1. Describe the structure and functions of different kinds of glial cells.
Glia cells are like the “glue”, they support the neurons of the Nervous system by holding them together.
• Astrocytes- “star shaped”, wraps around the presynaptic terminal of functionally related axons, supports the blood brain barrier, provides nutrients, and repairs scar tissue
• Microglia- act as part of the immune system, remove waste material and viruses and fungi from the brain
• Oligodendrocyte- forms myelin sheath in the central nervous system cells, won’t repair damaged axons, exists in the CNS
• Shwaan cells- form myelin sheath outside of the central nervous system and therefore exists in the peripheral nervous system will repair damaged axons.
• Radial
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Glia- guide the migration of neurons and their axons and dendrites during embryonic development 2. What is the resting potential? What ions are involved? How are they distributed across the membrane? How is the membrane charged? A resting potential is the difference in voltage of the neuron inside the membrane with respect to the outside of the membrane. The membrane consists of slightly negatively charged ions in comparison to the outside of the membrane. The ions involved are Na+ (sodium), K+ (potassium), and Cl- (chloride). 3. Describe the electrical and ionic events that generate an action potential? An action potential is the change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell. When the cell reaches the threshold, sodium channels open and sodium enters in a process called depolarization (when the inside of the cell becomes less negative). Potassium channels then begin to open when the sodium channels begin closing. Potassium leaves the cell in a process called hyperpolarization (when inside the cell becomes more negative). 4. What is an EPSP, an IPSP? Where are they generated? What effects do they have on succeeding neurons? An EPSP is an excitatory postsynaptic potential that makes the neuron more likely to fire an action potential.
It’s a temporary depolarization of postsynaptic membrane potential, caused by the flow of positively charged ions into the postsynaptic cell as a result of opening ligand-gated ion channels. An IPSP is an inhibitory postsynaptic potential synaptic potential that makes a neuron less likely to generate an action potential. An IPSP occurs when synaptic input selectively opens the gates for potassium ions to leave the cell (carrying a positive charge with them) or for chloride ions to enter the cell (carrying a negative charge). IPSP’s result from the flow of negative ions into the cell, known as hyperpolarization.
5. Describe the role of vesicle and calcium (C++) in the release of transmitter.
The presynaptic terminal stores high concentrations of neurotransmitter molecules in vesicles, which are tiny nearly spherical packets. These molecules are then released by depolarization. Depolarization opens voltage-dependent calcium gates in the presynaptic terminal. After calcium enters the terminal, it causes exocytosis, which is the burst of release of neurotransmitters from the presynaptic neuron. After its release from the presynaptic cell, the neurotransmitter diffuses across the synaptic cleft to the postsynaptic membrane, where it attaches to the receptor.
6. What are the differences between ionotropic and metabotropic
effects? Neurotransmitters exert metabotropic effects by initiating a sequence of metabolic reactions that are slower and longer lasting than ionotropic effects. Metabotropic synapses depend on many neurotransmitters, like dopamine, norepinephrine, serotonin, and sometimes GABA and glutamate. When a neurotransmitter attaches to a metabotropic receptor, it bends the receptor protein that goes through the membrane of the cell. Bending the receptor protein detaches the G protein which can then takes its energy elsewhere in the cell. The G protein activates a secondary messenger inside the cell, and this elicits post-synaptic changes. When the neurotransmitter binds to an ionotropic receptor, it twists the receptor enough to open its central channels, which is shaped to let a certain type of ion to pass through. The channels controlled by a neurotransmitter are ligand-gated channels. Ionotropic effects being immediately after the transmitter attaches. Most of the excitatory ionotropic synapses use the neurotransmitter glutamate and most of the inhibitory ionotropic synapses use the neurotransmitter GABA.
So you could find a multitude of acetylcholine in each synaptic vessel. The vesicles' contents are then released into the synaptic cleft, and about half of the acetylcholine molecules are hydrolyzed by acetylcholinesterase, an enzyme that causes rapid hydrolysis of acetylcholine. But soon, there are so many acetylcholine molecules that this enzyme cannot break them all down, and the remaining half reach the nicotinic acetylcholine receptors on the postsynaptic side of the
Based on the findings presented, Dr. Green made the correct diagnosis in predicting that this gentleman had a spinal cord injury.
Canavan disease is an inherited disorder that causes progressive damage to the nerve cells in the brain. It is in the group of rare genetic disorders called Leukodystrophies. Leukodystrophies are characterized by the degeneration of myelin, which is the fatty covering that insulates nerve fibers. The myelin is necessary for rapid electrical signals between the neurons. I chose this disease because I had never heard of it and it seems to only affect a very small amount of people. Also it isn’t very common so I wanted to learn more about it, which helped when looking for information
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
“Guillain-Barre is an immune mediated response that triggers destruction of the myelin sheath covering the pe...
