vision - u-szeged.hu · 5 tears • lubricates and protects •plasma ultrafiltrate, slightly...

Vision

Kap

osv

ári P

éter

Vision

Kap

osv

ári P

éter

Vision

Kap

osv

ári P

éter

Vision

Kap

osv

ári P

éter

5

Tears

• lubricates and protects

•plasma ultrafiltrate, slightly hypertonic, 1 ml / day

• rinsing out foreign objects

• lyzozym + secretory antibodies + antigenes

• emotional tool

• reflex: afferent: n. V. ------> brainstem (pons)

• efferents: n. VII----> ggl. pterygopalatinum -----> n.V. --> glands

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ggl. pterygopalatinum

Lacrimal gland

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intraocular pressure: ~16 Hgmm, due to the aqueous humor measuring: tonometry •composition: plasma ultrafiltrate

•production: active, epithelial cells in the ciliary body

•drainage: passive, transcellular vesicular transport

role of the pupil

trabecular meshwork

Schlemm chanels

Intraocular pressure

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Tonometry

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Circulation of the aqueous humor

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Glaucoma

Pre

tect

um

III. cranial nerv

Edinger–Westphal nucleus

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n. III.

n. VI.

n. III.

n. III.

n. IV.

n. III.

Accomodation triad

• Lens accomodation • Pupil contraction • convergating eyemovement

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Pupil wide Pupil narrow

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Cornea 39 diopter

Cataracta Normal

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Removing the old lens

Inserting the new lens

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papilla n. optici

fovea

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Cells of the retina

Cells of the retina

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Photoreceptors duplicity theory: receptors for scotopic and photopic vision

scotopic: rods, 500 nm maximum, no colors

photopic: cones, 555 nm, colors

mesopic: at dusk and dawn

cones: 6 million, very dense at the fovea

rods: 120 million, none in the fovea, very dense parafoveal

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Receptor density across the retina R

ecep

tor

den

sity

(1

03/m

m2)

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Dark current

membrane potential~ -30 mV

Glutamate

Dark current

membrane potential~ -30 mV

Glutamate

Nernst equation Goldman–Hodgkin–Katz

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Scotopic, mesopic and photopic vision

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Purkinje shift

• Photopic • Mesopic • Scotopic

Purkinje shift

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Retinal cells: I. receptors (cones and rods) II. bipolar cells III. ganglion cells IV. horizonthal cells (connecting receptors, contrast, color, vision) V. amacrin cells (connecting ganglion and bipolar, cells) VI. Müller glial cells (nutrition, K+ uptake, blood-retina barrier) VII. pigment epithel cells

57 light

light

rods cones

ON and OFF ganglion

RF center

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2, 3,5 ipsilateral 1, 4,6 contralateral

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lesions in the visual field

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Retinotopic representation in the visual cortex (cat)

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Retinotopic representation in the visual cortex (human)

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Orientation sensitivity in the pimary visual cortex

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Orientation sensitivity in the pimary visual cortex

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Orientation columns

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orientation direction length

response response response válasz

a látó- kéregben

receptive field light stimulating

inhibitory

stim. stim. stim.

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Hypercolumn in the primary visual cortex

~1000 neurons

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Orientation columns in the primary visual cortex

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Figure 1: A single unit in the left posterior hippocampus activated exclusively by different views of the actress Jennifer Aniston.

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