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Dr Pallab Kanti NathDr Pallab Kanti Nath
MD AnaesthesiologyMD Anaesthesiology
Basic level class for technicians
Five Senses
Vision (Sight)
Smell (olfaction)
Taste
Touch
Hearing
Equilibrium is also considered a special sense, fou...
Taste (Gustation)
Taste buds are found in papillae of the tongue mucosa
Papillae - three types: filiform, fungiform, and
circumvallate
Fu...
Taste Sensation
• There are five basic taste sensations
– Sweet – sugars, saccharin, alcohol, and
some amino acids
– Salt ...
Activation
 To be tasted, first must be dissolved in saliva, diffuse into the
pore and make contact with gustatory hairs...
Taste is carried by two cranial nerves
 Facial: anterior 2/3rds of tongue
 Glossopharyngeal: posterior 1/3rd
 Taste tri...
Sense of Smell (Olfaction)
• The organ of smell is the olfactory epithelium,
which covers the superior nasal concha
• Olfa...
Olfactory epithelium
Detects chemicals in solution
Covered by mucous to trap airborne molecules
Physiology
Substance ...
Vision
Accessory Structures
Eyebrows
Shade the eyes
Prevent perspiration into eye
Eyelids
Palpabrae protects eye
Lev...
Extraocular muscles
 Movement is controlled by 6 muscles
 Four Rectus muscles: Superior,
Inferior, Lateral, Medial
 Tw...
Extra ocular muscles
Lacrimal Apparatus
• Consists of the lacrimal gland and
associated ducts
• Lacrimal glands secrete tears
• Tears
– Contain...
Lacrimal Apparatus
Structure of the Eyeball
Fibrous Tunic
• Forms the outermost coat of the eye and is
composed of:
– Opaque sclera (posteriorly)
– Clear cornea (ante...
Vascular Tunic (Uvea)
• Has three regions: choroid, ciliary
body, and iris
• Choroid region
–A dark brown membrane that
fo...
Vascular Tunic
• A thickened ring of tissue surrounding the
lens
• Composed of smooth muscle bundles
(ciliary muscles)
• A...
• The colored part of the eye
• Pupil – central opening of the iris
– Regulates the amount of light entering the eye
durin...
Pupil Dilation and Constriction
Sensory Tunic: Retina
• A delicate two-layered membrane
• Pigmented layer – the outer layer that
absorbs light and prevent...
Sensory Tunic: Retina
The Retina: Ganglion Cells and the
Optic Disc
• Ganglion cell axons:
– Run along the inner surface of the retina
– Leave t...
The Retina: Ganglion Cells and the Optic Disc
Figure 15.10b
Retinal Photoreceptors
• Rods:
– Respond to dim light
– Are used for peripheral vision
• Cones:
– Respond to bright light
...
Blood Supply to the Retina
• The neural retina receives its blood
supply from two sources
– The outer third receives its b...
Inner Chambers and Fluids
• The lens separates the internal eye into anterior
and posterior segments
• The posterior segme...
Anterior Segment
• Composed of two chambers
– Anterior – between the cornea and the iris
– Posterior – between the iris an...
Anterior Segment
Figure 15.12
Refraction and Lenses
• When light passes from one transparent
medium to another its speed changes and it
refracts (bends)...
Refraction and Lenses
• Photoreception – process by which the eye
detects light energy
• Rods and cones contain visual pigments
(photopigments)
...
Photoreception:
Functional Anatomy of Photoreceptors
Rods
• Functional characteristics
– Sensitive to dim light and best suited for night vision
– Absorb all wavelengths of vi...
Cones
• Functional
characteristics
– Need bright light for
activation (have low
sensitivity)
– Have pigments that
furnish ...
The Ear: Hearing and Balance
• The three parts of the ear are the inner, outer,
and middle ear
• The outer and middle ear ...
The Ear: Hearing and Balance
Figure 15.25a
Outer Ear
Auricle or Pinna
ear composed of elastic cartilage & skin to direct sound
waves to external auditory canal
Ex...
Middle Ear (Tympanic Cavity)
• A small, air-filled, mucosa-lined cavity
– Flanked laterally by the eardrum
– Flanked media...
Ear Ossicles
• The tympanic cavity contains three small
bones: the malleus, incus, and stapes
– Transmit vibratory motion ...
Inner Ear
• Bony labyrinth
– Tortuous channels worming their way through the
temporal bone
– Contains the vestibule, the c...
Inner Ear
The Cochlea
• The scala tympani terminates at the round
window
• The scalas tympani and vestibuli:
– Are filled with peril...