Neurogenesis, the production of new nerve cells, has been a revolutionary finding as nerve formation has always been thought to end with adulthood. It has not been until recently that such dogma has been contradicted as research findings report that neurogenesis continues in the hippocampus throughout most of the adult life of mammals and primates (1). Recent correlations have been further made between neurogenesis and depression as the latter depletes neuron cells in the brain while antidepressive drugs have demonstrated to increase neuronal growth
Microglial are the resident macrophage of the central nervous system (CNS) parenchyma that participate in both CNS innate and adaptive immunity as well as taking part in many CNS development and homeostasis maintenance to support brain integrity. Credited to these roles, emerging evidence implicates microglial as key player that executing both beneficial and detrimental effects in various CNS-related neurological disease including neurodegeneration, neoplastic disease as well as neural development disorders.
Firstly, there is various of sensing activities as in seeing and hearing as in a sense of understanding of what is seen and heard. Secondly the sense of feeling in numerous parts of the body from the head to the toes. The ability to recall past events, the sophisticated emotions and the thinking process. The cerebellum acts as a physiological microcomputer which intercepts various sensory and motor nerves to smooth out what would otherwise be jerky muscle motions. The medulla controls the elementary functions responsible for life, such as breathing, cardiac rate and kidney functions. The medulla contains numerous of timing mechanisms as well as other interconnections that control swallowing and salivations.
In their inactive state neurons have a negative potential, called the resting membrane potential. Action potentials changes the transmembrane potential from negative to positive. Action potentials are carried along axons, and are the basis for "information transportation" from one cell in the nervous system to another. Other types of electrical signals are possible, but we'll focus on action potentials. These electrical signals arise from ion fluxes produced by nerve cell membranes that are selectively permeable to different ions.
During early childhood, there is a huge proliferation of connections between neurons, usually peaking around the age of two. The adolescent brain then cuts down the amount of connections, deciding which ones are important to keep and which can be let go. While there are various theories as to the molecular mechanisms by which pruning actually occurs, most agree that pruning is primarily carried out by a very motile form of glial cell, called microglia [1], and pre-programmed cell death (apoptosis). These microglia are thought to remove cellular debris and perform surveillance during the healing process of an injured brain, but in the healthy, developing brain they have a possibly more important function. If a synapse receives little activity, it is weakened and eventually deleted by microglia and other glial cells through a process called long-term depotentiation (LTD). After the synapse has been removed, the space and resources that it once used are taken by other synapses. These synapses are strengthened by long-term potentiation (LTP). These processes and various others take place throughout development, peaking at adolescence and reaching their base around the age of 21, and transform the brain to create more complex and efficient neuronal configurations.
Culter, Mary Ann, Joanne Dombrowski, Michael Doughtery, Paula Henderson, and Laura McNicholas. “The brain: understanding nuerobiology. The brain-lesson1-What does this part of the brain do?” NIH publication, Mar.20120.21.Apr.2014.
The myelin sheath is a fatty substance that surrounds the axons of the nerves and provides protection. It allows messages to be sent rapidly and accurately to the axons from long distances (Serono, 2010). The axons are the part of the nervous system that allows electrical transmission of signals throughout the brain and spinal cord. Without these electrical transmissions, the body would not be able to function properly (Serono, 2010).
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.
The neuron plays an important role in the occupation of the brain (Rollin Koscis). A neuron is...
Synaptic transmission is the process of the communication of neurons. Communication between neurons and communication between neuron and muscle occurs at specialized junction called synapses. The most common type of synapse is the chemical synapse. Synaptic transmission begins when the nerve impulse or action potential reaches the presynaptic axon terminal. The action potential causes depolarization of the presynaptic membrane and it will initiates the sequence of events leading to release the neurotransmitter and then, the neurotransmitter attach to the receptor at the postsynaptic membrane and it will lead to the activate of the postsynaptic membrane and continue to send the impulse to other neuron or sending the signal to the muscle for contraction (Breedlove, Watson, & Rosenzweig, 2012; Barnes, 2013). Synaptic vesicles exist in different type, either tethered to the cytoskeleton in a reserve pool, or free in the cytoplasm (Purves, et al., 2001). Some of the free vesicles make their way to the plasma membrane and dock, as a series of priming reactions prepares the vesicular ...