visual development Flashcards
optic nerve and cell in brain on transmission of an impulse
neurotransmitter (that prevents action potential?) not surewont be released if rhodopsin isnt bleached
answer:
compare and contrast FMRI and PET scans
PET scans activity
Fmri, exposed to magnet
h atoms in nucle line up with
Both show brain activity of patient
both detect O uptake and blood flow in regions of the brain
fMRI doesnt use radiotracers
-if t-helper cells are undergoing lysis there will be fewer in the body
-t-helper cells are responsible for activation of t-killer cells by releasing cytokines, t-killer cells which destroy infected body cells, infection more likely tp spread
-t-helper cells also activate b-cells
so less production of b-cells or plasma cells producing antibodies
what is inoculation of bacteria
bacteria mixed with molten agar
DNA has slight negative charge
heavier strands will move closer to the anode
lighter stands wont get as far
answer: other way around, Harder for longer pieces to move through the gel/ shorter pieces move quicker through the gel
how do changes in the blood vessels result in the redness and swelling seen at the site of inflammation
increased bloodflow to site of damage? more red pigment?
answer:
damage causes histamines to be released
vasodilation
which cortex is the visual cortex a part of
cerebral cortex
where do neurons receive visual info form
ocular dominance columns
why will vision be irreversibly impaired if vision is blocked during the critical period?
-synapses that receive visual stimulation and transmit action potentials to the visual cortex are strenghtened during the critical period
-synapses that don’t receive visual stimulation are removed because the neurones between them arent firing/transmitting action potentials
-So if visual stimulation doesnt occur during the critical periodthen their vision wont develop properly because the synaoses that dont receive visual stimulation are destroyed.
whats happened in the experiment that proved this?
-one eye in kitten and adult cats sewn up for several months
-after unsewn adult cats were able to see , no impairment to their vision
-but kittens were blind in that eye and the change is irreversible
-under microscope showed that cone
whatre the ethical issues with this experiment
animal research
what’re the 4 ethical frameworks that can be used when arguing for or against using animal research
-utilitarianism
-making autonomous decisions
-living a virtuous life
-rights and duties
whatre the benefits of animal research?
-theyre only carried out when necessary and there are strict guidelines that scientists have to follow
-the similarities between animals and humans means we can apply the results from animal research experiments to humans- no need to experiment on people until were mostly confident its safe-allows us to carry out research which would be unethical to humans & helps to develop drugs that could save lives
-allows us to test effects on whole organism- other body tissues may play a role in physiological responses
-could be argued that animals cant make autonomous decisions as they aren’t conscious
(4 ethical frameworks)
-utilitarianism, if the research leads to drugs which saves lives or info which greatly develops our medical knowledge then the ends may justify the means
whatre the negatives of animal research
-all organisms have the right to not suffer
-unethical to cause pain or stress to a living creature
-there are alternatives like cell cultures
Define the term critical window
if it happen within a certain window it never will.
Describe what happens during the critical window of visual development
synapses that dont transmit impulses to neurones are removed
OCCULAR DOMINANCE COLUMNS are in the visual cortex and contain the neurones that receive info from our eyes.
Eyes receive visual imput
synapses receive visual stimulation, neurones betwen the synapses that get visually stimualted are firing
-if they arent receiving visual stimulation they’re removed
(if visual stimulation doesnt occur during the critical period many synapses will have been removed so the visual cortex wont develop properly)
Explain how the results of Hubel and Wiesel’s experimentations with kittens and monkeys contributed to research into human brain function
-kitten and adult cats had one eye sewn up for months
-when unstitched, adult cats’ vision returned to normal but baby cats were blind in one eye permanently
-looked under microscope, occular dominance columns had shrunk for the sewn eyes and the unsewn eye occular dominance columns had expanded, suggesting the expanded columns had taken over the columns that werent being stimulated
(occular dominance columns of big cats didn’t change)
-need to receive visual stimulation in both eyes early in life for visual cortex to develop properly critical period as it will never develop properly if not in early development
-humans have similar occular dominance columns as monkeys and cats so this can be applied to humans
Discuss the ethical reasons for and against the use of animal models in research
benefits:
-the similarities between animals and humans often means that we can apply results from animal research to humans
-can help identify is there are any dangers of treatment before testing on humans
-animals aren’t considered conscious in the same way humans are, cant really make autonomous decisions
-research using animal testing can lead to development of new drugs or treatments that save lives or ease pain, ends justify means, utilitarianism
-more accurate to use an entire organism than a cell culture, other body tissues could affect physiological responses
-scientists have strict guidelines to follow to make testing as humane as possible
Drawbacks:
-there are other options like cell cultures
-shouldn’t cause suffering in animals
