SOCM EAP The General and Special Senses PFN: SOMAPL19. Terminal Learning Objective. References. Hours: 2.0

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1 SOCM EAP The General and Special Senses PFN: SOMAPL19 Hours: 2.0 Slide 1 Terminal Learning Objective Action: Communicate knowledge of The General and Special Senses Condition: Given a lecture in a classroom environment Standard: Received a minimum score of 75% on the written exam IAW course standards Slide 2 References Essentials of Anatomy and Physiology (6th edition; 2013; Martini; Bartholomew) Slide 3 1

2 Reason All that we experience about the world is brought to us by our senses. Unless a receptor is stimulated, we experience nothing. Life would be impossible without sensation; because an organism could not respond to an environmental challenge or to disturbed homeostasis without it. As a SOCM Medic / Corpsman your knowledge of this system will enhance your patient treatment skills. Slide 4 Agenda Define the medical vocabulary components related to the general and special senses Distinguish between the general senses and the special senses Identify the receptors for the general senses and how they function Identify the receptors and processes involved in the sense of smell Slide 5 Agenda Identify the receptors and processes involved in the sense of taste Identify the parts of the eye and their functions Communicate the ability to see objects and distinguish colors Communicate how the central nervous system processes information related to vision Slide 6 2

3 Agenda Identify the receptors and processes involved in the sense of equilibrium Identify the parts of the ear and their roles in the process of hearing Communicate the effects of aging on smell, taste, vision, and hearing Slide 7 The Medical Vocabulary Components Related to the General and Special Senses Slide 8 Vocabulary Development akousis hearing; acoustic baro pressure; baroreceptors circa about; circadian circum around; circumvillate papillae cochlea snail shell; cochlea dies day; circadian emmetro proper measure; emmetropia incus anvil; incus (auditory ossicle) iris colored circle; iris Slide 9 3

4 Vocabulary Development labyrinthos network of canals; labyrinth lacrima tear; lacrimal gland lithos a stone; otolith macula spot; macula lutea malleus a hammer; malleus (auditory ossicle) myein to shut; myopia noceo hurt; nociceptor olfacere to smell; olfaction Slide 10 Vocabulary Development ops eye; myopia oto ear; otolith presbys old man; presbyopia skleros hard; sclera stapes stirrup; stapes (auditory ossicle) tectum roof; tectorial membrane tympanon drum; tympanum vallum wall; circumvallate papillae vitreus glassy; vitreous body Slide 11 Differences Between the General Senses and the Special Senses Slide 12 4

5 The General Senses Sensory Basics Sensory receptors Specialized cells or cell processes that monitor external or internal conditions Simplest are free nerve endings Slide 13 The General Senses Receptors and Receptive Fields Slide 14 The General Senses More Sensory Basics Receptive field The area monitored by a single receptor cell Adaptation Reduction in sensitivity at a receptor or along a sensory pathway in the presence of a constant stimulus Slide 15 5

6 The General Senses General versus Special Senses General senses Temperature, pain, touch, pressure, vibration, and proprioception Receptors throughout the body Special senses Smell, taste, vision, balance, and hearing. Receptors located in sense organs (e.g., ear, eye) Slide 16 The General Senses Key Note Stimulation of a receptor produces action potentials that propagate along the axon of a sensory neuron. The frequency or pattern of action potentials contains information about the stimulus. A person s perception of the nature of that stimulus depends on the path it takes inside the CNS. Slide 17 Check on Learning Receptor A has a circular receptive field with a diameter of 2.5 cm. Receptor B has a circular receptive field 7.0 cm in diameter. Which receptor provides more precise sensory information? A. Receptor A. B. Receptor B. C. Both receptors are equally precise. D. Neither receptor is considered precise. Slide 18 6

