SEPTEMBER 19, 2022 SENSES Meet the team KYLIE Nika Sensation are relatively meaningless bites of information that result when the brain processes electrical signals that come from the sense organs eyes sensory organ, part of the sensory nervous system, that reacts to visible light and allows us to use visual information for various purposes including seeing things, keeping our balance, and maintaining circadian rhythm. PROCESS 1. The eyes gather and focus light waves into a precise area at the back of the eyes. 2. This area absorbs and transforms light waves into impulses - a process called transduction LIGHT WAVES EYES: sTRUCTURES Cornea - the transparent part of the eye that covers the iris and the pupil and allows light to enter the inside. Pupil - The round opening in the center of the iris Iris - The colored tissue at the front of the eye Lens - clear part of the eye behind the pupil and iris that focuses rays of light on the retina to form clear images Retina - the light-sensitive layers of nerve tissue at the back of the eye that receive images and sends them as electric signals through the optic nerve to the brain EYES: sTRUCTURES Visual pathways: eyes to brain The nerve impulse flows through the optic nerve as it exits from the back of the eye. Optic nerves partially cross over and make a major stop in the thalamus. Primary Visual Cortex - transforms nerve impulses into simple visual sensations, such as textures, lines and colors. Visual Association Areas. Color vision A ray of sunshine is called white light because it contains all the light waves in the visible spectrum. A rainbow is a result from sunlight separating and turning into waves of different lengths. Our visual system transforms light waves of various lengths into different colors. Opponentprocess theory TRICHROMATIC THEORY The trichromatic theory says that human eyes only perceive three colors of light: red, blue, and green. The wavelengths of these three colors can be combined to create every color on the visible light spectrum. The opponent process theory states that ooking at one color for a long period causes those receptor cells to become fatigued. Color blindness inability to distinguish the different shades of colors from each other. Monochromats total color blindness Dichromats trouble distinguishing red from green. EARS Sound Waves - is the noise pattern caused by the motion of energy traveling through a medium (such as air, water, or any other liquid or solid matter) as it propagates from the sound source. Loudness - subjective experience of a sound's intensity. High Frequency - sounds waves are close together, resulting in high sounds or pitch Low Frequency - sound waves are apart, resulting in low sounds or pitch Pitch - subjective experience of a sound being high or low. EARS Decibel - a unit of measurement of the intensity of a sound or the power level of an electrical signal by comparing it to a specified level on a logarithmic scale. Ears: sTRUCTURES Outer Ear Pinna Auditory Canal Eardrum Middle Ear Hammer Anvil Stirrup Oval Window Inner Ear Cochlea Semi-circular canals AUDITORY BRAIN AREAS Primary Auditory Cortex transforms nerve impulses into basic auditory sensations Auditory Association Area combines meaningless auditory sensations into perceptions AUDITORY CUES Calculating direction By calculating the slight difference in time Calculating pitch Frequency Theory only applies to low-pitched sounds. states that the rate at which nerve impulses reach the brain determines how low the pitch of a sound is. Place Theory Brain determines medium to higher pitched sounds Calculating Loudness calculated from the frequency or rate of how fast or how slow nerve impulses arrive from the auditory nerve. Vestibular system The endolymph in that semicircular canal flows into an expansion of the canal called the ampulla. Within the ampulla is a sensory organ called the crista ampullaris that contains hair cells, the sensory receptors of the vestibular system. These receptors send vestibular information via the vestibulocochlear nerve to the cerebellum and to nuclei in the brainstem called the vestibular nuclei. The vestibulocochlear nerve consists of the vestibular and cochlear nerves, also known as cranial nerve eight (CN VIII) Meniere's disease: Disorder of the inner ear that can lead to dizzy spells (vertigo) and hearing loss. In most cases, Meniere's disease affects only one ear. Considered as a chronic condition. Symptoms include episodes of vertigo, hearing loss, tinnitus, and pressure in the affected ear. Vertigo: whose symptoms are dizziness and nausea, results from malfunction of the semicircular canals of the vestibular system. Vertigo usually is due to an issue with the inner ear. Symptoms include dizziness, feeling sick, and loss of balance. Motion sickness: Consists of feelings of discomfort, dizziness, and nausea. Nausea and weakness caused when information to the brain from the semicircular canals conflicts with information from eyes and position sensors in the back and lower limbs. TASTE Taste is called a chemical sense because the stimuli are various chemicals. On the surface of the tongue are receptors, called taste buds, for five basic tastes: sweet, salty, sour, bitter, and umami. The function of taste buds is to perform transduction, which means transforming chemical reactions into nerve impulses The tongue is covered with projections called papillae. 