ELAINE N. MARIEB EIGHTH EDITION 8 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Lecture Slide Presentation by Jerry L. Cook, Sam Houston University ESSENTIALS OF HUMAN ANATOMY & PHYSIOLOGY PART A Special Senses

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings I. Introduction 1) There are 5 senses: touch, taste, smell, sight and hearing 2) Touch is actually a combination of temperature, pressure, pain and proprioceptors 3) Special senses a) Include sight, smell, hearing, taste & equilibrium b) All of these have either large, complex organs or localized clusters of receptors

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings II. Eye and Vision 1) The most studied of the senses 2) 70% of the sensory receptors are located in the eyes 3) Vision is the sense that requires the most learning and is often fooled. Often you see what you expect to see 4) Anatomy of the eye: a) Adult eye is about 1 inch in diameter b) Protection: fat cushion, bony orbit, eyelids, eye lashes and various glands

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Accessory Structures of the Eye

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Accessory Structures of the Eye c) Glands: 1. Tarsal gland: 2. Ciliary gland: 3. Conjunctiva: 4. Lacrimal apparatus: 5. Tears contain lysozyme, which kills bacteria

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Accessory Structures of the Eye Figure 8.1a 6. Lacrimal sac: provides passage of lacrimal fluid towards nasal cavity

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 5) Internal structures of the eyeball a) The eye is a hollow sphere formed by 3 tunics (coats) filled with humors (fluid) b) Tunics: 1. Sclera: white of the eye 2. Cornea: (only organ that can be transplanted without worry of rejection) Figure 8.1a

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 3.Vascular tunic: A. Choriod layer: prevents light from scattering B. Ciliary body: C. Iris: colored part of the eye 4) Retina: where vision is initiated

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Structure of the Eye Figure 8.3a

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 6) Nervous tissue a) Photoreceptors: receptors that respond to light b) Rods: Located on the periphery and see gray tones in dim light c) Cones: 1. See detail and color in bright light 2. Types of cones: blue, green, red 3. White: all three cones are stimulated

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cone Sensitivity Figure 8.6

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings d) Optic disc (blind spot): e) Fovea centralis: pit of cones with the highest visual acuity 7) Lens: 8) Humors: a) Aqueous: watery fluid between the cornea and lens b) Vitreous: gel-like substance filling most of the eye

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9) Refraction: a) When light moves through a substance, it bends b) The lens is set for distant vision (20 feet) and flattens for closer vision c) Accommodation: the reflex changing the lens shape for close vision d) The refraction causes the image to be flipped from right to left and upside- down.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Images Formed on the Retina Figure 8.10

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Lens Accommodation Figure 8.9

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

10) Visual Pathway a) Light enters through the pupil b) Lens flips and focuses the object on the retina c) Rods and cones are stimulated d) Image travels over the optic nerve e) Impulses cross at the optic chiasm f) Image is interpreted in the occipital lobe of the brain Figure 8.11

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Visual Pathway Figure 8.11

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 11) Binocular vision: Because the eyes give a slightly different view, we see 3-D or with depth perception 12) Eye reflexes: a) Convergence: b) Photopupillary c) Accommodation papillary reflex: pupils constrict when viewing close objects

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings III. Hearing and balance 1) Mechanoreceptors: respond to movement 2) Even though hearing and equilibrium are in the same area and share a nerve, they are not actually related 3) Anatomy a) Outer ear: 1. Pinna:

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Anatomy of the Ear 2. External auditory canal: narrow chamber leading to the eardrum 3. Ceruminous gland: protect and moisten ear 4. Tympanic membrane: b) Middle ear 1. Pharyngotympanic (Eustachian) tube: connects the ear and throat to equalize pressure Figure 8.12

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Ear Figure 8.12

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 2. Ossicles: Malleus, incus and stapes, bones transferring sound 3. Oval window: c) Inner ear: 1. Osseous labyrinth: filled with perilymph 2. Cochlea:

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

4) How the ear works: a) Sound is collected by the pinna and funneled through the external auditory canal b) Tympanic membrane vibrates and passes the sound through the ossicles to the oval window c) Endolymph in the cochlea bends hair cells in the organ of corti d) Impulses travels over the acoustic nerve to the temporal lobe

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Hearing Figure 8.16a–b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 5) Hair cells: a) Hair cells respond to movement b) Long fibers: low pitchShort fibers: high pitch c) Auditory receptors will adapt to a continual sound 6) Equilibrium: a) Static equilibrium: 1. Not moving

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 2. Maculae: report the position of the head based on gravity b) Dynamic equilibrium 1. Body is moving 2. Semicircular canals: 3 tubes in each ear used to detect movement of the head 3. Crista ampullaris: located in the semicircular canal, consists of hair cells that bend when the fluid moves c) Vestibular nerve: carries impulses to the brain

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Organs of Equilibrium Figure 8.14a–b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Function of Maculae Figure 8.13a–b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings IV. Chemical senses 1) Chemoreceptors: respond to chemicals in solution 2) Smell a) Olfactory receptors are located in the roof of the nasal cavities, so sniffing increase smell b) When smell is stimulated, it sends impulses over the olfactory nerve Figure 8.12

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings c) Smell is closely associated with emotions and are a long lasting part of our memories and emotions d) Olfactory neurons adapt quickly when exposed to the same stimulus

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 3) Taste: a) Papillae: projections on the tongue containing the taste buds b) Taste bud: 1. Found on the tongue, soft palate and cheeks 2. Gustatory cells: cells in the taste buds responding to a specific chemical 3. Most respond to more than one chemical

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Anatomy of Taste Buds Figure 8.18

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings c) Facial, glossopharyngeal and vagus nerve carry impulse to the brain d) There are 5 taste sensations: sweet, salt, sour, bitter and umani (meat flavor) e) Actual taste involves: taste, smell, texture and sight f) Spicy foods like chili pepper stimulate pain receptors