Daily Activity 2.3: Glial Cells
What did scientists think was the purpose of glial cells 20 years ago?
In the last 20 years ago, there was a brain scientists that believed that neurons communicated to each other, they represented thoughts, and that glia were kind of like a stucco and mortar holding the house together. They were also considered simple insulators for neuron communication. There is a few of types of glial cells, but recently scientists have begun to focus on a particular type of glial cell it is called the astrocyte; it’s an abundant in the cortex. As you go up the evolutionary ladder, astrocytes in the cortex increase in size and number, with humans having the most astrocytes and also the biggest. Scientists also discovered that astrocytes communicate to themselves in the cortex and they are also capable of sending information to neurons. Astrocytes are also the adult stem cell in the brain and control blood flow to regions of brain activity.
•What new discoveries have been made since?
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Neuroscientists found that glia have receptors of receiving docks for the many of the same chemical messages used by neurons.
These receptors enable them to eavesdrop on the neurons and respond in ways that help strengthen their messages. For example, neurons are removed from rodents of where they were found to form very few synapses and to produce very little synaptic activity until they were surrounded by glial cells known as astrocytes. Once the astrocytes were introduced, the number of synapses jumped, and synaptic activity increased by 10 times. Studies have shown that without glial cells, neurons and their synapses fail to function
properly. •What are astrocytes and why are they the subject of so much research? Astrocytes are star-shaped cells are part of the so called "glial population", the non-neuron cells they form the brain background and that for a long time were considered mere “housekeepers" of the real players, the neurons. Brain function is the result of electrical impulses passing between neurons, transmitting the information necessary for all those extraordinary abilities of this brains ours, from memory storage and motor control to personality quirks. Astrocytes are often referred to, and historically have been regarded as, support cells of the mammalian CNS. Astrocytes they play a more active role in higher neural processing than previously recognized. Astrocytes can potentially serve as novel therapeutic targets, it is critical to understand how astrocytes execute their diverse supportive tasks while maintaining neuronal health. The research since the mid-1990s has shown that astrocytes propagate intercellular Ca2+ waves over long distances in response to stimulation, and, similar to neurons, release transmitters are called gliotransmitters in a Ca2+- dependent manner
A synapse is the space between a presynaptic neuron and postsynaptic neuron. This is the location where chemical and electrical messages are transmitted from one neuron to another. Synapses are essential to neuronal function. They serve as a means of communication between neurons.
Astrocytes are star-shaped glial cells in the brain and spinal cord. They are the most abundant cell of the human brain. Astrocytes provide neurons with metabolic support, control local blood flow, and regulate the maintenance of synapses. They are a critical part of normal neural functioning. (3)
The neurons or brain cells are shaped like trees. Young brain cells, called soma, resemble an acorn or small seed of a tree. The seed sprouts limbs when stimulated, called dendrites. Further on in development, the cell will grow a trunk like structure called an axon. The axon has an outer shell, like the bark of a tree, called the myelin sheath. Finally, at the base of the cell, there are root-like structures called axon terminal bulbs. Through these bulbs and the dendrite of another cell, cells communicate with each other through electrochemical impulses. These impulses cause the dendrites to
messages to the rest of the body. The brain is made up of many different
Eric Beck meets criteria for Bipolar 1 disorder. He shows some signs of General Anxiety Disorder as well. Anxiety disorders are the most coming co-occurring disorder with Bipolar 1. To be diagnosed with Bipolar 1 disorder you must meet criteria for Major Depressive Episode and Manic Episode. Eric meets criteria for part A of Major Depressive Episode due to his extensive history of depression. He stated that “I suffer even when doing things, I should enjoy.” He often had feelings of guilt or worthlessness. Along with this Eric struggled from a lack of concentration. He also had recurrent thoughts of death and has tried to commit suicide.
Zhan, Y., Paolicelli, R.C., Sforazzini, F., Weinhard, L., Bolasco, G., Pagani, F., Vyssotski, A.L., Bifone, A., Gozzi, A., Ragozzino, D., et al. (2014). Deficient neuron-microglia signaling results in impaired functional brain connectivity and social behavior. Nature neuroscience 17, 400-406.
Neurons and glia (cells that support neurons) are specialized cells for electrical signaling over long distances. Understanding neuronal structure is important for understanding neuronal function.
