anatomy and physiology of sensory system ppt

The tongue is covered with small bumps, called papillae, which contain taste buds that are sensitive to chemicals in ingested food or drink. 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). Light passes through the eyeball via the cornea, pupil, and lens. The three types of cone opsins, being sensitive to different wavelengths of light, provide us with color vision. However, the tendon of the oblique muscles threads through a pulley-like piece of cartilage known as the trochlea. These two structures bend the lens, allowing it to focus light on the back of the eye. In order to get to the first layer, the sclera, you may have to clear away some fat and connective tissue. Common disorders of vision and hearing are also considered, including glaucoma, cataract, age-related hearing impairment and conductive hearing impairment. Once the gustatory cells are activated by the taste molecules, they release neurotransmitters onto the dendrites of sensory neurons. Inner ear Cochlea, which contains the hair cells (receptors) within the Organ of Corti. The difference in visual acuity between the fovea and peripheral retina is easily evidenced by looking directly at a word in the middle of this paragraph. Eventually, patterns of ganglion cells signals are integrated within the brain (in the occipital cortex) to generate the perception of complex images. Some travel to the cerebrum, specifically to the primary olfactory cortex that is located in the inferior and medial areas of the temporal lobe. See Full PDF Download PDF Related Papers THE SKELETON BONES AND JOINTS Action potentials from ganglion cells, whose axons form the optic nerves, represent patterns of light. Not surprisingly, dishes that contain meat are often described as savory. The retina is composed of several layers and contains specialized cells for the initial processing of visual stimuli. The exact position of the head is interpreted by the brain based on the pattern of hair-cell depolarization. Physiology concerns the functions of body partswhat they are and what they do. Specifically, photons cause some of the double-bonded carbons within the chain to switch from a cis to a trans conformation. Sensation is the activation of sensory receptor cells at the level of the stimulus. The inner ear contains the cochlea and vestibule, which are responsible for audition and equilibrium, respectively. This will depolarize the hair cell membrane, triggering nerve impulses that travel down the afferent nerve fibers attached to the hair cells. The humors are fluids filling the anterior and posterior chambers of the eye. consent of Rice University. The posterior cavity is the space behind the lens that extends to the posterior side of the interior eyeball, where the retina is located. Body parts form a well-organized unitthe human organism. As vibrations of the ossicles travel through the oval window, the fluid of the scala vestibuli and scala tympani moves in a wave-like motion. The video makes the statement (at 0:45) that specialized cells in the retina called ganglion cells convert the light rays into electrical signals. What aspect of retinal processing is simplified by that statement? The hair cells along the length of the cochlear duct, which are each sensitive to a particular frequency, allow the cochlea to separate auditory stimuli by frequency, just as a prism separates visible light into its component colors. Hearing involves the signal transduction of mechanical waves into neural signals in the cochlea, within the inner ear. The auditory receptors for the ear (shown below) include the: Within the inner ear, the 3 semicircular canals are arranged at right angles to each other, and they contain hair cells and fluid similar to the cochlea. 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. Somatosensation is considered a general sense, as opposed to the special senses discussed in this section. Receptor cell types can be classified on the basis of their structure. The incus, in turn, articulates with the stapes. Therefore, the olfactory neurons are regularly replaced within the nasal epithelium, after which the axons of the new neurons must find their appropriate connections in the olfactory bulb. However, this increased sodium intake can increase blood volume and blood pressure, increasing the risk of cardiovascular diseases in the elderly. Wavelengths of electromagnetic radiation longer than 720 nm fall into the infrared range, whereas wavelengths shorter than 380 nm fall into the ultraviolet range. As an Amazon Associate we earn from qualifying purchases. Different types of stimuli are sensed by different types of receptor cells. The ampulla contains the hair cells that respond to rotational movement, such as turning the head while saying no. The stereocilia of these hair cells extend into the cupula, a membrane that attaches to the top of the ampulla. Stand there and cover one eye without squinting. The dorsal root contains only the axons of sensory neurons, whereas the ventral roots contain only the axons of the motor neurons. Proprioceptors - near junction General Sense Organs between tendons and muscles. Many internal structures are delicate and tear easily such as the retina. This book uses the The first half of the pathway is the projection from the RGCs through the optic nerve to the lateral geniculate nucleus in the thalamus on either side. Protein fibers tether adjacent hairs together within each array, such that the array will bend in response to movements of the basilar membrane. The pigments in human eyes are specialized in perceiving three different primary colors: red, green, and blue. In many of the special senses, the axons leaving the sensory receptors have a topographical arrangement, meaning that the location of the sensory receptor relates to the location of the axon in the nerve. Modality refers to the way that information is encoded, which is similar to the idea of transduction. Different types of papillae are found in different regions of the tongue. They preferentially absorb light at different wavelengths, shown in the figure below. The central integration may then lead to a motor response. This spasm is a reflex that is initiated by stretch receptors to avoid muscle tearing. 