«Chemical Changes Purpose The purpose of this lab was to find out the indications of chemical changes and reactions when mixing two different substances, which ...» Document abstract
$5.95
6 word format
Language : english
physics & chemistry
case study
date published
26/09/2007
review : not yet assessed
level : General public
requested 1 times
SummaryThe purpose of this lab was to find out the indications of chemical changes and reactions when mixing two different substances, which are listed specifically in the Observations section. The purpose is also to find out how a percent by mass solution is made up. The data and observations that is recorded will help find out the indications of chemical changes and reactions. Since this is a very big part of the lab, it is imperative to take detailed notes and observations. Besides recording data, it is necessary to know how to calculate it. It will be needed to find out how a percent by mass solution is made up. It is also very important to have a good method of approach towards calculating this data because this is what drives the whole lab. Without the percent by mass solution calculations, we would not be able to make up the chemical solutions.
« Introduction: The drive to find a single chemical to induce flowering in plants started the 8-16 hours needed to trigger flowering after a LD, changes in the ...» Document abstract
$2.95
3 word format
Language : english
biology
summaries
date published
02/08/2007
review : not yet assessed
level : Advanced
requested 0 times
SummaryFor years, man has been trying to find a single chemical that triggers flowering in plants. Although this single chemical has not been found, several of the Gibberellins show promising results as an active florigen – such as GA5 and GA6 and possibly GA1 and GA4. Results have shown that these GAs seem to travel intact from the leaf to the shoot apex just after a single long day photoperiod. Gibberellins also seem to accumulate in sufficient amounts to trigger flowering. Gibberellins have also been shown to cause petiole elongation. Much research still needs to be done to draw definite conclusions about the role of Gibberellins as a florigen, but much of the evidence looks promising.
Table of Contents- Abstract:
- Introduction:
- Results
- King and Evans describe the advancement in proving that Gibberellins can replace the Long Day (LD) photoperiod in flowering plants
- Certain Gibberellins seem to have a greater effect on flowering than others
- The first visible change in the GAs level in plants is in the leaf soon after a long day photoperiod
- Conclusion:
« information transfer between neurons in the CNS occurs via chemical synapses. specific protein receptors to produce biochemical and excitability changes in the ...» Document abstract
$2.95
3 word format
Language : english
biology
research papers
date published
26/11/2007
review : not yet assessed
level : Advanced
requested 1 times
SummaryClasses of Neurotransmitters Much of the information transfer between neurons in the CNS occurs via chemical synapses. These synapses use a variety of messengers (neurotransmitters) that are released in a Ca2+-dependent fashion from presynaptic terminals and act on specific protein receptors to produce biochemical and excitability changes in the receiving cell. There are two primary groups of neurotransmitters—low–molecular-weight amines and neuroactive peptides. These agents act on two classes of receptors, ligand-gated ion channels, at which the binding of the transmitter directly opens ion channels in the membrane, and G protein coupled receptors. The activated G protein then acts on ion channels or alters biochemical second-messenger systems. Physiologists classify synaptic transmission according to the speed of transmission (fast or slow) and according to the nature of the response (excitatory or inhibitory). Fast synaptic transmission occurs on a time scale of up to several hundred milliseconds and is mediated primarily by amine neurotransmitters acting at ligand-gated ion channels. Slow synaptic communication occurs on the scale of seconds to minutes or longer through the actions of either amines or peptides acting on G protein coupled receptors. Different ion channels determine whether transmitter effects are excitatory (depolarizing) or inhibitory (hyperpolarizing). Moreover, an excitatory synaptic input can exert an inhibitory influence on the firing characteristics of a region. For example, the release of an excitatory neurotransmitter onto an inhibitory interneuron can result in the inhibitory neuron diminishing the activity of a population of cells. Conversely, inhibition of inhibitory interneurons can enhance regional excitability. This provides a great deal of flexibility in controlling and fine-tuning the inputs and outputs of a region.
« tasted the forbidden fruit, the CIA sowed the seeds of the chemical manipulations of LSD has been found by many to cause profound changes in the mental state. ...» Document abstract
$3.95
4 word format
Language : english
biology
school essay
date published
27/11/2007
review : not yet assessed
level : Advanced
requested 0 times
SummaryWhen Albert Hofmann created LSD 25 during experimentation in his laboratory, he had no idea what was to become of it, or what kind of an impact it would have. "Dr. Humphry Osmond invented the term 'psychodelic', which was later amended to 'psychedelic to get rid of the nuthouse connotation of 'psycho'." (Wolfe 39). This term encompasses a whole generation, a cultural revolution that took place during the 60's. Since its creation, LSD, among other psychedelics, has had a great impact on the American culture.
« gated ion channels allow the flow of ions in response to changes in membrane Certain ion channels that are gated directly by chemical neurotransmitters such as ...» Document abstract
$5.95
6 word format
Language : english
biology
research papers
date published
26/11/2007
review : not yet assessed
level : Advanced
requested 0 times
SummaryStructure and Function of Voltage-Gated Ion Channels Voltage-gated ion channels allow the flow of ions in response to changes in membrane voltage and are key elements in neuronal excitation and inhibition. Although ion channels can usually pass more than a single type of ion, voltage-gated channels are named according to the predominant ion that flows when the channel is open. Ion channels that are selective for Na+, K+, Ca2+, or Cl– have been described in neuronal membranes. Certain ion channels that are gated directly by chemical neurotransmitters such as glutamate and acetylcholine are selective for Na+, K+, and Ca2+ but exclude Cl– and are called nonselective cationic channels.