1. Filiform papillae- sharp with no taste buds 2. Vallate - Leaf-shaped 3. Fungiform papilla - rounded with taste buds 4. Circumvallate papillae - large papillae with taste buds Back to Navigation Page Taste Sensations 1 Sweet receptors Sugars, amino acids 2 Sour receptors - Acids 3 Bitter receptors Alkaloids 4 Salty receptors Metalions 5 Umami - Glutamate, aspartate (MSG,meats) Taste Taste buds Taste buds are formed by groupings of taste receptor cells with hairlike extensions and these are found on the sides of the papillae. Chemicals dissolved in the saliva actives the taste buds which then produces nerve impulse. Taste molecules bind to receptors on this extension and cause chemical changes. Taste information is transmitted to the medulla, thalamus, and limbic system, and to the gustatory cortex Supertaster A person who tastes certain flavors and foods more strongly than other people. Supertasters sensitive to bitter flavors in all foods and drinks. People with this gene are particularly sensitive to a chemical called 6-npropylthiouracil (PROP). Supertasters may have more, stronger taste buds Flavor Taste (gustation) and smell (olfaction) are chemical senses that employ receptors on the tongue and in the nose that bind directly. We can only figure out what flavour our food is when we combine sensation of smell and taste together. a e s t h e t i c c a n d l e s OLFACTION is called a chemical sense because its stimuli are various chemicals that are carried by the air. The upper part of the nose has a small area that contains receptor cells for olfaction. People can lose their sense of smell if a virus or inflammation destroys the olfactory receptors. Desensitises once an odorant is bound and does not respond to another odorant for some time is called Adaptation. Olfactory cells : the receptors for smell and are located in two 1inch-square patches of tissue in the uppermost part of the nasal passages. Olfactory cells trigger nerve impulses that travel to SMELL the brain, which interprets the impulses as different smells. r o g u k nd c a B SENSATIONS 1. Olfactory receptors with hair pick up the chemical composition of the“odorant”. 2. They send these impulses from the olfactory epithelium to the olfactory nerve processes. 3. These olfactory nerve processes project through the foramina in the cribriform plate to the olfactory bulb. 4. The axons of neurons of the olfactory bulb project to the olfactory tract. 5. Lastly, impulses are transmitted via the olfactory nerve. FUNCTIONS OF OLFACTIONS Provides numerous functions to humans, influencing ingestive behavior, awareness of environmental hazards and social communication. Important for detecting food and providing good taste quality, for avoiding potential dangerous situations in longand short distance, like fire and microbial threats. Touch Touch Includes pressure, temperature, and pain. Beneath the outer layer of skin are a half-dozen miniature sensors that are receptors for the sense of touch. third Skin The skin, the largest organ in the body, is the sensory organ for touch. The skin contains a variety of nerve endings, combinations of which respond to particular types of pressures and temperatures. When you touch different parts of the body, you will find that some areas are more ticklish, whereas other areas respond more to pain, cold, or heat. receptors in the skin Somatosensory system Pacinian corpuscle Mechanoreceptors This system is responsible for all the sensations we feel – cold, hot, smooth, rough, pressure, tickle, itch, pain, vibrations, and more. This is a special nerve endings that serve as mechanoreceptors sensitive to vibration and pressure and are crucial for proprioception, and adapt very quickly. There are four known types of mechanoreceptors whose only function is to perceive indentions and vibrations of the skin: Merkel’s disks, Meissner’s corpuscles, Ruffini’s corpuscles, and Pacinian corpuscles. receptors in the skin Thermoreceptors nocireceptor Proprioceptors These receptors perceive sensations related to the temperature of objects the skin feels. There are two basic categories: hot & cold receptors. The highest concentration of thermoreceptors can be found in the face and ears. These receptors detect pain or stimuli that can or does cause damage to the skin and other tissues of the body. They can detect pain that is caused by mechanical stimuli (cut or scrape), thermal stimuli (burn), or chemical stimuli (poison from an insect sting). They sense the position of the different parts of the body in relation to each other and the surrounding environment. Proprioceptors are found in tendons, muscles, and joint capsules. This location in the body allows these special cells to detect changes in muscle length and muscle tension. are there any questions? Thank You!
