Drugs In the body

-injection directly into the vein

first it passes throughout the body through the veins. depending on actual route. it enters venous system and gets returned to heart with deoxygenated blood before travelling to lung and back to the heart.

orally take a pill

it diffuses into capillaries in the stomach and small intestine that connect to blood vessels that go directly to the liver. remnants travel to small intestine where finish dissolving.

on skin with a patch, it can be absorb into the skin

the pill gets absorbed into the stomach lining and acid breaks it down in the gastrointestinal tract

directly crossing plasma membrane

the mechanism of transport of drugs can be divided into two types; simple diffusion and carrier-medicated transport

three ways drugs go through; first being passive transfusion by lipophilic drugs through the membrane.

second being passive transfusion by hydrophilic drugs through pores and gap junctions

third being active transport of larger molecules by transport proteins

the body receives chemical information from molecules such as drugs and hormones- outside the cell

those molecules than bind to receptors on the cell, activating the receptor and generating a biochemical or electric signal inside the cell

molecules that bind to a receptor are called ligands

the binding can be specific and reversible. a ligand may activate or inactive a receptor; activation may increase or decrease particular cell function

The majority of drugs which act on enzymes act as inhibitors and most of these are competitive

compete for binding with enzymes substrate

molecules have a specific three-dimensional structure which allows only substances that fit precisely to attach to it.

Increased volume of distribution for lipid-soluble drugs

The distribution of a drug between fat and lean tissues may influence its pharmacokinetics

when drugs are taken orally they pass through the gastrointestinal tract, absorbed by stomach acid and then finally reach the liver

once in liver enzymes convert prodrugs to active metabolites or convert active drugs to inactive forms

metabolizing drugs is via a specific group of cytochrome P-450 enzymes

it binds to the target receptor site, they can either block the physiological function of the protein, or mimics it's effect

Proteins are large, complex molecules that play many critical roles in the body

most of the work in cells and are required for the structure, function, and regulation of the body’s tissues and organs.