Neural & Hormonal Systems: Overview of Neurons, Neurotransmitters, Lecture notes of Psychology

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Module 3 Neural and Hormonal Systems Neural Communication  Biological Psychology  branch of psychology concerned with the links between biology and behavior  some biological psychologists call themselves behavioral neuroscientists, neuropsychologists, behavior geneticists, physiological psychologist, or biopsychologists  Neuron  a nerve cell  the basic building block of the nervous system  Approx. 100 billion neurons (1011)  Approx. 100 trillion synapses (1014) The Nervous System The Nervous System  Nervous System  the body’s speedy, electrochemical communication system  consists of all the nerve cells of the peripheral and central nervous systems  Central Nervous System (CNS)  the brain and spinal cord  Peripheral Nervous System (PNS)  the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body The Nervous System  Nerves  neural “cables” containing many axons  part of the peripheral nervous system  connect the central nervous system with muscles, glands, and sense organs Central Nervous System The Brain and Neural Networks Complex Neural Network Interconnected neurons form networks in the brain. Theses networks are complex and modify with growth and experience. Neural Communication  Dendrite  the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body  Axon  the extension of a neuron, ending in branching terminal fibers, through which messages are sent to other neurons or to muscles or glands  Myelin [MY-uh-lin] Sheath  a layer of fatty cells segmentally encasing the fibers of many neurons  enables vastly greater transmission speed of neutral impulses Neural Communication Terminal branches of axon (form junctions with other cells) Dendrites (receive messages from other cells) : Axon (passes messages away from the cell body to other neurons, muscles, or glands Cell body —— (the cell’s.life-~ Myelin sheath (covers the axon of some e neurons and helps speed Neural impulse _ feural impulses) (electrical signal traveling ny down the axon) Synapse Synapse [SIN-aps] a junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. This tiny gap is called the synaptic gap or cleft. Neurotransmitters Neurotransmitters (chemicals) released from the sending neuron travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing it to generate an action potential. Reuptake Neurotransmitters in the synapse are reabsorbed into the sending neurons through the process of reuptake. This process applies the brakes on neurotransmitter action. Dopamine Pathways Dopamine pathways are involved with diseases such as schizophrenia and Parkinson’s disease. From Mapping the Mind, Rita Carter, © 1989 University of California Press Neurotransmitters SOME NEUROTRANSMITTERS AND THEIR FUNCTIONS Neurotransmitter Acetylcholine (ACh) GABA (gamma- aminobutyric acid) Glutamate Function Enables muscle action, learning, and memory. Influences movement, learn- ing, attention, and emotion. Affects mood, hunger, sleep, and arousal. Helps control alertness and arousal. A major inhibitory neuro- transmitter. A major excitatory neuro- transmitter; involved in memory. Examples of Malfunctions With Alzheimer’s disease, ACh-producing neurons deteriorate. Excess dopamine receptor activity linked to schizophrenia. Starved of dopamine, the brain produces the tremors and decreased mobility of Parkinson’s disease. Undersupply linked to depression; Prozac and some other antidepressant drugs raise serotonin levels. Undersupply linked to seizures, tremors, and insomnia. Oversupply can overstimulate brain, pro- ducing migraines or seizures (which is why some people avoid MSG, monosodium glu- tamate, in food). Lock & Key Mechanism Neurotransmitters bind to the receptors of the receiving neuron in a key-lock mechanism. Neural Communication  Acetylcholine [ah-seat-el-KO-leen]  a neurotransmitter that, in addition to its role in learning and memory, triggers muscle contraction  Endorphins [en-DOR-fins]  “morphine within”  natural, opiate-like neurotransmitters  linked to pain control and to pleasure The Nervous System  Autonomic Nervous System  the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart)  Sympathetic Nervous System  division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations  Parasympathetic Nervous System  division of the autonomic nervous system that calms the body, conserving its energy The Nervous System Central (brain and spinal cord) Nervous system Autonomic (controls self-regulated action of internal organs and glands) Skeletal (controls voluntary movements of skeletal muscles) Sympathetic (arousing) Parasympathetic (calming) Peripheral Central Nervous System The Spinal Cord and Reflexes Simple Reflex The Endocrine System  Endocrine System  the body’s “slow” chemical communication system  a set of glands that secrete hormones into the bloodstream