Bio 152 module 3

Bio 152 module 3 Lateral view of the cornea and sclera of the eye. (Both are highlighted in blue.) Lateral view of the eye. The choroid and ciliary body are in blue. The anterior portion is the iris with the pupil in the center. The retina is the inner sensory layer of the eye. Lateral view of the lens and vitreous body, which contains the vitreous humor. Vision pathway. The left visual fields are in purple. The right visual fields are in orange. Each eye has a left and a right visual field. The medial fibers of the optic nerves cross at the optic chiasm. Visual information then travels through the optic tracts and thalamus to the occipital lobe. VISION PATHWAY -- Sensory information gathered from the left side of the body (bilateral left visual fields) will eventually be interpreted in the right side of the brain and is reversed for the right visual fields. Information from the left visual field of each eye is gathered onto the ride side of each retina. The information from each retina is carried through the optic nerves to the optic tract. Only the medial fibers of the optic nerves cross at the optic chiasm. The left side of the brain receives information from the medial side of the left eye and the lateral side of the right eye (bilateral right visual fields). The situation is reversed for the right side of the brain, with the right side of the brain receiving information from the bilateral left visual fields. Anterior view of the left eye extrinsic muscles. The superior rectus is in blue. Diplopia: view of how double vision appears to a patient. One test for abducens nerve damage is to have a person look left and right while keeping the head still. If the lateral rectus does not receive nervous signals from the abducens nerve, the eye is unable to rotate laterally when looking to the same side. The affected eye deviates medially when looking forward because of the imbalance in muscle tone between the medial and lateral recti. External and internal view of the ear. The auricle funnels sound into the external acoustic meatus, which terminates at the tympanic membrane (blue). The middle ear is filled with air. It contains the malleus (blue), incus, and stapes, which transmit sound vibrations from the tympanic membrane to the cochlea. Inner ear: the vestibule (blue), three semicircular canals, and the cochlea. Note that CNVII (facial nerve) is also located in the inner ear region. The facial nerve innervates a muscle called the stapedius, which is attached to the stapes. The stapedius controls the amount of tension on the bone, allowing for increased or decreased vibration to help control the intensity of sounds. Cross section of the cochlea with its three chambers Scala vestibuli, cochlear duct, and Scala tympani. The organ of Corti is housed within the cochlear duct. Cross section of the organ of Corti within the cochlear duct. The stereocilia and the cochlear nerve are in blue. Process of hearing --- The process of hearing happens in a series of events. First, sound waves are funneled into the external auditory canal causing the eardrum to vibrate. The vibrations transmit to the ossicles, which push against fluid inside the cochlear duct. The movement of the fluid causes movement of the stereocilia in the organ of Corti. The movement of the stereocilia then stimulates the neurons to send impulses through the cochlear nerve to the primary auditory cortex of the temporal lobe. The auditory pathway is a unique sensory pathway because the ascending pathways cross in addition to sending signals to the same side of the brain. The result is that sounds from each ear are equally interpreted on the left and right sides of the brain. Midsagittal view of the olfactory pathway. Olfactory nerves → olfactory bulbs → olfactory tracts→ temporal lobes Any odor interpreted by the brain is due to a combination of many different chemical substances. Smell is defined as a combination of a limited number of primary odors that are detectable by the brain. Animals, such as dogs, have a much wider range of detectable smells and, therefore, have a larger amount of brain space dedicated to smell interpretation. Generally, odors can be isolated to seven primary odors: floral (roses), ethereal (dry-cleaning fluid), camphorates (mothballs), musky (perfumes), peppermint (mint gum), pungent (vinegar) and putrid (rotten eggs). The tongue contains taste buds as well as the surface of the mouth and wall of the pharynx. The tongue is responsible for manipulating food within the oral cavity to form a bolus. The frenulum (highlighted in blue) attaches the body of the tongue to the floor of the mouth. Cross section of tongue with view of the three types of papillae (circumvallate, fungiform, and filiform). Taste buds (highlighted in blue) are located within circumvallate and fungiform papillae. The taste pathway begins as food chemicals contact the gustatory hairs, which generate an action potential in dendrites that are wrapped around the gustatory cells. The nerve impulse is carried by afferent fibers through two cranial nerve pairs, the facial nerves, and the glossopharyngeal nerves, which transmit the impulse to the thalamus and ultimately to the parietal lobe to be interpreted as taste. The facial nerve carries information from the anterior two-thirds of the tongue, while the glossopharyngeal nerve carries information from the posterior one-third of the tongue. Histological view of a taste bud inside a taste pore. There are five primary tastes: sweet, salty, sour, bitter, and savory (also called umami). The sweet taste is produced by many compounds, including sugars and some amino acids. The salty taste is produced by many metal salts, especially NaCl. The sour taste is produced by acids like acetic acid (in vinegar). The bitter taste is produced by many drugs like aspirin. The savory taste is due to certain amino acids and is found in many foods like fish, ripe tomatoes, aged cheeses, and soy sauce. 