CHAPTER 13~ The Nervous System: Neural Tissue
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57 terms
Terms | Definitions |
|---|---|
 Nervous System | provides swift, breif responses to stimuli It includes all the NEURAL TISSUE in the body |
| NEURAL TISSUE | carries information from one part of the body to another in the form of electrical impulses |
| Central Nervous System | The brain and spinal cord |
| Peripheral Nervous System | all the neural tissue outside the CNS: somatic, autonomic and special vesceral sensory receptors |
| Afferent division | division of nervous system which transmits sensory information from somatic and visceral receptors and special sense organs to the CNS |
| Efferent Division | division of nervous system which carries motor commands to muscles and glands |
| Somatic Nervous System (SNS) | The part of the peripheral nervous system that controls voluntary movement of skeletal muscles |
| Automatic Nervous System (ANS) | Automatic involuntary regulation of smooth muscle and glandular activity are under the control of the parasympathetic and sympathetic. |
| Receptors may be classified as Somatic and Visceral | ... |
| Neurons | nerve cells that are responisible for information transfer and processing |
| Neuroglia or Glial Cells | supporting cells in the nervous system |
| Typical Neuron has | Cell Body (Soma), Axon-Carries information in the form of nerve impulses and Several dendrites |
| Four Types of Neuroglia in CNS | Astrocytes, Oligodendrocytes, microglia, ependymal cells |
| Astrocytes | largest, most numerous glial cells; maintain blood-brain barrier to isolate CNS from general circulation; provide structural support for CNS; regulate ion and nutrient concentrations; perform repairs to stabilize tissue and prevent further injury |
| Oligodendrocytes | wrap CNS axons in a myelin sheath |
| Nodes of Ranvier | gaps between the myelin wrappings along the axon |
| Internodes | large areas wrapped in myelin |
| White Matter | regions primarily containing myelinated axons; appear glossy and white |
| microglia | smallest neuroglial cells; phagocytic cells that enculf cellular debris, waste products and pathogens. increase in number as a result of infection or injury |
| Ependymal Cells | atypical epithelial cells that line chambers and passageways filled with cerebrospinal fluid(CSF) in the brain and spinal cord. assist in producing, circulating and monitoring CSF |
| Cerebrospinal fluid | the fluid in and around the brain and spinal cord |
| Ganglia | Groups of neuron cell bodies in the PNS. |
| Peripheral Nerves | axons in PNS which are bundled together and wrapped in connective tissue |
| PNS glial cell types... | Satellite cells and Schwann cells |
| Satellite cells | surround neuron cell bodies within ganglia |
| Schwann Cells (neurolemmocytes) | cover all peripheral axons, wheather myelinated or unmyelinated. |
| Perikaryon | cytoplasm surrounding the nucleus of a neuron |
| Collarterals | Side branches from an axon |
| Telodendria | series of fine, terminal extensions branching from the axon tip. They end at synaptic terminals. |
| Synapse | a site of intercellular communication between a neuron and another cell. |
| Synaptic knob | located where one neuron synapses on another |
| Anaxonic | no distinguishable axon |
| Bipolar | 1 axon, 1 dendrite |
| Pseudounipolar | dendrite and axon are countnuous at one side of the cell body, dendrite and axon are continuous at one side of cell body |
| Multipolar | neuron with several dendrites and one axon |
| 3 Functional Caterories of a Neurons | Sensory Neurons, Motor Neurons, and Interneurons (association neurons) |
| Sensory Neurons | neurons that carry incoming information from the sense receptors to the CNS. |
| Exteroceptors | sensory neurons that provide information from the external environment |
| Proprioceptors | sensory neurons that monitor position and movement of joints |
| Interoceptors | monitor digestive, respiratory, cardiovascular, urinary, and reproductive systems |
| Motor Neurons | forms efferent pathways that stimulate or modify the activity of a peripheral tissue, organ, or organ system |
| Interneurons (association neurons) | central nervous system neurons that internally communicate and intervene between the sensory inputs and motor outputs. |
| Interneurons (association neurons) | *located between sensory and motor neurons * classified as Excitatory or Inhibitory on the basis of their effects on postsynaptic neurons |
| Neural Regeneration | Neurons have very limited ability to regenerate after an injury. When an entire peripheral nerve is severed, only relativley small number of axons within the nerve will successfully reestablish normal synaptic contacts. Complete nerve funstion is inpaired permently. |
| Excitablility | the ability of a cell membrane to conduct electrical impluses, the cell membranes of skeletal muscle fibers and most neurons are excitable. |
| Action Potentials | changes in the flow of sodium and potassium ions, which cause changes in the transmembrane potential |
| Nerve Impulse | an action potential traveling along an axon |
| Neuroeffector Junctions | synapses permit communication between a neuron and another cell |
| A Synapse may be Chemical (involving a neurotransmitter) More Common | or A Synapse may Electrical (with direct physical contact between cells) |
| Sequence of events of a Chemical Synapse | Chemical transmitter is released upon depolarization of nerve The chemical interacts with a receptor on the next neuron If the chemical is excitatory, it will more than likely increase the permeability of the next cell to sodium ions, and depolarize that cell. If the chemical is inhibitory, it will more than likely increase the permeability of the next cell to chloride ions, and hyperpolarize that cell. So, for the most part, calcium ions are involved in the actual release of the chemical transmitter from the nerve terminal, and sodium or chloride ions are involved in the next cell upon which the chemical transmitter interacts. |
| Electrical Synapses | Allows action potentials to spread from presynaptic cell to postsynaptic cell via gap junctions ii. Not as common as chemical synapses |
| Neuronal Pools | roughly 20 billion interneurons can be classified into this |
| Divergence | spread of information from one neuron to several neurons or one neuronal pool to several pools. Facilitates the widespread distribution of a specific input. |
| Convergence | presence of synapses from several neurons on one postsynaptic neuron. permits variable control of motor neurons. |
| Serial Processing | is a pattern of stepwise information processing, from one neuron to another or from one neuronal pool to the next. This is the way sensory information is relayed between processing centers in the brain |
| parallel Processing | is a pattern that processes information by several neurons or neuronal pools at one time. MAny different responses occure at the same time |
| Reverberation | neuronal circuits utilizing positive feedback to continue the activity of the circuit. collateral axons establish a circuit to continue to stimulate presynaptic neurons |
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