Crazy Bulk Review – Detailed and HonestGli ormoni orjoni agire in due modi: Gli ormoni sono prodotti da ghiandole endocrine che li riversano nei liquidi corporei e a seconda delle loro secrezione possono essere classificati come: Sono degli ormoni costituiti da oligopeptidi o ormoni steroidei. Vengono steroiidei sotto forma di preormoni e solo dopo una successiva ormoni steroidei divengono attivi. Gli ormoni protidici viaggiano nel circolo sanguigno fino ad arrivare alle cellule bersaglio. Qui, essendo polari, non riescono ad oltrepassare la membrana ma si legano a particolari recettori intramembranali.
ormoni steroidei - English translation - omosironews.info Italian-English dictionary
Gli ormoni possono agire in due modi: Gli ormoni sono prodotti da ghiandole endocrine che li riversano nei liquidi corporei e a seconda delle loro secrezione possono essere classificati come: Sono degli ormoni costituiti da oligopeptidi o proteine. Vengono sintetizzati sotto forma di preormoni e solo dopo una successiva modificazione divengono attivi.
Gli ormoni protidici viaggiano nel circolo sanguigno fino ad arrivare alle cellule bersaglio. Qui, essendo polari, non riescono ad oltrepassare la membrana ma si legano a particolari recettori intramembranali. I corticosteroidi derivano dal colesterolo per rimozione della catena laterale dell'anello D del colesterolo e aggiunta di atomi di ossigeno nella molecola per formare gruppi chetonici e ossidrilici.
Gli ormoni steroidei si possono suddividere in due classi: Gli ormoni steroidei formano un gruppo di ormoni lipofili che agiscono sul metabolismo, sulla crescita e la riproduzione. Anch'essi viaggiano nel flusso circolatorio, trasportati da particolari proteine che prendono il nome di carrier: Questo fa in modo che l'ormone possa raggiungere le cellule bersaglio.
Qui, essendo di natura lipidica, entra nella cellula e trova i suoi recettori a livello citoplasmatico o a livello nucleare. Sono composti chimici derivati dalla modificazione di amminoacidi. Hanno caratteristiche comuni coi neurostrasmettitori ed alcuni di loro sono difatti anche neurotrasmettitori ed azioni che possono essere identificate in tal senso ma dislocate dal circuito sinaptico a quello endocrino.
Nelle rispettive ghiandole le cellule secernenti difatti sono identificabili come tipiche o simili a quelle del tessuto nervoso o pseudo-nervose derivate evolutivamente da cellule originariamente nervose. Alcuni esempi sono le catecolamine e gli ormoni tiroidei tiroxina e triiodotironina derivanti dall'aminoacido tirosina , la serotonina derivante dal triptofano e l' istamina derivante dall'aminoacido istidina. Generalmente questo tipo di molecole, a differenza degli ormoni steroidei e peptidici, determina azioni opposte in cellule diverse, a causa della presenza di recettori di tipo diverso generalmente indicati come alfa e beta, si veda ad esempio Recettore degli ormoni tiroidei in cellule-bersaglio nelle quali si debbano esplicare azioni rispettivamente opposte o comunque diverse; ad esempio l'adrenalina determina la costrizione dei vasi periferici e la dilatazione di quelli centrali; solitamente nei casi in cui i recettori siano in comune con altre molecole, la molecola secondaria agisce solo su uno dei due recettori ad esempio la noradrenalina.
Per numerosi ormoni sono stati realizzati analoghi caratterizzati da una struttura chimica e da un effetto endocrino equiparabili. Analoghi dell' insulina vengono utilizzati nel trattamento del diabete mellito e analoghi dell' adrenalina sono usati in otorinolaringoiatria. Esistono inoltre analoghi di fattori di rilascio ormonale: I livelli specifici degli ormoni sono regolati dal sistema nervoso centrale , che riceve dei segnali da molti sensori interni ed esterni es.
Le tropine attivano le ghiandole endocrine, stimolandole a produrre ormoni specificati e appropriati azione alla situazione. Composto chimico — A chemical compound is an entity consisting of two or more atoms, at least two from different elements, which associate via chemical bonds. Many chemical compounds have a numerical identifier assigned by the Chemical Abstracts Service. For example, water is composed of two atoms bonded to one oxygen atom, the chemical formula is H2O.
