1. General sensation Composed of sensory receptors throughout the body.
General senses
Touch, pressure, pain, heat, cold, stretch, vibration.
Special senses
Vision, hearing, equilibrium, olfaction, taste.
Relative to the source of the stimuli.
Exteroceptors
Interoceptors
Propioceptors (sketetal muscle). Conscious.
General structure (histology, activity 1)
Modified dendrites.
Free nerve endings
Merkel discs in epidermis
Hair follicle receptors
Meissner corpuscles: light touch
Ruffini corpuscles: deep pressure and stretching.
Pacinian corpuscles: pressure recptor.
Muscle spindles
Golgi tendon organs
Receptor physiology
Act as signal transducers. Direct relationship between importance and number of clustering of the receptors; punctuate distribution.

2. Special Senses
Vision
Olfaction
Taste
Hearing and equilibrium

3. 1. Vision Organ: Eye ball Accessory structures Activity 1
Lacrimal apparatus.
Lacrimal gland: secretes tears; solution of salts and lyzozyme.
Lacrimal canals
Nasolacrimal canal
Eyelids (papebrae)
Medial and lateral canthus
Caruncle
Conjunctiva. Mucus membrane that lines inner surface of eyelids. Stratified squamous and stratified cilindrical epithelium.
Eyelashes
Ciliary glands: lubricate eyeball
Tarsal glands: lubricate eyeball
6 extrinsic eye muscles
Activity 1

4. The eye and associated accessory structures
Site where
conjunctiva
merges with
cornea
Eyebrow
Eyelid
Eyelashes
Pupil
Palpebral
fissure
Lacrimal
caruncle
Medial
commissure
(canthus)
Lateral
commissure
(canthus)
Sclera
(covered by
conjunctiva)
Iris
Eyelid
(a)

5. The lacrimal apparatus
gland
Lacrimal sac
Excretory ducts
of lacrimal gland
Lacrimal punctum
Lacrimal canaliculus
Nasolacrimal duct
Inferior meatus
of nasal cavity
Nostril

6. The eye and associated accessory structures
Levator palpebrae
superioris muscle
Orbicularis
oculi muscle
Eyebrow
Tarsal plate
Palpebral
conjunctiva
Tarsal
glands
Cornea
Palpebral
fissure
Eyelashes
Bulbar
conjunctiva
Conjunctival
sac
Orbicularis
oculi muscle
(b)

7. Controlling cranial nerve
Extrinsic eye muscles
Trochlea
Superior oblique muscle
Superior oblique tendon
Superior rectus muscle
Axis at
center
of eye
Lateral rectus muscle
Conjunctiva
Inferior
rectus muscle
Medial
rectus muscle
Lateral
rectus muscle
Optic
nerve
Inferior
rectus
muscle
Inferior
oblique
muscle
Annular ring
(a)
(b)
Controlling cranial
nerve
Name
Action
Lateral rectus
Moves eye laterally
VI (abducens)
Medial rectus
Moves eye medially
III (oculomotor)
Superior rectus
Elevates eye and turns it medially
III (oculomotor)
Inferior rectus
Depresses eye and turns it medially
III (oculomotor)
Inferior oblique
Elevates eye and turns it laterally
III (oculomotor)
Superior oblique
Depresses eye and turns it laterally
IV (trochlear)
(c)

8. Internal structure of the eye
Composed of 3 layers or tunics
External
Cornea (transparent) and Sclera (white).
Middle
Anterior
Iris: radial smooth muscle (III ocoulomotor)
Uvea: vasculariazed.
Cilliar body(muscles) : control the curvature of the lens (cristaline).
Cilliary processes: secrete aqueous humor.
Posterior
Choroid: dark pigment.
Inner
Retina: sensory region
Additional internal structures
Humor vitreous
Macula lutea (yellow spot): high cone density
Fovea centralis: area of maximum (very high amount of cones) sight acuity.
Sclera venous sins( Schlemm canal)
Ciliary zonule
Activity 2 (eye dissection next class)

9. Internal structure of the eye (sagittal section)
Ora serrata
Sclera
Ciliary body
Choroid
Ciliary zonule
(suspensory
ligament)
Retina
Macula lutea
Cornea
Fovea centralis
Iris
Pupil
Posterior pole
Anterior
pole
Optic nerve
Anterior
segment
(cavity)
Lens
Scleral venous sinus
(Canal of Schlemm)
Central artery
and vein of the retina
Posterior segment (cavity)
(contains vitreous humor)
Optic disc
(blind spot)
(a)

