Additional details from recitation from 1/23/2008
What does the nervous system do?
My answers/expected answers
sensory information (visual, auditory, gustatory, olfactory, visceral info from soft organs)
More generally, the nervous system gathers information, filters and processes that information, and
Why study neuroanatomy?
Because specifics in the form can tell us about function.
General organization of the Nervous System
Brain, spinal cord
Peripheral nerves exit the spinal cord at levels appropriate for their targets in the body.
the nerves innervating your big toe exit the spinal cord in your lower back, not up at the back of the
neck; and you wouldn't expect visual information to be carried on a nerve in the leg - it makes no sense
to have a nerve come from the eyes, travel through the body, enter the spinal cord & have that
information have to travel the length of the spinal cord to get processed.
- collects input (sensory information)
- contains cell bodies of motor neurons (output):
- somatic - to skeletal muscles
Spinal reflexes are mediated completely within the cord, connecting the incoming sensory neurons with
the outgoing motor neurons.
This makes reflexes fast, and means that you don't need a cortex, or any
other parts of the brain to react to, for example, painful stimuli.
I had learned this as an undergraduate, but I guess I didn't truly appreciate it until working in a lab.
the time, I had to harvest cells from the spinal cords of lampreys, which are a species of jawless fish
that look an awful lot like eels.
I learned to do the dissection, and was performing my first dissection
on my own, late at night.
To do this, I had to cut the heads off of young lampreys, then pin them down
on a dissecting tray.
When I stuck the pins in,
the tail of the lamprey contracted, and wrapped around
I screamed - I was very freaked out - and had to consciously remind myself that this was
just a reflex of the lamprey, which automatically swims away from anything that puntures its skin, and
that the thing wasn't still alive, and about to exact its revenge on me, even though I had cut its head off.