The Cochlea
• The “floor” of the cochlear duct is composed
of:
– The bony spiral lamina
– The basilar membrane, which supp...
The Cochlea
Transmission of Sound to the Inner Ear
• The route of sound to the inner ear follows this
pathway:
– Outer ear – pinna, au...
Transmission of Sound to the Inner Ear
Thank you
special sense organs (anatomy and physiology) - a brief discussion
special sense organs (anatomy and physiology) - a brief discussion
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special sense organs (anatomy and physiology) - a brief discussion

brief discussion on special senses, Basic level class for technicians. topics discussed include eyes and vision, nose and sense of smell, tongue and sense of taste and ears and hearing

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special sense organs (anatomy and physiology) - a brief discussion

  1. 1. Dr Pallab Kanti NathDr Pallab Kanti Nath MD AnaesthesiologyMD Anaesthesiology Basic level class for technicians
  2. 2. Five Senses Vision (Sight) Smell (olfaction) Taste Touch Hearing Equilibrium is also considered a special sense, found in the ear
  3. 3. Taste (Gustation)
  4. 4. Taste buds are found in papillae of the tongue mucosa Papillae - three types: filiform, fungiform, and circumvallate Fungiform and circumvallate papillae contain taste buds Appx 10,000 taste buds - 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 Buds
  5. 5. Taste Sensation • There are five basic taste sensations – Sweet – sugars, saccharin, alcohol, and some amino acids – Salt – metal ions – Sour – hydrogen ions – Bitter – alkaloids such as quinine and nicotine – Umami – elicited by the amino acid glutamate
  6. 6. 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 Physiology of Taste
  7. 7. Taste is carried by two cranial nerves  Facial: anterior 2/3rds of tongue  Glossopharyngeal: posterior 1/3rd  Taste triggers reflexes in digestion such as increasing saliva & gastric juice Gustatory Pathway 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
  8. 8. Sense of Smell (Olfaction) • The organ of smell is the olfactory epithelium, which covers the superior nasal concha • Olfactory receptor cells are bipolar neurons with radiating olfactory cilia • Olfactory receptors are surrounded and cushioned by supporting cells • Basal cells lie at the base of the epithelium
  9. 9. Olfactory epithelium Detects chemicals in solution Covered by mucous to trap airborne molecules Physiology 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 anosmia (without smells) from head injuries; unicinate fits (olfactory hallucinations) Olfaction
  10. 10. Vision Accessory Structures Eyebrows Shade the eyes Prevent perspiration into eye Eyelids Palpabrae protects eye Levator palpebrae superioris raises eyelid Eyelashes trigger blinking Conjunctiva Mucous membrane over eyelids and anterior surface of eyeball (white part) Vascular, when irritated eyes are blood shot
  11. 11. Extraocular 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
  12. 12. Extra ocular muscles
  13. 13. Lacrimal Apparatus • Consists of the lacrimal gland and associated ducts • Lacrimal glands secrete tears • Tears – Contain mucus, antibodies, and lysozyme – Enter the eye via superolateral excretory ducts – Exit the eye medially via the lacrimal punctum – Drain into the nasolacrimal duct
  14. 14. Lacrimal Apparatus
  15. 15. Structure of the Eyeball
  16. 16. Fibrous Tunic • Forms the outermost coat of the eye and is composed of: – Opaque sclera (posteriorly) – Clear cornea (anteriorly) • The sclera protects the eye and anchors extrinsic muscles • The cornea lets light enter the eye
  17. 17. Vascular Tunic (Uvea) • Has three regions: choroid, ciliary body, and iris • Choroid region –A dark brown membrane that forms the posterior portion of the uvea –Supplies blood to all eye tunics
  18. 18. Vascular Tunic • A thickened ring of tissue surrounding the lens • Composed of smooth muscle bundles (ciliary muscles) • Anchors the suspensory ligament that holds the lens in place Ciliary Body
  19. 19. • The colored part of the eye • Pupil – central opening of the iris – Regulates the amount of light entering the eye during: • Close vision and bright light – pupils constrict • Distant vision and dim light – pupils dilate • Changes in emotional state – pupils dilate when the subject matter is appealing or requires problem-solving skills Iris
  20. 20. Pupil Dilation and Constriction
  21. 21. Sensory Tunic: Retina • A delicate two-layered membrane • Pigmented layer – the outer layer that absorbs light and prevents its scattering • Neural layer, which contains: – Photoreceptors that transduce light energy – Bipolar cells and ganglion cells – Amacrine and horizontal cells
  22. 22. Sensory Tunic: Retina
