Vision. By: Karen, Jaqui, and Jen

Transcription

1 Vision By: Karen, Jaqui, and Jen

2 Activity: Directions: Stare at the black dot in the center of the picture don't look at anything else but the black dot. When we switch the picture you can look around the imagie. Will you see color in the second image.?

3

4

5 Major Structures of the eye: Cornea: Second structure that light hits in the eye. It's like a clear window that covers the Iris, Pupil and anterior chamber.. The Cornea s purpose is to let light rays enter the eye and converge the light rays. Anterior Chamber: Part of the eye that is filled with Aqueous Humor which fills the space between the back surface of the Cornea and the front surface of the Vitreous. Its function is to nourish the cornea, iris, and lens by nutrients, and removes waste products. Iris: Pigmented tissue lying behind the cornea and gives color to the eye and controls the the amount of light coming in. functions like a camera

6 Major structures of the eye: Lens: Is a transparent, biconvex intraocular tissue that helps bring rays of light to focus in the retina. Retina: The retina is the light sensitive nerve tissue in the eye that converts images from the eye s optical system into electrical impulses that are sent along the optic nerve to the brain, to interpret as vision. Optic Nerve: the largest sensory nerve of the eye. It carries impulses for sight from the retina to the brain. Extraocular Muscles: There are six extraocular muscles in each eye. Rectus Muscles Oblique Muscle

7 Optic Nerve Blind Spot

8 Anatomy of Sight: The wall of the eyeball is made up of three layers: Sclera- is the outermost protective layer. This surrounds the eyeball and attaches to the cornea, which is the clear front surface of the eye. Choroid- Is the middle layer that contains blood vessels that deliver oxygen and nutrients to the inside parts of the eye. Retina- Is the innermost of the three layers. The optic nerve carries signals from the retina to the brain (Occipital part of brain), which interprets them to the image you are seeing.

9 Anatomy of sight: 1. Light rays reflect off an object and enter the eyes through the cornea, which then you can see the object. 2. The cornea bends the rays that passes through the cornea bending the light rays to go through the pupil. 3. Then the light rays pass through the lens, which changes shape so it can further bend the rays and focus on them onto the retina. 4. The retina is in the back of the eyeball it is a thin tissue layer that contains millions of tiny light-sensing nerve cells. a. Cones- When there is bright light, cones provide clear, sharp central vision and detect colors and fine details. b. Rods- allow the eyes to detect motion and help us see in dim light and at night. 5. These cells in the retina convert the light into electrical impulses. The optic nerve sends these impulses to to brain which produces an image.

10

11 Physiology Stimulus & Receptor Cell Light rays reflect off an object and enter the eyes through the cornea, which then you can see the object. The light rays go through the eyeball and eventually hits the Retina at the back of the eyeball. The retina is made up of millions of light receptors called rods and cones. Rods are much more sensitive to light than cones. Each eye has about 125 million rods that help us see in dim light and detect shades of gray, but they cannot distinguish colors. In comparison, the 6 million cones in each eye allow us to see in bright light and they also sense color and detail.

12 Physiology Stimulus Affecting the Receptor Cell The Stimulus for the eyes would be light bouncing off objects The Receptor Cells would be the Cone and Rod shaped cells letting us see shapes and color. The rod and cone photoreceptors signal their absorption of photons via a decrease in the release of the neurotransmitter glutamate to bipolar cells at its axon terminal. Since the photoreceptor is depolarized in the dark, a high amount of glutamate is being released to bipolar cells in the dark.

13

14

15 Physiology Pathway to Receptor Cell The stimulus is detected by light, which enters the iris It passes through the retina, and goes into the choroid It bounces back onto the retina and hits the rods and cones The photoreceptors pick up the light and send signals to the bipolar cells which receive and pass onto the ganglion cells They send axons along the interior surface of retina and towards the optic nerve cell

16 Physiology Pathway to the Brain The first in the pathway - special sensory cell, the photoreceptors - converts light energy into a neuronal signal that is passed to the bipolar cell and the amacrine cell and then to the ganglion cell exit the retina via the optic nerve, with the nasal fibers from each eye crossing in the optic chiasm and terminating in the opposite side of the brain.

17 Cranial Nerves and Interpretation Area The Cranial Nerves are the optic nerves running from the eye to the brain. The Interpretation Area for vision is in the occipital lobe of the brain.

18 Homeostatic Imbalances: Glaucoma Macular Degeneration The treatments for Glaucoma and Macular Denergeration can save remaining vision but do not improve eyesight Damages optic nerve Loss Center Field Vision Vision loss can keep decreasing until none is left Blurred, distorted, or vision loss Medication, surgery, Laser trabeculoplasty Surgery, medications

19 Sources e-stimuli