11. Circulation of aqueous humor
Posterior
segment
containing
vitreous
humor
Cornea
Lens
Iris
Lens
epithelium
Cornea
Lens
Corneal epithelium
ANTERIOR
Corneal endothelium
Aqueous humor
Anterior chamber
Ciliary zonule
(suspensory
ligament)
Anterior
segment
Posterior chamber
Scleral venous
sinus
Ciliary
processes
Limbus (corneal-
scleral junction)
Ciliary body
Ciliary
muscle
Anterior ciliary vein
Bulbar
conjunctiva
Sclera

12. Focusing for distant and close vision
Sympathetic +
Nearly parallel rays
from distant object
Lens
Ciliary zonule
Ciliary muscle
Inverted
image
Ciliary muscle
Lens
(a) Lens is flattened for distant vision
Ciliary zonule
(suspensory ligaments)
Parasympathetic +
Divergent rays
from close object
Inverted
image
(c) Anterior segment viewed from behind
(b) Lens bulges for close vision

13. Histology of the retina
Sensory tunic
Outer pigmented epithelial layer
Inner neural layer.
Photoreceptors: cones or rods.
Bipolar neurons
Ganglion
Axons of ganglions
Activity 3

16. Photoreceptors of the retina
Process of
bipolar cell
Light
Light
Light
Synaptic
terminals
Inner
fibers
Rod cell
body
Rod cell
body
Nuclei
Cone cell
body
Mitochondria
Outer
fiber
Retinal
(b)
Opsin
Inner segment
Connecting
cilia
Apical microvillus
Outer segment
Discs being
phagocytized
Pigmented layer
Discs containing
visual pigments
Pigment cell
nucleus
Melanin
granules
Basal lamina
(border with choroid)
(a)

17. (contralateral) fiber Lateral geniculate body of thalamus
Visual fields of the eyes and visual pathway to the brain, inferior view
Fixation
point
Right eye
Left eye
Optic nerve
Supra-
chiasmatic
nucleus
Pretectal
nucleus
Optic chiasma
Optic tract
Lateral
geniculate
body
Superior
colliculus
(sectioned)
Uncrossed
(ipsilateral) fiber
Crossed
(contralateral) fiber
Lateral geniculate
body of thalamus
Optic
radiation
Superior colliculus
Occipital lobe (visual cortex)
Corpus callosum
(a)
(b)

18. 2. Olfaction Sensory structure: Activity 1
Olfactory epithelium. Chemoreceptor.
Olfactory receptor cell: bipolar neuron (I)
Support cells: pseudo stratified ciliated epithelium.
Basal cells.
Activity 1

19. Olfactory Frontal lobe epithelium of cerebrum Olfactory tract
Olfactory receptors
Olfactory
epithelium
Frontal lobe
of cerebrum
Olfactory tract
Mitral cell
Olfactory
tract
Olfactory
bulb
Glomeruli
Nasal
conchae
Cribriform plate
of ethmoid bone
Filaments of
olfactory nerve
Lamina propria
connective tissue
Route of
inhaled air
Olfactory
gland
Axon
Basal cell
Olfactory receptor
cell
Olfactory
epithelium
Supporting cell
Dendrite
Mucus
Olfactory cilia
Route of inhaled
air containing odor
molecules

20. Green:Bowman’s gland cell
Red: support cell
Blue:bipolar neuron
Green:basal cell
Green:Bowman’s gland cell

21. 3. Taste Sensory structure Activity 2
Taste bud. Chemoreceptor. Mechanoreceptor. Thermo receptor.
Basic tastes: sweet, sour, salt, bitter.
Types (location in figure)
Fungiform papillae (mushrooms)
Circunvallate papilla (globes)
Filiform papilla
Cell types
Gustatory (taste) cells: bipolar neurons.
Support cells
Activity 2

22. Fg: fungiform papillae
Fl: filliform papillae
Weather’s Fucntional Histology

23. Location and structure of taste buds on the tongue
Taste fibers
of cranial
nerve
Gustatory
hair
Epiglottis
Taste
pore
Palatine tonsil
Lingual tonsil
Basal cell
Foliate
papillae
Circumvallate papilla
Connective
tissue
Gustatory
receptor
cells
Stratified
squamous
epithelium
of tongue
(c)
Gustatory (taste) cells
Taste
pore
Connective
tissue
Basal
cells
(b)
Taste bud
Fungiform
papillae
(a)
(d)

