Senses PDF

1 Senses © 2019 McGraw-Hill Education  2 Senses Sense: ability to perceive stimuli Sensation: conscious awareness of st...

1 Senses © 2019 McGraw-Hill Education  2 Senses Sense: ability to perceive stimuli Sensation: conscious awareness of stimuli received by sensory neurons Sensory receptors: sensory nerve endings that respond to stimuli by developing action potentials © 2019 McGraw-Hill Education  3 Classification of Senses Figure 9.1 © 2019 McGraw-Hill Education  4 Types of Senses General senses: receptors over large part of body that sense touch, pressure, pain, temperature, and itch somatic provide information about body and environment visceral provide information about internal organs Special senses: smell, taste, sight, hearing, and balance © 2019 McGraw-Hill Education  5 Types of Receptors 1 Mechanoreceptors: detect movement Example, touch, pressure, vibration Chemoreceptors: detect chemicals Example, Odors Photoreceptors: detect light © 2019 McGraw-Hill Education  6 Types of Receptors 2 Thermoreceptors: detect temp. changes Nociceptors: detect pain © 2019 McGraw-Hill Education  7 Types of Touch Receptors 1 Merkel’s disk: detect light touch and pressure Hair follicle receptors: detect light touch Meissner corpuscle: deep in epidermis localizing tactile sensations © 2019 McGraw-Hill Education  8 Types of Touch Receptors 2 Ruffini corpuscle: deep tactile receptors detects continuous pressure in skin Pacinian corpuscle: deepest receptors associated with tendons and joints detect deep pressure, vibration, position © 2019 McGraw-Hill Education  9 Sensory Receptors in the Skin Figure 9.2 © 2019 McGraw-Hill Education  10 Pain Pain is an unpleasant perceptual and emotional experience Pain can be localized or diffuse. Localized: sharp, pricking, cutting pain rapid action potential Diffuse: burning, aching pain slower action potentials © 2019 McGraw-Hill Education  11 Pain Control Local anesthesia: action potentials suppressed from pain receptors in local areas chemicals are injected near sensory nerve General anesthesia: loss of consciousness chemicals affect reticular formation © 2019 McGraw-Hill Education  12 Referred Pain Referred Pain originates in a region that is not source of pain stimulus felt when internal organs are damaged or inflamed sensory neurons from superficial area and neurons of source pain converge onto same ascending neurons of spinal cord © 2019 McGraw-Hill Education  13 Areas of Referred Pain Figure 9.3 © 2019 McGraw-Hill Education  14 Olfaction Olfaction is the: sense of smell occurs in response to odorants receptors are located in nasal cavity and hard palate we can detected 10,000 different smells Figure 9.4a © 2019 McGraw-Hill Education  15 Olfaction Process 1. Nasal cavity contains a thin film of mucous where odors become dissolved. 2. Olfactory neurons are located in mucous. Dendrites of olfactory neurons are enlarged and contain cilia. 3. Dendrites pick up odor, depolarize, and carry odor to axons in olfactory bulb (cranial nerve I). 4. Frontal and temporal lobes process odor. © 2019 McGraw-Hill Education  16 Olfactory Epithelium and Olfactory Bulb Figure 9.4b © 2019 McGraw-Hill Education  17 Taste Taste buds: sensory structures that detect taste located on papillae on tongue, hard palate, throat Inside each taste bud are 40 taste cells Each taste cell has taste hairs that extend into taste pores © 2019 McGraw-Hill Education  18 The Tongue Figure 9.5 © 2019 McGraw-Hill Education  19 Taste Process 1. Taste buds pick up taste and send it to taste cells. 2. Taste cells send taste to taste hairs. 3. Taste hairs contain receptors that initiate an action potential which is carried to parietal lobe. 4. Brain processes taste. © 2019 McGraw-Hill Education  20 Types of Tastes 1. Sweet 2. Sour 3. Salty 4. Bitter 5. Umami Certain taste buds are more sensitive to certain tastes. Taste is also linked to smell. © 2019 McGraw-Hill Education  21 Pathways for the Sense of Taste Figure 9.6 © 2019 McGraw-Hill Education  22 Vision Accessory Structures Eyebrow: protects from sweat shade from sun Eyelid/Eyelashes: protects from foreign objects lubricates by blinking © 2019 McGraw-Hill Education  23 The Eye and Accessory Structures 1 Figure 6.7a © 2019 McGraw-Hill Education (a) ©Eric Wise  24 The Eye and Accessory Structures 2 Conjunctiva: thin membrane that covers inner surface of eyelid Lacrimal apparatus: produces tears Extrinsic eye muscles: help move eyeball © 2019 McGraw-Hill Education  25 Lacrimal Gland Structures Figure 9.7c © 2019 McGraw-Hill Education  26 Extrinsic Eye Muscles Figure 9.8 © 2019 McGraw-Hill Education  27 Anatomy of Eye Hollow, fluid filled sphere Composed of 3 layers (tunics) Divided into chambers © 2019 McGraw-Hill Education  28 The Eye Figure 9.9 © 2019 McGraw-Hill Education  29 Fibrous Tunic Outermost Tunic