Lecture 2 Flashcards
The nervous system I : Overall structure (47 cards)
How does an organism flexibly behave
1 - register ( sense environment )
2 - transform ( interpret - make sense of those signals )
3 - Generate appropriate response
Behaviour
an organisms internally coordinated response as a result of changes in its internal or external environment
Behaviour in simple organisms eg
plants ( although phototropism - growing plant follows path of sun )
Behaviour in complex organisms eg.
animals
- Involves constant monitoring
why does an animal need an NS?
to integrate the complex signals and select appropriate response from many options
what happens in complex system
if a change is strong enough, it causes the signal to be transmitted down the chain of cells ( neural pathway )
–> this is a chain that feedsback on its self ( cycles of signal generation ) –> which will eventually reach some output system eg. Motor neurone leading to some behaviour
cascade of cascades
communication of signals from one cell to the next as the cell changes its internal chemistry and as a result another cell changes its internal chemisty
ADHD example
have to think about every little movement so not much left attention for other things
register
sense info from environment
eg. magnetic fields - birds sense it and plan flight direction but humans cannot do that
transformation
internal change ( coordinated response )
process change
eg. prick by needle, there is a mechanical change but if your under anaesthesia, you won’t recognise this change
res
Response
brains respond
no conscious thought
automatic
difference between plant and animal ?
Animal can register more than just light, but also sound
animals can respond to complex stimuli eg. chainsaw and we can’t always predict their behaviour
Only multicellular animal without NS
sponge
Nervous system
network of electro-chemically active cells ( neurones) that are specialised to communicate with eachother
direction of signal transfer
1 - strong enough chemical change
2 - signal
3 - change to active from inactive
etc.
simplest form of NS
uncentralised
( hydra - sea star eg. ) - no nerve centre
every part is as important
evenly set our network of neurones condensed to ring an radial arms
cell body – axon – cell body – axon
hydra - what does nerve centre control
activity of groups of other neurones
actions of distant body parts
structurally centralised NS examples
flatworm
leech
insect
( with separate CNS ) - protobrain, nerve cord , PNS
nerve cords scattered around body
CNS - brain, nerve cord
PNS - all other neurones spread out
NS of vertebrates ( animal with spine just like us ) structure
CNS + PNS more clearly separated
NS vertebrates function
more hierarchy organised
brain - specialised to direct communication between neurones control actions of distant body parts
PNS more under control of CNS
CNS
brain + spinal cord
encased in bones
brain - skull
spinal cord - vertebrates
PNS - input from sense organs
somatic NS
somatic NS
picks up info from environment ( 5 senses )
and produces output in muscles
voluntary control
