Transcript Visual organ

Sense organs
1. Analizators
2. Classification of sense
organs
3. Smell organ
4. Visual organ
• Eye general structure
• Sclera
• Сornea
• Choroid
• Iris
• Retina
ANALIZATOR
sense organ + nerve +
cortex (field)
Sense organs
Primary sensory
1. Eye
2. Smell organ
Secondary
sensory
1. Ear
2. Taste buds
Sensory
endings
(receptors)
1. Receptor of pain
2. Paccinian body
3. Bulb of Krause
Smell organ
Olfactory epithelium: olfactory cells, supporting
cells, basal cells
Smell analizator =
olfactory mucosa+n.olfactorius+hippocamp
The olfactory
epithelium
is tall, pseudostratified columnar
epithelium about 60 mm in
height
lacking goblet cells and with no
distinct basal lamina
contains three types of cells:
sustanticular or supporting,
basal and olfactory.
Eye
Visual analizator =
retina+n. opticus+occipital lobe
cortex
Eye
Eye tunics
1. Fibrosa (sclera+cornea)
2. Vascular (uveal tract):
choroid+ciliary body+iris
3. Retina: blind+visual
Eye systems
1. Dioptric (cornea, lens,
vitreus body)
2. Visual (retina)
3. Accomodative (ciliary body)
TUNICA FIBROSA
The eye’s outermost tunic has
two main components
The anterior surface forms the
transparent cornea
The posterior – opaque (white)
sclera.
The junction between the cornea
and sclera is the limbus.
Cornea
Cornea
1.Anterior epithelium (str. sq.
nonker.)
2.Ant. limiting membrane
(Bowman’s)
3.Substantia propria
4.Post. limiting membrane
(Descemet’s)
5.Endothelium
Sclera
is opaque white connective
tissue (dense fibrous tissue,
about 1mm thick)
is composed of flat bundles of
collagen fibers, which lie
mainly parallel to the surface
The sclera has three layers:
episclera
substantia propria
lamina fusca
TUNICA VASCULOSA
(UVEAL TRACT)
components:
1) choroid (posterior part)
2) ciliary body (middle)
3) iris (anterior).
Choroid
1.Suprachoroid
2.Vascular lamina
(melanocytes)
3.Choroidcapillaris
4. Basal complex (membrane
of Bruch)
Sclera and choroid
Ciliary body
Ciliary body
1. Suprachoroid
2. Vascular lamina
3. Basal complex (membrane of
Bruch)
Has ciliary processes and the
ciliary muscles
The ciliary processes are
irregular epithelium covered
connective tissue outgrowth of
the ciliary body that extends
toward the lens
Iris
1. Anterior epithelium
2. Ant. limiting membrane
3. Vascular layer
4. Post. limiting membrane
5. Posterior epithelium
Lens
capsule
epithelium
lens fibers
Lens
The lens capsule is an elastic and
transparent basal lamina that
covers the entire lens and prevents
wandering cells from penetrating it.
Subcapsular epithelium. The height of
this low cuboidal epithelium
beneath the capsule on the anterior
lens surface increases to columnar
near the lens equator, where cell
division occurs
Lens fibers are long, narrow,
hexagonal, specialized epithelial
cells that make up most of lens..
Retina
blind and visual
Retina
Pigmental layer
Pigmented cells functions
1. Synthesis of melanin granules that
absorb stray light in the eye chamber
2. Phagocytosis and digestion of apical
parts of the photoreceptors
3. Active participation in ion transport,
since they maintain an electrical
potential between the two surfaces of
the epithelium membrane
4. They participate in the processes of
vitamin A esterification.
Scheme of retina
Nerve cells of retina
8
6
4
Nerve cells of retina
There are three layers of retinal neurons
1st one (No4 - external nuclear layer)
contains perikaryons of rode and cone
cells - bipolar sensory cells
2nd - inner nuclear layer (No6) contains
perikaryons of bipolar associative cells
3rd layer is ganglionic layer (No8) with large
multipolar associative neurons.
Additional neurons horizontal and amacrine
cells which lie in inner nuclear layer and
have inhibiting function
• Horizontal and amacrine cells do not
have axons or dendrites, only neuritic
processes conducting in both directions.
Rod and cone cells
Retina’s layers
1. Pigment cell layer
2. Layer of rods and cones
3. External limiting membrane
4. External nuclear layer
5. External plexiform layer
6. Inner nuclear layer
7. Inner plexiform layer
8. Ganglionic layer
9. Layer of optic nerve fibers
10. Internal limiting membrane
Areas of retina with special
functions
Blind macula - optic papilla
Yellow macula - fovea
Yellow macula - fovea
Blind macula - optic
papilla
• The exit site from the retina of axons
derived from ganglion cells is
represented by the optic disc.
• The optic disc includes the optic papila, a
protrusion formed by the axons entering
the optic nerve, and the lamina cribrosa
of the sclera, pierced by the axons of the
optic nerve.
• Photoreceptors terminate at the edges of
the optic disc, which represents the “blind
spot” of the retina.
•
The central artery and vein of the retina
pass through the optic disc.