1. Sensory System Part 1 (organ of smell, eye)
Lecture for medical students
Department of histology,
cytology and embryology KhNMU

2. 1.Sensory Organs 2. Nerves 3. Brain Centers (Analyzers)
Sensory Systems
1.Sensory Organs
2. Nerves
3. Brain Centers (Analyzers)

3. 3 types of Sensory Organs:
1. Primary, Nerve-sensory (Olfactory,
Visual)
2. Secondary, Sensoepithelial (Taste,
Equilibrium, Hearing)
3. Sensory Nerve Endings

4. Organ of Olfaction (Smell) 3. Olfactory cells having cilia and
is located in the mucous membrane of the upper and middle nasal conchae,
Consists of:
1. Supporting cells
2. Basal cells
3. Olfactory cells having cilia and
axons, forming nerve

6. Cilia of olfactory cells are irritated by odorous substances.
Under the epithelium locate Bowman's glands producing solvents increase the concentration of odoriferous substances.
Organ develops from olfactory dimple arising from first brain vesicle

7. Organ of olfaction gets 10000 smells, 1000 genes are responsible for smell
It is the most ancient sensory organ
Wet weather increases smell
Without this organ a person becomes anxious
Smell of lavender keeps anxiety away

8. The Eye. Visual organ ＊the complex photoreceptor organ
＊ fibrous tunic (corneoscleral)
the wall contains vascular tunic (uvea)
neural tunic (retina)
eyeball contents: lens, vitreous body,
aqueous humor
accessory structures: eyelids, conjunctiva, glands

9. Optic Nerve
Cornea
Sclera
Retina
Uvea

10. I. Fibrous tunic：has two main portions
sclera: dense regular connective tissue
cornea: contains 5 layers:
outer corneal epithelium
Bowman's membrane
stroma
Membrane of Descemet
endothelium

11. Cornea contains free nerve endings permeable, avascular, transparent transplantation

12. II. Uvea – loose c.t., 3 parts:
1. Choroid – is nutritive CT, contains capillaries, melanocytes, continuous to:
2. Ciliary body is a CT belt, contains muscles, continues to ligament, keeping the lens, changes its shape
and to
3. Iris CT contains muscles reduce or dilate pupil at its center

13. Pupil
Lens
Iris
Ciliary Body
Optic Nerve
Cornea
Sclera
Retina
Choroid

14. LIMBUS is the junction between sclera and cornea
Iris
Ciliary body
Iris constrictor,
dilator muscles regulate pupil
Ciliary body muscles relax the lens, keeping by suspensory ligament
Suspensory ligament

15. Lens Anterior chamber – behind the cornea
Posterior chamber – behind the iris
Aqueous humor of chambers is produced by ciliary body epithelium
(Glaucoma)
output through venous sinus to canal of Schlemm
Lens
Anterior chamber

16. LENS is transperent elastic body, covered by flattened epithelium, consists of fibers
VITREOUS BODY is transperent, colorless, contains 99% of water, hyaluronic acid, collagen

17. VitreousBody Lens Choroid Sclera Retina Cornea Pupil Optic Nerve Iris
Ciliary Body
Optic Nerve
VitreousBody
Cornea
Sclera
Retina
Choroid

18. 10 layers of nerve cells and their processes:
III. Retina
pigment cells (outermost)
Contains 2 sheaths
9 layers of n.cells and processes
chain of 3 neurons:
layer of visual cells (rods and cones) – outer nuclear,
layer of bipolar cells – inner nuclear,
layer of ganglionic cells.
10 layers of nerve cells and their processes:

19. Optic Nerve
Ora serrata
Cornea
Sclera
Retina
Choroid

20. Retina
Choroid
Sclera
Muscles

21. Ganglionic l. Inner nuc. Outer nu. Pigment epith.. Choroid Sclera
Ganglionic layer
Inner nuclear layer
Outer nuclear layer
Pigment epithelium
Pigment epithelium

22. 10 9 8 7 6 5 4 3 2 1
III II I
Pigment epithelium

23. Ultrastructure of rod and cone cells
Rod Cone
Outer slender conical, wider segment cylinder shorter
Membrane closed opened, continue
Limiting to cell membrane
disks
Visual rhodopsin iodopsin
pigment
Sensitive to black, white blue, green, red lights
twilight vision (krok)

24. Rod Cone
Cone Rod

25. The way of light waves Through the cornea Anterior chamber Pupil
Posterior chamber
Lens
Vitreous body
Through all layers of the retina to rods and cones

26. Ganglionic l. Inner nuc. Outer nu. Pigment epith.. Choroid Sclera
Ganglionic layer
Inner nuclear layer
Outer nuclear layer
Pigment epithelium
Pigment epithelium

27. Optic Nerve (blind macula)
is made of axons of ganglionic cells
Central Fovea (yellow macula)
is the place of the best vision,
contains the biggest amount of cones,
the rest layers are displaced

28. 3 functional apparatuses of the eye

29. Lens III.Iris II. Cornea Vitreous body Chambers
Ciliary body
Optic Nerve (blind m.)
Central Fovea (yellow m.)
Sclera
I. Retina is photosensitive
Vitreous body
II. Cornea
dioptric
(refractive)
apparatus
II.Cornea
III. Uvea
accomodative apparatus
III.Iris
accomodative
apparatus

30. Accessory structures:
Conjunctiva - CT
Eyelids – loose and elastic connective tissue, muscles, covered by skin epithelium, containing sebaceous glands – Meibomian and Zeis;
and sweat glands – Moll)
Lacrimal glands

32. Embryonic development of eye
Primary brain vesicle Optic vesicle
Optic stalk Optic cup Retina
Ectoderm Lens placode
Lens vesicle Lens
Ectoderm Outer corneal epithelium
Eyelids
Mesenchyme: rest Cornea, Uvea, Sclera,
Vitreous body

33. Chapter 9 Eye and Ear
Development of eye

34. Mesenchyme
ectoderm
brain vesicle
Optic cup
Lens placode

35. Mesenchyme
pigment epithelium
Vitreous body
Retina
Lens
Optic stalk