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An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen ion, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid.
Hydrolysis is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile.
A buffer solution is an acid or a base aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa. Its pH changes very little when a small amount of strong acid or base is added to it. Buffer solutions are used as a means of keeping pH at a nearly constant value in a wide variety of chemical applications. In nature, there are many living systems that use buffering for pH regulation. For example, the bicarbonate buffering system is used to regulate the pH of blood, and bicarbonate also acts as a buffer in the ocean.
In chemistry, an acid dissociation constant is a quantitative measure of the strength of an acid in solution. It is the equilibrium constant for a chemical reaction
A pH indicator is a halochromic chemical compound added in small amounts to a solution so the pH (acidity or basicity) of the solution can be determined visually or spectroscopically by changes in absorption and/or emission properties. Hence, a pH indicator is a chemical detector for hydronium ions (H3O+) or hydrogen ions (H+) in the Arrhenius model. Normally, the indicator causes the color of the solution to change depending on the pH. Indicators can also show change in other physical properties; for example, olfactory indicators show change in their odor. The pH value of a neutral solution is 7.0 at 25°C (standard laboratory conditions). Solutions with a pH value below 7.0 are considered acidic and solutions with pH value above 7.0 are basic. Since most naturally occurring organic compounds are weak electrolytes, such as carboxylic acids and amines, pH indicators find many applications in biology and analytical chemistry. Moreover, pH indicators form one of the three main types of indicator compounds used in chemical analysis. For the quantitative analysis of metal cations, the use of complexometric indicators is preferred, whereas the third compound class, the redox indicators, are used in redox titrations (titrations involving one or more redox reactions as the basis of chemical analysis).
In chemistry, there are three definitions in common use of the word base, known as Arrhenius bases, Brønsted bases, and Lewis bases. All definitions agree that bases are substances that react with acids, as originally proposed by G.-F. Rouelle in the mid-18th century.
In cell biology, extracellular fluid (ECF) denotes all body fluid outside the cells of any multicellular organism. Total body water in healthy adults is about 60% of total body weight; women and the obese typically have a lower percentage than lean men. Extracellular fluid makes up about one-third of body fluid, the remaining two-thirds is intracellular fluid within cells. The main component of the extracellular fluid is the interstitial fluid that surrounds cells.
In chemistry and biochemistry, the Henderson–Hasselbalch equation
A hydrogen ion is created when a hydrogen atom loses or gains an electron. A positively charged hydrogen ion (or proton) can readily combine with other particles and therefore is only seen isolated when it is in a gaseous state or a nearly particle-free space. Due to its extremely high charge density of approximately 2×1010 times that of a sodium ion, the bare hydrogen ion cannot exist freely in solution as it readily hydrates, i.e., bonds quickly. The hydrogen ion is recommended by IUPAC as a general term for all ions of hydrogen and its isotopes. Depending on the charge of the ion, two different classes can be distinguished: positively charged ions and negatively charged ions.
In chemistry, neutralization or neutralisation is a chemical reaction in which acid and a base react quantitatively with each other. In a reaction in water, neutralization results in there being no excess of hydrogen or hydroxide ions present in the solution. The pH of the neutralized solution depends on the acid strength of the reactants.
An acid–base titration is a method of quantitative analysis for determining the concentration of an acid or base by exactly neutralizing it with a standard solution of base or acid having known concentration. A pH indicator is used to monitor the progress of the acid–base reaction. If the acid dissociation constant (pKa) of the acid or base dissociation constant (pKb) of base in the analyte solution is known, its solution concentration (molarity) can be determined. Alternately, the pKa can be determined if the analyte solution has a known solution concentration by constructing a titration curve.
Indometacin, also known as indomethacin, is a nonsteroidal anti-inflammatory drug (NSAID) commonly used as a prescription medication to reduce fever, pain, stiffness, and swelling from inflammation. It works by inhibiting the production of prostaglandins, endogenous signaling molecules known to cause these symptoms. It does this by inhibiting cyclooxygenase, an enzyme that catalyzes the production of prostaglandins.
