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34 Cards in this Set
- Front
- Back
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Describe neurons and their excitability
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The elecctrical excitability of their membranes allow them to receive, transfer, process, and store information. All based in membrane electrical potential |
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Define Electrical excitability |
A property related to receptors and ion channels in cell membranes. "Electrical" due to movement of ions across the membrane |
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What are Ion channels |
Allow more or loss ions to cross the membrane. Non-excitable do not change back on electrical potential |
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Neuroglia PNS vs CNS |
PNS: Schwann cells CNS: Oligodenroccytess, astrocytes, microglial and ependymal cells |
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Basic Characteristics of a Neuron |
Nucleus, cytoplasm, and plasma membrane Electrically excitable Soma = synthetic machinery (golgi, ER - Large amouts) High rate of protein synthesis and metab. |
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Axon and Cytoplasm |
Constitutes 95% of the cytoplasm. |
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What is Axonal Transport? |
Transport of substances back to the cell -Active energy requiring -Slow, Fast, and Retrograde |
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What is Slow Axonal Transport? |
Components moving out of the vell body down to the axon terminals Consists of soluble substances and cytoskeletal proteins such as neurofiliaments and components of microtubules. Few mm/day |
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What is Fast Axonal Transport |
Includes synaptic vesicles, neurotransmitter components and mitochondria. up to 400mm/day |
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What is Retrograde Transport |
Important for feedback from axon terminals that can modify neuronal metabolism and responsiveness |
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What are the 6 categories of neurons |
Sensory Motor Preganglionic Autonomic Postgalglionic Autonomic Local Interneurons Projection neurons |
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Types of Neurons by shape |
Multipolar - multiple dentrites Bipolar - process at each end Unipolar - single process Pseudounipolar - Sing procces that divides into two |
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What are the 3 zones of function on a neuron? |
Receptor, conductor, effector |
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Describe the Receptor zone |
Receives information. Dendrites and cell body Most elements do not produce AP but use graded potentials |
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Describe the Conductor zone |
Formed by a long cellular process which can make up most of the volume of the neuron (axon).
Transmits electrical signal (AP) to other cells |
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What is Actionpotential? |
A self sustaining electrical potential change that can move down an axon to its terminals Selective sodium and potassium ion channels. Needed for long/rapid responses |
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Axons and Speed |
The speed at which an action potential an move down an axon, depends upon the thickness of the axons |
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Describe Myelination |
Lipid rich neuroglial membranes around the axons Insulates axons from one another and controls the ionic environment of the axon |
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What are Nodes of Ranvier |
Spaces between adjacent segments of myelin that are separated by spaces at regular intervals on the axon May have ion channels at the nodes |
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What does myelination allow for? |
The long areas of the axon to be bypassed by a conducted axon potential. Successive membrane depol takes time and myelination increases axon conduction velocity of signals. |
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What is Saltatory conduction |
The jumping of AP from one node to the next |
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Myelinated vs unmyelinated conduction |
M: 150 m/s U: 10 m/s |
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Describe the Effector Zone |
Formed usually at the end of the axon where the action potential signal is communicated to other cells through the synapse.
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Describe a neuromuscular synapse |
Axon AP causes the release of a chemical (actetylcholine) which induces a response in the muscle (contraction) - motor end plate |
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What are Astrocytes |
Neuroglial celsl that act to surround all cellular elements of the CNS. They form a continuous layer on the surface of the CNS called the Glial-pial membrane, also to blood vessels in the CNS |
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How are astrocytes connected? |
They are interconnected through a systemp of gap junctions that allow them to communicated with each other. Contributes to the preas of electrical potentials across the brain |
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What are the primary Astrocyte functions in the CNS? |
1) Isolated and regulation of the neural environment of the CNS 2) Scavenge potassium 3) Inactivate neurotranmitters in the synaptic cleft 4) Supply nutrients to neurons 5) Contribute to restriction of substances that can enter the nervous system 6) Development- assist in proper neuron migration in the CNS |
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What happens with calcium and glutamate regulation failure |
Result in increase in intracellular calcium in neurons and cell death -cause of neuronal cell loss after ischemia |
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Describe Schwann Cells |
Form myelin around PNS axons. |
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Neuroglia and injury |
Astrocytes respond to an area of tissue damage by walling off the injured area with astrocytic process, and re-establishing the isolated CNS environment |
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Describe Microglia |
Macrophages of the CNS. Important in the response to injury and with phagocytize dead CNS tissue and injured cells |
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What are Gitter cells |
Peripheral macrophages that supplement CNS microglial in areas of direct CNS injury |
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Consequences of Neuroinflammation |
Macrophages can produce cytotoxic compounds that have bee implicateed in the pathological progression after injury to the CNS May produce more injury Low level inflam have been implicated in the progression of neurogenerative disease |
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Postnatal Development and Neurons |
Neurons generally stop dividing except for glial cells to adulthood Hippocampus may be able to divide and for new nuerons |