7 The Receptors for the General Senses and How They Function Slide 19 The General Senses Receptors for the general senses are scattered throughout the body and are relatively simple in structure Classified according to nature of stimulus Nociceptors sensitive to pain Thermoreceptors sensitive to temperature Mechanoreceptors sensitive to physical distortion resulting from touch, pressure, and body position Chemoreceptors sensitive to chemical stimuli Slide 20 The General Senses Pain definitions Nociceptors Receptors for tissue damage to lead to the sensation of pain Fast (prickling) pain Localized pain carried quickly to the CNS on myelinated axons Slow (burning) pain Generalized pain carried on slow un myelinated axons Referred pain Perception of pain in a part of the body not actually stimulated Slide 21 7

8 The General Senses Referred Pain Slide 22 The General Senses Temperature Thermoreceptors detect temperature change Free nerve endings Found in dermis, skeletal muscle, liver, hypothalamus Fast adapting Cold receptors greatly outnumber warm receptors Slide 23 The General Senses Touch, Pressure, and Position Mechanoreceptors Receptors that respond to physical distortion of their cell membranes Tactile receptors Sense touch, pressure, or vibration Baroreceptors Sense pressure changes in walls of blood vessels, digestive organs, bladder, lungs Proprioceptors Respond to positions of joints and muscle Slide 24 8

9 The General Senses Tactile Receptors Fine touch or pressure receptors Highly detailed information about a stimulus Crude touch or pressure receptors Poorly localized information about a stimulus Important types: free nerve ending, root hair plexus, tactile disks, tactile corpuscles, lamellated corpuscles, Ruffini corpuscles Slide 25 The General Senses Tactile Receptors in the Skin Slide 26 The General Senses Baroreceptors Provide pressure information essential for autonomic regulation Arterial blood pressure Lung inflation Digestive coordination Bladder fullness Slide 27 9

10 The General Senses Baroreceptors and the Regulation of Autonomic Functions Slide 28 The General Senses Proprioceptors Monitor joint angle, tension in tendons and ligaments, state of muscular contraction Include: Free nerve endings Golgi tendon organs Muscle spindles Slide 29 The General Senses Chemical Detection Chemoreceptors respond to chemicals dissolved in body fluids that surround them and monitor the chemical composition of blood and tissues Chemicals that can be sensed include: Carbon dioxide Oxygen Hydrogen ions Slide 30 10

11 The General Senses Locations and Functions of Chemoreceptors Slide 31 Check on Learning When the nociceptors in your hand are stimulated, what sensation do you perceive? A. Temperature. B. Deep Pressure. C. Pain. D. The position of your hand. Slide 32 The Receptors and Processes Involved in the Sense of Smell Slide 33 11

12 The Special Senses Smell Olfactory Organs Olfactory epithelium Olfactory receptor cells Neurons sensitive to odorants Supporting cells Basal (stem) cells Olfactory glands Mucus secreting cells Slide 34 The Special Senses Smell The Olfactory Organs Slide 35 The Special Senses Smell The Olfactory Pathways Axons from olfactory receptors penetrate cribriform plate of the ethmoid bone Synapse in olfactory bulb Olfactory tract projects to: Olfactory cerebral cortex Hypothalamus Limbic System Slide 36 12

13 Check on Learning How does sniffing repeatedly help to identify faint odors? A. Sniffing removes distracting odors. B. Sniffing evaporates the mucus buildup and increases exposure of olfactory epithelium. C. Sniffing increases the neural sensitivity of the olfactory epithelium. D. Sniffing increases the number of odorant molecules exposed to the olfactory epithelium. Slide 37 The Receptors and Processes Involved in the Sense of Taste Slide 38 The Special Senses Taste Taste (Gustatory) Receptors Taste buds Found within papillae on tongue, pharynx, larynx Contain gustatory cells, supportive cells Taste hairs (cilia) extend into taste pores Sense salt, sweet, sour, bitter Also sense umami, water Synapse in the medulla oblongata Slide 39 13

14 The Special Senses Taste Gustatory Receptors Slide 40 The Special Senses Taste The Taste Pathways The taste buds are monitored by the facial (CN VII), glossopharyngeal (CN IX), and vagus (CN X), which synapse in the medulla oblongata The postsynaptic neurons synapse in the thalamus with touch, pressure, and proprioception axons, and then projects to the primary sensory cortex Slide 41 The Special Senses Taste The Taste Pathways (continued) A conscious perception of taste is produced as the information is correlated with other sensory data, e.g. trigeminal nerve (CN V) provides information about the texture of food, along with taste related sensations such as peppery or spicy hot Slide 42 14