A compound can be converted to a different chemical composition by interaction with a chemical compound via a chemical reaction. In this process, bonds between atoms are broken in both of the compounds, and then bonds are reformed so that new associations are made between atoms. A chemical element bonded to a chemical element is not a chemical compound since only one element.
Examples are the diatomic hydrogen and the polyatomic molecule sulfur. Chemical compounds have a unique and defined chemical structure held together in a spatial arrangement by chemical bonds. Pure chemical elements are not considered chemical compounds, failing the two or more atom requirement, though they often consist of molecules composed of multiple atoms. There is varying and sometimes inconsistent nomenclature differentiating substances, which include truly non-stoichiometric examples, from chemical compounds, other compounds regarded as chemically identical may have varying amounts of heavy or light isotopes of the constituent elements, which changes the ratio of elements by mass slightly.
Characteristic properties of compounds include that elements in a compound are present in a definite proportion, for example, the molecule of the compound water is composed of hydrogen and oxygen in a ratio of 2,1. In addition, compounds have a set of properties. The physical and chemical properties of compounds differ from those of their constituent elements, however, mixtures can be created by mechanical means alone, but a compound can be created only by a chemical reaction.
Some mixtures are so combined that they have some properties similar to compounds. Other examples of compound-like mixtures include intermetallic compounds and solutions of metals in a liquid form of ammonia.
Compounds may be described using formulas in various formats, for compounds that exist as molecules, the formula for the molecular unit is shown. For polymeric materials, such as minerals and many metal oxides, the elements in a chemical formula are normally listed in a specific order, called the Hill system. Teoria dei segnali — According to Alan V. Oppenheim and Ronald W. Schafer, the principles of signal processing can be found in the classical numerical analysis techniques of the 17th century.
Oppenheim and Schafer further state that the digitalization or digital refinement of techniques can be found in the digital control systems of the s and s. Feature extraction, such as understanding and speech recognition. Quality improvement, such as reduction, image enhancement.
Including audio compression, image compression, and video compression and this involves linear electronic circuits as well as non-linear ones. The former are, for instance, passive filters, active filters, additive mixers, integrators, non-linear circuits include compandors, multiplicators, voltage-controlled filters, voltage-controlled oscillators and phase-locked loops.
Continuous-time signal processing is for signals that vary with the change of continuous domain, the methods of signal processing include time domain, frequency domain, and complex frequency domain. This technology was a predecessor of digital processing, and is still used in advanced processing of gigahertz signals. Digital signal processing is the processing of digitized discrete-time sampled signals, processing is done by general-purpose computers or by digital circuits such as ASICs, field-programmable gate arrays or specialized digital signal processors.
Typical arithmetical operations include fixed-point and floating-point, real-valued and complex-valued, other typical operations supported by the hardware are circular buffers and look-up tables. Examples of algorithms are the Fast Fourier transform, finite impulse response filter, Infinite impulse response filter, nonlinear signal processing involves the analysis and processing of signals produced from nonlinear systems and can be in the time, frequency, or spatio-temporal domains.
Nonlinear systems can produce complex behaviors including bifurcations, chaos, harmonics. Cellula — The cell is the basic structural, functional, and biological unit of all known living organisms. A cell is the smallest unit of life that can replicate independently, the study of cells is called cell biology. Cells consist of cytoplasm enclosed within a membrane, which contains many such as proteins. Organisms can be classified as unicellular or multicellular, while the number of cells in plants and animals varies from species to species, humans contain more than 10 trillion cells.
Most plant and animal cells are only under a microscope. The cell was discovered by Robert Hooke in , who named the unit for its resemblance to cells inhabited by Christian monks in a monastery. Cells emerged on Earth at least 3. Prokaryotes are single-celled organisms, while eukaryotes can be either single-celled or multicellular, prokaryotic cells were the first form of life on Earth, characterised by having vital biological processes including cell signaling and being self-sustaining.
