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?