Sclera: firm, white outer part helps maintain eye shape, provides attachment sites, protects internal structures Cornea: transparent structure that covers iris and pupil allows light to enter and focuses light © 2019 McGraw-Hill Education  30 Vascular Tunic 1 Middle tunic Contains blood supply Choroid: black part (melanin) delivers O2 and nutrients to retina Ciliary body: helps hold lens in place Suspensory ligaments: help hold lens in place © 2019 McGraw-Hill Education  31 Vascular Tunic 2 Lens: flexible disk focuses light onto retina Iris: colored part surrounds and regulates pupil © 2019 McGraw-Hill Education  32 Vascular Tunic 3 Pupil: regulates amount of light entering lots of light = constricted little light = dilated © 2019 McGraw-Hill Education  33 Lens and Ciliary Body Figure 9.10 © 2019 McGraw-Hill Education  34 The Iris Figure 9.11 © 2019 McGraw-Hill Education  35 Nervous Tunic 1 Innermost tunic Retina: covers posterior 5/6 of eye contains 2 layers Pigmented retina: outer layer keeps light from reflecting back in eye © 2019 McGraw-Hill Education  36 Nervous Tunic 2 Sensory retina: contains photoreceptors (rods and cones) contains interneurons Rods: photoreceptor sensitive to light 20 times more rods than cones can function in dim light © 2019 McGraw-Hill Education  37 Nervous Tunic 3 Cones: photoreceptor provide color vision 3 types blue, green, red © 2019 McGraw-Hill Education  38 Retinal Rod 1 Figure 9.12c © 2019 McGraw-Hill Education  39 Retinal Rod 2 Figure 9.12d © 2019 McGraw-Hill Education  40 Pigments and Pigment Protein Rhodopsin: photosensitive pigment in rod cells Opsin: colorless protein in rhodopsin Retinal: yellow pigment in rhodopsin requires vitamin A © 2019 McGraw-Hill Education  41 Effects of Light on Rhodopsin 1 1. Light strikes rod cell 2. Retinal changes shape 3. Opsin changes shape 4. Retinal dissociates from opsin 5. Change rhodopsin shape stimulates response in rod cell which results in vision 6. Retinal detaches from opsin 7. ATP required to reattach retinal to opsin and return rhodopsin to original shape © 2019 McGraw-Hill Education  42 Effects of Light on Rhodopsin 2 Figure 9.13 © 2019 McGraw-Hill Education  43 The Retina 1 Rods and cones synapse with bipolar cells of sensory retina Horizontal cells of retina modify output of rods and cones Bipolar and horizontal cells synapse with ganglion cells Ganglion cells axons’ converge to form optic nerve © 2019 McGraw-Hill Education  44 The Retina 2 Figure 9.12a © 2019 McGraw-Hill Education  45 The Retina 3 Macula: small spot near center of retina Fovea centralis: center of macula where light is focused when looking directly at an object only cones ability to discriminate fine images © 2019 McGraw-Hill Education  46 The Retina 4 Optic disk: white spot medial to macula blood vessels enter eye and spread over retina axons exit as optic nerve no photoreceptors called blind spot © 2019 McGraw-Hill Education  47 The Retina 5 Figure 9.14 © 2019 McGraw-Hill Education  48 Chambers of the Eye 1 Anterior chamber: located between cornea and lens filled with aqueous humor (watery) aqueous humor helps maintain pressure, refracts light, and provide nutrients to inner surface of eye Posterior chamber: located behind anterior chamber contains aqueous humor © 2019 McGraw-Hill Education  49 Chambers of the Eye 2 Vitreous chamber: located in retina region filled with vitreous humor: jelly-like substance vitreous humor helps maintain pressure, holds lens and retina in place, refracts light © 2019 McGraw-Hill Education  50 Functions of the Eye 1 The eye functions much like a camera. The iris allows light into the eye, which is focused by the cornea, lens, and humors onto the retina. The light striking the retina produces action potentials that are relayed to the brain. Light refraction and image focusing are two important processes in establishing vision. © 2019 McGraw-Hill Education  51 Functions of the Eye 2 Light Refraction Bending of light Focal point: point where light rays converge occurs anterior to retina object is inverted © 2019 McGraw-Hill Education  52 Functions of the Eye 3 Focusing Images on Retina Accommodation: lens becomes less rounded and image can be focused on retina enables eye to focus on images closer than 20 feet © 2019 McGraw-Hill Education  53 Focusing by the Eye Figure 9.15 © 2019 McGraw-Hill Education  54 Neuronal Pathway for Vision Optic nerve: leaves eye and exits orbit through optic foramen to enter cranial cavity Optic chiasm: where 2 optic nerves connect Optic tracts: route of ganglion axons © 2019 McGraw-Hill Education  55 Visual Pathway 1 Figure 6.17b © 2019 McGraw-Hill Education (b) ©McGraw-Hill Education/Rebecca Gray  56 Visual Pathway 2 Figure 6.17a,c © 2019 McGraw-Hill Education  57 Visual Defects 1 Myopia: nearsightedness image is in front of retina