Welcome it is a great day to learn about the Brain

What does the Brain do? Stand up Walk around – every person you pass – tell them a different function the brain performs Do this until you are told to stop

Why do we study the Brain? Back at your tables – report back what you learned about what the brain does… did you learn anything new?

We are going to start small and go big

Neurons: The Building Blocks of the Nervous System Module 7: Neural and Hormonal Systems

What are the primary parts of a typical neuron? Nervous system Neurons Dendrites Soma Axon Terminal branches of Axon Myelin Sheath

Nervous System The electrochemical communication system of the body Sends messages from the brain to the body for movement Brings information to the brain from the senses

Neuron The basic building block of the nervous system -- a nerve cell Neurons perform three basic tasks –Receive information –Carry the information –Pass the information on to the next neuron

Neurons Neurons “fire” -- send an impulse down their length -- or they don’t “fire” Neurons come in a variety of shapes, sizes, etc.

Parts of the Neuron

Parts of the Neuron - Dendrites

Parts of the Neuron - Soma

Parts of the Neuron - Axon

Parts of the Neuron – Myelin Sheath

Parts of the Neuron - Terminals

Time to Move Locate the person furthest from you Go to that person Introduce yourself

Pick an A and D A = Axon D= Dendrite With your partner explain the relationship between neurons

Neuron

Neural Communication: The Neural Impulse

Action Potential A brief electrical charge that travels down the axon of the neuron. A neural impulse Considered an “on” condition of the neuron

Refractory Period The “recharging phase” when a neuron, after firing, cannot generate another action potential Once the refractory period is complete the neuron can fire again

Resting Potential The state of a neuron when it is at rest and capable of generating an action potential The neuron is set and ready to fire

Neuron firing like a Toilet 1.Like a Neuron, a toilet has an action potential. When you flush, an “impulse” is sent down the sewer pipe

Neuron firing like a Toilet 2. Like a neuron, a toilet has a refractory period. There is a short delay after flushing when the toilet cannot be flushed again because the tank is being refilled

Neuron firing like a Toilet 3.Like a Neuron, a toilet has a resting potential. The toilet is “charged” when there is water in the tank and it is capable of being flushed again 4.Like a Neuron, a toilet operates on the all-or-none principle – it always flushes with the same intensity, no matter how much force you apply to the handle

All-or-None Principle The principle that if a neuron fires it will always fire at the same intensity All action potentials are of the same strength. A neuron does NOT fire at 30%, 45% or 90% but at 100% each time it fires.

Communication Between Neurons Module 7: Neural and Hormonal Systems

Synapse The tiny, fluid filled gap between the axon terminal of one neuron and the dendrite of another neuron The action potential cannot jump the gap

Neurotransmitters A 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

Excitatory Effect A neurotransmitter effect that makes it more likely that the receiving neuron will generate an action potential (impulse) The second neuron is more likely to fire.

Inhibitory Effect A neurotransmitter effect that makes it less likely that the receiving neuron will generate an action potential (impulse) The second neuron is less likely to fire.

Neural Communication: The Neural Chain Module 7: Neural and Hormonal Systems

Receptor Cells Specialized cells in the sensory systems of the body that can turn other kinds of energy into action potentials that the nervous system can process Receptor cells in the eye turn light into a neural impulse the brain understands.

Sensory Nerves Nerves that carry information to the central nervous system Connect the sense organs to the brain and spinal cord

Interneurons Nerve cells in the brain and spinal cord responsible for processing information related to sensory input and motor output

Motor Nerves Nerves that carry information from the central nervous system Carries messages from the brain and spinal cord to other parts of your body

A Neural Chain

The Structure of the Nervous System Module 7: Neural and Hormonal Systems

The Nervous System

Central Nervous System (CNS) The brain and spinal cord The brain is the location of most information processing. The spinal cord is the main pathway to and from the brain.

Spinal Cord

Divisions of the Nervous System

Peripheral Nervous System (PNS) The sensory and motor nerves that connect the central nervous system to the rest of the body Peripheral means “outer region” The system is subdivided into the somatic and autonomic nervous systems.

Divisions of the Nervous System

Somatic Nervous System The division of the peripheral nervous system that controls the body’s skeletal muscles Contains the motor nerves needed for the voluntary muscles

Divisions of the Nervous System

Autonomic Nervous System The division of the peripheral nervous system that controls the glands and muscles of the internal organs Monitors the autonomic functions Controls breathing, blood pressure, and digestive processes Divided into the sympathetic and parasympathetic nervous systems

Divisions of the Nervous System

Sympathetic Nervous System The part of the autonomic nervous system that arouses the body to deal with perceived threats Fight or flight response

Divisions of the Nervous System

Parasympathetic Nervous System The part of the autonomic nervous system that calms the body Brings the body back down to a relaxed state

Divisions of the Nervous System

The Sympathetic and Parasympathetic Divisions of the Autonomic Nervous System