3 285-296 doi: 10.1083/jcb.201003144). In addition, each photoreceptor cell of the fovea is connected to a single RGC. Bulbous corpuscles are also known as Ruffini corpuscles, or type II cutaneous mechanoreceptors. Additionally, pain is primarily a chemical sense that interprets the presence of chemicals from tissue damage, or similar intense stimuli, through a nociceptor. When it contracts, it laterally rotates the eye, in opposition to the superior oblique. 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 This intimate connection between the olfactory system and the cerebral cortex is one reason why smell can be a potent trigger of memories and emotion. Frequencies as low as 20 Hz are detected by hair cells at the apex, or tip, of the cochlea. The maculae are specialized for sensing linear acceleration, such as when gravity acts on the tilting head, or if the head starts moving in a straight line. Muscles in the iris alter pupil size to vary light entering the eye. Pressure, vibration, muscle stretch, and the movement of hair by an external stimulus, are all sensed by mechanoreceptors. You will work in groups of two or three to dissect an eye. Have the subject stand with their back to the whiteboard. Lower frequency waves move the region of the basilar membrane that is near the tip of the cochlea. The organs of Corti contain hair cells, which are named for the hair-like stereocilia extending from the cells apical surfaces (Figure 14.8). What may be happening with your cone cells within your retinas? Using a tuning fork, have a subject sit with their eyes closed. 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. In many sensory organs, additional cells and tissues will contribute to the process of signal transduction. Nociceptive Pain. The nasal epithelium, including the olfactory cells, can be harmed by airborne toxic chemicals. (a) All photoreceptors have inner segments containing the nucleus and other important organelles and outer segments with membrane arrays containing the photosensitive opsin molecules. The three major spaces within the cochlea are highlighted. Other overlooked senses include temperature perception by thermoreceptors and pain perception by nociceptors. 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. Comparing the peak sensitivity and absorbance spectra of the four photopigments suggests that they are most sensitive to particular wavelengths. The afferences to the peri 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. Humans have five special senses: olfaction (smell), gustation (taste), equilibrium (balance and body position), vision, and hearing. The photoreceptors (rods and cones) change their membrane potential when stimulated by light energy. An individual sensory modality represents the sensation of a specific type of stimulus. Check with your instructor to determine which way they want you to cut the eye in half. Anatomy and Physiology Anatomy is the branch of science that deals with the structure (morphology) of body partsforms and organization. mucous membrane that lines the anterior surface of the eye and the posterior surface of the eyelid. Dr. Reed discovered that she is a non-taster, which explains why she perceived bitterness differently than other people she knew. Each olfactory sensory neuron has dendrites that extend from the apical surface of the epithelium into the mucus lining the cavity. The visual stimulus in the middle of the field of view falls on the fovea and is in the sharpest focus. Olfactory neurons will undergo adaptation and decrease signals to the brain with constant exposure to a stimulus. If you exhibit some degree of colorblindness, what type? For the sake of convenience, we will use the terms ventral and dorsal in reference to structures within the spinal cord that are part of these pathways. The fluid-filled tube, now called the scala tympani, returns to the base of the cochlea, this time travelling under the cochlear duct. The general sense that is usually referred to as touch includes chemical sensation in the form of nociception, or pain. sight, touch, hearing, taste, smell. Watch this video to learn more about a transverse section through the brain that depicts the visual pathway from the eye to the occipital cortex. The photoisomerization is reversed by a series of enzymatic changes so that the retinal responds to more light energy. Transmembrane receptors are activated by chemicals called ligands. When the stereocilia bend toward the tallest member of their array, tension in the protein tethers opens ion channels in the hair cell membrane. If you think that you can see colors in the dark, it is most likely because your brain knows what color something is and is relying on that memory. Phenylthiocarbamide (PTC), also known as phenylthiourea (PTU), is only detected by ~70% of the population on average. Sensory (olfactory) neurons are present at the top of the nasal cavity, extending their axons into the cranium. LM 1600. Stretch receptors monitor the stretching of tendons, muscles, and the components of joints. Distinguish between anatomy and physiology, and identify several branches of each Describe the structure of the body, from simplest to most complex, in terms of the six