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

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) important for attentiveness, emotions, sleeping, dreaming, and learning Prepares you for action 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), sleep probs 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 imbalance 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) Affects movement 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 patient with depression Ex: block dopamine receptors in a patient with schizophrenia

NPR, Savant, and Crash Course Links Crash course Nervous System http://www.youtube.com/watch?v=x4PPZCLnVkA Crash Course “Your Chemical Brain” https://www.youtube.com/watch?v=W4N-7AlzK7s