15 The Special Senses Key Note Olfactory information is routed directly to the cerebrum, and olfactory stimuli have powerful effects on mood and behavior. Gustatory sensations are strongest and clearest when integrated with olfactory sensations. Slide 43 Check on Learning Why are tastes as different as salt and sugar undifferentiated if the surface of the tongue is completely dry? A. Taste receptors (chemoreceptors) are sensitive only to molecules in solution. B. When the surface is dry epithelial cells expand preventing enough receptors to distinguish tastes. C. The pores close in a dry environment preventing the substance from reaching the receptor. D. The statement is false, You can taste salt or sugar with a dry tongue. Slide 44 The Parts of the Eye and Their Functions Slide 45 15

16 The Special Senses Vision Accessory Structures of the Eye Eyelids (palpebra) and glands Superficial epithelium of eye Conjunctiva Lacrimal apparatus Tear production and removal Extrinsic eye muscles Slide 46 The Special Senses Vision The Accessory Structures of the Eye Slide 47 The Special Senses Vision The Lacrimal Apparatus Lacrimal gland produce tears Bathe conjunctiva Contain lysozyme to attack bacteria Tears drain into nasal cavity Pass through lacrimal canals, lacrimal sac, nasolacrimal duct Slide 48 16

17 The Special Senses Vision The Accessory Structures of the Eye Slide 49 The Special Senses Vision Extrinsic Eye Muscles Move the eye Six muscles cooperate to control gaze Superior and inferior rectus Lateral and medial rectus Superior and inferior oblique Slide 50 Slide 51 17

18 The Special Senses Vision The Sectional Anatomy of the Eye Slide 52 The Special Senses Vision Layers of the Eye Fibrous tunic Outermost layer Vascular tunic Intermediate layer Neural tunic Innermost layer Slide 53 The Special Senses Vision Layers of the Eye Fibrous tunic Sclera Dense fibrous connective tissue White of the eye Cornea Transparent Light entrance Slide 54 18

19 The Special Senses Vision Functions of the Vascular Tunic Provide a route for blood vessels Control amount of light entering eye Adjust diameter of pupil Secrete and absorb aqueous humor Adjust lens shape for focusing Slide 55 The Special Senses Vision Layers of the Eye Vascular tunic Iris Boundary between anterior and posterior chambers Ciliary body Ciliary muscle and ciliary process Attachment of suspensory ligaments Choroid Highly vascular Slide 56 The Special Senses Vision The Pupillary Muscles Slide 57 19

20 The Special Senses Vision Layers of the Eye Neural tunic (Retina) Outer pigmented part Absorbs stray light Inner neural part Detects light Processes image Communicates with brain Slide 58 The Special Senses Vision Organization of the Retina Photoreceptor layer Bipolar cells Amacrine, horizontal cells modify signals Ganglion cells Optic nerve (CN II) Slide 59 The Special Senses Vision Retinal Organization Slide 60 20

21 The Special Senses Vision Chambers of the Eye Two cavities Ciliary body, lens between the two Anterior cavity Anterior chamber Between cornea and iris Posterior chamber Between iris and lens Posterior cavity Vitreous body Slide 61 The Special Senses Vision The Aqueous Humor Secreted by ciliary processes into posterior chamber Flows into anterior chamber Maintains eye shape Carries nutrients and wastes Reabsorbed into circulation Leaves at scleral venous sinus Excess humor leads to glaucoma Slide 62 The Special Senses Vision Eye Chambers and Circulation of Aqueous Humor Slide 63 21

22 The Special Senses Vision The Lens Supported by suspensory ligaments Built from transparent cells Surrounded by elastic capsule Lens and cornea focus light on retina Bend light (refraction) Accommodation changes lens shape Slide 64 The Special Senses Vision Focal Point, Focal Distance, and Accommodation Slide 65 The Special Senses Vision Visual Abnormalities Slide 66 22

