Examples of cell assembly in the following topics:
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- If a stimulus creates a strong enough input signal in a nerve cell, the neuron sends an action potential and transmits this signal along its axon.
- The axon of a nerve cell is responsible for transmitting information over a relatively long distance, and so most neural pathways are made up of axons.
- The basic neuronal function of sending signals to other cells includes the capability for neurons to exchange signals with each other.
- In 1949, neuroscientist Donald Hebb proposed that simultaneous activation of cells leads to pronounced increase in synaptic strength between those cells, a theory that is widely accepted today.
- Cell assembly, or Hebbian theory, asserts that "cells that fire together wire together," meaning neural networks can be created through associative experience and learning.
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- It is not a physical component of a cell but rather a name for the gap between two cells: the presynaptic cell (giving the signal) and the postsynaptic cell (receiving the signal).
- In an electrical reaction, the electrical charge of one cell is influenced by the charge an adjacent cell.
- Presynaptic cell: a specialized area within the axon of the giving cell that transmits information to the dendrite of the receiving cell.
- Postsynaptic cell: a specialized area within the dendrite of the receiving cell that contains receptors designed to process neurotransmitters.
- During the refractory phase this particular area of the nerve cell membrane cannot be depolarized; the cell cannot be excited.
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- Neurons are specialized cells that transmit chemical and electrical signals.
- The brain is made up entirely of neurons and glial cells, which are non-neuronal cells that provide structure and support for the neurons.
- The cell body contains a specialized structure, the axon hillock, which serves as a junction between the cell body and the axon.
- Myelin is produced by glial cells (or simply glia, or "glue" in Greek), which are non-neuronal cells that provide support for the nervous system.
- In the central nervous system, the glial cells that form the myelin sheath are called oligodendrocytes; in the peripheral nervous system, they are called Schwann cells.
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- Neurotransmitters are chemicals that transmit signals from a neuron across a synapse to a target cell.
- Neurotransmitters are chemicals that transmit signals from a neuron to a target cell across a synapse.
- A neuron has a negative charge inside the cell membrane relative to the outside of the cell membrane; when stimulation occurs and the neuron reaches the threshold of excitement this polarity is reversed.
- When the chemical message reaches the axon terminal, channels in the postsynaptic cell membrane open up to receive neurotransmitters from vesicles in the presynaptic cell.
- When acetylcholine binds to the nicotinic receptor, the postsynaptic cell is depolarized.
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- Each taste bud is flask-like in shape and formed by two types of cells: supporting cells and gustatory cells.
- Gustatory cells are short-lived and are continuously regenerating.
- An ion channel in the taste cell wall allows Na+ ions to enter the cell.
- This depolarizes the cell and floods it with ions, leading to a neurotransmitter release.
- The third allows sodium ions to flow down the concentration gradient into the cell.
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- Every person is made up of cells, each of which contains chromosomes.
- Gene regulation is the process by which cells differentiate.
- Among other things, it is the process in which a cell determines which genes it will express and when.
- Cell differentiation is a process by which a less specialized cell becomes a more specialized cell.
- For example, as a zygote develops, gene regulation changes some cells into brain cells and others into liver cells.
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- A zygote begins as a one-cell structure that is created when a sperm and egg merge.
- During the first week after conception, the zygote rapidly divides and multiplies, going from a one-cell structure to two cells, then four cells, then eight cells, and so on.
- This process of cell division is called mitosis.
- After 5 days of mitosis there are 100 cells, and after 9 months there are billions of cells.
- As the cells divide, they become more specialized, forming different organs and body parts.
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- Neural impulses occur when a stimulus depolarizes a cell membrane, prompting an action potential which sends an "all or nothing" signal.
- The sensory input stage is when the neurons (or excitable nerve cells) of the sensory organs are excited electrically.
- Depolarization, also referred to as the "upswing," is caused when positively charged sodium ions rush into a nerve cell.
- During the refractory phase this particular area of the nerve cell membrane cannot be depolarized.
- Damage to the myelin sheath from disease can cause severe impairment of nerve-cell function.
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- The inner ear contains the receptor cells necessary for both hearing and equilibrium maintenance.
- Fluid movement within these canals stimulates hair cells of the organ of Corti, a ribbon of sensory cells along the cochlea.
- These hair cells transform the fluid waves into electrical impulses using cilia, a specialized type of mechanosensor.
- Hair cells in the cochlea perform the transduction of these sound waves into afferent electrical impulses.
- Auditory nerve fibers connected to the hair cells form the spiral ganglion, which transmits the electrical signals along the auditory nerve and eventually on to the brain stem.
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- Chromosomes are structures in the nucleus of a cell containing DNA, histone protein, and other structural proteins.
- Research dating back to the 1800s shows that every living creature has a specific set of chromosomes in the nucleus of each of its cells.
- Chromosomal abnormalities can occur during fetal development if something goes wrong during the replication of the cells.