June 4, 2023

Copyright Sheffield Hallam University

After swallowing an aspirin tablet it will go on a journey through your digestive system absorption the tablet will travel down the esophagus into the stomach where it is dissolved into much smaller particles these particles will continue their journey into the small intestine where most of them will be absorbed into the blood the small intestine wall off-the-court

Lumen are lined with tiny villi which stick out to provide a large surface area for the nutrients inside the food to be absorbed looking closer at these below you can see they have a rich blood supply an hour covered in a thin layer of epithelial cells the aspirin molecules will work their way through the epithelial cells and into the bloodstream where they are

Carried around the body distribution blood plasma contains complex molecules called alderman albumin is a protein made by the liver which transports nutrients around the body albumin also binds to drugs that enter the bloodstream here you can see some of the aspirin molecules binding to the albumin all the aspirin particles that have been bound will be filtered

Out as a class through the liver and only the remaining aspirin molecules will get through and have any effect on the body different drugs will bind to albumin in different amounts depending on their affinity for plasma protein the next stop on the journey is the liver the aspirin rich blood will enter the liver through the hepatic portal vein at the bottom and

It will exit at the top via the hepatic vein at this stage even more of the aspirin will be removed through a process called first pass metabolism the livers job is a bit like a filter it will metabolize drugs before they reach the rest of the body it does this in a few steps phase 1 metabolism first aspirin is hydrolyzed breaking off ethanoic acid and leaving

Behind salicylic acid this salicylic acid isn’t water-soluble so it can’t be excreted in urine yet phase 2 metabolism an ionized group is then added to the salicylic acid forming clicker enoyed which is water-soluble and can be excreted in urine a lot less of the aspirin will continue its journey onto the rest of the body including the site of the pain only 68%

Of orally taking aspirin will have any effect at all because of all the filtering that the body has done this percentage is called the drugs oral bioavailability if drugs are not administered orally eg intravenously or bucoli then they can bypass the small intestine and liver so none of this culturing takes place and they are 100% bioavailability we are now at the

Site to some skin tissue damage tissues in the skin are creating prostaglandins which are causing inflammation the prostaglandins are sending messages to the nerves in the skin responsible for the sensation of pain once the a spring arrives in the blood supply at the site it prevents the production of prostaglandins and the tissue which will reduce the swelling

And stop the messages being sent to the nerves but at the seaters pain excretion any remaining aspirin in the blood will go round and round the blood supply going back through the liver several times until it is all used up or filtered out of the body it traveled into the kidneys and then into the bladder for excretion

Transcribed from video
Aspirin Journey through the body – 3D Animation By 3D Steve