1. What are the five special senses? 2. What are the two parts of the outer layer of the eye? 3. What is included in the middle layer of the eye? 4. The pupil is a hole in the . 5. The inner sensory layer is the . 6. What are the two types of photoreceptors and their functions? 7. The interior of the eye (posterior to the lens) is filled with . 8. True or False: The vision pathway begins as the optic tracts, crosses at the optic chiasm and then moves through the optic nerve. 9. Where is the LGN located? 10. True or False: The nasal visual field is the visual field on the lateral sides of each eye. 11. What allows for 3-D vision? 12. True or false: Only the medial fibers cross at the optic chiasm. 13. The left side of the brain receives information from the of the left eye and the of the right eye. 14. On a piece of paper, draw the visual pathway using two different colors. Note one comment below about what you learned about the vision pathway: 15. The medial rectus turns the eye . The medial rectus is controlled by CN . 16. Review all the extrinsic eye muscle locations. 17. What is a cataract? 18. What does diplopia mean? 19. What is the purpose of the auricle? 1. Vision, smell, taste, hearing and equilibrium (balance) 2. Sclera and cornea 3. Choroid, the ciliary muscle and the iris. 4. Iris 5. Retina 6. The more numerous cells are rods which are stimulated in dim light. Rods are more sensitive to light but do not generate sharp or color images. The cones operate in bright light helping to generate sharp color images. 7. Vitreous fluid 8. False 9. Thalamus 10. False 11. Overlapping information in the nasal visual fields allows for 3-D vision, called the binocular visual field. 12. True 13. The left side of the brain receives information from the medial side of the left eye and the lateral side of the right eye (bilateral right visual fields). 14. See figure in module 15. Medially, CN III, oculomotor 16. See figure in module. 17. Cataracts are lenses that slowly become hardened and cloudy over time. 18. Double vision 19. The auricle (Figure 1) is shaped to funnel sound waves into the external acoustic canal so that sounds can be detected. 20. Earwax which serves to trap foreign materials. 21. Tympanic membrane 22. Stapes 20. What is the purpose of cerumen? 21. The inner end of the external acoustic meatus terminates at the . 22. What bone touches the inner ear to transmit vibrations? 23. The semicircular canals contribute in this way to the body's sense. 24. The is the sense organ for the auditory system. 25. The movement of the stereocilia stimulates the neurons to send impulses through the nerve to the lobe of the brain. 26. What is unique about the way the auditory pathway travels to the brain? 27. What is the difference between nerve deafness vs. conduction deafness? 28. Review all figures in the auditory and vestibular systems. 29. Olfactory nerves contain what type of receptor cells? 30. The olfactory nerves travel through what bone? 31. What is the order of the olfactory nerve pathway? 32. What is smell? 33. Label all olfactory landmarks. 34. What is the anatomical word for taste? 35. True or false: The apex of the tongue is located on the anterior aspect of the mouth. 36. What is a bolus? 37. What type of papillae contain taste buds? 38. True or false: Gustatory cells are the chemoreceptors of the taste buds. 39. What is the purpose of basal cells? 40. True or false: The taste pathway sends signals via only one cranial nerve to the brain. 41. What is anosmia? 42. Review all figures of the gustatory system. 23. Vestibular sense 24. Organ of Corti 25. Cochlear nerve; temporal lobe. 26. The auditory pathway is a unique sensory pathway because the ascending pathways cross in addition to sending signals to the same side of the brain. The result is that sounds from each ear are equally interpreted on the left and right sides of the brain. 27. Conduction deafness occurs from damage to the outer or middle ear structures. Nerve deafness occurs from damage to the nerve pathway. 28. See figures in module. 29. Bipolar receptor cells 30. Ethmoid (cribriform plate) 31. Olfactory nerves → olfactory bulbs → olfactory tracts→ temporal lobes 32. Smell is defined as a combination of a limited number of primary odors that are detectable by the brain. 33. See figure in module 34. Gustation (gustatory system) 35. True 36. A compact mass of food, prepared by the tongue and teeth. 37. Circumvallate and fungiform papillae both contain taste buds 38. True 39. Basal cells serve as stem cells, which divide and differentiate into new supporting cells which then form new gustatory cells. 40. False (two nerves- facial and glossopharyngeal) 41. The loss of smell 42. See figures in module