Everything psychological is simultaneously

_________ Every idea, mood, urge is a biological happening

Love, laugh, and cry with your body Many people talk separately about biological and

psychological influences on behavior “To think, feel, or act without a body would be like

running without legs”

Biological Bases of Behavior

Biological Psychologists: branch of

psychology concerned with the links between _________ & __________ Each system is composed of subsystems that

are in turn composed of even smaller subsystems

Biological Psychologists

Structure and CommunicationStructure and Communication

The basic building block of the nervous system -- a nerve _____

Neurons perform three basic tasks Receive Carry Pass on to the next

neuron

Neurons – What are they?

The brain is made up of approximately ________ neurons.100 billion

electrochemical electrochemical informationinformation

Sensory Neurons (a.k.a. Afferent Neurons) carry incoming information from the sense receptors to the CNS.

Motor Neurons (a.k.a. Efferent Neurons) carry outgoing information from the CNS to muscles and glands.

Interneurons connect the two neurons.

Kinds of Neurons

Sensory Neuron Interneuron Neuron

Motor Neuron

• Sensory neurons take info. from the senses to the brain.

• Interneurons take messages from sensory neurons to other parts of the brain or to motor neurons.

• Motor neurons take info. from the brain to the rest of the body.

Structure of a Neuron

Structure of a Neuron – Dendrites

Structure of a Neuron – Soma

Structure of a Neuron – Axon

Structure of a Neuron – Neural Impulse

Structure of a Neuron – Myelin Sheath

Structure of a Neuron – Terminals

Neurons come in a variety of shapes and sizes, but they all have the same basic structure

Neurons – magnified view

Neuron – another view

Neurons send messages to other neurons – this is

what keeps every part of our body in communication with every other part.

Neurons “fire” – send an impulse (message) down their length – or they don’t “fire”

Neurons – How do they work?

This “firing” of impulse messages is called the

action potential. Action potential: is a brief electrical charge

that travels down the axon of the neuron.

Action Potentialshttp://brainu.org/files/movies/action_potential_cartoon.swf

Resting Potential: when a neuron is

at rest and capable of generating an action potential There are fluids inside and outside of the

neuron, filled with electrically charged particles (ions) When the neuron is at rest, there is a negative

charge on the inside of the neuron compared to the outside.

What causes an impulse to fire or not fire?

Stimulation from inputs to dendrites causes

the cell membrane to open briefly Positively charged sodium ions flow in

through the cell membrane If resting potential rises above threshold,

an action potential starts to travel from the cell body down the axon Threshold - Each neuron receives excitatory

and inhibitory signals from many neurons. When the excitatory signals minus the inhibitory

signals exceed a minimum intensity (threshold) the neuron fires an action potential.

Action Potentials, cont.

Refractory period - The “recharging phase”

when a neuron, after firing, cannot generate another action potential

Action Potential, cont.

All-or-None Principle: if a

neuron fires it will always fire at the same intensity A strong stimulus can trigger more

neurons to fire, and to fire more often, but all action potentials are of the same strength and speed.

A neuron does NOT fire at 30%, 45% or 90% but at 100% each time it fires.

Neuron Communication

Just like a gun, there is no “part-way” firing

Action Potential

Instructor’s Notes

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So what, exactly, are

neurotransmitters and what do they do?

Neurotransmitters: chemical

messenger that travels across the synapse from one neuron to the next

Can influence whether the second neuron will generate an action potential or not

Neurotransmitters

NeurotransmitterNeurotransmitter FunctionFunction ExamplesExamples

Acetylcholine (ACh)Acetylcholine (ACh)Released by motor neurons

controlling skeletal muscles. Enables muscle action, attention, arousal, and

memory

• With Alzheimer’s disease, ACh-producing neurons deteriorate.

• Some ACh receptors stimulated by nicotine.

Dopamine (DA)Dopamine (DA)

Influences voluntary movement, learning,

attention, and pleasurable emotions

• Excess dopamine receptor activity linked to schizophrenia.

• Decreased levels produce the decreased mobility and tremors of Parkinson’s disease.

Serotonin Serotonin

Affects mood, hunger, sleep, and arousal

• Undersupply linked to depression and obsessive-compulsive disorder.

• Prozac and some other antidepressant drugs raise serotonin levels.

Select Neurotransmitters

How Neurotransmitters Influence Us • Serotonin

pathways are involved with mood regulation.

• Dopamine pathways are involved with diseases such as:

• Schizophrenia (too much DA)

• Parkinson’s disease (not enough DA).

Select Neurotransmitters (cont.)

Neurotransmitter Function Examples

Norepinephrine (NE)Helps control alertness,

mood, and arousalUndersupply can depress mood.

GABA (gamma-aminobutyric acid)

A major inhibitory neurotransmitter

Undersupply linked to seizures, tremors, and

insomnia.

Endorphins Contribute to pain relief and perhaps to some pleasurable emotions

(“Runner’s High”)

Resemble opiate drugs in structure and effects

Glutamate A major excitatory

neurotransmitter; involved in memory

Oversupply can overstimulate brain,

producing migraines or seizures (which is why some people avoid MSG,

monosodium glutamate, in food)