Chemistry ConnectionsEpisode #24  

Welcome to Chemistry Connections, my name is Josh Beigman and along with Henry Stanton we are your hosts for episode #24 called The Chemistry of a Crocodile's Stomach. Today we will be discussing the Chemistry of the most powerful digestive system in the animal kingdom.

Segment 1: Introduction to The Chemistry of a Crocodile's Stomach

• Crocodiles are able to digest almost anything they eat, so they swallow their food whole and then digest it.
• Crocodile stomachs are strong enough to dissolve anything they eat, which is the whole animal. This includes meat, cartilage, and even bone. They are able to eat rotten carcasses without feeling any effect from dangerous bacteria. 
• Their stomachs have even been found to be able to dissolve steel nails. 
• We found this interesting and wanted to learn more about it, so we made a podcast episode about it.
• Crocodiles are large reptiles that prey on a variety of animals, which means that they have to be able to digest almost all kinds of animals.

Segment 2: The Chemistry Behind a Crocodile's Stomach

• The HCl in the stomach helps break down what the crocodile has eaten faster because the Cl- ions denature the proteins because the Hydrogen bonds that were between the proteins are now replaced by ion dipole bonds between the Cl- ions and the proteins, which is a stronger type of bond. These denatured proteins are now able to be digested by enzymes like pepsin.
• All animal stomachs use HCl to break down the food they ingest. The HCl is produced by water and carbon dioxide reacting to make H2CO3, which dissociates into H+ and HCO3-. The HCO3- are exchanged for Cl- ions through an anion exchanger. The H+ ions and Cl- ions are then pumped into the stomach and break down the food.
• The reaction to create carbonic acid, or H2CO3, is catalyzed by the presence of an enzyme called Carbonic anhydrase. 
• The difference between a crocodile's stomach and a human's stomach is the amount of acid they are able to produce.
• Crocodiles are able to produce large amounts of HCl because their hearts have (aorta) a way to redirect CO2 from the lungs and send it to the stomach instead, which allows for more H+ ions to be produced, since CO2 is necessary for its production, so having more of it allows for more H+ to be produced. The pH of a crocodile's stomach is between 1 and 3.

Segment 3: Personal Connections

We always knew that stomach acid is extremely powerful, and that some animals are able to eat just about anything and come out none the worse for it. Human stomachs can't safely digest rotten food, and yet some animals like vultures and other scavengers eat nothing but food infested with lethal bacteria. After taking AP chemistry this year, we realized we had enough knowledge to understand the process of these super strong animal stomachs, so we used this project as an opportunity to investigate this 

Thank you for listening to this episode of Chemistry Connections. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. 

Sources:

https://www.abc.net.au/science/articles/2008/02/11/2159238.htm 

https://www.britannica.com/animal/crocodile-order 

https://teachmephysiology.com/gastrointestinal-system/stomach/acid-production/ 

https://en.wikipedia.org/wiki/Hydrochloric_acid 

https://en.wikipedia.org/wiki/Gastric_acid 

https://www.ifst.org/lovefoodlovescience/resources/protein-acid-denaturation 

Music Credits

Warm Nights by @LakeyInspired