Taste & Smell Senses, Year 1 Biology 2024 PDF

The Special Senses SENSE OF Taste (Gustatory) THE NERVOUS SYSTEM Year 1- Biology 232 Dr. Rai Khalid FAROOQ Physiology Dept, CMMS [email protected] Special Senses – Taste (Gustatory) 4,000 taste buds on papillae of tongue Some buds on hard palate, pharynx and epiglottis. 5 known tastes : Sweet, Sour,...

The Special Senses SENSE OF Taste (Gustatory) THE NERVOUS SYSTEM Year 1- Biology 232 Dr. Rai Khalid FAROOQ Physiology Dept, CMMS [email protected] Special Senses – Taste (Gustatory) 4,000 taste buds on papillae of tongue Some buds on hard palate, pharynx and epiglottis. 5 known tastes : Sweet, Sour, Salty, Bitter, and Umami (Japanese name for meaty taste). Taste buds open at taste pores. Special Senses – Taste (Gustatory) Taste buds open at taste pores. Gustatory Pathway How the brain receive taste information? Taste buds open at a taste pore They have supporting cells and a number of elongated taste cells that end in microvilli When molecules bind to receptor proteins of microvilli, nerve signals are generated in sensory nerve fibers that go to the brain through neurotransmitters such as ATP and Serotonin. Signals reach the gustatory (taste) cortex, located primarily in the parietal lobe, where they interpreted as particular taste. The Special Senses SENSE OF Smell (Olfactory) THE NERVOUS SYSTEM Year 1- Biology 232 Dr. Rai Khalid FAROOQ Physiology Dept, CMMS [email protected] Sense of Smell Approximately 80 to 90% of what we perceive as “taste” actually is due to the sense of smell. This account for the dulled taste of food when we have cold or a stuffed-up nose. Our sense of smell depends on 10-20 million olfactory cells located in the olfactory epithelia high in the roof of the nasal cavity. Olfactory cells are modified neurons. Each cell ends in a tuft of about five olfactory cilia, which bear receptors for odor molecules. Special Senses – Smell (Olfactory) 10 – 20 million olfactory receptor cells in olfactory epithelia in the roof of the nasal cavity. Olfactory receptor cells are modified neurons that have specialized cilia extensions. Number of olfactory cells declines with age. Nerve fibers from similar olfactory cells lead to the same neuron in the olfactory bulb. The only sense in which its perception does not require synapse in the thalamus. Special Senses – Smell (Olfactory) 10 – 20 million olfactory receptor cells in olfactory epithelia in the roof of the nasal cavity. Olfactory receptor cells are modified neurons that have specialized cilia extensions. Number of olfactory cells declines with age. Nerve fibers from similar olfactory cells lead to the same neuron in the olfactory bulb. The only sense in which its perception does not require synapse in the thalamus. Olfactory Coding of Odorant Receptors How the Brain Receives Odor Information? An odor (odorant) contains many odor molecules, which activate a characteristic combinations of receptor proteins. If you smell a rose or daisy or a dandelion (different types of flowers), the different chemicals emanating from each will stimulate different receptor proteins or combination of receptor proteins in the nasal cavity which in turn will activate a corresponding cells in the olfactory bulb. When the neurons communicate this information via the olfactory tract to the olfactory area of the cerebral cortex, then we know we have smelled either a rose, a daisy or a dandelion. The olfactory cortex is located in the temporal lobe. Some areas of the olfactory cortex receive smell sensations, and other areas contain olfactory memories. For example, a smell of certain food may remind you of a favorite dish of your mother’s cooking. This is because, the olfactory bulb send extensions to certain areas in the brain and certain smells or aromas bring back memories and emotions related to these certain smells. This is because olfactory bulbs have direct connections with the limbic system and its centers for emotion (amygdala) and memory (hippocampus). The number of olfactory cells decline with age. Older people tend to apply excessive amount of perfume or cologne before they can detect its smell. Olfactory Pathway