levels of organization Identify the functional characteristics of human life Identify the four requirements for human survival This is how Dr. Reed is able to visualize and count papillae on the surface of the tongue. Research at the turn of the 20th century led to recognition of the fifth taste, umami, during the mid-1980s. Possible cuts include: To be able to best see the eyes structures, you should work very carefully. Yes or no? Some other organisms have receptors that humans lack, such as the heat sensors of snakes, the ultraviolet light sensors of bees, or magnetic receptors in migratory birds. Students can then test for sensitivities for each by starting with a series at the low end of the concentrations. sodium ions), Various neurons that respond to physical movements, Neurons responding to stretch and contraction of muscles & tendons. Overlaying the ciliary body, and visible in the anterior eye, is the iristhe colored part of the eye. 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 . 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. View the University of Michigan WebScope to explore the tissue sample in greater detail. There are two types of photoreceptorsrods and coneswhich differ in the shape of their outer segment. Practicing careful dissecting is an important skill. Similar to the olfaction tests, serial dilutions of basic chemicals can be used to test for variable sensitivity in subjects. Accessibility StatementFor more information contact us atinfo@libretexts.org. Some cranial nerves contain only sensory axons, such as the olfactory, optic, and vestibulocochlear nerves. The posterior cavity is filled with a more viscous fluid called the vitreous humor. (b) Tissue of the retina shows a dense layer of nuclei of the rods and cones. Perception is the central processing of sensory stimuli into a meaningful pattern. spearmint, orange, anise). The anterior and posterior vertical canals are oriented at approximately 45 degrees relative to the sagittal plane (Figure 14.12). With your right eye (left closed), stare at the cross, and move the paper towards your eyes until the circle disappears. This will help to underscore the relationships between the different components. The taste known as umami is often referred to as the savory taste. Nociception is the sensation of potentially damaging stimuli. Corrective lenses: If you have contacts, keep them in, but if you wear glasses you may want to try the test with and without them to see just how much your corrective lenses improve your vision! One is oriented in the horizontal plane, whereas the other two are oriented in the vertical plane. There, amacrine cells additionally contribute to retinal processing before an action potential is produced by the RGC. One major group of bitter-tasting molecules are alkaloids. The eye itself is a hollow sphere composed of three layers of tissue. Most auditory stimuli contain a mixture of sounds at a variety of frequencies and intensities (represented by the amplitude of the sound wave). Describing sensory function with the term sensation or perception is a deliberate distinction. The cochlea encodes auditory stimuli for frequencies between 20 and 20,000 Hz, which is the range of sound that human ears can detect. The sphere of the eye can be divided into anterior and posterior chambers. Do you and your lab partner vary in your sensitivities? citation tool such as, Authors: J. Gordon Betts, Kelly A. 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. Sucrose and NaCl are common tests for sweet and salty. Mechanoreceptors in the skin, muscles, or the walls of blood vessels are examples of this type. LM 812. The pain and temperature receptors in the dermis of the skin are examples of neurons that have free nerve endings. ________. This is because the fovea is where the least amount of incoming light is absorbed by other retinal structures (see Figure 14.15). 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. Taste buds are arranged along the tongue epithelium. This explains why some elderly people salt their food more than younger people do. 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. Salty taste is simply the perception of sodium ions (Na+) in the saliva. If you drag your finger across a textured surface, the skin of your finger will vibrate. Merkel cells are located in the stratum basale of the epidermis. Use a microscope to explore the cellular aspect of a taste bud. The neurons can then communicate with other neurons in the nervous system via synapses and networks to coordinate responses. The scala tympani and scala vestibuli lie on either side of the cochlear duct. The peripheral nerve provides the pathway for motor, sensory and vegetative axons belonging to the peripheral nervous system. At the uppermost tip of the cochlea, the scala vestibuli curves over the top of the cochlear duct. Sphere. Specific locations along the length of the duct encode specific frequencies, or pitches. Additionally, we possess general senses, also called somatosensation, which respond to stimuli like temperature, pain, pressure, and vibration. When the frontal lobe of the brain moves relative to the ethmoid bone, the olfactory tract axons may be sheared apart. The olfactory receptor neurons are located in a small region within the superior nasal cavity (Figure 14.4). The tube is normally closed but will pop open when the muscles of the pharynx contract during swallowing or yawning. Receptor cells can be classified into types on the basis of three different criteria: cell type, position, and function. Eyelid. In addition, two separate clusters of hair cells the saccule and utricle are oriented to detect vertical and horizontal movements.
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