The renin-angiotensin system (RAS), also known as renin-angiotensin-aldosterone system (RAAS) is well-known for its role in regulating blood pressure, fluid volume, and capillary perfusion. It is one of the most important systems studied by those interested in the cardiovascular system and those involved in the pathogenesis of heart and renal diseases. The renin-angiotensin system exists in two frameworks: a circulating system and multiple local, tissue-specific systems. Local RAS have been found
high blood pressure. If hypertension is left untreated, it can cause severe health problems such as stroke and heart failure. In order to treat hypertension, the drug Losartan is used. Losartan is an angiotensin-II receptor antagonist (AIIRA). In other words, it can also be known as angiotensin receptor blocker. (Allen 2012) There are generally two categories of hypertension, primary hypertension and secondary hypertension. The causes of primary hypertension are usually unknown and it develops gradually
cardiovascular system, reninangiotensin-aldosterone system and sympathetic nervous system (Foex & Sear, 2004). This research paper aims to study the dysfunction of renin-angiotensin-aldosterone system in pathophysiology of hypertension and the effects of an antihypertensive drug, losartan on the angiotensin II type 1 receptors in response to the disease. Pathophysiology of hypertension Renin is a type of protein enzyme secreted by the juxtaglomerular apparatus of the kidneys when the blood pressure
through the renin-angiotensin-aldosterone regulatory pathway. The kidneys, which are a major location for water retention regulation (and through changes in blood volume regulate blood pressure), notice decreases in blood pressure and release renin, an enzyme that alters the conformation of proteins, which converts angiotensinogen into angiotensin I. Next, angiotensin I is altered into the conformation of angiotensin II by the action of angiotensin converting enzyme. Angiotensin II then causes many
important roles in inter-neuronal communication. Receptor sites are made up of proteins and the ion channels in the cell membranes are proteins. The link between the receptor sites and the protein channels sometimes is the guanine nucleotide-binding protein, better known as G Protein. (1) The basic structure and function of these shall be explored in the following. In order for neuron communication to occur, the post-synaptic neuron must have receptor sites for the neurotransmitters released by the
(138). Dwarfism, according to the Greenberg Center, is the result of a genetic condition caused by a new mutation or a genetic change.In 1994, the Center reports that the gene for achondroplasia was found and labeled “fibroblast growth factor receptor 3 (FGFR3).”This discovery of at least one cause of dwarfism was a breakthrough because dwarfs in the past were simply regarded as inexplicable freaks.But now there is biological evidence of a gene, in which,“the mutation, affecting growth, especially
effects on many organs and tissues. The Insulin Receptor and Mechanism of Action Like the receptors for other protein hormones, the receptor for insulin is embedded in the plasma membrane. The insulin receptor is composed of two alpha subunits and two beta subunits linked by disulfide bonds. The alpha chains are entirely extracellular and house insulin binding domains, while the linked beta chains penetrate through the plasma membrane. The insulin receptor is a tyrosine kinase. In other words, it functions
RAAS (Renin Angiotensin Aldosterone System) plays a role in the homeostatic process such as blood pressure and fluid volume control1. Renin is secreted in the blood from cells that are lining the glomeruli of the kidneys. The renin-secreting cells are sensitive to changes in blood flow and blood pressure. Angiotensinogen, a glycosylated protein that is primarily synthesized and secreted by the liver as well as other tissues is the sole precursor for angiotensin peptide. Renin catalyzes the conversion
creating pressure waves in the endolymph inside the cochlear duct. These waves then causes the membrane to vibrate, which in turn cause the hairs cells of the spiral organ to move against the tectorial membrane. The bending of the stereo cilia produces receptor potentials that in the end lead to the generation of nerve impulses. The External or Outer Ear - comprises of the auricle or pinna which is the fleshy part of the outer ear. It is cup-shaped and collects and amplifies sound waves which then passes
In John Steinbeck’s The Chrysanthemums, the reader is introduced to the seemingly timid and shy Elisa Allen. Elisa is routinely planting her yearly sets of Chrysanthemums, which appear to be the sole receptor of her caring and gentle touch, but all the while it is evident that “the chrysanthemum stems seemed too small and easy for her energy.” Her hidden eagerness seems not only out of place, but out of touch with her dry and wilted surroundings, of which her husband, Henry, abruptly interrupts her
