* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download topic 6.5 Neurons
Biochemistry of Alzheimer's disease wikipedia , lookup
Embodied language processing wikipedia , lookup
Subventricular zone wikipedia , lookup
Environmental enrichment wikipedia , lookup
Convolutional neural network wikipedia , lookup
Artificial general intelligence wikipedia , lookup
Types of artificial neural networks wikipedia , lookup
Electrophysiology wikipedia , lookup
Holonomic brain theory wikipedia , lookup
Apical dendrite wikipedia , lookup
Activity-dependent plasticity wikipedia , lookup
Neural oscillation wikipedia , lookup
Endocannabinoid system wikipedia , lookup
Neural engineering wikipedia , lookup
Multielectrode array wikipedia , lookup
Node of Ranvier wikipedia , lookup
End-plate potential wikipedia , lookup
Mirror neuron wikipedia , lookup
Metastability in the brain wikipedia , lookup
Axon guidance wikipedia , lookup
Neuromuscular junction wikipedia , lookup
Neural coding wikipedia , lookup
Caridoid escape reaction wikipedia , lookup
Central pattern generator wikipedia , lookup
Nonsynaptic plasticity wikipedia , lookup
Single-unit recording wikipedia , lookup
Clinical neurochemistry wikipedia , lookup
Premovement neuronal activity wikipedia , lookup
Biological neuron model wikipedia , lookup
Neuroregeneration wikipedia , lookup
Optogenetics wikipedia , lookup
Pre-Bötzinger complex wikipedia , lookup
Feature detection (nervous system) wikipedia , lookup
Molecular neuroscience wikipedia , lookup
Neurotransmitter wikipedia , lookup
Circumventricular organs wikipedia , lookup
Synaptogenesis wikipedia , lookup
Chemical synapse wikipedia , lookup
Development of the nervous system wikipedia , lookup
Stimulus (physiology) wikipedia , lookup
Synaptic gating wikipedia , lookup
Channelrhodopsin wikipedia , lookup
Neuropsychopharmacology wikipedia , lookup
Neurons and Neurotransmitters Nervous System – Central nervous system (CNS): • Brain • Spinal cord – Peripheral nervous system (PNS): • Sensory neurons • Motor neurons (somatic and autonomic) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Nervous System The Nervous System Central Nervous System (CNS) Brain Peripheral Nervous System (PNS) Spinal Cord • Motor Neurons Somatic Nervous System voluntary movements via skeletal muscles Sympathetic - “Fight-or-Flight” responses • Sensory Neurons Autonomic Nervous System organs, smooth muscles Parasympathetic - maintenance Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Divisions of the autonomic nervous system The Nervous System • A physical organ system like any other • 2 main kinds of cells – Neurons – Glia Neurons Basic units of the nervous system Receive, integrate, and transmit information Operate through electrical impulses Communicate with other neurons through chemical signals More about neurons and neuronal anatomy later Glial cells • 100 billion neurons • 10x more glial cells • Glial cells – Support neurons (literally, provide physical support, as well as nutrients) – Cover neurons with myelin – Clean up debris – “Housewives” Astrocytes • Regulate external environment (ions, etc.) • Most abundant glial cell • May contribute to blood-brain barrier and to synapses Three main types of neurons • Sensory Neurons • Interneurons • Motor Neurons Sensory (Afferent) vs. Motor (Efferent) sensory (afferent) nerve e.g., skin Neurons that send signals from the senses, skin, muscles, and internal organs to the CNS motor (efferent) nerve Neurons that transmit commands from the CNS to the muscles, glands, and organs Gray’s Anatomy 38 1999 e.g., muscle The Withdrawal Reflex Neuron Anatomy and Neural Communication Neurons Dendrites Cell Body Myelin Sheath Axon of another neuron Axon Dendrites of another neuron Neural Anatomy 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 Neural Anatomy and communication Synapse junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron tiny gap at this junction is called the synaptic gap or cleft Synapse movie Specific Parts: The Neuron Structure Specific Parts: The Neuron Function 1. 3. 2. Neurons = 3 functions: Reception, Conduction, Transmission Action Potential When dendrites stimulated, the delicate balance is altered Membrane breaks down Positively charged ions rush in (depolarization) Charge = less negative Causes release of chemicals from terminal buttons Relay Race • Action Potential starts at dendrite – Through cell body – Down Axon – Axon Terminals • How does it get to the next cell’s dendrites? • Neurons don’t touch – Synapse = millionth inch gap – In synapse = vesicles w/ neurotransmitters » Chemical messengers that transmit info Communication • Impulse releases neurotransmitter from vesicles • Neurotransmitter enters synaptic gap • Neurotransmitter binds to receptors on the receiving neuron Myelin Sheath – Fatty material made by glial cells – Insulates the axon – Allows for rapid movement of electrical impulses along axon – Nodes of Ranvier: gaps in myelin sheath where action potentials are transmitted – Multiple sclerosis is a breakdown of myelin sheath – Speed of neural impulse Ranges from 2 – 200+ mph Myelinization clip Myelin conduction clip Neurotransmitters chemical messengers that traverse the synaptic gaps between neurons when released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether it will generate a neural impulse Neurotransmitters (>60) • Acetylcholine (ACh) – 1st substance identified as NT – Links motor neurons and muscles (contract or relax) • e.g. curare vs black widow spider – Also involved in memory, learning, sleep, dreaming (acetylcholine movie) • Endorphins (the brain’s own morphine) – 1973 injected rats with morphine – Bound like NTs – Brain had receptors for exogenous substance? • Brain must produce its own morphine • Released during pain and discomfort More neurotransmitters Receptor binding movie