Sense organs

1. Analizators2. Classification of sense

organs3. Smell organ4. Visual organ• Eye general structure• Sclera• Сornea• Choroid• Iris• Retina

ANALIZATOR

sense organ + nerve + cortex (field)

Sense organs

Primary sensory

1. Eye2. Smell organ

Secondary sensory

1. Ear2. Taste buds

Sensory endings (receptors)

1. Receptor of pain2. Paccinian body3. Bulb of Krause

Smell organOlfactory 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.

EyeVisual 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.Suprachoroid2.Vascular lamina (melanocytes)3.Choroidcapillaris4. 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 epithelium2. Ant. limiting membrane3. Vascular layer4. Post. limiting membrane5. Posterior epithelium

Lens

capsuleepitheliumlens 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

4

6

8

Nerve cells of retinaThere 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 papillaYellow 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.