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Sensory System

Sensory System. Chapter 17. Olfaction . Sense of smell Olfactory organs in nasal cavity Olfactory epithelium lines the interior portion of the nasal cavity Covered with olfactory receptors(hairs/cilia)

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Sensory System

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  1. Sensory System Chapter 17

  2. Olfaction • Sense of smell • Olfactory organs in nasal cavity • Olfactory epithelium lines the interior portion of the nasal cavity • Covered with olfactory receptors(hairs/cilia) • Underneath, the lamina propria(areolar tissue), contains olfactory glands or Bowman’s glands (olfactory glands) • Secretions that form a thick mucus • Also contain blood vessels and nerves

  3. Olfactory Receptors • Highly modified neurons • Contain odorant binding proteins • Odorants are chemicals that stimulate olfactory receptors • They bind to the proteins which causes the initiation of an action potential to the CNS • Millions of olfactory receptors • Dog has 72x what humans have

  4. Olfactory Pathways • Very sensitive • 4 molecules of odorants can activate an olfactory receptor • Message must be sent to the olfactory cortex within the temporal lobe before you’re aware of it • Odorants stimulate Olfactory Receptors  action potential initiated  pass through the Ethmoid bone to the olfactory bulbs within the cerebrum  message passed to the olfactory nerves  hypothalamus (remember emotions) which trigger emotional/behavior responses • perfumes

  5. Gustation • Taste-provides information about foods/liquids consumed • Gustatory Receptors = taste receptors, on superior surface of tongue • Gustatory Receptors + specialized epithelial cells = taste buds • Approx. 3000 per adult • Contain about approx. 40 gustatory receptors each • Projections or taste hairs that collect chemicals

  6. Lingual Papillae • Lingual papillae (3 types) • Filiform papillae = friction (don’t contain taste buds) • Fungiform papillae = contain 5 or so taste buds • Circumvallate papillae = 100 taste buds—form “V” shape in back of tongue

  7. Gustatory Pathway • Taste buds are controlled by the facial, glossopharyngeal, and vagus nerves. • Conscious perception of taste is processed with other sensory data • Texture of food • Taste • Afferent Neural connection between Olfaction and Gustation • More sensitive to taste when your sense of olfaction is working properly • When your ill, airborne molecules cannot reach the olfactory receptors = meals taste dull

  8. Gustatory Pathway • Dissolved chemicals contact taste hairs  depending upon the chemical, various protein channels will open  initiates an immediate release of neurotransmitter to the postsynaptic cell postsynaptic cell generates action potential  CNS • Primary taste sensations • Sweet • Salt • Sour • Bitter • Umami = amino acids, peptides found in beef/chicken products • Water = in pharynx, hold water in mouth triggers hormone secretion leading to water loss in kidneys

  9. Taste Lab • Get with a partner (need a notebook and pencil) • On the paper, draw a simple illustration of the tongue • Grab 2 q-tips per partner • Dip the q-tip into the unknown solution and roll it on various regions of your tongue • See if you can identify regions of hypersensitivity and the type of taste being stimulated • Once identified, pencil them in on your tongue diagram

  10. Vision/Equilibrium & Hearing Chapter 17

  11. Accessory Structures of the Eye Eyelids • Palpebrae • Keep surface lubricated • Free from dust/debris • Protect surface • Palpebrae fissure • Gap between each palpebrae or eyelids • Lateral/medial canthus (connection of palpebrae) • Eyelashes • Long hairs • Prevent foreign matter and insects from reaching the surface

  12. Accessory Structures of the Eye Eyelashes are associated with abnormally large sebaceous glands • Tarsal glands • Along the inner margin • Secrete a lipid-rich product, prevents palpebrae from sticking together • Lacrimal Caruncle • At the medial canthus • Thick secretions • Can be invaded by bacteria/infection • Sty • Infection of a sebaceous gland or tarsal gland causing swelling

  13. Accessory Structures of the Eye • Conjunctiva • Epithelium covering the inner surface of eyelids • Conjunctivitis: “pink eye”, damage, irritation to the conjunctiva • Redding due to blood vessel dilation • Caused by infection

