerPoints (fundamentals A&P 11th edition) Pearson PowerPoints (fundamentals A&P 11th edition) Lecture PowerPoint slides from the textbook In addition, each photoreceptor cell of the fovea is connected to a single RGC. The group of axons called the olfactory tract connect to the olfactory bulb on the ventral surface of the frontal lobe. Receptor cells can be further categorized on the basis of the type of stimuli they transduce. Protein fibers tether adjacent hairs together within each array, such that the array will bend in response to movements of the basilar membrane. Other cranial nerves contain both sensory and motor axons, including the trigeminal, facial, glossopharyngeal, and vagus nerves (however, the vagus nerve is not associated with the somatic nervous system). Cell Biology, 2010 vol. Because of this, it will decrease the ability of other stimuli to elicit pain sensations through the activated nociceptor. In addition, two separate clusters of hair cells the saccule and utricle are oriented to detect vertical and horizontal movements. Young, James A. People fall into two groups known as tasters and non-tasters based on the density of papillae on their tongue, which also indicates the number of taste buds. By containing toxic alkaloids, the plant is less susceptible to microbe infection and less attractive to herbivores. Other species and artificial technologies can detect other parts of this energy spectrum. The sweet taste is the sensitivity of gustatory cells to the presence of glucose dissolved in the saliva. (b) Tissue of the retina shows a dense layer of nuclei of the rods and cones. The unit of Hertz measures the frequency of sound waves in terms of cycles produced per second. Some cranial nerves contain only sensory axons, such as the olfactory, optic, and vestibulocochlear nerves. Therefore, as the frequency of a sound changes, different hair cells are activated all along the basilar membrane. Are you very sensitive to tastes? Specific wavelengths of sound cause specific regions of the basilar membrane to vibrate, much like the keys of a piano produce sound at different frequencies. sucrose), Bitter (various, common test is Ca2+), sour (H+), and umami (glutamate). Stressed or damaged tissues release chemicals that activate receptor proteins in the nociceptors. Once any sensory cell transduces a stimulus into a nerve impulse, that impulse has to travel along axons to reach the CNS. However, at the exact center of the retina is a small area known as the fovea. These cells release neurotransmitters onto a bipolar cell, which then synapses with the optic nerve neurons. The eyes are located within either orbit in the skull. The stereocilia of the hair cells extend into a viscous gel called the otolithic membrane (Figure 14.11). 6.3: Somatosensation Photoreceptors in the eyes, such as rod cells, are examples of (c) specialized receptor cells. Why or why not? Movements of the head cause dislocations of the fluid in the chambers around the hair cells. The sphere of the eye can be divided into anterior and posterior chambers. Odorants can be detected by some sensitive individuals at concentrations below the micromolar range. On top of the otolithic membrane is a layer of calcium carbonate crystals, called otoliths. What is the distance between the fovea and optic disk in your left eye? The angle of the tendon through the trochlea means that contraction of the superior oblique rotates the eye laterally. The images in your peripheral vision are focused by the peripheral retina, and have vague, blurry edges and words that are not as clearly identified. Bulbous corpuscles are also known as Ruffini corpuscles, or type II cutaneous mechanoreceptors. The dynamics of capsaicin binding with this transmembrane ion channel is unusual in that the molecule remains bound for a long time. Connections between the body and the CNS occur through the spinal cord. The membrane covering the round window will bulge out or pucker in with the movement of the fluid within the scala tympani. Perception is dependent on sensation, but not all sensations are perceived. Can you explain any differences? Describe the arrangement of sensory and motor regions in the spinal cord. However, the tendon of the oblique muscles threads through a pulley-like piece of cartilage known as the trochlea. Until recently, only four tastes were recognized: sweet, salty, sour, and bitter. The difference in inertia between the hair cell stereocilia and the otolithic membrane in which they are embedded leads to a shearing force that causes the stereocilia to bend in the direction of that linear acceleration. HISTORICAL NOTE: The standard map of taste buds common in many lab manuals has been disproved by subsequent research (J. Learning Objectives. consent of Rice University. Individuals can map their tongues for taste buds, once sensitivity thresholds have been determined. At the molecular level, visual stimuli cause changes in the photopigment molecule that lead to changes in membrane potential of the photoreceptor cell. Others project to structures within the limbic system and hypothalamus, where smells become associated with long-term memory and emotional responses. Use a microscope to explore the cellular aspect of a taste bud. Accessibility StatementFor more information contact us atinfo@libretexts.org. Comparison of Color Sensitivity of Photopigments. As a result, a large part of the neural function of the eyes is concerned with moving the eyes and head so that important visual stimuli are