23 The Special Senses Vision Image Formation Slide 67 The Special Senses Vision Key Note Light passes through the cornea, crosses the anterior cavity to the lens, transits the lens, crosses the posterior chamber, and then penetrates the retina to stimulate the photoreceptors. Cones, most abundant at the fovea and macula lutea, provide detailed color vision in bright light. Rods, dominant in the peripheral retina, provide coarse color free vision in dim light. Slide 68 Check on Learning The lens of the eye changes shape to adjust for focusing objects at differences in distances. When the lens is very round what is the distance of the object in focus? A. The very round lens would put the object at a far distance. B. The very round lens would put the object at a close distance. C. The very round lens would put the object at a medium distance, shape changing from horizontal flat at close distance and vertically flat at far distance. D. The very round lens would put the object at a medium distance, shape changing from horizontal flat at a far distance and vertically flat at close distance. Slide 69 23

24 How We are Able to See Objects and Distinguish Colors Slide 70 The Special Senses Vision Visual Physiology Photoreceptors Cells specialized to respond to photons, packets of light energy Two types of photoreceptors Rods Highly sensitive, non color vision In peripheral retina Cones Less sensitive, color vision Mostly in fovea, center of macula lutea Site of sharpest vision Slide 71 The Special Senses Vision The Structure of Rods and Cones Slide 72 24

25 The Special Senses Vision Photoreceptor Anatomy Outer segment Discs with visual pigments Light absorption by rhodopsin Opsin + retinal Inner segment Synapse with bipolar cell Control of neurotransmitter release Effect on bipolar cells Slide 73 Photon Retinal changes shape Retinal and opsin are reassembled to form rhodopsin Regeneration Retinal restored Opsin ADP enzyme ATP Bleaching (separation) Opsin Opsin inactivated Slide 74 Slide 75 25

26 Check on Learning What would be the effect, if any, of individuals born without cone cells or a very limited number of cone cells? A. They will be completely blind with no cells, a limited number of cells would affect their vision and depending upon the number may be legally blind. B. Their vision will be largely unaffected. C. They would be able to see black and white and gray scale, but not color. They would be color blind. D. They will only see color, not black and white and would be night blind. Slide 76 How the Central Nervous System Processes Information Related to Vision Slide 77 The Special Senses Vision The Visual Pathway Ganglion cells axon converge at optic disc Axons leave as the optic nerve (CN II) Some axons cross at optic chiasm Synapse in thalamus bilaterally Thalamic neurons project to visual cortex Located in occipital lobes Contains map of visual field Slide 78 26

27 The Special Senses Vision The Visual Pathway Slide 79 Check on Learning What nerve is responsible for Vision and what is unique to this nerve s pathway to the brain? A. CN III Oculomotor, it is the only cranial nerve to enter the brain below the medulla oblongata. B. CN IV Optic, each nerve (right and left) make several crosses from the eye to the brain, the most predominant is the optic chiasm. C. CN II Optic, each optic nerve (right and left) cross at a point called the optic chiasm. D. CN VI Oculomotor, The fibers of each optic tract (right and left) proceed to the thalamic nucleus while the remaining half proceeds to the cerebral cortex and brainstem. Slide 80 The Receptors and Processes Involved in the Sense of Equilibrium Slide 81 27

28 Equilibrium and Hearing Sensory Functions of the Inner Ear Dynamic equilibrium Static equilibrium Hearing Slide 82 Equilibrium and Hearing Overview of the Ear Bony labyrinth Surrounds membranous labyrinth Surrounded by fluid perilymph Consists of vestibule, semicircular canals, cochlea External, and middle ear feed sound to cochlea Slide 83 Equilibrium and Hearing The Anatomy of the Ear Slide 84 28

