Dosage form

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 Dosage Forms: - Dosage forms are the carrier through which drug molecules are delivered to sites of action within the body. - Every dosage forms is a combination of the drug and different kinds of non–drug components called as Excipients or additives. - The additives are used to give a particular shape to the formulation, to increase stability, palatability & more elegance to preparations. TYPES OF DOSAGE FORM 1. Solid dosage forms            2. Liquid dosage forms 3. Semi-solid dosage forms 1. Solid dosage forms  Tablets: 1. These are solid unit dosage forms of medicaments intended for oral administration which are prepared by molding or by compression with or without excipient 2. The tablets can be prepared by two methods namely as a I) Dry granulation, II) Wet Granulation Capsule: 1. Capsules are solid unit dosage forms in which one or more medicaments enclosed within a gelatin shell. 2. Capsules mainly divided into two parts namely as – B...
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TRANSPORT ACROSS CELL MEMBRANE

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          TRANSPORT ACROSS CELL MEMBRANE 




TWO TYPES SS CELL OF TRANSPORT ACROSS CELL  MEMBRANE-

1. ACTIVE TRANSPORT
2. PASSIVE TRANSPORT

 1. ACTIVE TRANSPORT -

  Substances that are too large or polar diffuse across the lipid bilayer on their own through membrane proteins called carriers, permeases, channels, and transporters. Unlike active transport, this process does not involve chemical energy. So the passive mediated transport is totally dependent upon the permeability nature of cell membrane, which in turn, is a function of organization and characteristics of membrane lipids and proteins. 

 Types of Active transport: 

 1. Diffusion: Diffusion is the movement of particles from an area of high concentration to an area of low concentration.
                       
                      Any time a substance is moving from high
concentration to low concentration we say that it is
moving down the concentration gradient
                   
                       No energy (ATP) is required for these processes


 2. Facilitated diffusion: The process of the movement of molecules across the cell membrane via special transport proteins that are embedded within the cellular membrane is known as facilitated diffusion or called carrier-mediated diffusion. Many large molecules, such as glucose, are insoluble in lipids and too large to fit into the porins, therefore, it will bind with its specific carrier proteins, and the complex will then be bonded to a receptor site and moved through the cellular membrane. 

 3. Filtration: Filtration is the process of the movement of water and solute molecules across the cell membrane due to hydrostatic pressure generated by the system. Depending on the size of the membrane pores, only solutes of a certain size may pass through it. The membrane 
pores of the Bowman's capsule in the kidneys are very small, and only albumins (smallest of the proteins) can filter through. On the other hand, the membrane pores of liver cells are extremely large, to allow a variety of solutes to pass through and be metabolized. 

 4. Osmosis: Osmosis is the type of diffusion of water molecules across a semi-permeable membrane, from a solution of high water potential to a region of low water potential. A cell with a less negative water potential will draw in water but this depends on other factors as well such as solute potential (pressure in the cell e.g. solute molecules) and pressure potential (external pressure e.g. cell wall). 
Active transport: Active transport is the movement of a substance against its concentration gradient (i.e. from low to high concentration). It is an endergonic process that, in most cases, is coupled to the hydrolysis of ATP. 

 Types of active transport: 

 1. Primary active transport: Primary active transport, also called direct active transport, directly uses energy to transport molecules across a membrane. Example: Sodium-potassium pump, which helps to maintain the cell potential.

2. Secondary active transport: Secondary active transport or co-transport, also uses energy to transport molecules across a membrane; however, in contrast to primary active transport, there is no direct coupling of ATP; instead, the electrochemical potential difference created by pumping ions out of the cell is instrumental. The two main forms of active transport are antiport and symport.

(a) Antiport: In antiport, two species of ion or solutes are pumped in opposite directions across a membrane. One of these species is allowed to flow from high to low concentration which yields the entropic energy to drive the transport of the other solute from a low concentration region to a high one. Example: the sodium-calcium exchanger or antiporter, which allows three sodium ions into the cell to transport one calcium out. 

 (b) Symport: Symport uses the downhill movement of one solute species from high to low concentration to move another molecule uphill from low concentration to high concentration (against its electrochemical gradient). Example: glucose symporter SGLT1, which co-transports one glucose (or galactose) molecule into the cell for every two sodium ions it imports into the cell
Location: यूनाइटेड किंगडम

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