centered on the fovea. Stand there and cover one eye without squinting. Comparing the peak sensitivity and absorbance spectra of the four photopigments suggests that they are most sensitive to particular wavelengths. There are at least 30 different genes coding for bitter taste receptors. Overlaying the ciliary body, and visible in the anterior eye, is the iristhe colored part of the eye. The outermost layer is the fibrous tunic, which includes the white sclera and clear cornea. The semicircular canals contain several ampullae, with some oriented horizontally and others oriented vertically. Gustation is the special sense associated with the tongue. They can also be classified functionally on the basis of the transduction of stimuli, or how the mechanical stimulus, light, or chemical changed the cell membrane potential. Legal. Without moving your eyes off that word, notice that words at the beginning or end of the paragraph are not in focus. A special sense is one that has a specific organ devoted to it, namely the eye, inner ear, tongue, or nose. Possible Specimens & Models for examination: (sheep or cow) eyeballs for dissection, microscope slides of the retina, and models of eyes. The tube is normally closed but will pop open when the muscles of the pharynx contract during swallowing or yawning. Patterns of signals are integrated in the cerebellum and parietal cortex. Vision is the special sense of sight that is based on the transduction of light stimuli received through the eyes. what type of matter or energy they detect and subsequently transduce to produce our perceptions (e.g. Proprioceptors - near junction General Sense Organs between tendons and muscles. They preferentially absorb light at different wavelengths, shown in the figure below. The middle ear is connected to the pharynx through the Eustachian tube, which helps equilibrate air pressure across the tympanic membrane. Sphere. are not subject to the Creative Commons license and may not be reproduced without the prior and express written Proprioceptive Sensations- relating to the physical state of the body (position, tendons, muscles, equilibrium) Visceral Sensations- sensations from the internal organs Deep Sensations- come from the deep tissues (fascia, muscles, and bone) 4 Detection and Transmission of Tactile Sensations Interrelaitons Among the Tactile Sensations of Touch, The nasal epithelium, including the olfactory cells, can be harmed by airborne toxic chemicals. In order to get to the first layer, the sclera, you may have to clear away some fat and connective tissue. Toward the edges of the retina, several photoreceptors converge on RGCs (through the bipolar cells) up to a ratio of 50 to 1. Humans have five special senses: olfaction (smell), gustation (taste), equilibrium (balance and body position), vision, and hearing. The movement of two canals within a plane results in information about the direction in which the head is moving, and activation of all six canals can give a very precise indication of head movement in three dimensions. In this example, the ON-center cell will send a maximum rate of action potentials along its axon (in the optic nerve) to the brain if the brightest light is striking photoreceptors near the center of its portion of the retina and the surrounding photoreceptors in that portion are receiving minimal light. (Micrograph provided by the Regents of University of Michigan Medical School 2012), (a) The olfactory system begins in the peripheral structures of the nasal cavity. Watch this animation to learn more about the inner ear and to see the cochlea unroll, with the base at the back of the image and the apex at the front. Osmoreceptors respond to solute concentrations of body fluids. With your right eye (left closed), stare at the cross, and move the paper towards your eyes until the circle disappears. Sensory neurons can have either (a) free nerve endings or (b) encapsulated endings. The extraocular muscles are innervated by three cranial nerves. There are four types of papillae, based on their appearance (Figure 14.3): circumvallate, foliate, filiform, and fungiform. Uploaded on Jan 02, 2020 James P Dunbar + Follow tion visceral pain pain transmission noxious stimuli referred visceral pain Whereas spinal information is contralateral, cranial nerve systems, with some exceptions, are mostly ipsilateral, meaning that a cranial nerve on the right side of the head is connected to the right side of the brain. Taste can be identified using solutions of chemicals known to stimulate distinct receptor proteins. If you drag your finger across a textured surface, the skin of your finger will vibrate. By comparing the activity of the three different cones, the brain can extract color information from visual stimuli. The transparent cornea covers the anterior tip of the eye and allows light to enter the eye. b. Merkel disks - attached to nerve endings of the epidermis. When the pressure waves from the scala move the basilar membrane, the tectorial membrane slides across the stereocilia. Eventually, there are electrical and chemical signals within our brains. Similar to the olfaction tests, serial dilutions of basic chemicals can be used to test for variable sensitivity in subjects. All of our muscles and organs depen. She recognized that her sense of taste was unique compared with other people she knew. The tongue is covered with small bumps, called papillae, which contain taste buds that are sensitive to chemicals in ingested food or drink. Using the model of the ear