BRAIN, BODY, AND BEHAVIOR

Chapter 3

Examining the Brain

Study the brain in detail because it is the part of us that controls every thought, action, and feeling

The Brain uses 20% of all our oxygen, eats up most sugar we take in, and is made up of about 100 billion nerve cells

The Cerebral Cortex

Outermost layer of the brain High level of thinking occurs in

this area If the cortex were untwisted and

spread out it is about the size of a large bath towel

The Hemispheres

Halves The brain is divided into two halves A fissure is what separates the two

halves Each hemisphere controls the

opposite side of the body The corpus callosum helps each half

of the brain communicate with the other half

The Lobes

The Cerebral Cortex is divided into four major sections called Lobes Frontal Lobe Parietal Lobe Occipital Lobe Temporal Lobe

The Lobes

Frontal Lobe Foremost area The motor strip is located in the

frontal lobe This allows movement of the body

Parietal Lobe Located behind the Frontal Lobe Sensory strip is located here

Allows a person to feel sensations

The Lobes

Occipital Lobe Very back of the brain Devoted to making sense out of

what we see The brain sits in a fluid that acts like a

shock absorber so the brain can move back and forth

Temporal Lobe Bottom of the brain Major centers for hearing

The Frontal Lobe

Prefrontal Area Located behind your forehead Allows us to re-experience past

events Frontal Association Area

Heavily packed with nerve cells Phineas Gage

Railroad worker Experienced damage to his frontal

association area and changed drastically

Hemispheres and Handedness When dealing with small, fine

movements, such as writing one hemisphere will have dominance

The intelligence of right versus left handed people is about the same

Myths: If a left handed child is forced to use their right hand they may become insane

Parents would sometimes make their children switch to using their right hands

Tasks of the Cerebral Hemispheres Left Hemisphere handles verbal

or speech material The right hemisphere deals with

objects in space, art, music, and some mathematical reasoning

Both hemispheres work together in virtually everything we do

The Lower Brain

The lower brain is located deep inside the skull with the cerebral cortex fitting over and around it

Cortex means “bark” as on a tree Bark protects a tree just like the cortex

protects our lower brain

The Thalamus

Oval mass of nerve cells Relay station to send incoming

and outgoing messages to and from various parts of the brain

Hypothalamus

Located below the thalamus (hypo means “below”)

Size of a large pea Controls rage, pleasure, hunger,

thirst, and sexual desire

The Limbic System

Contains structures involved in basic emotions and to some extent memory

2 Structures are important in the limbic system Amygdala – responsible for emotional

responses especially aggression Hippocampus – allows us to form

memories Memories are not stored in the hippocampus If the hippocampus is damaged new memories

cannot be formed

The Cerebellum

Looks like a ball of yarn a little larger than a golf ball

Complex Balance, coordination, gets you

where you need to go First day of school you followed your

schedule but within a week you no longer had to “pay attention” - you magically arrived

The Reticular Activating System (RAS) Sits at the base of the brain

inside of the spinal cord Reticular means “net” and the RAS

catches nerve impulses Regulates alertness and

sleepiness Sensitive to steady sounds Major blow to the head may cause the

RAS to shut down Change in rhythm can stir up the RAS

Brain Communication

All parts of our brain has to communicate with one another as well as our body

We need nerve cells that are separate but able to alternate signals from one circuit to another

The Neuron

Each nerve cell is separate from the others

The body of the neuron has fibers sticking out from it Short fibers are called dendrites

Look like branches Axons carry the message from the cell to

other neurons Thousands of terminals that sit opposite a receptor

for another neuron Message comes to a receptor on a

dendrite, goes through the cell and then goes out the cell’s axon to another neuron

The Synapse Junction point

Space is located between the endings of the axon and the waiting dendrites

Electricity will not go over spaces So what tells our body we are in pain?

Neurotransmitters

Chemical “messengers” deliver messages to across the synapse

Different molecules have different shapes and make-ups

Acetylcholine regulates your body’s movement and memory

Dopamine – shortage of this is a main role in Parkinson’s Disease

Endorphins – made by the body and is a natural form of morphine

The Central and Peripheral Nervous Systems Central Nervous System

Brain and Spinal Cord All nerve impulses must enter and exit

by the spinal cord In an emergency the spinal cord reacts

before the brain does The spinal cord has very few

synapses to slow down messages

The Peripheral Nervous System Everything minus the brain and

spinal cord Somatic Nervous System

Composed of sensory and motor nerves

The Autonomic System Controls the things we do

automatically Breathe, digest food, pupil dilating, heart

Can be overridden by the brain

The Endocrine System

The Pituitary Gland Master gland of the body – bean

shaped unit that is attached and controlled by the hypothalamus

2 jobs Send messages that will start other

glands going Determine how tall or short we will

be When things are not working properly

incredible growth can occur Poor nutrition can also affect your growth

The Endocrine System

The Thyroid Gland Sits inside the neck Controls metabolism Overactive Thyroid

Can result in restlessness, nervousness, and anxiety

Underactive Thyroid Can result in a sad mood, or even

depression

The Endocrine System

Adrenal Glands Pump adrenaline into the

bloodstream Adrenaline prepares us for emergencies

Even sends out a chemical that will help the blood clot faster incase we are cut

Do not have to be in an emergency for the adrenal glands to start working Important tests, talking to a judging

audience

Right Brain vs Left Brain

Which are you the most? Do you agree or disagree with the

description? Why or why not? Use two examples

that prove or disprove the summaries?