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Lecture 4

BIO120H1 Lecture Notes - Lecture 4: Orans, Potential Energy, Myelin


Department
Biology
Course Code
BIO120H1
Professor
M.Cadotte
Lecture
4

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Lecture 4
[Endocrine/Nervous /Peripheral systems]
-endocrine + nervous systems regulate [balance] animal physio [their body]
KEY THOUGHTS:
Organization of nervous system
Evolution of nervous system
Neural communication = how the neurons are connected to each other + they send signals
Membrane potential = how NA goes iN and K comes out and they fix those chemical gradients
Cells of the Nervous system ARE CALLED: Neurons AKA Excitable cells
The reason for the name “excitable cells” is because they send INFORMATION when they are happy and
excited [TURNED ON]
The excitable cells [neurons] they send chemical + electrical signals BACK + FOURTH
HOW IT WORKS:
We have a nervous system with two methods of input [afferent] + output [efferent]
In between both those methods, we have an integrating centre [the bridge] for the neuron to pass
through from INPUT to OUTPUT.
Integrating centre is the brain which is in the CNS. The CNS has a cluster of nerves together.
Input + output mnethods are in the PNS [anything outside of the brain + spinal cord].
The input is SENSORTY organs. Ex. fingers are sensory organs like when you touch something
HOT, your finger senses it + SENDS it to your brain. The brain sends the signal back to the
output [efferent]. So the input is the sensors which sense the hotness in your fingers and travels
down the bridge of the integrating centre and delivers the messages to the output aka the
effectors.
Deviation of the PNS + CNS
EXAMPLE: Niegarians [jellyfish] : has ONE division[input + output region is in the SAME place] of all
the nerves CONNECTED together in something caklled a NERVE NET. This means that information is
going in TWO directions [no specific order] so the input + output neurons can travel quickly + randomly.
Evolution of the BRAIN
HOWDOES IT LOOKS LIKE? It’s bilaterally symmetrical.
Bilaterally symmetrical:
We have a left side and a right side.
Cephalization: It’s a PATTERN of LOCATING sensory + nervous integrating centres [brain] at the
ANTERIOR [front] part of the body
Example of Cephalization: JELLYFISH+ STARFISH [spongebob square pants] don’t have cephalization
Ganglia: in the brain, its interconnected neural cells [cluster of cells] this is what is in the CNS. These are
also grouped together in the INTERIOR end of the brain. The function of the ganglia is that it processes
information to the CNS. Another fact is that ganglia can exist by itself like some animals don’t have a
brain so instead they can have the ganglia.
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