find the following structures: ear canal, tympanum (tympanic membrane), ossicles (malleus, incus, stapes in order moving inward into the ear), cochlea, semicircular canals. When a large group of photopigments is bleached, the retina will send information as if opposing visual information is being perceived. The superior oblique originates at the posterior orbit, near the origin of the four rectus muscles. The fluid-filled tube, now called the scala tympani, returns to the base of the cochlea, this time travelling under the cochlear duct. The otoliths essentially make the otolithic membrane top-heavy. a. Stimuli from varying sources, and of different types, are received and changed into the electrochemical signals of the nervous system. Students can then test for sensitivities for each by starting with a series at the low end of the concentrations. Physical changes in these proteins increase ion flow across the membrane, and can generate an action potential or a graded potential in the sensory neurons. The middle ear contains the ossicles and is connected to the pharynx by the Eustachian tube. The olfactory receptor neurons are located in a small region within the superior nasal cavity (Figure 14.4). Once the gustatory cells are activated by the taste molecules, they release neurotransmitters onto the dendrites of sensory neurons. This complexity allows you to be aware of your surroundings and take appropriate actions. They provide information about the position or movement of different parts of the body as well as the length and extent of contraction along with muscle tension. Therefore, visual acuity, or the sharpness of vision, is greatest at the fovea. Modality refers to the way that information is encoded, which is similar to the idea of transduction. For example, when the superior rectus contracts, the eye rotates to look up. The Eustachian (or auditory) tube connects the middle ear cavity to the pharynx (it is an evolutionary descendant of pharyngeal pouches). Explain your answer. Other monosaccharides such as fructose, or artificial sweeteners such as aspartame (NutraSweet), saccharine, or sucralose (Splenda) also activate the sweet receptors. In humans, from 100-200 different functional receptor proteins have been identified (there are over 1000 in rodents). Blunt force trauma to the face, such as that common in many car accidents, can lead to the loss of the olfactory nerve, and subsequently, loss of the sense of smell. Visual acuity refers to the sharpness or clarity of vision and is an indication of the focusing capacities of your eyes, especially the lens and cornea. Receptors are the cells or structures that detect sensations. The large, fleshy structure on the lateral aspect of the head is known as the auricle. When it contracts, it laterally rotates the eye, in opposition to the superior oblique. The general sense that is usually referred to as touch includes chemical sensation in the form of nociception, or pain. Watch this video to learn about Dr. Danielle Reed of the Monell Chemical Senses Center in Philadelphia, Pennsylvania, who became interested in science at an early age because of her sensory experiences. Other transmembrane proteins, which are not accurately called receptors, are sensitive to mechanical or thermal changes. Tilting the head causes the otolithic membrane to slide over the macula in the direction of gravity. Phenylthiocarbamide (PTC), also known as phenylthiourea (PTU), is only detected by ~70% of the population on average. Before interacting with a photon, retinals flexible double-bonded carbons are in the cis conformation. Each of the senses is referred to as a sensory modality. Rotational movement of the head is encoded by the hair cells in the base of the semicircular canals. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. The retinal molecule has two isomers, (a) one before a photon interacts with it and (b) one that is altered through photoisomerization. The cochlea encodes auditory stimuli for frequencies between 20 and 20,000 Hz, which is the range of sound that human ears can detect. For example, in the retina, axons from RGCs in the fovea are located at the center of the optic nerve, where they are surrounded by axons from the more peripheral RGCs. Sour flavors are, essentially, the perception of acids in our food. Dr. Reed discovered that she is a non-taster, which explains why she perceived bitterness differently than other people she knew. There are two types of photoreceptorsrods and coneswhich differ in the shape of their outer segment. All of the other muscles are innervated by the oculomotor nerve, as is the levator palpebrae superioris. When the frontal lobe of the brain moves relative to the ethmoid bone, the olfactory tract axons may be sheared apart. View the University of Michigan WebScope to explore the tissue sample in greater detail. Ichikawa et al., ISBN 0-89640-030-1). Sour taste is the perception of H+ concentration. sodium ions), Various neurons that respond to physical movements, Neurons responding to stretch and contraction of muscles & tendons. Tasting PTC is correlated with the dominant genotype. Textbook content produced by OpenStax is licensed under a Creative Commons Attribution License . Photoreceptors in the eyes, such as rod cells, are examples of (c) specialized receptor cells. Information is integrated along the brain stem and in the temporal cortex. In addition, certain pharmaceuticals, such as antibiotics, can cause anosmia by killing all the olfactory neurons at