Neural and Hormonal SystemsARE A UNION OF OPPOSITES!

Will Explain Why We FEEL

Pain

Strong

Sick

Nervous

It all Starts with the Neuron

Neuron Structure

Neurons do NOT touch each other- the space in between is call the synapse.

Neural Structure Metaphorically• Dendrite is like a tree. Also, each branch is a

telephone wire that carries incoming messages to you. Dendrites DETECT

• All or None is like a gun. Fires completely or not at all.

• Myelin is like the insulation that covers electrical wires.

• Neuron is like a silicon chip in a computer that receives and transmits information between input and output devices as well as between other chips.

• Axon is like an electrical cable that carries information. Axons ANNOUNCE

• (Union of Opposites)

• Resting Potential is like a battery. Stable until electrical charge stimulates it.

• Terminal Button is like the nozzle at the end of a hose, from which water is squirted.

• Synapse is like a railroad junction, where two trains may meet.

How a Neuron Fires

It is an electrochemical process• Electrical inside the neuron (MS)• Chemical outside the neuron (in

the synapse in the form of a neurotransmitter).

• The firing is called Action Potential.

The All-or None Response

• The idea that either the neuron fires or it does not- no part way firing.

• Like a gun

Steps of Action Potential• Dendrites receive neurotransmitter from

another neuron across the synapse.• Reached its threshold- then fires based on the

all-or-none response.• Opens up a portal in axon, and lets in positive

ions (Sodium) which mix with negative ions (Potassium) that is already inside the axon (thus Neurons at rest have a slightly negative charge).

• The mixing of + and – ions (Union of Opposites) causes an electrical charge that opens up the next portal (letting in more K) while closing the original portal.

• Process continues down axon to the axon terminal.

• Terminal buttons turns electrical charge into chemical (neurotransmitter) and shoots message to next neuron across the synapse.

Action Potential

Neural Impulse Like a Toilet: FLUSH!• all-or-none principle - the toilet either flushes

completely or not at all; it doesn’t flush a little or a lot• Like a Toilet Because…• direction of impulse - the toilet only flushes one way,

the impulse can’t come the other direction (you hope!)• refractory period - after you flush the toilet, it won’t

flush again for a certain period of time, even if you push the handle repeatedly

• threshold - you can push the handle a little bit, but it won’t flush until you push the   handle past a certain critical point - this corresponds to the level of excitatory neurotransmitters that a neuron must absorb before it will fire

• resting potential- if you are using a toilet with a tank, the water in the tank can represent resting potential. The toilet is “waiting” to fire, and the water in the tank represents the overall negative charge inside the neuron waiting for depolarization

• action potential - the action potential is represented by opening the flap in the tank and the water draining (flushing) down into the bowl

• See Neural Impulse Clip

Neurotransmitters “The KEYS” to Transmission2 Types (Excitatory/Inhibitory)2 Ways to Change Their Effect

(Agonist and Antagonist)Union of Opposites

•Chemical messengers released by terminal buttons through the synapse.

•We should know at least 4 types and what they do and how they “UNLOCK” the Receptor Sites.

How Neurons Communicate

Agonists and AntagonistsUnion of Opposites

How Neurons Communicate

Dopamine (Inhibits)• Its function is motor movement, alertness,

motivation, reward • (pp. 156 in CP)

Lack of dopamine is associated with Parkinson’s disease.Overabundance is associated with schizophrenia.

How is an alcoholic like Parkinson’s?

Acetylcholine (Excites!)•Its function is motor movement and

maybe memory.

To much and you will….

Not enough and you will….

Lack of ACH has been linked to Alzheimer’s disease.

Serotonin• Function deals with mood control , sleep, appetite, control.

• (pp. 156 in CP)

Lack of serotonin has been linked to depression.Prozac=SSRI “Selective Serotonin Reuptake Inhibitor”

Endorphins•Function deals with pain

control.

We become addicted to endorphin causing feelings.

Types of Neurons

Sensory NeuronsMotor NeuronsInter Neurons

Sensory Neurons(Afferent Neurons)

•Take information from the senses to the brain.

Inter Neurons• Take

messages from Sensory Neurons to other parts of the brain or to Motor Neurons.

Motor Neurons(Efferent Neurons)

•Take information from brain to the rest of the body.

Biological Difference: Nucleus Accumbens

• A region in the frontal cortex that directs motivation to seek rewards.

• The nucleus accumbens is activated by anticipated or received awards (i.e., monetary, chocolate). Mouse Party

• “Mind on Drugs!• A team at the National Institutes

of Mental Health in 2005 saw that the nucleus accumbens responded more in adolescents than in adults when they received a reward (Monastersky, 2007, para 27).

Biological Difference: Dopamine

• One reason the nucleus accumbens acts up more in adolescence is due to the different ways the younger brains deal with the neurotransmitter dopamine.

• Dopamine, the brain chemical involved in motivation and in reinforcing behavior, is particularly abundant and active in the teen years (Wallis, 2004, para 21)

• In addition to pleasure, novel situations will cause dopamine to squirt into the nucleus accumbens.

• Psych Sim: “Mind on Drugs”• Mouse Party

Divisions of the Nervous System

Sympathetic Nervous System

Flight or Fight Response

A Simple Reflex

A Simplified Neural Network

Neurons that learn to work together as a team.

The Endocrine SystemA system of glands that secrete hormones.Similar to nervous system, except hormones work a lot slower than neurotransmitters.

Neurotransmitters

Hormones

The Major Endocrine Glands