L16 Axonal Guidance: What is axonal guidance? - Correct Answer e.g. development of the eye and visual maps -retinotectal system
L16 Axonal Guidance: Where are motor neurons produced? - Correct Answer Ventral spinal cord
L16 Axonal Guidance: How do the axons from the motor neurons connect ...
ZOO 3603C - Exam 3 Practice Questions
(ANSWERED)
L16 Axonal Guidance: What is axonal guidance? - Correct Answer e.g. development of
the eye and visual maps -retinotectal system
L16 Axonal Guidance: Where are motor neurons produced? - Correct Answer Ventral
spinal cord
L16 Axonal Guidance: How do the axons from the motor neurons connect to their
target? - Correct Answer All neurons have a cell body where the nucleus is located
and one axon.
L16 Axonal Guidance: Do the axons have to be close to their target? - Correct Answer
Do the axons have to be closNo, they can be very, very far away.
L16 Axonal Guidance: How does an axon find its correct target and so become
innervated perfectly? - Correct Answer chemoaffinity hypothesis
L16 Axonal Guidance: What does the optical vesicle equal? - Correct Answer The
developing eye.
L16 Axonal Guidance: What is the optical vesicle? - Correct Answer The optic vesicle
is an outgrowth of the forebrain neuroepithelium.
L16 Axonal Guidance: How are the lens induced in the ectoderm? - Correct Answer
When the optic vesicle meets the surface ectoderm.
L16 Axonal Guidance: How is the optic cup formed? - Correct Answer The optic
vesicle then inverts on itself to form the optic cup and the lens delaminates from the
ectoderm
L16 Axonal Guidance: When does the eye become two layered? - Correct Answer
When the optical vesicle inverts on itself to form the optic cup.
L16 Axonal Guidance: What layer forms the neural retina? - Correct Answer The inner
layer.
L16 Axonal Guidance: What layer forms the pigmented retina? - Correct Answer The
outer layer.
L16 Axonal Guidance: What forms the sclera? - Correct Answer The surrounding
neural crest cells.
L16 Axonal Guidance: How is the optic nerve formed? - Correct Answer When the
neural retina sends axons down the optic stalk.
, L16 Axonal Guidance: What part of the neuronal cell is the growth cone? - Correct
Answer The business end.
L16 Axonal Guidance: Where so the growth cones have to go? - Correct Answer
L16 Axonal Guidance: what are the retinotectal connections - Correct Answer temp -->
rostral, Nasal --> caudal, Dorsal --> LAteral, Ventral --> medial
L16 Axonal Guidance: What do we use in place of the mammalian retinotectal
projection? - Correct Answer Electrophysiological recording of retinotectal connections
in the frog.
L16 Axonal Guidance: What is the evidence for retinotecal projections? - Correct
Answer Evidence = rotate frog eye, axons reconnect to their original places, frog jumps
wrong way.
L16 Axonal Guidance: How do axonal growth cones travel all that distance and get
PRECISELY to the correct location? - Correct Answer Roger Sperry - chemoaffinity
hypothesis
1 : 1 connections between retinal ganglion cells and tectal cells
L16 Axonal Guidance: What are some of the problems for retinotecal projections? (1) -
Correct Answer Problem 1 - too molecularly demanding - need more genes than are in
the genome just for the retinotectal system
L16 Axonal Guidance: What are some of the problems for retinotecal projections? (2) -
Correct Answer Problem 2- Growth during development.
L16 Axonal Guidance: What are some of the problems for retinotecal projections? (3) -
Correct Answer Problem 3- Spreading/Compression.
L16 Axonal Guidance: What happens when half the eye or half the tectum is ablated? -
Correct Answer Means the frog can only see half of the world, half blind.
L16 Axonal Guidance: What happens if the ablated tectum or eye is left for 4 weeks? -
Correct Answer Cut axons have reconnected in the remaining tectum.
Now full vision is restored
Therefore shifting connections, NOT rigid 1:1 connections
L16 Axonal Guidance: Is vision restored with humans? - Correct Answer Even works in
humans - George Stratton in 1890's found that after 4 days he could start to see the
right way up again
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