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Ch 11 Part 2 - Groch Biology
Ch 11 Part 2 - Groch Biology

... 5. Also called the nerve impulse. _____ 6. Period when a neuron cannot be restimulated because it's sodium gates are open. _____ 7. Mechanism by which ATP is used to move sodium ions out of the cell and potassium ions into the cell; completely restores and maintains the resting conditions of the neu ...
Nervous Tissue
Nervous Tissue

... • Neurons are electrically excitable due to the voltage difference across their membrane • Communicate with 2 types of electric signals – action potentials that can travel long distances – graded potentials that are local membrane changes only ...
ACTION POTENTIALS
ACTION POTENTIALS

... diffuses into cell  becomes more depolarized  more Na+ channels open (+ feedback) ...
Slideshow
Slideshow

... membrane has a negative charge. • As the figure shows, a Na+ / K+ pump in the cell membrane pumps sodium out of the cell and potassium into it. • However, more potassium ions leak out of the cell. Thus the inside of the membrane builds up a net negative charge relative to the outside. ...
Chapter 44
Chapter 44

... • Deter the membrane potential from reaching threshold ...
File
File

... • Myelination is the presence of myelin around the neuron. Myelin is not part of the structure of the neuron but consists of a thick layer mostly made up of lipids, present at regular intervals along the length of the axon. • Such fibers are called myelinated fibers. • The water-soluble ions carryin ...
The Neuron - Austin Community College
The Neuron - Austin Community College

... Their magnitude varies directly with the strength of the stimulus – the stronger the stimulus the more the voltage changes and the farther the current goes Sufficiently strong graded potentials can initiate action potentials if they maintain threshold by the time reach the trigger zone ...
Effects of cutting a mixed nerve
Effects of cutting a mixed nerve

... It is an auto-immune disease in which there is patchy loss of myelin sheath of nerve fibers leading to disruption of nerve impulse conduction. Cause: Antibodies mistakenly attack and destroy Schwann cells, thus also destroying the myelin sheath. Signs & symptoms: Patchy destruction of myelin in the ...
Ion channel disorders by Dr Susan Tomlinson
Ion channel disorders by Dr Susan Tomlinson

... Nerve and muscle cell membranes have the unique feature of being electrically active. Ion channels are membrane-bound proteins which allow the passage of charged particles (ions) across the membrane of nerve cells and maintain the electrical activity of the membrane. Dysfunction of ion channels (eit ...
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Neural Pathways

... outside 3. channels then automatically close very quickly, but this causes the neighboring channels to open 4. it proceeds like a wave along the membrane to the tip of the axon 5. then it arrives at the synapse ...
Nervous Systems - Groupfusion.net
Nervous Systems - Groupfusion.net

... membrane generate a net negative membrane potential (-70mV) • A sodium-potassium pump is used to move K+ back into the cell and Na+ back out of the cell to maintain the constant concentration gradients. ...
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M. Woodin

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Neurobiology of the Senses

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PRINCIPLES OF SENSORY TRANSDUCTION

... the somatosensory system. Two dorsal root ganglion (DRG) cells (blue) send peripheral axons to be part of a touch receptor, whereas a third cell (red) is a pain receptor. By activating the neurons of touch receptors receptors, direct touching of the skin or electrical stimulation of an appropriate a ...
MUSCLE AND NERVE BIOPSIES · A 24
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Chapter 14 - WordPress.com
Chapter 14 - WordPress.com

... those inferior to it  Enlargements areas of coordination of incoming and outgoing messages o Cervical enlargement o Lumbar enlargement  Conus medullaris + filum terminale = cauda equina  The spinal cord is divided into 31 segments, each associated with a pair of o Dorsal root ganglia- contain cel ...
The Nervous System
The Nervous System

... Developmental Aspects of the Nervous System A. The nervous system begins to form in the first month of embryonic development. Therefore maternal and environmental factors may impair brain development. Mothers that smoke impair the body’s ability to carry oxygen sufficiently which increased the chan ...
Introduction to Skeletal Muscle
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Chapter 48: The Nervous System
Chapter 48: The Nervous System

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Rheobase



Rheobase is a measure of membrane excitability. In neuroscience, rheobase is the minimal current amplitude of infinite duration (in a practical sense, about 300 milliseconds) that results in the depolarization threshold of the cell membranes being reached, such as an action potential or the contraction of a muscle. In Greek, the root ""rhe"" translates to current or flow, and ""basi"" means bottom or foundation: thus the rheobase is the minimum current that will produce an action potential or muscle contraction.Rheobase can be best understood in the context of the strength-duration relationship (Fig. 1). The ease with which a membrane can be stimulated depends on two variables: the strength of the stimulus, and the duration for which the stimulus is applied. These variables are inversely related: as the strength of the applied current increases, the time required to stimulate the membrane decreases (and vice versa) to maintain a constant effect. Mathematically, rheobase is equivalent to half the current that needs to be applied for the duration of chronaxie, which is a strength-duration time constant that corresponds to the duration of time that elicits a response when the nerve is stimulated at twice rheobasic strength.The strength-duration curve was first discovered by G. Weiss in 1901, but it was not until 1909 that Louis Lapicque coined the term ""rheobase"". Many studies are being conducted in relation to rheobase values and the dynamic changes throughout maturation and between different nerve fibers. In the past strength-duration curves and rheobase determinations were used to assess nerve injury; today, they play a role in clinical identification of many neurological pathologies, including as Diabetic neuropathy, CIDP, Machado-Joseph Disease, and ALS.
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