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Sense Organs.

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Presentation on theme: "Sense Organs."— Presentation transcript:

1 Sense Organs

2 Chemoreceptors Taste and smell sensory receptors
Most primitive sense, all animals have it Important in finding food, locating a mate and detecting chemicals Location varies by animal Jacobsen’s organ - snakes

3 Taste 4 primary types of taste
Sweet, sour, salty, bitter, umami? Cheeses, broth, seafood, Asian foods Microvilli of taste cell has receptor proteins for food molecules

4 Smell 10 – 20 million olfactory cells!! (modified neurons)
Declines with age Located on roof of nasal cavity Olfactory bulb (extension of brain) has direct connection with limbic system (emotions and memory) Smell and taste work together in cerebral cortex Sometime molecules from smell travel to mouth and you taste it

5 Vision Photoreceptors – sensitive to light
Some animals have “eye spots”, some have image forming eyes Insects have color vision, shorter spectrum but includes ultraviolet light Some fish, all reptiles, most birds monkeys, apes and humans only mammals Stereoscopic vision (binocular – in front) Panoramic vision – eyes on side, prey

6 Human Eye

7 Human eye 3 layers Sclera – clear outer layer
Cornea – refracts light rays Conjunctive – moistens Pupil – light enters Choroid – middle, includes blood vessels iris – color of eye, regulates light entrance Ciliary muscle – holds lens in place Retina – inner layer, metallic Rods –sensitive to light, black and white, night vision Cones – color vision Fovea centralis – acute vision

8 Eye Lens Aqueous humor Vitreous humor
Refracts and focuses light, can be replaced Aqueous humor Water solution, anterior of eye, behind lens Glaucoma – pressure builds up Vitreous humor Gel material in posterior of eye Stabilizes the shape of eye, support retina Optic nerve – sends info to brain Blind spot – optic nerve exits the retina, no rods or cones

9 Disorders of eye Presbyopia – old-sightedness Nearsighted (myopia)
lens loses its ability to accommodate near objects Nearsighted (myopia) Elongated eyeball, image in focus in front of retina Farsighted (hyperopia) Shortened eyeball, image focused behind the retina Astigmatism Cornea or lens is uneven, image is fuzzy Cataract – aging, exposure to sun, lens is milky and cannot transmit light rays

10 Hearing and balance – The Ear
Mechanoreceptors sensitive to pressure, sound waves and gravity Outer ear – pinna flap, auditory canal Middle ear – tympanic membrane (ear drum) Ossicles – stapes (stirrup), incus (anvil), malleus (hammer) Eustachian tube – equalization of pressure Inner ear – contains fluid Semicircular canals, vestibule – equilibrium Cochlea - hearing

11 Sound Auditory canal tympanic membrane malleus incus stapes oval window  endolymph in cochlea  hair cells of cochlea  synapse with nerve fibers of auditory nerve basilar membrane “organ of corti” nerve impulse travels to brain stem  auditory area of cerebral cortex = sound!!

12 Sense of Balance Semicircular canals – mechanoreceptors
Rotational equilibrium – head rotation Gravitational equilibrium – straight line movement

13 Sensory receptors in animals
Lateral line – fish – Detects water currents and pressure waves Collection of hair cells with cilia Statocysts – gravitational equilibrium Cnidarians, molluscs, crustaceans Give information only about the head

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