Polyelectrolytes are polymers whose repeating units bear an electrolyte group. Polycations and polyanions are polyelectrolytes. These groups dissociate in aqueous solutions (water), making the polymers charged. Polyelectrolyte properties are thus similar to both electrolytes (salts) and polymers and are sometimes called polysalts. Like salts, their solutions are electrically conductive. Like polymers, their solutions are often viscous. Charged molecular chains, commonly present in soft matter systems, play a fundamental role in determining structure, stability and the interactions of various molecular assemblies. Theoretical approaches to describing their statistical properties differ profoundly from those of their electrically neutral counterparts, while technological and industrial fields exploit their unique properties. Many biological molecules are polyelectrolytes. For instance, polypeptides, glycosaminoglycans, and DNA are polyelectrolytes. Both natural and synthetic polyelectrolytes are used in a variety of industries.
Ion chromatography separates ions and polar molecules based on their affinity to the ion exchanger. It works on almost any kind of charged molecule—including large proteins, small nucleotides, and amino acids. However, ion chromatography must be done in conditions that are one unit away from the isoelectric point of a protein.
Absorption is the journey of a drug travelling from the site of administration to the site of action.
The Gibbs–Donnan effect is a name for the behaviour of charged particles near a semi-permeable membrane that sometimes fail to distribute evenly across the two sides of the membrane. The usual cause is the presence of a different charged substance that is unable to pass through the membrane and thus creates an uneven electrical charge. For example, the large anionic proteins in blood plasma are not permeable to capillary walls. Because small cations are attracted, but are not bound to the proteins, small anions will cross capillary walls away from the anionic proteins more readily than small cations.
Polar auxin transport is the regulated transport of the plant hormone auxin in plants. It is an active process, the hormone is transported in cell-to-cell manner and one of the main features of the transport is its asymmetry and directionality (polarity). The polar auxin transport functions to coordinate plant development; the following spatial auxin distribution underpins most of plant growth responses to its environment and plant growth and developmental changes in general. In other words, the flow and relative concentrations of auxin informs each plant cell where it is located and therefore what it should do or become.
A symporter is an integral membrane protein that is involved in the transport of two different molecules across the cell membrane in the same direction. The symporter works in the plasma membrane and molecules are transported across the cell membrane at the same time, and is, therefore, a type of cotransporter. The transporter is called a symporter, because the molecules will travel in the same direction in relation to each other. This is in contrast to the antiport transporter. Typically, the ion(s) will move down the electrochemical gradient, allowing the other molecule(s) to move against the concentration gradient. The movement of the ion(s) across the membrane is facilitated diffusion, and is coupled with the active transport of the molecule(s). In symport, two molecule move in a 'similar direction' at the 'same time'. For example, the movement of glucose along with sodium ions.
Acid–base extraction is a subclass of liquid–liquid extractions and involves the separation of chemical species from other acidic or basic compounds. It is typically performed during the work-up step following a chemical synthesis to purify crude compounds and results in the product being largely free of acidic or basic impurities. A separatory funnel is commonly used to perform an acid-base extraction.
Liberation is the first step in the process by which medication enters the body and liberates the active ingredient that has been administered. The pharmaceutical drug must separate from the vehicle or the excipient that it was mixed with during manufacture. Some authors split the process of liberation into three steps: disintegration, disaggregation and dissolution. A limiting factor in the adsorption of pharmaceutical drugs is the degree to which they are ionized, as cell membranes are relatively impermeable to ionized molecules.
References
- ↑ Stephanie T. Weiss (1 January 2009). High-Yield Pharmacology. Lippincott Williams & Wilkins. pp. 3–. ISBN 978-0-7817-9273-8.
- ↑ D. T. Okpako (22 February 1991). Principles of Pharmacology: A Tropical Approach. Cambridge University Press. pp. 118–. ISBN 978-0-521-34095-3.
- ↑ "Angelfire". Archived from the original on 2016-03-05. Retrieved 2014-01-07.
- ↑ Mahoney BP, Raghunand N, Baggett B, Gillies RJ (Oct 2003). "Tumor acidity, ion trapping and chemotherapeutics.I Acid pH affects the distribution of chemotherapeutic agents in vitro". Biochem Pharmacol. 66 (7): 1207–18. doi:10.1016/s0006-2952(03)00467-2. PMID 14505800.