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... Action potentials, often referred to as neural spikes, result from an active process which generates a traveling electrical impulse. The process is often termed an “all or none” process, meaning that if the membrane potential crosses some threshold, there will be an action potential. For potentials ...
Nervous Tissue
Nervous Tissue

... • Myelin is produced by Schwann cells in PNS and Oligodendrocytes in CNS • Nodes of Ranvier — gaps in myelin sheath along the axon ...
Somatic Sensation - PROFESSOR AC BROWN
Somatic Sensation - PROFESSOR AC BROWN

... 2. These action potentials are conducted into the Central Nervous System (spinal cord and brain), where they excite adjacent nerve cells (2nd order, 3rd order, etc. neurons) 3. By this mechanism, excitation eventually reaches specialized regions of the cerebral cortex where conscious sensation occur ...
neuron - Cloudfront.net
neuron - Cloudfront.net

... Made up of 12 pairs of cranial nerves and 31 pairs of spinal nerves, all bundled together Usually in charge of voluntary reactions to stimuli, like skeletal muscle movement ...
HUMAN PHYSIOLOGY
HUMAN PHYSIOLOGY

... I. There are two different subtypes of ACh receptors: nicotinic and muscarinic. A. Nicotinic receptors enclose membrane channels and open when ACh bonds to the receptor. This causes a depolarization called an excitatory postsynaptic potential (EPSP) in skeletal muscle cells. B. The binding of ACh to ...
The Nervous System
The Nervous System

... Cell reaches a charge difference of –70mV More Cations (Na+ & K+) on the outside More anions inside and very little Na+ & K+ K+ is diffusing out (high to low) Na+ can’t diffuse in so remains high outside Sodium/potassium pump increases this difference ...
Slide 1
Slide 1

... Voltage-gated calcium (CA2) channels permit CA to enter the cell. As CA2 rises, it binds with the neuron, preventing additional calcium from entering. Increased calcium concentrations can cause dephosphorylation or permanent inactivation of a channel. ...
Biology Notes: The Nervous System and Neurons
Biology Notes: The Nervous System and Neurons

... ReView (at the end of the PowerPoint you should be able to answer these questions)   1. What is the function of the nervous system?  2. List the 4 main parts and describe the purpose of the 4 main parts of a neuron.  3. The nervous system is divided into 2 parts.  What are they and what do they incl ...
A17 - Viktor`s Notes for the Neurosurgery Resident
A17 - Viktor`s Notes for the Neurosurgery Resident

... a) pacinian corpuscles, hair cells (hearing and balance): mechanical distortion opens epithelial sodium channels (ENaC) in receptor membrane → Na+ influx produces generator potential; number of channels opened is proportionate to stimulus intensity. b) rods and cones: responses depend on heterotrime ...
Modeling and Imagery
Modeling and Imagery

... • Vary by # of dendrites, length of axon • Structure determines role – many types (bipolar, multipolar, golgi I, golgi II…etc.) ...
Investigating Pain, Touch, and Temperature Sensations: Is a small
Investigating Pain, Touch, and Temperature Sensations: Is a small

... sometimes seen in persons with CdLS. Dr. Anthonie Kline and Dr. Laird Jackson picked up on these observations and tried to verify this in a larger group of patients by sending out a questionnaire to CdLS families. The results were quite suggestive: 90% responded that the individual with CdLS in thei ...
CHAPTER 10: NERVOUS SYSTEM I
CHAPTER 10: NERVOUS SYSTEM I

... When threshold potential is reached, the rapid opening of Na+ channels results in rapid depolarization (and even reversal of the membrane potential [MP] to +30mV) a. This event is called the action potential. b. The action potential represents the start of the nerve impulse on a neuron. ...
CHAPTER 10: NERVOUS SYSTEM I
CHAPTER 10: NERVOUS SYSTEM I

... When threshold potential is reached, the rapid opening of Na+ channels results in rapid depolarization (and even reversal of the membrane potential [MP] to +30mV) a. This event is called the action potential. b. The action potential represents the start of the nerve impulse on a neuron. ...
Document
Document

... • Mixed nerve with five major branches ...
Document
Document

... • Provides cushioning function • May play role in regulation of autonomic functions such as respiration and vomiting ...
The Spinal Cord and Reflexes Notes
The Spinal Cord and Reflexes Notes

... the Spinal Cord. are very fast and most never reach the brain ...
REGULATION nervous system
REGULATION nervous system

... 2) Whether a neuron is myelinated or not a) Small non- myelinated neuron’s speed ~ 2 meters/sec b) Large myelinated neuron’s speed ~ 100 meters/sec Myelinated neurons are faster because the impulse “jumps” from one node of Ranvier to the next node of Ranvier This is called SALTATORY CONDUCTION ...
Disuse
Disuse

...  There is a latent period of spontaneous discharge and electrical stimulation of the axon results in normal neuromuscular transmission, after this period the neuromuscular function fails abruptly.  Silent synapses: neuromuscular junctions that are largely intact, but in which there is insufficient ...
RULE 099.37 OCCUPATIONAL CARPAL TUNNEL SYNDROME
RULE 099.37 OCCUPATIONAL CARPAL TUNNEL SYNDROME

... Median minus ulnar palmar latency abnormal > 0.3 msecs. 2. Median motor latency (wrist to APB at 8 cm.) Abnormal latency > 4.5 msecs. Median minus ulnar motor distal latency abnormal > 1.8 msecs. 3. Median sensory distal latency (wrist to digit at 14 cm.) Abnormal latency > 3.5 msecs. 4. Fourth digi ...
Poster No: 1064 - Orthopaedic Research Society
Poster No: 1064 - Orthopaedic Research Society

... DISCUSSION. Disturbance of axonal flow therefore threatens the survival of neurons and appears to be one cause of neurological dysfunction. In this study, compression of the peripheral branches of motor neurons in the nerve root led to impairment of axonal flow and central chromatolysis in the neuro ...
No Slide Title
No Slide Title

... Which part of the pituitary gland is controlled by the ...
ARIEL LEVINE Postdoctoral Associate, The Salk Institute for
ARIEL LEVINE Postdoctoral Associate, The Salk Institute for

... orchestrate motor programs, as well as their cellular properties and connectivity are poorly understood. We have identified a population of premotor spinal neurons that may provide the cellular basis for encoding coordinated motor output programs. These molecularly-defined “motor synergy encoder” ( ...
Action Potential - Angelo State University
Action Potential - Angelo State University

... 4. Repolarization: the membrane returns to its resting potential, after having been depolarized by a stimulus. The Amount of Change in the Potential is Proportional to the Strength of Stimulus up to a Point. The larger the stimulus, the more the RMP will change - A small stimulus: -70mV to -60mV (de ...
SENSATION AND PERCEPTION
SENSATION AND PERCEPTION

... • Energy detected is physical pressure on tissue. • Many nerve endings in the skin act as touch receptors. • Touch is both an active and passive sense. • Changes in touch provide most important sensory information. ...
An Herbalist`s View of the Nervous System
An Herbalist`s View of the Nervous System

... Axon terminal Terminal knob Presynaptic membrane Synaptic cleft ...
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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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