The Nervous System Our nervous system is involved in thinking, dreaming, feeling, moving, sleeping, and more Regulates internal functions When we learn a new behavior or new information, it registers the experience and changes to store it

Two Main Parts of the Nervous System Central Nervous System – Brain – Spinal Cord Peripheral Nervous System – Nerve cells that send messages between the central nervous system and all the parts of the body

The Nervous System The Central Nervous System The BrainThe Spinal Cord The Peripheral Nervous System The Somatic Nervous System The Autonomic Nervous System The Sympathetic Nervous System The Parasympathetic Nervous System

The Nerve Cells Neurons – Send and receive messages from other structures throughout the body (like muscles and glands) – Each of us have more than 100 billion neurons, most of which are in the brain

Parts of the Neuron The Cell Body (Soma) – Produces the energy to fuel the activity of the cell – Nucleus is in the cell body Axon – Carries messages away from the cell body – One axon per cell body – Covered with a fatty insulation known as the “Myelin Sheath” Helps speed up the transmission of messages Protects Axon – Axon terminals branch from the end of the axon Dendrites – Thin fibers branching out from the cell body – Carries information to the cell body

Neural Communication Messages are sent from the axon terminals of one neuron to the dendrites of other neurons – Messages cross the SYNAPSE the space between the axon terminal of one neuron and the dendrite of another neuron – Messages can only travel in one direction – New synapses can develop between neurons when we learn something new – Synapse disruption can occur  concussions

The Message Sent: Neurotransmitters Chemicals stored in sacs, or vesicles, in the axon terminals Neurons can fire neurotransmitters hundreds of times per second Chemical neurotransmitters are converted into an electric pulse which travels the length of the neuron

Neurotransmitters Acetylcholine – Control of muscles Dopamine – Motor behavior – Too little plays a role in Parkinson’s disease, as seen in the tremors and rigid, uncoordinated movements – Too much contributes to schizophrenia Noradrenaline – Prepares the body for action Serotonin – Emotional arousal and sleep

The Central Nervous System Consists of the neurons of the brain and spinal cord Spinal cord is a column of nerves (about as thick as your thumb) which is protected by the bones of the spine – Responsible for spinal reflexes, like removal of your hand from a hot stove response faster than the brain can register the pain of being burned

The Peripheral Nervous System Responsible for transmitting messages between the central nervous system and all other parts of the body Divided into two parts: – The Somatic Nervous System – The Autonomic Nervous System

The Somatic Nervous System Transmits sensory messages to the central nervous system Activated by touch, pain, changes in temperature, and changes in body position Enables us to experience sensations of hot/cold and to feel pain/pleasure

The Autonomic Nervous System Autonomic = “occurring involuntarily” Regulates the body’s vital functions – Heartbeat – Breathing – Digestion – Blood pressure Two divisions: – Sympathetic Nervous System – Parasympathetic Nervous System

Sympathetic vs. Parasympathetic Prepares the body for action  “Fight or Flight” – Suppresses digestion – Increases heart rate – Increases respiration – Elevates blood pressure Calms the body after emergencies – Normalizes heart rate – Normalizes blood pressure – Slows breathing – Normalizes digestion

The Nervous System The Central Nervous System The BrainThe Spinal Cord The Peripheral Nervous System The Somatic Nervous System The Autonomic Nervous System The Sympathetic Nervous System The Parasympathetic Nervous System