They are simpler and smaller than eukaryotic cells, and lack membrane-bound organelles such as the nucleus, prokaryotes include two of the domains of life, bacteria and archaea. The DNA of a prokaryotic cell consists of a chromosome that is in direct contact with the cytoplasm. The nuclear region in the cytoplasm is called the nucleoid, most prokaryotes are the smallest of all organisms ranging from 0.
Though most prokaryotes have both a cell membrane and a wall, there are exceptions such as Mycoplasma and Thermoplasma which only possess the cell membrane layer. The envelope gives rigidity to the cell and separates the interior of the cell from its environment, the cell wall consists of peptidoglycan in bacteria, and acts as an additional barrier against exterior forces.
It also prevents the cell from expanding and bursting from osmotic pressure due to a hypotonic environment, some eukaryotic cells also have a cell wall. Inside the cell is the region that contains the genome, ribosomes.
The genetic material is found in the cytoplasm. Prokaryotes can carry extrachromosomal DNA elements called plasmids, which are usually circular, linear bacterial plasmids have been identified in several species of spirochete bacteria, including members of the genus Borrelia notably Borrelia burgdorferi, which causes Lyme disease.
Though not forming a nucleus, the DNA is condensed in a nucleoid, plasmids encode additional genes, such as antibiotic resistance genes. Organismo vivente — In biology, an organism is any contiguous living system, such as an animal, plant, fungus, protist, archaeon, or bacterium. All known types of organisms are capable of some degree of response to stimuli, reproduction, growth and development and homeostasis.
An organism consists of one or more cells, when it has one cell it is known as an organism. Most unicellular organisms are of microscopic scale and are thus described as microorganisms. Humans are multicellular organisms composed of trillions of cells grouped into specialized tissues.
An organism may be either a prokaryote or a eukaryote, prokaryotes are represented by two separate domains—bacteria and archaea. Eukaryotic organisms are characterized by the presence of a cell nucleus. Fungi, animals and plants are examples of kingdoms of organisms within the eukaryotes, estimates on the number of Earths current species range from 10 million to 14 million, of which only about 1. In , a set of genes from the last universal ancestor of all living organisms living was identified.
The term organism first appeared in the English language in and it is directly related to the term organization.
There is a tradition of defining organisms as self-organizing beings. An organism may be defined as an assembly of molecules functioning as a more or less stable whole that exhibits the properties of life. Dictionary definitions can be broad, using such as any living structure, such as a plant, animal, fungus or bacterium, capable of growth.
Many definitions exclude viruses and possible man-made non-organic life forms, as viruses are dependent on the machinery of a host cell for reproduction. A superorganism is an organism consisting of individuals working together as a single functional or social unit. There has been controversy about the best way to define the organism, several contributions are responses to the suggestion that the category of organism may well not be adequate in biology.
Viruses are not typically considered to be organisms because they are incapable of autonomous reproduction and this controversy is problematic because some cellular organisms are also incapable of independent survival and live as obligatory intracellular parasites. Metabolismo — Metabolism is the set of life-sustaining chemical transformations within the cells of living organisms.
These enzyme-catalyzed reactions allow organisms to grow and reproduce, maintain their structures, usually, breaking down releases energy and building up consumes energy. The chemical reactions of metabolism are organized into metabolic pathways, in one chemical is transformed through a series of steps into another chemical.
Enzymes act as catalysts that allow the reactions to proceed more rapidly, enzymes also allow the regulation of metabolic pathways in response to changes in the cells environment or to signals from other cells. The metabolic system of a particular organism determines which substances it will find nutritious, for example, some prokaryotes use hydrogen sulfide as a nutrient, yet this gas is poisonous to animals. The speed of metabolism, the rate, influences how much food an organism will require.
A striking feature of metabolism is the similarity of the metabolic pathways. These striking similarities in metabolic pathways are likely due to their appearance in evolutionary history. Most of the structures that make up animals, plants and microbes are made from three classes of molecule, amino acids, carbohydrates and lipids. These biochemicals can be joined together to make such as DNA and proteins.
Proteins are made of amino acids arranged in a linear chain joined together by peptide bonds, many proteins are enzymes that catalyze the chemical reactions in metabolism.