Physiology 3120 Lecture 1: Neuro1
9 May 2018
School
Department
Course
Professor
Physiology 3120
Dr. Pruszynski
Lecture 1
The brain, neurons and synaptic transmission
Nervous system
- Brain is just a part of the NS
- Some creatures have a NS but not a brain
- Collection of some centralized thing (like brain) in some creatures but also
decentralized mechanisms that are stretched through the ANS and PNS etc
- These systems work together
o Info from body, tissue, viscera goes to spinal cord to get processed
in some way then goes to brain
- NS is broader than the brain – important concept
The brain – 1011 neurons, 1015 synapses
- Brain is complex on the outer layer is the cerebral cortex
o Thin tissue surrounding brain
- Focus on the scale
o 100 billion neurons (1011)
▪ give you a lot of behavior and action that you associate with complex beings (ex:
humans) and other animals
▪ walking thinking, thinking feeling
▪ actions are all centralized to the central neural tissue
▪ there’s 10^15 synapses(connection bw the neurons)
▪ each of the neurones is connecting to thousands of other neurons
▪ all the connections let the brain do the processing it does
▪ behaviour arises from the interactions of the neurons
What is the brain for?
- Survival
o Senses & responds environment
- To make complex judgements of environment
- Brain is only centralized clustering of neurons to co-localize sensory info, ability to make motor
outputs, take in sensory inputs from variety of modalities
- You can integrate all these things in one space
Sea squirt: the creature that eats its own brain
- Begins its life as an egg
- Egg hatches
- Turns into tadpole like creature
- It swims in sea and it fits a rock it loves (has lots of nutrients flowing by it)
- Then it takes the nutrients out of its out brain and consumes it (eats it) for
energy
- Once it no longer has to move around, has to make sensory movement judgments or make
decisions it no longer needs to waste energy on this centralized system of brain
Some basic anatomy
- brain is functionally specialized
- sometimes the name is given on anatomy
- other times its named after geometry of brain
o ex: gyrus - exposed area of brain
o ex: sulcus – creves area of brain
- there can be many names for one part of brain
o ex: within the precentral sulcus is the primary motor cortex
- outer layer of brain=cerebral cortex
- brain is separated into 4 major lobes separated by major sulci (evolutionarily conserved –
meaning its seen in other creatures as well)
o central sulcus
▪ in front of it is frontal lobe
▪ behind it is the parietal lobe
o lateral sulcus
▪ below it is temporal lobe
▪ back of brain is occipital lobe
- inside of brain you see the brain stem
- there is a distinctive bw physiology and anatomy
Cells in the nervous system
- nerve cells (aka neurons)
o do information processing
o are electrically excitable
o have synaptic elements
o produce AP
o propagate info around brain
- glial cells (aka glia)
o support operation of neurons by maintaining brain environment
o 10X more glia than neurons critical element
o more than just hold neurons together
▪ supply backup glucose from glycogen
▪ remove neurotransmitters (if you don’t remove neurotransmitters, you are
useless creature bc the waste products interfere with neurons)
▪ remove ammonia (by-product of metabolism)
▪ take up K+
▪ provide myelin sheaths for axon, to aid information transmission (by allowing
propagation of AP down the axon)
Document Summary
Some creatures have a ns but not a brain. Brain is just a part of the ns. Collection of some centralized thing (like brain) in some creatures but also decentralized mechanisms that are stretched through the ans and pns etc. Info from body, tissue, viscera goes to spinal cord to get processed in some way then goes to brain. Ns is broader than the brain important concept. Brain is complex on the outer layer is the cerebral cortex: thin tissue surrounding brain. Brain is only centralized clustering of neurons to co-localize sensory info, ability to make motor outputs, take in sensory inputs from variety of modalities. You can integrate all these things in one space. Sea squirt: the creature that eats its own brain. It swims in sea and it fits a rock it loves (has lots of nutrients flowing by it) Then it takes the nutrients out of its out brain and consumes it (eats it) for energy.