29 Equilibrium and Hearing Anatomy of the Ear External ear Pinna (auricle) External acoustic canal Tympanic membrane (eardrum) Middle ear Auditory ossicles Connect tympanic membrane to inner ear Auditory tube Connection to nasopharynx Inner ear Slide 85 Equilibrium and Hearing The Anatomy of the Ear Slide 86 Equilibrium and Hearing The Structure of the Middle Ear Slide 87 29

30 Equilibrium and Hearing Anatomy of the Inner Ear Vestibule Membranous sacs Utricle Saccule Receptors for linear acceleration, gravity Semicircular canal with ducts Receptors for rotation Cochlea with cochlear duct Receptors for sound Slide 88 Equilibrium and Hearing The Structure of the Inner Ear Slide 89 Equilibrium and Hearing Receptors of the Inner Ear Hair cells Mechanoreceptors Stereocilia on cell surface Bending excites/inhibits hair cell Information on direction and strength of mechanical stimuli Slide 90 30

31 Equilibrium and Hearing The Anatomy of the Ear Slide 91 Equilibrium and Hearing Equilibrium Semicircular ducts Connect to utricle Contains ampulla with hair cells Stereocilia contact cupola Gelatinous mass distorted by fluid movement Detects rotation of head in three planes Anterior, posterior, lateral ducts Slide 92 Equilibrium and Hearing The Vestibular Complex Slide 93 31

32 Equilibrium and Hearing Equilibrium (continued) Saccule and utricle Hair cells cluster in maculae Stereocilia contact otoliths (heavy mineral crystals) Gravity pulls otoliths Detect tilt of head Sensory axons in vestibular branch of CN VIII Slide 94 Equilibrium and Hearing The Vestibular Complex Slide 95 Equilibrium and Hearing The Equilibrium pathway CN VIII Vestibulocochlear carries information to vestibular nucleus, which integrates the information and relays the information to: Cerebellum Cerebral cortex Motor nuclei Slide 96 32

33 Equilibrium and Hearing Slide 97 Check on Learning The special sense of equilibrium and hearing is provided by a receptor complex called the inner ear. Where is the inner ear located? A. The inner ear is located within the external acoustic canal. B. The inner ear is located in the temporal bones of the skull. C. The inner ear is located in the sphenoid bones of the skull. D. The inner ear is located between the temporal bones and sphenoid bones of the skull. Slide 98 The Parts of the Ear and Their Roles in the Process of Hearing Slide 99 33

34 Equilibrium and Hearing Overview of Hearing Sound waves vibrate tympanic membrane Ossicles transfer vibration to oval window Oval window presses on perilymph in vestibular duct Pressure wave distorts basilar membrane Hair cells of spiral organ press on tectorial membrane Slide 100 Equilibrium and Hearing The Cochlea and the spiral organ Slide 101 Equilibrium and Hearing The Cochlea and the Spiral organ Slide

35 External acoustic canal Movement of sound waves Tympanic membrane Sound waves arrive at tympanic membrane. Slide 103 External acoustic Incus canal Malleus Stapes Movement of sound waves Tympanic membrane Sound waves arrive at tympanic membrane. Movement of tympanic membrane causes displacement of the auditory ossicles. Slide 104 External acoustic canal Incus Malleus Stapes Oval window Movement of sound waves Tympanic membrane Sound waves arrive at tympanic membrane. Movement of tympanic membrane causes displacement of the auditory ossicles. Movement of the stapes at the oval window establishes pressure waves in the perilymph of the vestibular duct. Slide

