Neurotransmitters 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. Neurotransmitters can also produce their effects by modulating the production of other signal-transducing molecules ("second messengers"messengers") in the post-synaptic cells (Cooper, Bloom and Roth 1996). Nine compounds -- belonging to three chemical families -- are generally believed to function as neurotransmitters somewhere in the central nervous system (CNS) or periphery. In addition, certain other body chemicals, for example adenosine, histamine, enkephalins, endorphins, and epinephrine, have neurotransmitter-like properties, and many additional true neurotransmitters may await discovery. The first of these families, and the group about which most is known, is the amine neurotransmitters, a group of compounds containing a nitrogen molecule which is not part of a ring structure. Among the amine neurotransmitters are acetylcholine, norepinephrine, dopamine, and serotonin. Acetylcholine is possibly the most widely used neurotransmitter in the body, and all axons that leave the central nervous system (for example, those running to skeletal muscle, or to sympathetic or parasympathetic ganglia) use acetylcholine as their neurotransmitter. Within the brain acetylcholine is the transmitter of, among other neurons, those generating the tracts that run from the septum to the HIPPOCAMPUS, and from the nucleus basalis to the CEREBRAL CORTEX -- both of whbasalis to the CEREBRAL CORTEX -- both of which seem to be needed to sustain memory and learning. It is also the neurotransmitter released by short-axon interneurons of the BASAL GANGLIA. Norepinephrine is the neurotransmitter released by sympathetic nerves (e.g., those innervating the heart and blood vessels) and, within the brain, those of the locus coe... ... middle of paper ... ...d at the axon endings of motor neurons, where they stimulate the muscle fibers to contract. And they and their close relatives are produced by some glands such as the pituitary and the adrenal glands. In this chapter, we will review some of the most significant neurotransmitters. Acetylcholine was the first neurotransmitter to be discovered. It was isolated in 1921 by a German biologist named Otto Loewi, who would later win the Nobel Prize for his work. Acetylcholine has many functions: It is responsible for much of the stimulation of muscles, including the muscles of the gastro-intestinal system. It is also found in sensory neurons and in the autonomic nervous system, and has a part in scheduling REM (dream) sleep. The well-known poison botulin works by blocking acetylcholin, causing paralysis. The botulin derivative botox is used by many people to temporarily eliminate wrinkles --a sad commentary on our times, I would say. On a more serious note, there is a link between acetylcholine and Alzheimer's disease: There is something on the order of a 90% loss of acetylcholine in the brains of people suffering from that debilitating disease. Bibliography Biopsychology, pinel 2002
In the beginning phases of muscle contraction, a “cocked” motor neuron in the spinal cord is activated to form a neuromuscular junction with each muscle fiber when it begins branching out to each cell. An action potential is passed down the nerve, releasing calcium, which simultaneously stimulates the release of acetylcholine onto the sarcolemma. As long as calcium and ATP are present, the contraction will continue. Acetylcholine then initiates the resting potential’s change under the motor end plate, stimulates the action potential, and passes along both directions on the surface of the muscle fiber. Sodium ions rush into the cell through the open channels to depolarize the sarcolemma. The depolarization spreads. The potassium channels open while the sodium channels close off, which repolarizes the entire cell. The action potential is dispersed throughout the cell through the transverse tubule, causing the sarcoplasmic reticulum to release
Chemistry of Psilocybin and Synaptic Transmitters Involved Psilocybin is a type of hallucinogenic mushroom that is ingested by eating the raw fungi. The mushroom can also be made into a tea and drunk. In some of the later studies done on psilocybin, the drug was synthetically produced and then either inhaled or injected by an IV. The drug enters the blood stream and can cross the blood brain barrier because of it relative metabolic similarity to serotonin (Fuller 1985). This means that since psilocybin is chemical resemblance to the neurotransmitter serotonin, psilocybin can trick the protein channels embedded in the membrane of the blood vessel and pass through as if it were serotonin and not a drug.
Cannibalism is a long-standing taboo in our society; the thought of humans preying on other humans for a food source disgusts and astounds us. Though the practice is not common amongst modern day humans there is some evidence to suggest that ancient humans resorted to such measures, and a recent discovery in Madagascar attests to the possibility that some carnivorous dinosaurs fed on their own species (Perkins, 2003).
...lism is from the character of Shrimper when he enthusiastically tells Turner about “delicious long pork,” and closest portrayal of cannibalism is Jack Sparrows tentative nibble of toenail. It seems that while the filmmakers may not have offered an accurate portrayal of “Pelegostos” or Carib life, they may have inadvertently offered a relatively accurate portrayal of early European colonists’ misinterpretations of “Pelegostos” or Carib life. As stated previously, “Early chroniclers did not explore alternative interpretations of the circumstantial evidence for cannibalism. Bones might have been kept for religious reasons, or boiled and cleaned for use as tools, household items, or musical instruments” (Myers 177); however, a more accurate portrayal of the indigenous people would have been contrary to the implicit goal of the filmmakers: to entertain and make money.
Bell, Rachel. "Historical Perspective." All about Cannibalism: The Ancient Taboo in Modern Times. Crime Library, n.d. Web. 20 Mar. 2014. .
