* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chapter 7: The Nervous System
Multielectrode array wikipedia , lookup
Premovement neuronal activity wikipedia , lookup
Patch clamp wikipedia , lookup
Neural coding wikipedia , lookup
Caridoid escape reaction wikipedia , lookup
Subventricular zone wikipedia , lookup
Signal transduction wikipedia , lookup
Clinical neurochemistry wikipedia , lookup
Holonomic brain theory wikipedia , lookup
Optogenetics wikipedia , lookup
Neural engineering wikipedia , lookup
Membrane potential wikipedia , lookup
Neuromuscular junction wikipedia , lookup
Nonsynaptic plasticity wikipedia , lookup
Action potential wikipedia , lookup
Microneurography wikipedia , lookup
Resting potential wikipedia , lookup
Feature detection (nervous system) wikipedia , lookup
Electrophysiology wikipedia , lookup
Axon guidance wikipedia , lookup
Development of the nervous system wikipedia , lookup
Single-unit recording wikipedia , lookup
Neurotransmitter wikipedia , lookup
Channelrhodopsin wikipedia , lookup
Synaptic gating wikipedia , lookup
End-plate potential wikipedia , lookup
Chemical synapse wikipedia , lookup
Node of Ranvier wikipedia , lookup
Biological neuron model wikipedia , lookup
Molecular neuroscience wikipedia , lookup
Neuropsychopharmacology wikipedia , lookup
Nervous system network models wikipedia , lookup
Neuroregeneration wikipedia , lookup
Synaptogenesis wikipedia , lookup
Chapter 7: The Nervous System The Communication System of the Body Nervous System • Master controlling and communicating system of the body The Nervous System : communication A. Neurons = masses of nerve cells that transmit information Two processes: 1. Dendrites – shorter, more numerous, receive information 2. Axons - send information Central Nervous System (CNS): brain and spinal cord. Peripheral Nervous System (PNS): nerves of the body -- Includes 31 pairs of spinal nerves -- And 12 pairs of cranial nerves Three Basic Functions of Nervous System •Sensory function: gathers info •Integrative function: bring the info together •Motor function: responds to signals Neuroglial cells (neuroglia) – supportive tissue of the nervous system (more numerous than neurons) • 5 Types of Cells: • • • • • Microglial cells Oligodendrocytes Astrocytes Ependymal cells Schwann cells Microglial cell – digest debris or bacteria Respond to immunological alarms Oligodendrocytes – makes the myelin sheath that provides insulation to the axon Astrocytes – connect blood vessels to neuron Ependymal cell- forms a membrane Schwaan cells – forms the insulating myelin sheath around a neuron Neuron (nerve cell) structure: • Axon – long section, transmits impulses • Dendrite – extend from the cell body; receive information • Neurofibril – fibers within the impulse • Chromatophilic substance (rough ER) – transport system • Myelin – insulation surrounding axons • Nodes of Ranvier – gaps in the insulation *Myelinated vs. Unmyelinated Myelinated (white matter) – myelinated axons Unmyelinated (grey matter) unmyelinated Facts about Neurons • Longevity: can live and function for a lifetime • Do not divide: fetal neurons lose their ability to undergo mitosis; neural stem cells are an exception • High metabolic rate: require abundant amounts of oxygen and glucose Classification of Neurons Functional Sensory – receives information from senses Motor – sends information to muscles, glands, organs Interneuron – relays information Structural Bipolar Unipolar Multipolar Cell Membrane Potential Resting Potential / Threshold Potential / Action Potential Nerve Impulse = weak electric current 1. Neuron membrane maintains resting potential 2. Threshold stimulus is received 3. Sodium channels open 4. Sodium ions diffuse inward, depolarizing the membrane 5. Potassium channels open 6. Potassium ions diffuse outward, repolarizing the membrane 7. The resulting action potential causes a local bioelectric current that stimulates adjacent portions of the membrane. 8. Wave of action potentials travel the length of the axon as a nerve impulse Nerve Impulse Speed of an impulse is proportionate to the DIAMETER of the AXON. Greater diameter = faster speed **Myelinated Axons conduct faster than unmyelinated ones** The Synapse A: Neuron (axon) B: Neuron (dendrite) 1.Mitochondria 2.Vesicle 3.Receptor 4.Synapse 5.Receptor 6.Calcium Channel 7.Releases neurotransmitter 8.Re-uptake Synapse - junction between two communicating neurons Nerve pathway - nerve impulse travels from neuron to neuron Dendrite → cell body → along axon -> synapse (gap) → dendrite To complete the signal, a NEUROTRANSMITTER is released in the gap to signal the next neuron. They can be two types: • Excitatory: increase membrane permeability, increases chance for threshold to be achieved • Inhibitory: decrease membrane permeability, decrease chance for threshold to be achieved Types of neurotransmitters in Humans Acetylcholine - stimulates muscle contraction Monoamines - Norepinephrine & Dopamine (sense of feeling good, low levels = depression) Serotonin (sleepiness) and mood Endorphins = reduction of pain, good mood Nerves – bundles of axons common to a section of the body • Types of Nerves: • Sensory: conduct impulses into the brain and spinal cord • Motor: carry impulses to muscles or gland • Mixed: contains both sensory and motor Nerve Pathways • Reflex Arc: simple pathway, only includes a few neurons (involuntary, instantaneous) • Reflex behavior • Knee-jerk reflex: maintains uprightness • Withdrawal reflex: avoids painful stimuli