An adult person who is illiterate and tries to read shows profound changes in deep brain. It came from a study where researchers helped illiterate woman from North India to read. In addition, the illiterate woman had scanned their brain before and after learning to read. The researchers found a big change in the brain after the women learned to read. They conclude that the brain of an adult is not flexible. The plasticity still actives in adult age.
Huntington's disease is an inherited neurodegenerative disorder. It is passed on to children from one or both parents (though two parents with Huntington's is extraordinarily rare) in an autosomal dominant manner. This is different from autosomal recessive disorder, which requires two altered genes (one from each parent) to inherit the disorder.
Neurotransmitters are chemicals made by neurons and used by them to transmit signals to the other neurons or non-neuronal cells (e.g., skeletal muscle; myocardium, pineal glandular cells) that they innervate. The neurotransmitters produce their effects by being released into synapses when their neuron of origin fires (i.e., becomes depolarized) and then attaching to receptors in the membrane of the post-synaptic cells. This causes changes in the fluxes of particular ions across that membrane, making cells more likely to become depolarized, if the neurotransmitter happens to be excitatory, or less likely if it is inhibitory.
Brains and the more nonessential parts of the nervous system are made up of neurons (Meadows, 1993 p. 266). The brain is made up of neurons, axons, dendrites, and synapse. They all have their individual job that contributes to the functioning of the body. The weight of the brain increases as a child develops into adulthood. According to Siegler & Alibali (2005, p13), the changes in the size of the brain make it possible for advanced thinking. The neurons are the functioning core of the brain (Brotherson, 2005). The brain begins to develop in the mother’s womb and continue to develop as the child develops. The neuron has branches protruding from the cell sending signals to the synapse and axon. The synapse and axon shapes the brain which allows connections to be made. Young children learn new information when they follow the same routine on a regular base. If a parent repeatedly calls a child a certain name, then connections form that allow the child to recognize that name over time and he or she will begin to respond to that name (Brotherson, 2005). Through repetitive experiences the axons and synapse strengthen causing learning to take place.
The neuron has two important structures called the dendrite and axon, also called nerve fibers. The dendrites are like tentacles that sprout from the cell and the axon is one long extension of the cell. The dendrites receive signals from other neurons, while the axon sends impulses to other neurons. Axons can extend to more than a meter long. Average sized neurons have hundreds of dendrites; therefore it can receive thousands of signals simultaneously from other neurons. The neuron sends impulses by connection the axon to the dendrites of another nerve cell. The synapse is a gap between the axon and the adjacent neuron, which is where data is transmitted from one neuron to another. The neuron is negatively charged and it bathes in fluids that contain positively charged potassium and sodium ions. The membrane of the neuron holds negatively charged protein molecules. The neuron has pores called ion channels to allow sodium ions to pass into the membrane, but prevent the protein molecules from escaping (potassium ions can freely pass through the membrane since the ion channels mostly restrict sodium ions). When a neuron is stimulated (not at rest), the pores open and the sodium ions rush in because of its attraction to the negatively charged protein molecules, which makes the cell positively charged. As a result, potential energy is released and the neurons send electrical impulses through the axon until the impulse reaches the synapse of any neurons near it.
...fficient chemical messenger that enable nerve cells to communicate with each other in the brain, allowing them to perform their jobs such as thinking, learning and remembering. (Alzheimer’s Association, 2014)
The brain consists of both neurons and glia cells. The neurons, which are cells housed in a cell body called a Soma, have branches which extend from them, referred to as dendrites. From these dendrites extend axons which send and receive impulses, ending at junction points called synapses. It is at these synapse points that the transfer of information takes place.
Dendrites are located on either one or both ends of a cell.The peripheral nervous system then takes the sensory information from the outside and sends the messages by virtue of neurotransmitters. Neurotransmitters are chemicals that relay signals through the neural pathways of the spinal cord. The neurotransmitter chemicals are held by tiny membranous sacs located in the synaptic terminals. Synaptic terminals are located at the ends of nerve cells. The release of neurotransmitters from their sacs is stimulated once the electrical nerve impulse has finished travelling along a neuron and reaches the synaptic terminal. Afterward, neurotransmitters travel across synapses thus stimulating the production of an electrical charge that carries the nerve impulse onward. Synapses are junctions between neighboring neurons. This procedure is reiterated until either muscle movement occurs or the brain picks up on a sensory reaction. During this process, messages are being transmitted from one part of the body onto the next. The peripheral and central nervous system are two crucial subdivisions of the nervous system. The brain and spinal cord make up the central nervous