  14. Accessory Structures of the Eye • The Lacrimal Apparatus • Produces, distributes, and removes tears • Reduce friction, remove debris, prevent bacterial infections, provide nutrients to that tissue • Parts • Lacrimal gland: secretes the tear substance with a lysozyme, to attack bacteria • Lacrimal puncta: 2 small pores that drain tears to canaliculi • Lacrimal Canaliculi: small canals that lead to the sac for disposal of tears • Lacrimal Sac: collects a portion of the tears before depositing them into the duct • Nasolacrimal duct/canal: found in the lacrimal bone, delivers the tears to nasal cavity

  15. The Eye • Wall of the eye-3 layers • Fibrous Tunic • Outermost layer • Contains: sclera and cornea • Provides support and protection, attachment for muscles, focusing • Vascular Tunic • Middle layer • Contains: iris, ciliary body, and choroid • Provides route for vessels, regulates amount of light, secreting and reabsorbing the aqueous humor, controls shape • Neural Tunic • Innermost layer • Retina • Contains light receptors

  16. Cornea • Transparent • No blood vessels • Doesn’t interfere with the passageway of light • Has numerous free nerve endings = sensitive

  17. Sclera • White portion of the eye • Contains small blood vessels and nerves

  18. Iris • Contains vessels, pigmented cells, and layers of muscle fibers • Change the shape changes the size of the pupil • Pupillary dilator muscles • Pupillary constrictor muscles • Central opening = pupil • Melanocytes • Density = color

  19. Ciliary Body • Contains ciliary muscle • Change lens shape

  20. Choroid • Delivers oxygen and nutrients to the retina

  21. Retina • Contains photoreceptors • Rods: variations of light, allow to see in low lighting • Cones: color vision, require more light, provide sharper vision • Not evenly distributed • 125 Million Rods along the periphery of retina • 6 Million Cones on retina’s posterior surface • Fovea Centralis, area of sharpest vision, reason why you look directly at something, highest concentration of rods/cones

  22. Optic disc • Region where the Optic nerve enters the eye • No photoreceptors because it is an opening • “blind spot”

  23. Chambers of the Eye • Anterior Cavity • Anterior chamber (cornea to iris) • Posterior chamber (iris to lens) • Filed with aqueous humor : circulating fluid for nutrient/waste transport, and cushion • Posterior Cavity • Everything behind the anterior cavity • Filled with Vitreous Humor: gelatinous mass that stabilizes the shape

  24. The Lens • Posterior to cornea • Held in place by suspensory ligaments that originate from the choroid • Change shape to focus image on photoreceptors due to refraction called accommodation • Lens becomes rounder to focus on a nearby object or flatter for a distant object • Astigmatism: light failing to refract properly due to an misshapen cornea/lens

  25. Visual acuity • Clarity of vision is rated against a normal standard • 20/20 a person can see details at 20 feet as clearly as a normal person should at 20 feet • 20/15 a person can see at 20 feet what a normal person can see at 15 • 20/30 a person can see at 20 feet what a normal person can see at 30 • 20/200 is legally blind • Caused by cataracts, glaucoma, corneal scarring, detachment of retina, accidental injuries or heredity factors.

  26. Sight Lab Groups of 3 • 2 groups  Visual Acuity • 2 groups  Peripheral vision disc • 1 group  Astigmatism/blind spot • 1 group  Page 455 in packet part B • 1 group  study with models

  27. Emotional Tears • proteins carrying hormones found in tears • Prolactin • Hormone in greater levels in women than men • When you have an emotional response, it is due to the onset production of hormones • These hormones are produced in the lacrimal gland which then are released through tears • Prolactin levels increase tremendously during breastfeeding, stimulates lactation • Women have a strong emotional responses while breast feeing

  28. Lasik Surgery • Operation • Patient is awake, given anesthetic eye drops • Step 1: Remove the conjunctiva tissue like a flap • Step 2: Remodel the cornea because the uneven amounts push on the lens causing a change in its shape or excess causes blurred vision • http://www.youtube.com/watch?v=O4kDC4sZ5Jg