once. The same is true for the inferior rectus, which is compensated by contraction of the inferior oblique. The axons of RGCs, which lie at the innermost layer of the retina, collect at the optic disc and leave the eye as the optic nerve (see Figure 14.15). The eyelids, with lashes at their leading edges, help to protect the eye from abrasions by blocking particles that may land on the surface of the eye. The highest concentration of bitter receptors appear to be in the posterior tongue, where a gag reflex could still spit out poisonous food. Follicles are also wrapped in a plexus of nerve endings known as the hair follicle plexus. The essential component is neurons, the major functional cells in nervous tissue. Along with audition, the inner ear is responsible for encoding information about equilibrium, the sense of balance. For humans, the only electromagnetic energy that is perceived by our eyes is visible light. Retinal is a hydrocarbon molecule related to vitamin A. They are the superior rectus, medial rectus, inferior rectus, and lateral rectus. The perceived sensations correspond to common chemicals: Salty (Na+), Sweet (disaccharides, e.g. Have your partner stand near the chart and tell you which line to read starting from the top. The superior oblique is innervated by the trochlear nerve. The taste known as umami is often referred to as the savory taste. The sensory receptors detect the surroundings, like temperature changes and the central nervous system controls our body. Also, we may have perceptions that are only present in the brain, even though the sensory organs are silent. Solutions can be prepared from common ingredients to test for sensitivity. When the stereocilia bend toward the tallest member of their array, tension in the protein tethers opens ion channels in the hair cell membrane. Sensory System f Sensory Organs (Receptors) Monitor the internal and external environment Transmit signals from periphery to CNS for processing Critical for homeostasis f Types of Sensory Receptors Functional Types Based on modality (type of environmental change they sense) 1. Concentration 1: ______________ Concentration 2: ______________ Concentration 3: ______________ Concentration 4: ______________ Concentration 5: ______________. The photoisomerization is reversed by a series of enzymatic changes so that the retinal responds to more light energy. The essential component is neurons, the major functional cells in nervous tissue. __________________ Average distance? Transmembrane receptors are activated by chemicals called ligands. In a darkened room, there is not enough light to activate cone opsins, and vision is entirely dependent on rods. The center of the retina has a small indentation known as the fovea. Perception is the central processing of sensory stimuli into a meaningful pattern. This means that its receptors are not associated with a specialized organ, but are instead spread throughout the body in a variety of organs. These receptors are G proteincoupled, and will produce a graded membrane potential in the olfactory neurons. This book uses the The molecule that activates this receptor is the amino acid L-glutamate. The scala tympani ends at the round window, which is covered by a membrane that contains the fluid within the scala. See Full PDF Download PDF Related Papers THE SKELETON BONES AND JOINTS The malleus is attached to the tympanic membrane and articulates with the incus. For example, a molecule in food can serve as a ligand for taste receptors. Anatomy and Physiology Anatomy is the branch of science that deals with the structure (morphology) of body partsforms and organization. As airborne molecules are inhaled through the nose, they pass over the olfactory epithelial region and dissolve into the mucus. Rhodopsin, the photopigment in rods, is most sensitive to light at a wavelength of 498 nm. These cells are located within the vestibule of the inner ear. When you can no longer read a line accurately with one eye, then this is the acuity for that eye. In addition to describing anatomy and function, the book also provides insight as to how sensory information is processed in the brain to provide the basis for . This vibration is amplified as it moves across the malleus, incus, and stapes. Physiology concerns the functions of body partswhat they are and what they do. Hearing involves the signal transduction of mechanical waves into neural signals in the cochlea, within the inner ear. A photon interacting with the molecule causes the flexible double-bonded carbons to change to the trans- conformation, forming all-trans-retinal, which has a straight hydrocarbon chain (Figure 14.17). There is more variability among individuals than accounted for by the original 1942 map (not shown, intentionally). Of course, it is often sweetened so that the sour taste is masked. BIO 1414 Human Anatomy & Physiology II - BIO 1414 Human Anatomy & Physiology II Unit 3 Autonomic Nervous System and Senses Part 1 By: Robert F. Allen, Professor of Biology Conjunctiva Covers the inner . Based on the animation, where do frequenciesfrom high to low pitchescause activity in the hair cells within the cochlear duct? Anosmia may also be related to some presentations of mild depression, because the loss of enjoyment of food may lead to a general sense of despair. Many of the somatosensory receptors are located in the skin, but receptors are also found in muscles, tendons, joint capsules, ligaments, and in the walls of visceral organs. Only a few recognized submodalities