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
The spectrum of logic behind cannibalism is wide in scope and varies in each tribe. In Africa there are a number of cannibalistic tribes, the two most notable being the Fang and Azande tribes. The Fang tribe occupied the Gabun district north of the Ogowh River in the French Congo. According to Mary Kingsley, “The Fang is not a cannibal for sacrificial motives” and is considered by many to be “morally superior to the Negro”. (encyclopedia.org) However, despite displaying higher moral standards, the Fang tribe has been purported to be “utterly indifferent to human life.” (encyclopedia.org) Yet, it was not indifference that served as the basis of practicing the acts of cannibalism but rather they simply found nothing wrong in doing so. In the Fang “a woman who bore ...
A number of neurotransmitters and neuromodulators, including acetylcholine (ACh), somatostatin and glutamate have been found to be deficient in Alzheimer's disease (AD).
Once the signal is sent, the ion balances out and becomes at rest. The electrical impulse that runs down the axon releases a chemical called acetylcholine, only one of many chemicals that transmits signals across the synapse. These substances are called neurotransmitters because they transmit data from one ...
Every society has it’s own cultural traditions and norms. Many of the traditions are passed down from generation to generation for so long that they become the norms of the culture. The Wari’ are no different than anyone else in that their traditions become cultural norms. In Consuming Grief: Compassionate Cannibalism in an Amazonian Society, Beth A. Conklin travels to the Wari’ people in order to study illness and death from both before and after they had foreign contact. While there she finds herself going into depth on the lifestyle of the Wari’ people and how their norm of cannibalism came about and how it was phased out by the outside world.
Neurotransmitters are essential for transferring information between neurons and are released from a presynaptic terminal into a synaptic cleft. When the neurotransmitters bind to the postsynaptic receptors (specialized protein molecules that capture and react to molecules of the neurotransmitter), it induces an ionic flux which depolarizes the neuron. Neurotransmitter binding may also cause metabolic changes such as the activation of secondary messenger systems. Efficient neurotransmitters must satisfy two requirements: the level of neurotransmitter in the synaptic cleft must be kept low in order to maximize the signal-to-noise ratio upon binding of fresh transmitter to its receptor; and the second requirement is the rapid replacement of a transmitter that is released from a presynaptic terminal (Glutamate and Glutamine in the Brain, 2000). I am choosing glutamate as my neurotransmitter of choice, so in order for glutamate to be an efficient neurotransmitter, a low external signal-to-noise ratio must be preset in order to prevent excitotoxicity which can damage and even kill nearby neurons. Glutamate must also need to be removed from the synapse or it must have to be resynthesized within the
Ranging from animals in the present time- lions, pigs, ants, otters, apes, poultry, mantis, spiders, scorpions, mice, etc., to approximately 100,000 years ago with the early humans, Neanderthals, to the beginning of the Mesozoic Era with possibly the first dinosaur, Coelophysis (Bossel et al 2001, Defleur et al 1999). The reasons for resorting to cannibalism vary according with their environment. Some animals resort to cannibalism for survival needs, ritual activities, or protecting their territory. This essay will look at animals that engaged in cannibalism across a large geological time scale.
Cannibalism, also known as anthropophagi, is defined as the act or practice of eating members of the same species. The word anthropophagi comes from the Arawakan language name for the Carib Indians of the West Indies. The Caribs are well known for their practice of cannibalism. Among humans, this practice has been attributed to people in the past all over the world, including rituals connected to tribal warfare. There are two kinds of cannibalism -- sociological and pathological. Sociological means living and eating in a culture where cannibalism is accepted, and the pathological means practicing cannibalism within a culture where it's not accepted. Much controversy exists over the idea of sociological cannibalism. Reports of social cannibalism are mostly pointed at the Americas and Africa, since these were the primary continents subjected to European killing and conquest sprees from the Middle Ages through modern times. Despite what anyone says, there are documented examples of cannibalistic cultures and practices. It was usually a spiritual ritual. In some cases, the bodies of enemies were consumed in order to abso...
This research paper will delve into the topic of cannibalism in native tribes of Brazil during the Portuguese colonization of the South American country. My research only the topic yielded very interesting results. Some scholars suggest that cannibalism (in the instances involving the Tupinamba tribe and their ritualistic practices) didn't even occur. This isn't to say, however, that cannibalism was completely nonexistent in Brazil, but arguing that it did not occur in the “savage” ways often described. I could easily sum up the accounts of various witnesses of cannibalism, but I will focus on the material that will mostly discuss the effect that cannibalism had on colonization in Brazil.
Shaw, 2001). Phenserine, a novel acetylcholinesterase inhibitor, has been shown to dramatically improve cognitive performance in rodents and is currently in clinical trials (N. Greig, Brossi, 1996). Studies of rats with forebrain cholinergic abrasions, known to increase Aβ in cerebral areas of the brain, have shown that Phenserine can protect against this and reduce βAPP production in animals (Haroutunian, 1997). Moreover, the absence of inhibitors of acetylcholinesterase displays a wide range of behavioral deficits in Caenorhabditis elegans (C. elegans), ranging from mild incoordination to almost complete paralysis, when mutated (Nguyen,