  29. Visual Disorders • Cataracts • Clouding or discoloration of the lens • Due to a precise balance of structural and biochemical characteristics • Symptoms: blurry vision, faded colors, glare, poor night vision, double vision • Lens transplants to fix • Develops as you age • Glaucoma • Intraocular pressure rises because the aqueous humor can’t be filter properly • Pressure distorts the soft tissues of the eye • Treated with drugs, surgery to enable drainage

  30. Color Vision • Anatomy of Rods and cones • Rod/cone refer to the outer segment’s shape • 3 types of cones • Blue Cones (16%) • Green Cones (10%) • Red Cones (74%) • If all 3 are stimulated, you perceive the color white • Combination is what allows us to understand different colors/shades

  31. Color Blindness • Unable to distinguish certain colors • Nonfunctional cones • Absent • Unable to manufacture the necessary pigments • Red-green color blindness • Most common, b/c inherited, other types due to damage • Located on the x chromosome • Remember XY so men have it more often b/c women have XX which both would need to be carriers • Red cones are missing • Red/green looks the same

  32. Cow Eye Dissection

  33. Sound • 2 senses • Equilibrium • Inform us of the position of the head in space • Monitors gravity, acceleration, rotation • Hearing • Detect and interpret sound waves

  34. Anatomy of the Ear • 3 main Regions • External Ear • Visible portion • Collects/directs sound waves and directs them to the middle ear • Middle Ear • Chamber within the temporal bone • Collect sound waves and transmit them to the inner ear • Inner Ear • Contains sensory organs for hearing and equilibrium

  35. External Ear • Auricle or pinna • Fleshy flap of cartilaginous tissue • Surrounds the external auditory canal • Protects the opening • Provides direction of sounds • External Auditory Canal • Passageway for sound waves to travel • Ends at the tympanic membrane • Tympanic Membrane • “ear drum” • Thin, semi-transparent, delicate • Separates external and middle ear • Ceruminous Glands • line the E.A.C., secrete waxy material called cerumen, that Prevents foreign objects from entering

  36. Middle EAR • Filled with air • Communicates with the nasopharynx through the auditory tube or Eustachian tube • Permits equalization of pressures on either sides, opens to pharynx • Can also lead to microorganisms entering the middle ear = ear infections • Auditory ossicles • 3 bones: connect the tympanic membrane with other inner ear structures • Malleus (tympanic membrane), incus (both bones)and stapes (oval window) • Vibrations of tympanic membrane, vibrates the 3 ossicles, oval window  hearing/equilibrium structures

  37. Inner Ear • Membranous Labyrinth: network of canals that holds receptors • Contains endolymph • Bony Labyrinth: dense bone that surrounds and protects the membranous labyrinth • Vestibule: contains membranous sacs called saccule and utricle which hold receptors that respond for balance • 3 Semi-circular Canals: enclose semicircular ducts that can be stimulated by rotation • Cochlea: spiral-shaped, cochlear duct, receptors that respond to hearing • Round Window: separates the perilymph from air of middle ear • Oval Window: moves the stapes which flaps on it causing stimulation • Between them is the perilymph, liquid

  38. Pathway of Sound • Sound waves external auditory canal and make the tympanic membrane vibrate. • Tympanic membrane vibration causes movement of auditory ossicles, sound waves amplified • Stapes moves against oval window, pressure waves generated • Travel from oval window and through the scalavestibuli (area of cochlea) • Hair cells in the cochlea detect movement and convert stimulus into nerve impulse which travels to the cochlear nerve. • Excess waves exit through the round window

  39. Balance • 2 structural and functional components of balance in the inner ear • Stationary Position and Linear Movements of Head • Evaluates position of head relative to gravity • Detects inner acceleration/deceleration • Utricle/Saccule: have hair cells that detect • Rotational Movements of Head • Evaluates movement of head • 3 semicircular canals with hair cells • Static balance: orientation of body relative to the pull of gravity • Kinetic balance: maintenance of body position in response to movement

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