action potentials animal systems
DESCRIPTION
Action PotentialTRANSCRIPT
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MO Figure
Action Potentials
Mike Hollingshead/Science Source
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Figure 1
Membrane ion channels
Include sodium (Na+), potassium (K+), and calcium (Ca2+) ion channels.
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Figure 2
Membrane potentialElectrical potential difference across the cell membrane caused by different concentrations of K+, Na+, and Cl- ions on each side of the membrane. Membrane potential of neurons is usually between -60 and -80 mV.
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Figure 2a
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Figure 2b
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Figure 3
The action potentialSmall changes in membrane potential (graded potentials) can be depolarizing or hyperpolarizing. A depolarizing potential that exceeds a threshold becomes an action potential.
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Figure 4
The action potential
During an action potential, membrane potential changes as a result of ion flow through voltage-gated Na+ channels, voltage-gated K+ channels, and the Na+/K+ pump.
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Figure 4
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Figure 5
The membrane depolarization during an action potential triggers action potentials in adjacent regions of an axon. Depolarization spreads down the length of the axon as a result.
The action potential
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Figure 5a
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Figure 5b
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Figure 5c
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Figure 6
Saltatory conduction
Some axons are myelinated by insulating glial cells. Ion channels are only present at the nodes of Ranvier between glia. Electrical current jumps from node to node, increasing the speed of neural transmission.
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Figure 6
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Figure 6a
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Figure 6b
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MO Figure
Neurons and SynapticCommunication
Photo Researchers, Inc./Science Source
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Figure 1
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Figure 2
Postsynaptic potentialsA signal from a presynaptic neuron may induce an inhibitory (IPSP) or excitatory (EPSP) potential in the postsynaptic neuron. An IPSP causes a hyperpolarization and makes a new action potential less likely to form. An EPSP causes a depolarization and increases the likelihood of a new action potential.
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Table 2a
Neurotransmitters
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Table 2b
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Table 2c
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Figure 3
GABA
g-aminobutyric acid (GABA) is an inhibitory neurotransmitter that triggers opening of Cl- channels in the postsynaptic
neuron, which hyperpolarizes its membrane.
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MO Figure
Structure and Function of theVertebrate Nervous System
Bartolommeo Eustachi, Tabulae Anatomicae, 2nd edition. Amsterdam, 1722.
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Figure 1
The nervous system
Subdivided into the central nervous system (CNS) and peripheral nervous system (PNS).
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Figure 2
White and gray matter
CNS contains both white and gray matter. White matter consists of myelinated axons. Gray matter consists of
unmyelinated axons, dendrites, and cell bodies.
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Figure 2a
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Figure 2b
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Figure 3
The peripheralnervous system (PNS)
Includes sensory and motor neurons and the autonomic nervous system (ANS).
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Figure 4
The autonomicnervous system
Contains antagonistic sympathetic and parasympathetic divisions.
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Figure 5
Regions of the brain
Subdivided into forebrain, midbrain, and hindbrain regions.
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Figure 6
The cerebral cortex
Includes the frontal, parietal, temporal, and occipital lobes.
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Figure 7
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MO Figure
The Human Brain:Language, Memory, and fMRI
Photo via Wikimedia Commons. Originally published by Fowlers & Wells.
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Figure 1
Brain language centers
Broca’s area is important for speech. Wernicke’s area is important for language comprehension.
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Figure 2
Functional MRI (fMRI)
Colors indicate sites of brain activity.
© 2008 Nature Publishing Group deCharms, R. Applications of real-time fMRI. Nature Reviews Neuroscience 9, 720–729 (2008) doi:10.1038/nrn2414. Used with permission.
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Figure 3
Functional MRI (fMRI)
These images were collected during a visual memory test. Red/yellow areas indicate regions with increased activity, and blue indicates decreased activity. Yellow indicates moderate activity.
© 2009 Nature Publishing Group Dickerson, B. and Eichenbaum, H. The Episodic Memory System: Neurocircuitry and Disorders. Neuropsychopharmacology 35, 86–104 (2009) doi:10.1038/npp.2009.126. Used with permission.
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Figure 4
Protein and brain activity
fMRI revealed that high-protein breakfasts (HP, dark blue) reduce brain activity in regions associated with food motivation and reward pathways compared to normal-protein breakfasts (NP, light blue).
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Figure 5
Aplysia
This sea slug with large, easily accessible neurons, is a good model organism in neurobiology to study the links between
specific neurons and behavior.
Martin Shields/Science Source.