Biological Basis of BehaviorChapter 2

How do we know how our body and brain work?

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What are the different ways for doctors to see inside your body?

• CAT (CT Scan)– noninvasive medical test that

helps physicians diagnose and treat medical conditions

– scans of internal organs, bones, soft tissue and blood vessels

– one of the best and fastest tools for studying the chest, abdomen and pelvis

PET- Positron Emission Tomography Scan

• nuclear medicine imaging• uses small amounts of radioactive material to

diagnose or treat a variety of diseases, including many types of cancers, heart disease and certain other abnormalities within the body

• scan measures important body functions

MRI- Magnetic Resonance Imaging

• uses a powerful magnetic field, radio frequency pulses and a computer to produce detailed pictures of organs, soft tissues, bone and virtually all other internal body structures.

Functional MR Imaging (F-MRI)

• imaging uses a powerful magnetic field, radio frequency pulses and a computer to produce detailed pictures of organs, soft tissues, bone and virtually all other internal body structures

• examine the anatomy of the brain

EEG- Electroencephalogram

• test used to detect abnormalities related to electrical activity of the brain

• most common reason an EEG is performed is to diagnose and monitor seizure disorders

Transcranial Doppler

• test that measures the velocity of blood flow through the brain's blood vessels

Ultrasound• Involves exposing part of the

body to high-frequency sound waves to produce pictures of the inside of the body

• Ultrasound is used to help physicians evaluate symptoms such as:

• pain • swelling • infection

How does our body work?

You’ve Got a Lot of Nerve!!• The brain is very complex with all

parts working together to produce everything you think, feel, and do.

• However, the brain can not work without your Nervous System.

• The nervous system acts as a choreographer; it constantly sends and receives messages that coordinate the stage show of human behavior.

It all begins with the Neuron

An individual nerve cellThese neurons send information throughout our whole body

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Three types of neurons–Sensory (sometimes called Afferent)

–Motor (sometimes called Efferent)

–Inter (interneuron)

Sensory Neurons(Afferent Neurons)

• Take information from the senses to the brain.

Activity

Motor Neurons(Efferent Neurons)

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

Activity

Inter Neurons• Takes messages from

Sensory Neurons to other parts of the brain

or to Motor Neurons.

Think of it this way…• You are sitting in math class and that

really annoying guy sneezes on the back of your head.

• Sensory nerves send the feeling of sticky wetness up your spinal cord to your brain.

• Sensory nerves pass the information off to interneurons.

• Interneurons then tell the motor nerves the plan.

• Motor nerves then travel down your body and help your hand reach around and smack the guy upside the head.

Reflexes• Normally, sensory

(afferent) neurons take info up through spine to the brain.

• Some reactions occur when sensory neurons reach just the spinal cord.

• Survival adaptation.

A Simple Reflex

So how does a neuron work??

I’m Glad you Asked!!!

Neuron StructureSynapse

Synapse

How Does A Neuron Work?How does it send a message in our body??

When a neuron is hanging out doing nothing, it is called Resting Potential

When it decides to go to work and send a message it is called Action Potential(the process by which a neuron fires)

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Steps of Action PotentialDendrites receive a chemical message

from another neuron across the synapse.Pieces of this chemical message stick to

the dendrite and these pieces keep adding up.

When the dendrite has taken as much of the chemical that it can hold the soma reaches its threshold and must fire

This is called the all-or-none response.

The All-or None Response• The idea that either

the soma (cell body) fires or it doesn’t –no part way firing–And it is same

strength each time…no stronger or weaker signals–And it is the same

direction each time

• The message then travels down the axon in the next neuron where it is stored waiting to reach its next threshold

• Terminal buttons turn these messages into chemicals (neurotransmitter) and shoots the message to next neuron across the synapse.

• The process is repeated again and again until the message reaches where it needs to go

Steps of Action Potential – cont.

• Sometimes there is to much chemical is sent across the synapse and it is involved in a process called Reuptake– Chemical that is extra goes back to the neuron

that sent it out • Natures version of recycling

– If Reuptake doesn’t happen, there could be some type of bodily problem

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Neural Network

Connections that are used continue to

grow & Connections that are not used die and are trimmed

away

Refractory Period

• The amount of time it takes for an excitable membrane to be ready for a second stimulus once it returns to its resting state following excitation

Field Trip

Neurotransmitters• Natural chemical

messengers released by terminal buttons

• Different ones do different things to your body.

• Each neurotransmitter has a specific shape that fits into a specific shape of a dendrite

• If the shape isn't right the neurotransmitter will not fit and will not work– Think of a key and a lock

• We should know at least 5 types and what they do.

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Acetylcholine (ACH)• Its function is memory, mood and motor

movementTo much and you will…

Not enough and you will experience…

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

shake

paralysis

Dopamine• Its function is motor movement and feelings

of excitementLack of dopamine is associated with Parkinson’s disease.•People can’t make smooth movements

Overabundance is associated with schizophrenia.

Serotonin• Deals with mood

control.Lack of serotonin has been linked to depression.

Too much..headaches

Norepinephrine• Plays a role in attention and focus• Plays a part in flight or fight

To much… fear andanxiety

Not enough…depression

Endorphins• Its function is with pain

control.– The body’s natural pain killer– “runners high”

We become addicted to endorphin causing feelings.

Now, although we have all of these neurotransmitters naturally in

our bodies, modern medicine has figured out a way to manipulate

them using what we call

Agonists and Antagonists

Agonists Chemicals that mimic the action

of a particular neurotransmitter Nicotine, morphine, and caffeine

are examples A copy of the “key”

Antagonists Chemicals that block the action of

a particular neurotransmitter. Because they occupy the receptor

site, they prevent otherneurotransmitters from acting.

Some drugs can block the neurotransmitter responsible for movement thus paralyzing an individual

Agonists and Antagonists

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