2/24/10
Biology 141 with Weeg at Pennsylvania State University - All Campuses
About this deck
By: Andrew Myers
Created: 2010-02-25
Size: 26 flashcards
Views: 13
Created: 2010-02-25
Size: 26 flashcards
Views: 13
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Refraction
bending of light as it passes between different substances A convex surface refracts parallel light waves to converge at a single point Cornea & lens refract light to focus the image on the retina image is upside down and reversed left to right
Cones Color vision
red, green, and blue cones Based on light absorbing pigments Low light sensitivity High resolution Rods Colorless vision High light sensitivity Low resolution Phototransduction
Basic eye anatomy
- Cornea
- Pupil
- Lens
- Retina
Cornea
Refraction of light waves
Pupil
Controls amount of light entering eye
Lens
Changes shape to focus image
Reflex control of pupil diameter
- Circular muscles of iris
- Radial muscles of iris
Circular muscles of iris
- Contraction decreases diameter of the pupil
- Parasympathetic control
- Very fast
Radial muscles of iris
- Contraction increases diameter of pupil
- Sympathetic control
- Slower response
Focusing light coming into the eye
- Refraction: bending of light as it passes between different substances
- A convex surface refracts parallel light waves to converge at a single point
- Cornea & lens refract light to focus the image on the retina
Cornea & lens refract light to focus the image on the retina
image is upside down and reversed left to right. The brain corrects this.
Lens attached to ciliary muscles via suspensory ligaments
- Muscle relaxed, ligaments taut, lens thin
- Muscle contracted, ligaments relaxed, lens thick
What happens when objects are closer to the eye
- Contraction of ciliary muscles makes lens thicker & more rounded
- Accomodation adjusts lens shape to focus light on retina
Refractive Disorders
- Myopia (near sighted)
- Hyperopia (far sighted)
Myopia (near sighted)
- Eye is too long
- Light is focused in front of retina
- Corrected with concave lens
Hyperopia (far sighted)
- Eye is too short
- Light focused behind retina
- Corrected with convex lens
Retina
- Photoreceptors
- Bipolar cells
- Ganglion cells
- Fovea: region of sharpest vision
- Optic disc: exit site of optic nerve
Ganglion cells
Axons form optic nerve
Optic disc: exit site of optic nerve
- No photoreceptors
- Blind spot
Photoreceptors
- Cones
- Rods
Cones
- Color vision: red, green, and blue cones
- Low light sensitivity
- High resolution
Color vision: red, green, and blue cones
Based on light absorbing pigments
Rods
- Colorless vision
- High light sensitivity
- Low resolution
Phototransduction
- In dark
- In light
In dark
- Rhodopsin inactive
- Na+ channels open - cell is depolarized
- Release of neurotransmitter
- Bipolar cells inhibited
In light
- Rhodopsin activated
- Na+ channels close
- Cell hyperpolarizes
- Neurotransmitter release decreases
- Bipolar cells stimulated
About this deck
By: Andrew Myers
Created: 2010-02-25
Size: 26 flashcards
Views: 13
Created: 2010-02-25
Size: 26 flashcards
Views: 13
About StudyBlue
STUDYBLUE makes things that make you better at school.
Things like online flashcards with photos and audio.
Things like personalized quizzes and friendly reminders about when (and what) to study next.
Think of it as a digital backpack™: access to all of your study materials online and on your phone.
STUDYBLUE exists to make studying efficient and effective for every student, for free. Join us.
“I have used this website for three exams, and I see a huge difference in my test results.”
Naj
Naj