Hyperopia: farsightedness image is behind retina Presbyopia: lens becomes less elastic reading glasses required © 2019 McGraw-Hill Education  58 Visual Defects 2 Astigmatism: irregular curvature of lens glasses or contacts required to correct Color Blindness: absence or deficient cones primarily in males Glaucoma: increased pressure in eye can lead to blindness © 2019 McGraw-Hill Education  59 Chart to Determine Color Blindness Figure 6.16 © 2019 McGraw-Hill Education (a) ©Steve Allen/Getty Images RF; (b) ©Prisma Bildagentur AG/Alamy  60 The Ear The organs of hearing and balance are located in the ears. Each ear is divided into three areas: 1. the external ear 2. the middle ear 3. the inner ear © 2019 McGraw-Hill Education  61 The External Ear Extends from outside of head to eardrum Auricle: fleshy part on outside External auditory meatus: canal that leads to eardrum Tympanic membrane: eardrum thin membrane that separates external and middle ear © 2019 McGraw-Hill Education  62 The Middle Ear 1 Air filled chamber with ossicles Malleus (hammer): bone attached to tympanic membrane Incus (anvil): bone that connects malleus to stapes Stapes (stirrup): bone located at base of oval window © 2019 McGraw-Hill Education  63 The Middle Ear 2 Oval window: separates middle and inner ear Eustachian or auditory tube: opens into pharynx equalizes air pressure between outside air and middle ear © 2019 McGraw-Hill Education  64 The Inner Ear 1 Set of fluid filled chambers Bony labyrinth: tunnels filled with fluid 3 regions: cochlea, vestibule, semicircular canals Membranous labyrinth: inside bony labyrinth filled with endolymph © 2019 McGraw-Hill Education  65 The Inner Ear 2 Endolymph: clear fluid in membranous labyrinth Perilymph: fluid between membranous and bony labyrinth Cochlea: snail-shell shaped structure where hearing takes place © 2019 McGraw-Hill Education  66 The Inner Ear 3 Scala vestibuli: in cochlea filled with perilymph Scala tympani: in cochlea filled with perilymph Cochlea duct: in cochlea filled with endolymph © 2019 McGraw-Hill Education  67 The Inner Ear 4 Spiral organ: in cochlear duct contains hair cells Tectorial membrane: in cochlea vibrates against hair cells Hair cells: attached to sensory neurons that when bent produce an action potential © 2019 McGraw-Hill Education  68 The Inner Ear 5 Vestibular membrane: wall of membranous labyrinth that lines scala vestibuli Basilar membrane: wall of membranous labyrinth that lines scala tympani © 2019 McGraw-Hill Education  69 Structure of the Ear Figure 9.18 © 2019 McGraw-Hill Education  70 Structure of the Inner Ear Figure 6.19 © 2019 McGraw-Hill Education (e) Courtesy of A. J. Hudspeth  71 Hearing Process 1 1. Sound travels in waves through air and is funneled into ear by auricle. 2. Auricle through external auditory meatus to tympanic membrane. 3. Tympanic membrane vibrates and sound is amplified by malleus, incus, stapes which transmit sound to oval window. 4. Oval window produces waves in perilymph of cochlea. © 2019 McGraw-Hill Education  72 Hearing Process 2 5. Vibrations of perilymph cause vestibular membrane and endolymph to vibrate. 6. Endolymph cause displacement of basilar membrane. 7. Movement of basilar membrane is detected by hair hairs in spiral organ. 8. Hair cells become bent and cause action potential is created. © 2019 McGraw-Hill Education  73 Effect of Sound Waves on Middle and Inner Ear Structures Figure 9.20 © 2019 McGraw-Hill Education  74 Balance (Equilibrium) Static equilibrium: associated with vestibule evaluates position of head relative to gravity Dynamic equilibrium: associated with semicircular canals evaluates changes in direction and rate of head movement © 2019 McGraw-Hill Education  75 Balance 1 Vestibule: inner ear contains utricle and saccule Maculae: specialized patches of epithelium in utricle and saccule surround by endolymph contain hair cells © 2019 McGraw-Hill Education  76 Balance 2 Otoliths: gelatinous substance that moves in response to gravity attached to hair cell microvilli which initiate action potentials © 2019 McGraw-Hill Education  77 Location and Structure of the Macula Figure 6.22 © 2019 McGraw-Hill Education (d) ©Susumu Nishinag/Science Source  78 Function of the Vestibule in Maintaining Balance Figure 6.23 © 2019 McGraw-Hill Education (d) ©Susumu Nishinag/Science Source  79 Balance 3 Semicircular canals: dynamic equilibrium sense movement if any direction Ampulla: base of semicircular canal Crista ampullaris: in ampulla © 2019 McGraw-Hill Education  80 Balance 4 Cupula: gelatinous mass contains microvilli float that is displaced by endolymph movement © 2019 McGraw-Hill Education  81 Semicircular Canals Figure 6.24 © 2019 McGraw-Hill Education  82 Function of the Crista Ampullaris Figure 6.25 © 2019 McGraw-Hill Education (a) ©Julie Jacobson/AP Photo