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.

The Basic Parts of a Neuron

Parts of the Neuron

A. Dendrites Thin, branching fibers lined with receptors at which the dendrite receives information from other neurons.

Parts of the Neuron - Dendrites

B. Cell Body/Soma Contains the (C) nucleus and other parts of the cell needed to sustain life

Parts of the Neuron - Soma

C. Axon Carries the message across the neuron

Parts of the Neuron - Axon

D. Myelin Sheath An insulating, fatty covering around the axon that speeds neural transmissions. Axons that are myelinated appear white. Known as “white matter.”

Parts of the Neuron – Myelin Sheath

E. Axon Terminal Buttons The branched end of the axon that contains neurotransmitters

Parts of the Neuron - Terminals

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

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

Neuron

Neuron

Neural Transmission

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 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 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 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 space between the terminal buttons on one neuron and dendrites of the next neuron

Neurotransmitters Chemicals contained in the terminal buttons that enable neurons to communicate. Neurotransmitters fit into receptor sites on the dendrites of neurons like a key fits into a lock.

Neurotransmitters

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

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.

Neurotransmitters

Acetylcholine (ACh) Enables muscle action, REM sleep, and memory Undersupply, as ACh-producing neurons deteriorate, marks Alzheimer’s disease

Dopamine Reward and Motivation, Motor Control over Voluntary Movements Excessive dopamine receptor activity is linked to schizophrenia; a lack of dopamine produces the tremors and lack of mobility of Parkinson’s disease

Serotonin Affects mood, hunger, sleep, and arousal Undersupply is linked to depression; Prozac and other anti-depressants raise serotonin levels

Helps to control alertness and arousal Norepinephrine Helps to control alertness and arousal Undersupply can depress mood

GABA Muscular movement; inhibition of brain activity Undersupply linked to seizures, tremors, and insomnia Anxiety disorders

Glutamate Involved in memory Oversupply can overstimulate the brain, producing migraines or seizures

Endorphins Natural opiates that are released in response to pain and vigorous exercise

Adrenaline Burst of Energy (small amounts in brain) Epinephrine Adrenaline Burst of Energy (small amounts in brain)

Drugs and Chemical Interactions with Neural Transmission

Prozac blocking the re-uptake of Serotonin

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

A Neural Chain

A Neural Chain

A Neural Chain

A Neural Chain

Most information travels from the body, up the spinal cord, is processed by the brain, sent back down the spinal cord, and then back to the body with behavior instructions. The exception to this general pathway is reflexes.

Reflexes are controlled by the spinal cord without any conscious effort on behalf of the brain. Reflexes serve as primitive responses that protect our bodies from danger and help us adjust to our surroundings.

Reflex We cough, for example, when an irritant enters our windpipe and we need to expel it through our mouth. We sneeze when we need to clear our nasal air passages of irritants and allergens. We blink when danger threatens the sensitive tissues of the eye and when we need to moisten and clean the cornea. (This reflex occurs 900 times an hour!) We yawn when nerves in the brain stem find there's too much carbon dioxide in the blood.

Reflex Spinal Cord