The Nervous System Your body’s communication network & control center Central Nervous System (CNS)-receives info & initiates response- brain & spinal cord Peripheral Nervous System (PNS)-gathers info from inside & outside the body NEURONS = Messengers & receivers of these transmissions

BASIC STRUCTURE OF NEURON Cell body-contains nucleus & cell membrane Dendrites-branching projections of the cell body, carry impulses into the cell Axon-Threadlike extension carries impulses to & from the cell, at the end of axon is the axon terminal Myelin Sheath-Insulates the axon & speeds up transmission of the impulses Synapse-point of contact at which impulses are passed from one cell to another

Voluntary Actions vs Reflex Actions Impulses passed via the brain What is the chain of events that happens from the instant you hear the phone ring until you pick up the phone? Every time a stimulus—such as a ringing telephone—is detected, the body's neurons send a nerve impulse through the nervous system. If the safety of our body requires a very quick response, the signals may pass directly to a motor neuron for instant, unthinking action. This is a reflex action. Signals sent via the spinal cord

REACTION TIME: The nervous system helps information travel through your body. It consists of the 5 senses, your brain, your spinal column, and the nerves that connect them all together. Suppose your eyes see a baseball sailing toward your head. They send a message about the approaching ball to your brain. This message travels to a part of your brain called the cerebrum through nerves. Your cerebrum sends this information to the cerebellum, which has to choose whether to move away, duck, or put a hand up to catch the ball. It finally decides that you should catch it—after all, you’re wearing your baseball glove! The cerebellum sends this decision as message through other nerves to the arm and hand,  activating the muscles used to catch the ball. The time it takes from when your eye first notices the ball to when your arm reaches up to catch it is an example of reaction time. Even though stimuli—or changes in your environment that you react to—travel very quickly along your nervous system as messages, your body doesn’t react instantly. Many athletes spend hours practicing to improve their reaction time. In this activity, you will conduct a simple, measurable experiment (the ruler drop test) to study reaction time and determine how it can be improved with practice.

How can reaction time be measured and improved? Procedure volunteer sits in a chair with good upright posture   places forearm so it extends over the edge of the table. places thumb and index (pointer) finger on either side of the bottom of the vertically placed ruler. The number “1” should be on the bottom, the “30” near the top.  hold the ruler so that the bottom of the ruler is at a height of 2cm above their fingers. Tell your volunteer that you will release the ruler without telling them. Their job will be to catch it with the thumb and forefinger as soon as they senses it dropping.   Drop the ruler. When your volunteer catches it, record the number on the ruler displayed just over their thumb. The lower the number, the faster their reaction time. Conduct several trials with the same volunteer. Make sure to record the results for each trial in a table similar to the following: Volunteer cm trial 1 cm trial 2 cm trial 3 cm trial 4 cm trial 5 cm trial 6 NAME  

Results = Muscle Memory Share results: When we begin to acquire a new physical skill through repetition, our nervous system creates new neural pathways. Here’s an example: when we practice something like catching a ruler over and over again, all the members of that neural pathway (eye, brain, muscles) become more well-connected and efficient. This phenomenon is often referred to as muscle memory. However, no matter how good your muscle memory for this task becomes, it will always take some time for the falling ruler to travel as a message from your eyes to your brain and from your brain to your fingers!

NEUROTRANSMITTERS chemicals released by vesicles in sending neuron travel across the synapse and bind to receptor sites on receiving neuron 2 TYPES = EXCITATORY = stimulate the brain, increase the likelihood that the neuron will fire an action potential INHIBITORY = calm the brain, balance mood & are depleted when excitatory are overactive

Lock & Key Mechanism Neurotransmitters bind to the receptors of the receiving neuron in a “key-lock mechanism”. https://www.youtube.com/watch?v=p5zFgT4aofA

Neurotransmitters: Serotonin various functions = body temp., sleep, mood, appetite, and pain Low levels =implicated in depression & probs with immune syst. Stimulant medications or caffeine in your daily regimen can cause a depletion of serotonin High = Serotonin Syndrome(mild to severe symptoms including seizures)

Neurotransmitters Con’t. Norepinephrine (AKA Noradreneline) Prepares you for action important for attentiveness, emotions, sleeping, dreaming, and learning causes blood vessels to contract & heart rate to increase GABA Gamma-Amino Butyric Acid An inhibitory neurotransmitter  “nature’s VALIUM-like substance” Related probs = anxiety, seizures, Huntington’s disease (nerve cell degeneration) Valium and similar antianxiety drugs work at GABA synapses

Neurotransmitters Con’t. Dopamine main focus neurotransmitter Affects neurons associated with voluntary movement role in learning, memory, and emotions Loss of dopamine-producing cells = Parkinson’s Disease Excess = focusing issues, less motivation, schizophrenia Stimulants (ex: cocaine, meds for ADD/ADHD, caffeine) cause dopamine to be pushed into the synapse so that focus is improved  BUT cause a depletion over time Acetylcholine triggers muscle contraction important role in arousal and attention Loss = linked to Alzheimer’s Disease

Neurotransmitters Con’t. Endorphins linked to pain control and to pleasure Reduce pain by inhibiting or “turning down” neurons that transmit pain information natural, opiate-like neurotransmitters “morphine within”

How Neurotransmitters Influence Us Although not the sole cause of schizophrenia, dopamine unbalance is consistently seen found in patients with schizophrenia Drugs that prevent dopamine from binding to receptors can reduce the symptoms of schizophrenia Dopamine pathways are involved with diseases such as Parkinson’s disease caused by a deterioration of brain neuron’s that produce dopamine (it is still unknown why this occurs) Preview Question 2: How do neurotransmitters affect our mood and behavior?

Neurotransmitters (see pg 99)

A & A Neurotransmission Agonist Increases production Activates the neuron receptor that it attaches to Antagonist Decreases production Deactivates the neuron receptor that it attaches to

Agonist and Antagonist Ex: mimic serotonin in a depressed patient Ex: block dopamine receptors in a Parkinson’s patient

NPR, Savant, and Crash Course Links http://www.npr.org/2013/08/10/210816604/ted-radio-hour-the-hackers https://www.youtube.com/watch?v=wgV5rcZtETg Crash course Nervous System http://www.youtube.com/watch?v=x4PPZCLnVkA Crash Course “Your Chemical Brain” https://www.youtube.com/watch?v=W4N-7AlzK7s