24. Gustatory cortex (in insula) Thalamic nucleus (ventral posterior
The gustatory pathway
Gustatory
cortex
(in insula)
Thalamic
nucleus
(ventral
posterior
medial
nucleus)
Pons
Solitary nucleus
in medulla oblongata
Facial
nerve (VII)
Vagus
(nerve X)
Glosso-
pharyngeal
nerve (IX)

25. 4. Hearing and balance
Organ: Ear (sensory receptor for hearing and equilibrium).
Outer ear. Hearing
Auricle
External acoustic meatus
Tympanic membrane
Ceruminous glands
Middle ear. Hearing
Tympanic cavity
Osicles
Malleus (hammer)
Incus (anvil)
Staples (stirrup). Connects with the oval window.
Pharingotimpanic tube. Pressure equalization of middle ear and environment.
Inner ear
Bony and membranous labyrinth
Cochlea: hearing
Vestible: equilibrium
3 perpendicular semicircular canals: equilibrium

26. Internal (inner) ear (labryinth)
Structure of the ear
Internal
(inner) ear
(labryinth)
External
(outer) ear
Middle
ear
Auricle
(pinna)
Helix
External
acoustic
meatus
Lobule
Pharyngotympanic
(auditory) tube
Tympanic membrane
(a)

27. Middle ear Middle ear. Hearing Tympanic cavity Osicles
Malleus (hammer)
Incus (anvil)
Staples (stirrup). Connects with the oval window.
Pharingotimpanic tube. Pressure equalization of middle ear and environment.

28. Structure of the middle ear
Entrance to mastoid antrum
in the epitympanic recess
Auditory
ossicles
Malleus
(hammer)
Semicircular
canals
Incus
(anvil)
Vestibule
Stapes
(stirrup)
Vestibular
nerve
External
acoustic
meatus
Cochlear
nerve
Cochlea
Tympanic
membrane
Oval window
(deep to stapes)
Pharyngotympanic
(auditory) tube
Internal
jugular vein
Round window
(b)

29. The three auditory ossicles in the right middle ear
Malleus
Incus
Epitympanic recess
Superior
Anterior
Pharyngotym-
panic tube
Tensor
tympani
muscle
Tympanic
membrane
(medial view)
Stapes
Stapedius
muscle

30. Inner ear Inner ear Bony labyrinth Membranous labyrinth
Contains perilymph; similar composition to CSF since it is connected to the arachnoid space.
Membranous labyrinth
Suspended in perilymph, contains endolymph.
Divisions:
Cochlea: organ of Corti, hearing VIII.
Vestible:
utricle and sacule. Macula; vertcial acceleration (equilibrium).
3 perpendicular semicircular canals
Semicircular duct. Ampula; angular acceleration (equilibrium).

31. Membranous labyrinth of the internal ear
Temporal
bone
Semicircular ducts in
semicircular canals:
Facial nerve
Vestibular nerve •
Anterior
Superior vestibular ganglion •
Posterior
Inferior vestibular ganglion •
Lateral
Cochlear nerve
Cristae ampullares
in the ampullae
Maculae
Spiral organ (of Corti)
Utricle in vestibule
Saccule in vestibule
Cochlear duct in cochlea
Stapes in
oval window
Round window

32. Modiolus Cochlear nerve, division of the vestibulocochlear
Anatomy of the cochlea
Modiolus
Cochlear nerve,
division of the
vestibulocochlear
nerve (VIII)
Oval
window
Spiral ganglion
Osseous
spiral lamina
Vestibular
membrane
(a)
Round window
Cochlear duct
(scala media)
Helicotrema

33. Tectorial membrane Vestibular membrane Cochlear duct (scala media)
Anatomy of the cochlea
Tectorial
membrane
Vestibular
membrane
Cochlear duct
(scala media)
Scala
vestibuli
Spiral
ganglion
Stria
vascularis
Spiral
organ
(of Corti)
Osseous
spiral
lamina
Scala
tympani
Basilar
membrane
(b)

34. Tectorial membrane Inner hair cell Afferent nerve fibers
Anatomy of the cochlea
Tectorial
membrane
Inner hair cell
Afferent nerve
fibers
Hairs (stereocilia)
Outer hair cells
Supporting
cells
Fibers of
cochlear
nerve
Basilar
membrane
(c)

36. Hearing physiology
Sound waves travel from the outer ear (timpanic membrane) middle ear (Malleus,Incus, staples, oval window) inner ear (scala tympani)/scala vestibuli stimulates the stereocillia of the organ of corti VIII
The round window serves as a pressure relief valve.

