hardware flow visualization physiology of the human eye

Hardware Flow Visualization

Physiology of the human eye

اندازه و مختلف هاي عدسي عملكردآنها انكساري قدرت گيري

چشم در نور شكست سطوح

چشم در در تطابق مكانيسم

Emmetropia

Hyperopia

Astigmatism

• Unequal curvatures in cornea & lens

Lens Accommodation

Slide 8.16Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

· Light must be focused to a point on the retina for optimal vision

· The eye is set for distance vision (over 20 ft away)

· The lens must change shape to focus for closer objects

Figure 8.9

Internal Anatomy of the Eye--Tunics

• Fibrous tunic: sclera & cornea

• Vascular tunic: choroid layer

• Sensory tunic: retina

Autonomic Regulation of the Iris

Pupil Constricts

Pupil Dilates

depth of focus

مايع ترشح و تشكيل چگونگي زالليه

• Ciliary process at the base of the iris produces aqueous humor

• Scleral venous sinus returns aqueous humor to the blood stream

• Glaucoma – any disturbance that increases aqueous humor volume and pressure which causes pain – ultimately the vitreous humor crushes the retina causing blindness

Circulation of the Aqueous Humor

The Two Layers of the Retina• Outer pigmented layer has a

single layer of pigmented cells, attached to the choroid tunic, which absorbs light to prevent light scattering inside

• Inner neural layer has the photosensory cells and various kinds of interneurons in three layers

visual acuity

همراه به مختلفشبكيه اليهآنها سلولهاي

• Light must cross through the capillaries and the two layers of interneurons to reach the photoreceptors, the rods and cones

Micrograph of the Retina

Light

Optic Nerve, Blind Spot, Fovea

به فوتورسپتورها تحريك مكانيسمنور برخورد دنبال

Neural Organization in the Retina

• Photoreceptors: rods (for dim light) and cones (3 colors: blue, green and red, for bright light)

• Bipolar cells are connecting interneurons

• Ganglion cells’ axons become the Optic Nerve

Neural Organization in the Retina

• Horizontal Cells enhance contrast (light versus dark boundaries) and help differentiate colors

• Amacrine cells detect changes in the level of illumination

The Optic Disc

• Axons of ganglion cells exit to form the optic nerve

• Blood vessels enter to serve the retina by running on top of the neural layer

• The location of the “blind spot” in our vision

Opthalmoscope Image of the Retina

• The Macula Lutea (“yellow spot”) is the center of the visual image

• The Fovea Centralis is a central depression where light falls more directly on cones providing for the sharpest image discrimination

• Light bouncing off RBCs’ hemoglobin causes “red eye” in flash photos

و تاريكي به تطابق مكانيسم روشنايي

Micrograph of the Retina

Light

شبکیه نورونی مداربندی

• Cone > Bipolar cell > Ganglion cell • Rod > Bipolar cell > Amacrine cell > Ganglion

cell

بینایی در ان اهمیت و مهارجانبی1. Amacrine Cells2. Excitation of Some Bipolar Cells

and Inhibition of Others—The Depolarizing and Hyperpolarizing Bipolar Cells

Downloaded from: StudentConsult (on 12 December 2009 05:27 PM)© 2005 Elsevier

visual acuity

an average of 60 rods and 2 cones

each ganglion

Three Types of Retinal Ganglion

• Transmission of Rod Vision by the W Cells• Transmission of the Visual Image and Color

by the X Cells• Transmit Instantaneous Changes in the Visual

Image by the y Cells

کورتکس فیزیولوژیکی و آناتومیکی ساختار بینایی

Organization and Functionof the Visual Cortex

Layered Structure of the PrimaryVisual Cortex

Eye Movements

Extrinsic Eye Muscles

• Lateral, medial, superior, and inferior rectus muscles (recall, rectus = straight); superior and inferior oblique muscles

Neural pathways for control ofconjugate movement of the eyes

Fixation Movements of the Eyes

• voluntary fixation mechanism• involuntary fixation mechanism• (1) a continuous tremor• (2) a slow drift• (3) sudden flicking• Saccadic Movement

و ارادي تثبيتي حركات كنترل چگونگيارادي غير

فوقاني چهارقلوي هاي نقشتكمه دربينايي

• Superior Colliculi Are Mainly Responsible for Turning the Eyes and Head Toward a Visual Disturbance

Horner’s Syndrome

Control of Pupillary Diameter