Anatomy Powerpoint for studying ~ I do not own the pictures, they are simply being used for studying purposes only.

1. The Special Senses Victoria Frawert Anatomy

2. The Senses There are five general senses: Touch, sight, taste, smell, and hearing. Equilibrium is considered a special sense as well, found in the ear. Chemical Senses (Taste & Smell) Chemoreceptors – Receptors for taste & smell that only respond to chemicals. Excited by chemicals dissolved in saliva & airborn chemicals dissolved in nasal membranes.

3. Taste buds: located in oral cavity; 10,000; most in tongue papillae; each taste bud has 40-100 epithelial cells made of 3 major types. Supporting Cells: separate and insulate Receptor Cells: deal with taste Basal cells: like stem cells, they give rise to new cells Taste Sensations Sweet at tip of tongue Salty & sour on the sides Bitter in the back

4. Physiology of Taste Activation To be tasted, first must be dissolved in saliva, diffuse into the pore and make contact with gustatory hairs which trigger neurotransmitters to elicit action potentials in these fibers. Adapt rapidly 3-5 seconds & completely in 1-5 minutes Taste Transduction Process in which stimulus energy is converted into a nerve impulse due to influx of different ions

5. Gustatory Pathway Taste is carried in two cranial nervers Facial: anterior 2/3rds of tongue Glossopharyngeal: posterior 1/3rd Taste triggers reflexes in digestion such as increasing saliva & gastric juice Influence of other sensations on taste Taste is 80% smell, when olfactory receptors are blocked food becomes bland Thermoreceptors, mechanoreceptors, nociceptors, temperature and texture can enhance or detract

6. Olfactory & Sense of Smell Structure Detects chemicals in solution Olfactory Epithelium: Located on roof of nasal cavity Contain olfactory receptor cells with columnar supporting cells Covered by mucous to trap airborn molecules Physiology In order to smell the substance must be in a gaseous state Must be water soluble to dissolve in olfactory epithelium Bind to protein receptors which open ion channels that send action potentials to olfactory bulb Pathway Send impulses from bulb down tract Thalmus Frontal Lobe or Hypothalmus to interpret and elicit emotional responses to odor Imablances include anosmias (without smells) from head injuries; unicinate fits (olfactory hallucinations)

7. Eye & Vision Accessory Structures Eyebrows Shade the eyes Prevent perspiration into eye Eyelids Palpabrae protects eye Levatorpalpebraesuperioris raises eyelid Eyelashes trigger blinking Conjunctiva Mucous membrane over eyelids and anterior surface of eyeball (white part) Vascular, when irritated eyes are blood shot

8. Lacrimal Apparatus Consist of gland and ducts that drain excess secretions into nasal cavity Secretes saline solution (tears) Contains mucous, antibodies, and lysosomes to clean eye & destroy bacteria Eye muscles Movement is controlled by 6 muscles Four Rectus muscles: Superior, Inferior, Lateral, Medial Two Oblique muscles: Superior, Inferior Nerve Innervation: abducens, trochlear, oculomotor Lens : Divides eye into anterior and posterior segments Transparent, flexible structure that can change shape to allow focus of light on retina Avascular Becomes less elastic through life causing focus impairment Cataract – cloudy lens due to thickening of lens or diabetes

9. Structure of the Eyeball Divided into 3 tunics Fibrous – dense avascular tissue Sclera: white part that protects, shapes, and provides attachment for eye muscles Cornea: buldgesanteriorly and allows light into eye Vascular Choroid – highly vascular & provides nutrition Ciliary Body – encircles lense and keeps it in place Iris – contains pupil and changes in shape due to light Sensory – contains the retina, which are photoreceptors of rods & cones Optic Disc (blind spot) – Where optic nerve exits eye Rods – dim light Cones – bright light and color Filled with humors to maintain shape Vitreous humor – in posterior Aqueous humor – in anterior (if undrained causes glaucoma)

10. Physiology Wavelength & Color Eyes respond to visible light spectrum Progresses from red to violet Refraction & lenses Light travels in straight lines and blocked by nontrasnparent objects Light reflects or bounces off a surface Reflection accounts for most of light reaching our eyes; as light changes mediums it can bend or refract. Focus Your lens refracts the light to your focal point which projects on your retina Images are upside down & reversed Myopia – nearsighted Hyperopia – farsighted Astigmatism – unequal curvature of lens leading to blur

11. Photoreception Photoreceptors are modified neurons Outer segment connected to inner, inner connects to cell body which has synaptic endings. Rods Sensitive to low light, best at night Cones Require high light, provides color

12. Ear: Hearing & Balance Structure – three areas: Outer, middle, & inner ear Outer Ear Auricle or Pinna: ear composed of elastic cartilage & skin to direct sound waves to external auditory canal External auditory meatus: Short curved tube from auricle to eardrum Lined with skin, sebaceous glands, & ceruminous glands (secrete earwax) Tympanic membrane ( ear drum ) boundary between outer & middle ear

13. Middle Ear (tympanic cavity) Small air filled mucus lined cavity Between eardrum & bony wall with two openings oval (vestibular) & round (cochlear) window Contains pharyngotympanic (auditory tube) running from middle ear to nasopharynx & helps equalize pressure Otitis Media – middle ear inflammation Inner Ear Behind eye socket & contains receptor information 2 Major divisions Bony (osseous ) labyrinth Vestibule – contains saccule and utricle which have equilibrium receptors that respond to gravity & changes of head position Cochlea – contains the organ of corti which is the sensory organ for hearing Semicircular Canals – respond to movement of head Membranous Labyrinth Series of sacs and ducts containing endolymph fluid to help conduct sound vibrations.

14. Sound & Mechanisms of Hearing Sound – a disturbance of pressure Frequency – measurement of offurrences of a repeated event per unit of time Distance between two crests is a wavelength Frequency is expressed in hertz Range for humans is 20-20,000 Hz Amplitude or height of wave is related to intensity Loudness is measured in decibles We can hear from .1 dB to over 120 dB Threshold for pain is 130 dB Hearing loss occurs with exposure to 90 dB Noisy restaurant is 70 dB, normal talking is 50 dB A rock concert is 120 dB. You do the math. Transmission Sound waves move through the air, membranes, bones, fluids to reach receptor cells in the organ of corti. Vibrations excite hair cells which send messages to cochlear nerve and brings the impulses to the brain for processing

15. Imbalances of Hearing Deafness – any hearing loss Conduction deafness When something hampers sound conduction to fluids of inner ear Ruptures, perforated eardrum can cause problems Sensorinerual Damage to neural structures of cochlear hair cells Can be partial or complete & generally there is gradual loss of hearing throughout life Cells can be damaged to extremely loud noises or prolonged exposure Can be fixed with cochlear implants Tinnitus Ringing of ear Symptom of pathology and not disease 1st symptom of cochlear nerve degeneration Can be from inflammation or medication or trauma

16. Meniere’sSyndrom Affects semicircular & cochlear canals Causes vertigo, nausea, vomitting Standing erect is near impossible Caused by excess fluid, rupture or infection Mild cases can be cleared with anti motion drugs, sometimes surgery Equilibrium & Orientation Responds to head movement without awareness Receptors of inner ear are divided into two parts Static Sensory receptors for static are the maculae Found in saccules and utricle Monitor position of head in space, control posture Dynamic Receptor for dynamic are the cristaampullaris Excited by head movement but major stimuli are rotatory These areas are at work when twirling or feeling ill on a boat