37. Sound: source and propagation
Area of
compressed
molecules
Area of
rarefaction
Wavelength
Crest
Air pressure
Trough
(a)
(b)
Time
Amplitude
(c)

38. Route of sound waves through the ear
External ear
Middle ear
Internal ear
Air
External
acoustic
meatus
Malleus, incus,
stapes
(ossicles)
Oval
window
Fluids in cochlear canals
Tympanic
membrane
Pinna
Upper and middle
Lower
Pressure
Time
Spiral organ
(of Corti)
stimulated
One
vibration
Amplitude
Amplification
in middle ear

39. Hz 20,000 (High notes) Hz 1500 Hz 500 Hz 20 (Low notes)
Resonance of the basilar membrane and activation of the cochlear hair cells
Stapes
Scala
vestibuli
Cochlear
nerve
Oval
window
Perilymph
Round
window
Scala
tympani
Basilar
membrane
Cochlear
duct
(a)
Base
Apex
Basilar
membrane
500 Hz
Relative
lengths
of basilar
fibers
within
different
regions
membrane
4000 Hz Hz
20,000
(High notes) Hz
1500 Hz
500 Hz 20
(Low notes)
24,000 Hz
(b)
(c)

40. cortex in temporal lobe
Simplified diagram of the auditory pathway to the auditory cortex of the brain
Medial
geniculate
body of
thalamus
Primary auditory
cortex in temporal lobe
Inferior colliculus
Lateral lemniscus
Superior olivary
nucleus (pons-
medulla junction)
Midbrain
Cochlear nuclei
Vibrations
Medulla
Vestibulocochlear
nerve
Vibrations
Spiral ganglion
of cochlear nerve
Bipolar cell
Spiral organ
(of Corti)

41. Equilibrium physiology
Located in the vestibular apparatus
Vestible
Utricle and saccule (sacs) within vesitble.
Receptor: Macculae (static equilibrium)
Hair cells (stereocillia) are embedded in the otholitic membrane which contain CaCO3 (otoliths). Respond to vertical acceleration.
Membranous semicircular ducts
Ampulla (located at the base of each perpendicular duct). Mechism of dynamic equilibrium (angular acceleration).
Receptor: Crista ampullaris. Stereocilia covered by a gelatinous cupula. Endolymph stimulates the recptor.

42. Macula of saccule Macula of utricle Kinocilium Otolithic Stereocilia
Structure of a macula
Macula of
saccule
Macula of
utricle
Kinocilium
Stereocilia
Otoliths
Otolithic
membrane
Hair bundle
Hair cells
Supporting
cells
Vestibular
nerve fibers

43. Otolithic membrane Kinocilium Ster eocilia Depolarization
The effect of gravitational pull on a macula receptor cell in the utricle
Otolithic
membrane
Kinocilium
Ster
eocilia
Depolarization
Hyperpolarization
Receptor
potential
(Hairs bent towar
kinocilium) d
(Hairs bent away
from kinocilium)
Nerve
impulses
generated in
vestibular fiber
Increased
impulse frequency
Decreased
impulse frequency
Excitation
Inhibition

44. Macula within the utriculus (otolith chamber) (Bouins, H&E, Bar = 36
Macula within the utriculus (otolith chamber) (Bouins, H&E, Bar = 36.4 µm). 1. ciliated sensory cells; 2. sustenticular cells; 3. connective tissue; 4. cupula (gelatinous matrix); 5. globular sensory epithelium; 6. collagenous connective tissue; 7. otolith chamber; 8. cranium.

45. Location and sturcture of a crista ampullaris
Flow of
endolymph
(a)
Crista
ampullaris
Fibers of
vestibular nerve
Cupula
(b)
Turning motion
Ampulla
of left ear
Ampulla of
right ear
Cupula
Cupula at rest
Position
of cupula
during turn
Position of cupula
during turn
Fluid motion in
ducts
Increased firing
Horizontal ducts
Decreased firing
(c)
(d)
Afferent fibers of vestibular nerve

47. Pathways of the balance and orientation system
Vestibular
receptors
Visual
receptors
Somatic
receptors
Input
Vestibular
nuclear
complex
Reticular
nuclei
Cerebellum
Central nervous
system processing
Oculomotor control
(cranial nerve nuclei
III, IV, VI)
(eye movements)
Spinal motor control
(cranial nerve nuclei XI
and vestibulospinal tracts)
(neck movements)
Output