exist within the sense of taste, or gustation. There are three cone photopigments, called opsins, which are each sensitive to a particular wavelength of light. Muscles in the iris alter pupil size to vary light entering the eye. Bulbous corpuscles are also present in joint capsules, where they measure stretch in the components of the skeletal system within the joint. The absorbance of rhodopsin in the rods is much more sensitive than in the cone opsins; specifically, rods are sensitive to vision in low light conditions, and cones are sensitive to brighter conditions. If you differ, then provide a possible explanation as to why: This lab has been adapted from Rice University and is licensed under a Creative Commons Attribution License License (3.0). For example, a bright blue light that has a wavelength of approximately 450 nm would activate the red cones minimally, the green cones marginally, and the blue cones predominantly. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix. Differentiate between upper motor neuron and lower motor neuron diseases. In many sensory organs, additional cells and tissues will contribute to the process of signal transduction. The organ of Corti, containing the mechanoreceptor hair cells, is adjacent to the scala tympani, where it sits atop the basilar membrane. You can repeat this with your left eye, staring at the circle. Until the retinal molecule is changed back to the 11-cis-retinal shape, the opsin cannot respond to light energy, which is called bleaching. Check with your instructor to determine which way they want you to cut the eye in half. Patterns of olfactory neuron activity can code for complex odors, integrated within the olfactory bulb and temporal cortex. The pigments in human eyes are specialized in perceiving three different primary colors: red, green, and blue. Pressure, vibration, muscle stretch, and the movement of hair by an external stimulus, are all sensed by mechanoreceptors. It has two separate regions, the cochlea and the vestibule, which are responsible for hearing and balance, respectively. At the end of the auditory canal is the tympanic membrane, or ear drum, which vibrates after it is struck by sound waves. The focused image is directed toward the fovea (or fovea centralis), which contains the highest density of photoreceptor neurons. The bony orbits surround the eyeballs, protecting them and anchoring the soft tissues of the eye (Figure 14.13). A similar mechanoreceptora hair cell with stereociliasenses head position, head movement, and whether our bodies are in motion. After a bright flash of light, afterimages are usually seen in negative. The C-shaped curves of the auricle direct sound waves toward the auditory canal. Sensory Receptors One of the characteristics of a living organism is its ability to respond to stimuli. Want to cite, share, or modify this book? The cells that interpret information about the environment can be either (1) a neuron that has a free nerve ending, with dendrites embedded in tissue that would receive a sensation; (2) a neuron that has an encapsulated ending in which the sensory nerve endings are encapsulated in connective tissue that enhances their sensitivity; or (3) a specialized receptor cell, which has distinct structural components that interpret a specific type of stimulus (Figure 14.2). As an Amazon Associate we earn from qualifying purchases. Not surprisingly, dishes that contain meat are often described as savory. __________________, ______________________________________________________________________________________________________________________________________________, Color-blindness can be tested with an appropriate Standard Pseudoisochromatic plates (e.g. If no axons are in place within the olfactory nerve, then the axons from newly formed olfactory neurons have no guide to lead them to their connections within the olfactory bulb. Publication types Review An exteroceptor is a receptor that is located near a stimulus in the external environment, such as the somatosensory receptors that are located in the skin. The inner ear is often described as a bony labyrinth, as it is composed of a series of canals embedded within the temporal bone. As one moves in either direction from this central point of the retina, visual acuity drops significantly. Loss of the sense of smell can result in food tasting bland. Sensation is the activation of sensory receptor cells at the level of the stimulus. This explains why some elderly people salt their food more than younger people do. This video gives an abbreviated overview of the visual system by concentrating on the pathway from the eyes to the occipital lobe. This first fiber in the pathway synapses on a thalamic cell that then projects to the visual cortex in the occipital lobe where seeing, or visual perception, takes place. Other stimuli include the electromagnetic radiation from visible light. A cross-sectional view of the cochlea shows that the scala vestibuli and scala tympani run along both sides of the cochlear duct (Figure 14.7). Lower frequency waves move the region of the basilar membrane that is near the tip of the cochlea. The eye is located within the orbit and surrounded by soft tissues that protect and support its function. Therefore, the umami flavor is often perceived while eating protein-rich foods. Similar to the smell test, list the concentrations of the two substances and circle the one where you can begin to taste the substance.

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