3.1 lecture

The Neuron

Chapter 3.1

1Wednesday, September 12, 12

Biological Psychology and Neuroscience-concerned with the links between biology and behavior


3.1: The Neuron– Neurons– Action potentials– Synaptic communication

3.2: The Brain 3.3: Methods of Brain Research 3.4: Nervous System and Endocrine

System

Agenda


Franz Gall Germany Early 1800’s bumps =

mental abilities

37 traits

Phrenology ≠ Neuroscience



Systems: A group of interacting, interrelated, or interdependent elements forming a complex whole.

Biological, Psychological, Social

What is the smallest level of analysis?

What is the smallest level of analysis?

Biological.

We will examine how at this level “we” take in information: organize, interpret, and store it; and use it.

Help neurons function properly– Dispose waste– Create myelin– Help neurons

communicate

“Mommy cells”

Glial cells


Neuron = Nerve Cell-receives, processes, and

transmits information

Nodes of Ranvier


Form follows function.

Get into a 4 groups. Make a cafeteria line.

Create a system of communication within the group that does not use sound or vision to convey a number. – Touching is OK.

Create a system of communication between groups using these. One catch: You cannot cross the gap.

The goal: We’re going to play silent telephone

islands. I’m going to give a number to a

group and see if we can get that number to the last student in line.


Electrochemically.– Between neurons, a signal travels chemically.– Within the neuron, a signal travels

“electrically.” There is no “beginning” but we will start

with this question. Where do neurons get the energy to

communicate?

How do these nerve cells exchange information?


Let’s start at the “beginning” with resting potential.


Resting potential:

13Wednesday, September 12, 12Fragrance in a balloon demonstration to represent the building of resting potential by the Na-K pumps.

Resting potential:– Generated by Sodium-Potassium pumps on neuron

membrane.– Ratio of

2 Positively charged K+ atoms inside 3 Positively charged Na+ atoms outside

– Outside the neuron, it is positively charged– Inside the neuron, it is negatively charged (-70

mV) In other words, the neuron is polarized.


Depolarization --> Threshold (sometimes)

After resting potential


The cell body and axon hillock are like a water gun, clown’s mouth, and a balloon.

In other words, it’s an adding machine. Only when there is enough

depolarization (Na+ ions) in the cell body and thus axon hillock, do we reach threshold.

Threshold analogy


We reach the “touching in our islands”

The action potential.

After Threshold


Action Potential parts

Nodes of Ranvier


Form follows function.

Action potential:– Positive Na atoms rush in and trigger a domino

effect down the axon. The region inside becomes slightly positively charged.

In other words, the cell becomes depolarized.

And guess what? It’s like dominoes. Once it starts, it can’t be stopped.– This is called the all-or-none principle.


Don’t forget the Nodes of Ranvier


Refractory period:– A period of time when

the neuron must become polarized again

– In other words…– The Na-K pumps make

Na+ ions go back outside the neuron to re-establish resting potential.

*1000 times/second

After the action potential

24Wednesday, September 12, 12Next slide is about the chemical communication Prefeace by bringing back idea of electrochemical communication.

Remember: communication is electroCHEMICAL.

•Neurons are NOT physically joined together.•Therefore how do they pass a signal across a

physical space known as a synapse?


The word "synapse" comes from Greek: "syn" meaning "together" and "haptein" meaning "to clasp."

“You are your synapses.”-Joseph Le Doux


Neurotransmitters (NT)– Exocytosis triggered by action potential– Released from the axon terminal buds.– NT’s cross synapse via diffusion.– Connect to correct receptor-channels on

dendrites of next neuron.– Unlock channels at the receiving site allowing

Na+ ions into the receiving neuron.


Depolarization --> Threshold

Which brings us to...


Excitatory: allow ____________into the neuron to depolarize the cell.

ACh (acetylcholine): excitatory NT

Inhibitory: allow __________ into the neuron to prevent firing GABA: inhibitory NT – keeps brain calmed down and not firing out of

control

Two Categories of Neurotransmitters (NT)


NT’s are “expensive” to make.

So neurons recycle, i.e. REUPTAKE.


Every chemical that affects behavior works at the synapse

They act like… Neurotransmitters (NT’s)

– Agonist: drug that mimics an NT’s effects.They are similar enough the NT to open receptor channel.They can block the reuptake of the NT in the synapse.

– Antagonist: They can block receptor site.

DRUGS


Curare:– Stops ACh from fitting into receptor sites (used by

natives on poison darts) Botox aka Botulin

– Blocks the release of Ach from the sending neurons (paralysis)

Black Widow venom:– Is similar to Ach and activates receptor sites

(seizures and convulsions)!

Agonist or Antagonist?


Dopamine (NT): Excessive levels in the brain associated

with schizophreniaLow levels associated with Parkinson’s

– Thorazine used for Schizophrenia Because it _____ dopamine

– L-Dopa used for Parkinsons– Because it _______ dopamine



Endorphins: natural pain killing NT– Toughens the membrane of

neurotransmitter sacs preventing them from breakingPain signal is stopped

Morphine, Heroin, and other opiates



– Low levels associated with depression– Administer Prozac – prevents reuptake

It is a _____________.

Seratonin (NT)


With so many NTs, are some found only in certain places?

How do they affect mood, memories, and mental abilities?

Can we boost or diminish these effects through drugs or diet?


Certain pathway uses 1 or 2 NT’s and that NT has a particular effect on a behavior and emotion.


Go to Catlink and find our homework assignment under Day 2 this week: “Explaining the Neuron.”

If you can teach it, you know it.


3.1 lecture

Education

Transcript of 3.1 lecture