36 External acoustic canal Incus Malleus Stapes Oval window Movement of sound waves Tympanic membrane Round window Sound waves arrive at tympanic membrane. Movement of tympanic membrane causes displacement of the auditory ossicles. Movement of the stapes at the oval window establishes pressure waves in the perilymph of the vestibular duct. The pressure waves distort the basilar membrane on their way to the round window of the tympanic duct. Slide 106 External acoustic canal Incus Malleus Stapes Oval window Movement of sound waves Vestibular duct (perilymph) Vestibular membrane Cochlear duct (endolymph) Basilar membrane Tympanic duct (perilymph) Tympanic membrane Round window Sound waves arrive at tympanic membrane. Movement of tympanic membrane causes displacement of the auditory ossicles. Movement of the stapes at the oval window establishes pressure waves in the perilymph of the vestibular duct. The pressure waves distort the basilar membrane on their way to the round window of the tympanic duct. Vibrations of the basilar membrane causes vibration of hair cells against the tectorial membrane. Slide 107 External acoustic canal Incus Malleus Stapes Oval window Cochlear branch of cranial nerve VIII Movement of sound waves Vestibular duct (perilymph) Vestibular membrane Cochlear duct (endolymph) Basilar membrane Tympanic duct (perilymph) Tympanic membrane Round window Sound waves arrive at tympanic membrane. Movement of tympanic membrane causes displacement of the auditory ossicles. Movement of the stapes at the oval window establishes pressure waves in the perilymph of the vestibular duct. The pressure waves distort the basilar membrane on their way to the round window of the tympanic duct. Vibrations of the basilar membrane causes vibration of hair cells against the tectorial membrane. Information about the region and the intensity of stimulation is relayed to the CNS over the cochlear branch of cranial nerve VIII. Slide

37 Slide 109 Equilibrium and Hearing Auditory Pathways Hair cells excite sensory neurons Sensory neurons located in spiral ganglion Afferent axons form cochlear branch of vestibulocochlear nerve (CN VIII) Synapses in cochlear nucleus in medulla Neurons relay to midbrain Midbrain relays to thalamus Thalamus relays to auditory cortex (temporal lobe) in a frequency map Slide 110 Equilibrium and Hearing Pathways for Auditory Sensations Slide

38 Equilibrium and Hearing Key Note Balance and hearing both rely on hair cells. Which stimulus excites a particular group depends on the structure of the associated sense organ. In the semicircular ducts, fluid movement due to head rotation is sensed. In the utricle and saccule, shifts in the position of otoliths by gravity is sensed. In the cochlea, sound pressure waves distort the basilar membrane. Slide 112 Check on Learning If the round window were not able to bulge out with increased pressure in the perilymph, how would sound perception be affected? A. The sound would be greatly amplified. B. The oval window could not move the perilymph, and there would be little or no perception of sound. C. The patient would be prone to infections. D. The patient would suffer migraine like pain. Slide 113 The Effects of Aging on Smell, Taste, Vision, and Hearing Slide

39 Aging and the Senses Impact of Aging on Sensory Ability Gradual reduction in smell and taste sensitivity as receptors are lost Lens changes lead to presbyopia (loss of near vision) Chance of cataract increases Progressive loss of hearing sensitivity as receptors are lost (presbycusis) Slide 115 Check on Learning How can a given food be both too spicy for a child and too bland for an elderly individual? A. The number and sensitivity of taste buds declines with age. B. The child has fewer receptors, so a little stimulation has a great effect. C. The child s chemoreceptors may be hyperactive. D. The adult has many more receptors to be stimulated. Slide 116 Questions? Slide

40 Terminal Learning Objective Action: Communicate knowledge of The General and Special Senses Condition: Given a lecture in a classroom environment Standard: Received a minimum score of 75% on the written exam IAW course standards Slide 118 Agenda Define the medical vocabulary components related to the general and special senses Distinguish between the general senses and the special senses Identify the receptors for the general senses and how they function Identify the receptors and processes involved in the sense of smell Slide 119 Agenda Identify the receptors and processes involved in the sense of taste Identify the parts of the eye and their functions Communicate the ability to see objects and distinguish colors Communicate how the central nervous system processes information related to vision Slide

41 Agenda Identify the receptors and processes involved in the sense of equilibrium Identify the parts of the ear and their roles in the process of hearing Communicate the effects of aging on smell, taste, vision, and hearing Slide 121 Reason All that we experience about the world is brought to us by our senses. Unless a receptor is stimulated, we experience nothing. Life would be impossible without sensation; because an organism could not respond to an environmental challenge or to disturbed homeostasis without it. As a SOCM Medic / Corpsman your knowledge of this system will enhance your patient treatment skills. Slide 122 Break Slide