development of vascular cognitive impairment and vascular dementia [1, 2]. Angiotensin I-converting enzyme (EC 3.4.15.1; ACE) plays an important role in the rennin-angiotensin system and it is a carboxyl-terminal dipeptidyl exopeptidase that catalyzes the conversion of angiotensin I to angiotensin II [3-6]. ACE converts an inactive form of decapeptide, angiotensin I, to a potent vasoconstrictor, octapeptide, angiotensin II, in addition; since the ACE is a multifunctional enzyme it also catalyzes
hallucinogens) stimulate 5-HT2A receptors (Kalat, 2004). Activation of these receptors causes cortical glutamate levels to increase. This is presumed to be a result of a "presynaptic receptor-mediated release" from neurons in the thalumus (Nichols, 2004). Early studies proposed that LSD antagonized the effects of serotonin on peripheral tissues. It was later proposed that the psychoactive properties of LSD may be a result of the blocking of serotonin receptors in the central nervous system
and deepening of the voice. The hormone produces these results when it is absorbed from the bloodstream by certain types of cells. Molecules of testosterone fit into receptor sites located inside the cells, just as a key fits into a lock. When the receptor site is filled , the cell is activated. There are a certain number of receptor sites in each cell. If only a few them get filled, the cell will respond at a low level. If all of these sites are filled, the cell produces its maximum response (http://www
of light that focus on specific places on the retina. This light-sensitive tissue that lines the back of the eye consists of interconnected neurons. The three diff erent types are receptor cells, bipolar cells and ganglian cells. When photoreceptors are stimulated, they change in structure of photopigments in the receptors and transduce light input into neural activity. (2) Electrical stimulus trave ls down the axon of bipolar cells to the ganglian cells. The ganglian cells are activated through nerve
Serotonin and Its Uses Serotonin (5-hydroxytryptamine, 5-HT) is a neurotransmitter in the brain that has an enormous influence over many brain functions. It is synthesized, from the amino acid L-tryptophan, in brain neurons and stored in vesicles. Serotonin is found in three main areas of the body: the intestinal wall; large constricted blood vessels; and the central nervous system. The most widely studied effects have been those on the central nervous system. The functions of serotonin are
(blood stream). If there were no receptor sites for the hormones in the body, then they would continue to flow along the river and probably not make their destination. However, there are systems of receptor sites that enable specific hormones to bind in specific places. Structure also plays a major role in determining which hormones are able to bind to which receptors. When these “messages in bottles'; reach their appointed destination, the binding into the receptor site causes a cascade of reactions
best-known opioid around, and arguably one of the most addictive substances known to man. Opiates and opioids (hereafter generically referred to as opioids) function by attaching to receptor sites in the body called mu-receptors, which are primarily located in the brain and the digestive system. When these receptors are activated in the brain they produce a rush of euphoria and a groggy state of well being (it is interesting to note that studies have shown that this action does not eliminate the
multiplicity in Joyce's works, diffuses into something necessarily plural: meanings. An ontological crisis is inextricable from this crisis of meaning and representation. In Joyce's stories the reader is displaced from her/his traditionally passive role as receptor of the knowledge an author seeks to impart, and "positioned as both reader and writer of text, in some ways playing as integral a part in constructing the work as the author does.(Benstock 17)" In the novel's opening story, "The Sisters," Joyce
virus travels down the digestive tract to the small intestine where it replicates itself in the B-cells and T-cells of the gut mucosa lining the intestine. Spread and Replication Poliovirus binds to a specific cell surface protein, polio virus receptor (PVR). This protein is an immunoglobin which contains three loops, Ig domains. Polio binds... ... middle of paper ... ...the polio vaccinations contaminated with SV40 and its link to cancer. Resources Flint, S., Enquist, L., Krug, R., Racaniello
emotions rests with neurotransmitters. Neurotransmitters are chemicals that act at the points where nerve cells connect with each other. The prevalence, or the presence or absence of specific amounts of neurotransmitters, as well as the density of receptor sites for specific neurotransmitters at nerve endings, will control to a wide extend the emotions to which we are subject (6). Pheromones are natural scents, which play an important role in sexual communication. Animals and humans release masses