hardware flow visualization physiology of the human eye
TRANSCRIPT
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