« Figure 3. Comparison of the subjects' oxygen consumption changes at various increases during exercise because the body is converting chemical energy from food ...» Document abstract
$5.95
6 word format
Language : english
sports
case study
date published
13/11/2007
review : not yet assessed
level : General public
requested 0 times
SummaryExercise causes numerous physiological changes in the body. Body temperature increases during exercise because heat is generated in proportion to our need to produce energy. Sweat is a by product of the body heat generated and is sent to the surface of the skin to evaporate and serves as a cooling mechanism. Aerobic exercise leads to the regeneration of ATP which causes an increased need for oxygen and an increased production of carbon dioxide. These two gases must be delivered and removed for the muscles to function properly. Oxygen is brought into the lungs of the body via inhalation and transferred from the pulmonary circuit to the heart via hemoglobin. The oxygenated blood passes through the heart and out into the body’s organs. Some hemoglobin red blood cells deliver the oxygenated blood to skeletal muscle being contracted during exercise. The muscle uses the oxygen to regenerate ATP aerobically. This process also produces carbon dioxide as a waste product. The carbon dioxide diffuses into capillary blood and travels back up through the heart and into the pulmonary circuit where it is taken to the lungs and disposed of by exhalation.
« Figure 3. Comparison of the subjects' oxygen consumption changes at various increases during exercise because the body is converting chemical energy from food ...» Document abstract
$5.95
6 word format
Language : english
biology
research papers
date published
13/11/2007
review : not yet assessed
level : Advanced
requested 0 times
SummaryPlants have served as both poisons and medicines. Dioscorides listed several hundred plant species in his first Materia Medica in 78 BC. Galen, in second-century Rome, catalogued plants, including those containing opiates, ergotamines, and other alkaloids. Pharmacognosy was established as an independent discipline in nineteenth century Europe.
Toxic plants are ingested by curious children, by foragers mistaking poisonous plants for edible fare, by herbalists mistaking poisonous plants for nontoxic remedies, by pleasure seekers attempting to attain natural highs, and by suicidal patients attempting to harm themselves. Over 122,000 plant ingestions or exposures were reported to 65 poison control centers serving more than 257 million people in 1998. Plant exposures represented 5.5% of total toxic exposures reported in 1998 (fourth after cleaning substances, analgesics and cosmetics/personal care products). Approximately 7% of plant ingestions required treatment at a health care facility, with four deaths reported. More than 68% of all plant ingestions reported were in children under age 6 years.
Toxic plants are ingested by curious children, by foragers mistaking poisonous plants for edible fare, by herbalists mistaking poisonous plants for nontoxic remedies, by pleasure seekers attempting to attain natural highs, and by suicidal patients attempting to harm themselves. Over 122,000 plant ingestions or exposures were reported to 65 poison control centers serving more than 257 million people in 1998. Plant exposures represented 5.5% of total toxic exposures reported in 1998 (fourth after cleaning substances, analgesics and cosmetics/personal care products). Approximately 7% of plant ingestions required treatment at a health care facility, with four deaths reported. More than 68% of all plant ingestions reported were in children under age 6 years.
« The burrows are often the least conspicuous of various skin changes. The chemical must be applied even beneath the fingernails, since ova and live mites are ...» Document abstract
$3.95
4 word format
Language : english
biology
research papers
date published
20/11/2007
review : not yet assessed
level : Advanced
requested 0 times
SummaryMites make up the largest group in the class Arachnida. Most are small arthropods, and many are barely visible. Mites have two body regions, a small cephalothorax and a larger, unsegmented abdomen. The cephalothorax and abdomen are broadly joined, giving most mites an oblong to globular appearance. Newly hatched larvae have three pairs of legs, and larvae acquire a fourth pair after the first molt. Mites are highly diverse. Some are parasitic, with both vertebrates and invertebrates serving as hosts; some are scavengers, some feed on plants, and many are free living and predaceous. Although most species are oviparous, some are ovoviviparous, and a few are viviparous. They occur worldwide and frequently in great numbers. Mites have been associated with disease transmission, allergies, and dermatologic manifestations. Of the approximately 35,000 species, about 50 are known to cause human skin lesions, and most of the cutaneous lesions are caused by mites feeding or burrowing in the skin. Since children and adults of all races are susceptible to these ubiquitous arthropods, they are responsible for considerable morbidity. The mites of medical importance are some of the sarcoptic mites, some of the trombiculid mites, a number of other acariform mites that infest organic substances such as grains and produce, and the gamasid mites that are vectors of several rickettsial and viral diseases. Dermatologic manifestations of mite bites may be seasonal, as with the trombiculids; individual cases or outbreaks of varying magnitude may be related to contact with mites that infest animals or various foods. Epidemics may occur, as is presently the case with scabies.
« Neuropeptides have been implicated as chemical mediators in pathways subserving a Measurements of neuropeptide concentration changes do not indicate which of ...» Document abstract
$6.95
7 word format
Language : english
biology
research papers
date published
26/11/2007
review : not yet assessed
level : Advanced
requested 1 times
SummaryThe past several decades have witnessed a veritable explosion of knowledge about the central nervous system (CNS), and in no area has this been as impressive as in peptide neurobiology. Numerous peptide neurotransmitter candidates have been identified and characterized, their CNS distributions mapped, and their genes cloned. The tenet “one neuron-one transmitter” erroneously attributed to Dale has been convincingly refuted with numerous demonstrations of neurons containing multiple peptides or combinations of peptide and nonpeptide neurotransmitters. Additionally, since the early 1980s there has been an embarrassment of riches in the form of knowledge about neurotransmitter receptor diversity, diversity of receptor-effector coupling, and neurotransmitter transporters. These discoveries have not yet been fully integrated into what is known about normal or aberrant CNS function, although dysfunction at virtually any level could conceivably lead to neuropsychiatric deficits.
knowledge network
Sort by
Subject :
Type :
Extension :
Language :
Size :