Autonomic division automatic not in our control o Regulates the activity of involuntary muscles cardiac and smooth and glands 1 Sympathetic division 2 Parasympathetic division Coordinates the body for the fight or flight response by speeding up metabolism heart rate and breathing while slowing down and regulating other functions Counters the sympathetic system by bringing up a relaxed state by slowing down metabolism heart rate and breathing and returning other functions to normal 2 cell types in the Peripheral Nervous System 3 types of neurons Neurons we have different types of neurons to make it easier for us to distinguish emotions sensations o Sensory takes impulses from sensory receptor to CNS o Interneuron receives information in the CNS and sends it to a motor neuron o Motor takes impulses from the CNS to an effector i e gland or muscle fiber Neuron structure o Cell body main cell where nucleus and most organelles reside o Dendrites many short extensions that carry impulses to a cell body o Axon nerve fiber single long extension that carries impulses away from the cell body The Myelin Sheath A lipid covering on long axons that acts to increase the speed of nerve impulse conduction insulation and regeneration in the PNS Schwann cells neuroglia that make up the myelin sheath in the PNS Nodes of Ranvier gaps between myelination on the axons Salutatory conduction conduction of the nerve impulse from node to Neuroglia supports and protects the neurons Schwann cells node Nerve impulses Resting potential and Action Potential RP Resting potential when the axon is not conducting a nerve impulse o More positive ions outside than inside the membrane o 70 mV inside the axon Resting Membrane Potential o More Na outside than inside more K inside than outside maintained by Na K pump which pumps 3 Na out and 2 K into the cell making the resting membrane potential in the neuron negative Action potential rapid change in the axon membrane that allows a nerve impulse to occur o Sodium gates open letting Na in Depolarization occurs More ions inside than outside Interior of axon loses negative charge 55 mV then 35 mV o Potassium gates open letting K out Repolarization occurs More ions inside than outside Interior of axon regains negative charge 70 mV Wave of depolarization repolarization travels down the axon Resting potential is restored by moving potassium inside and sodium outside Na Sodium K Potassium The synapse Small gap between the sending neuron presynaptic membrane and the receiving neuron postsynaptic membrane Transmission is accomplished across this gap by a neurotransmitter e g Acetylcholine dopamine serotonin Neurotransmitters are stored in synaptic vesicles in the axon terminals How does transmission across the synapse occur Nerve impulse reaches the axon terminal Calcium ions enter the axon terminal and stimulate the synaptic vesicles to fuse with the presynaptic membrane Neurotransmitters are released and diffuse across the synapse where they bind with the postsynaptic membrane to inhibit or excite the neuron Drug abuse They Both legal pharmaceuticals and illegal drugs of abuse have certain basic modes of action Promote the action of a neurotransmitter Replace or mimic a neurotransmitter or neuromodulator Interfere with or decrease the action of a neurotransmitter Examples of drugs Alcohol a depressant directly absorbed from the stomach and small intestine Alcohol is the most socially accepted form of drug use About 80 of college aged people drink Alcohol denatures proteins and causes damage to tissues such as the brain and liver chronic consumption can damage the frontal lobe High blood alcohol levels can lead to poor judgment loss of coordination or even coma and death Nicotine stimulant derived from tobacco plant Nicotine stimulates neurons to release dopamine that reinforces dependence on the drug It adversely affects a developing embryo or fetus Smoking increases heart rate and blood pressure Nicotine causes psychological and physiological dependency Cocaine stimulant derived from a shrub Cocaine causes a rush sensation that lasts from 5 30 minutes A cocaine binge occurs when a user takes the drug at ever higher doses resulting in hyperactivity little desire for food and sleep and an increased sex drive There is extreme physical dependence with this drug Crack is the street name for cocaine that is processed to a free base form for smoking Methamphetamine a stimulant that reverses the effects of fatigue and is a mood elevator Powder form is called speed and crystal form is called meth or ice High agitation is common after the rush and can lead to violent behavior Methamphetamine causes psychological dependency and hallucinations Ecstasy is the street name for a drug that has the same effects as meth without the Heroin depressant from the sap of the opium poppy plant It leads to a feeling of euphoria and no pain because it is delivered to the brain and converted hallucinations into morphine Side effects are nausea vomiting and depression of the respiratory and circulatory systems Heroin use can lead to HIV hepatitis and other infections due to shared needles Extreme dependency is common Marijuana psychoactive drug derived from a hemp plant called Cannabis It is most often smoked as a joint Occasional users experience mild euphoria alterations to vision and judgment as well as impaired motor coordination with slurred speech Heavy users may experience depression anxiety hallucinations paranoia and psychotic symptoms Long term use may lead to brain damage K2 Spice is a synthetic drug with higher potency than the active chemical in marijuana
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