Transcript Visual System Powerpont file for students

The Visual
System
Part 1
Aqueous humor
secreted from Ciliary body,
Flos to Anterior Chamber,
drains through
Canal of Schlemm
_________
Intrinsic Muscles of
the Eye: The Iris
• Iris
– circular.....________
– radial.....…________
• Dilating pupil for eye
exam: how to do it?
Pharmacology of
pupillary dilation:
_________
Intrinsic Muscles of the Eye:
Ciliary Muscle
• Ciliary muscle relaxed = tension on
zonular fibers = tension on lens =
flattened lens = _________________
• Ciliary muscle contracted = tension on
zonular fibers reduced = less tension on
lens = lens becomes more spherical
=__________________
• Eye strain
Using a Microscope or Binoculars
Near point of Accomodation
0.06
0.07
0.08
0.09
0.12
0.14
0.16
0.18
0.3
0.4
With Convergence
Demonstrate
Convergence
Extraocular muscles
Motor innervation by
CN III = __________
CN IV = __________
CN VI = __________
__________= misalignment of eyes
Due to _______________________
Lateral geniculate nucleus
a subdivision of the thalamus.
Visual reflexes:
___________, ___________,
___________, ___________.
Clinical Case Study:
Hyperprolactinemia,
p. 627-8 of text
The Visual
System
Part 2
The Retina
What do you notice with
regards to the connections
in this complex circuit?
What cells seem to have
axons?
What does this mean with
regards to sensory
coding?
S 15
Receptors for
light detection
Photoreceptor cells
4 light sensitive proteins:
- 1 type of _____
- 3 types of ______, each with a
single type
More membrane =
more photosensitive molecules =
more sensitive to light
Visual Acuity
• 120,000,000 rods and
6,000,000 cones per retina
• 1,200,000 retinal ganglion
cells & axons
• ____:___convergence ratio
• Fovea:
•Differences in spectral sensitivity due to 4 types of ______.
Web-based
color
deficiency test
_______ Theory of Color Vision
“Bleaching” of photopigments
_________
_________
The cascade of events initiated by light in a photoreceptor. The result of the cascade is to close a cGMP-gated
sodium channel, reducing the inward current and hyperpolarizing the membrane. Source: Kandel, Schwartz &
Jessell, Principles of Neural Science, 4th Edn
What is the advantage of this multistep process?
Hubel and Weisel Experiments
Lateral
Geniculate
Neurons
Youtube
Retinal
Ganglion
Cells
Visual
Cortex
Neurons
_____________in the Cortex
• Motion
sensitive
• Color and
shape sensitive