  23. 23. The Retina: Ganglion Cells and the Optic Disc • Ganglion cell axons: – Run along the inner surface of the retina – Leave the eye as the optic nerve • The optic disc: – Is the site where the optic nerve leaves the eye – Lacks photoreceptors (the blind spot)
  24. 24. The Retina: Ganglion Cells and the Optic Disc Figure 15.10b
  25. 25. Retinal Photoreceptors • Rods: – Respond to dim light – Are used for peripheral vision • Cones: – Respond to bright light – Have high-acuity color vision – Are found in the macula lutea – Are concentrated in the fovea centralis
  26. 26. Blood Supply to the Retina • The neural retina receives its blood supply from two sources – The outer third receives its blood from the choroid – The inner two-thirds is by the central artery and vein
  27. 27. Inner Chambers and Fluids • The lens separates the internal eye into anterior and posterior segments • The posterior segment is filled with a clear gel called vitreous humor that: – Transmits light – Supports the posterior surface of the lens – Holds the neural retina firmly against the pigmented layer – Contributes to intraocular pressure
  28. 28. Anterior Segment • Composed of two chambers – Anterior – between the cornea and the iris – Posterior – between the iris and the lens • Aqueous humor – A plasma like fluid that fills the anterior segment – Drains via the canal of Schlemm • Supports, nourishes, and removes wastes
  29. 29. Anterior Segment Figure 15.12
  30. 30. Refraction and Lenses • When light passes from one transparent medium to another its speed changes and it refracts (bends) • Light passing through a convex lens (as in the eye) is bent so that the rays converge to a focal point • When a convex lens forms an image, the image is upside down and reversed right to left
  31. 31. Refraction and Lenses
  32. 32. • Photoreception – process by which the eye detects light energy • Rods and cones contain visual pigments (photopigments) – Arranged in a stack of disk-like infoldings of the plasma membrane that change shape as they absorb light Photoreception: Functional Anatomy of Photoreceptors
  33. 33. Photoreception: Functional Anatomy of Photoreceptors
  34. 34. Rods • Functional characteristics – Sensitive to dim light and best suited for night vision – Absorb all wavelengths of visible light – Perceived input is in gray tones only – Sum of visual input from many rods feeds into a single ganglion cell – Results in fuzzy and indistinct images
  35. 35. Cones • Functional characteristics – Need bright light for activation (have low sensitivity) – Have pigments that furnish a vividly colored view – Each cone synapses with a single ganglion cell – Vision is detailed and has high resolution
  36. 36. The Ear: Hearing and Balance • The three parts of the ear are the inner, outer, and middle ear • The outer and middle ear are involved with hearing • The inner ear functions in both hearing and equilibrium
  37. 37. The Ear: Hearing and Balance Figure 15.25a
  38. 38. 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
  39. 39. Middle Ear (Tympanic Cavity) • A small, air-filled, mucosa-lined cavity – Flanked laterally by the eardrum – Flanked medially by the oval and round windows • Epitympanic recess – superior portion of the middle ear • Pharyngotympanic tube – connects the middle ear to the nasopharynx – Equalizes pressure in the middle ear cavity with the external air pressure
  40. 40. Ear Ossicles • The tympanic cavity contains three small bones: the malleus, incus, and stapes – Transmit vibratory motion of the eardrum to the oval window – Dampened by the tensor tympani and stapedius muscles
  41. 41. Inner Ear • Bony labyrinth – Tortuous channels worming their way through the temporal bone – Contains the vestibule, the cochlea, and the semicircular canals – Filled with perilymph • Membranous labyrinth – Series of membranous sacs within the bony labyrinth – Filled with a potassium-rich fluid
  42. 42. Inner Ear
  43. 43. The Cochlea • The scala tympani terminates at the round window • The scalas tympani and vestibuli: – Are filled with perilymph – Are continuous with each other via the helicotrema • The scala media is filled with endolymph
  44. 44. The Cochlea • The “floor” of the cochlear duct is composed of: – The bony spiral lamina – The basilar membrane, which supports the organ of Corti • The cochlear branch of nerve VIII runs from the organ of Corti to the brain
  45. 45. The Cochlea
  46. 46. Transmission of Sound to the Inner Ear • The route of sound to the inner ear follows this pathway: – Outer ear – pinna, auditory canal, eardrum – Middle ear – malleus, incus, and stapes to the oval window – Inner ear – scalas vestibuli and tympani to the cochlear duct • Stimulation of the organ of Corti • Generation of impulses in the cochlear nerve
  47. 47. Transmission of Sound to the Inner Ear
  48. 48. Thank you

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