The Ruminant Digestive System: The DUODENUM

In this seventh episode of the Series, we finally move from the ‘4-stomach structure’ to the small intestine, which completes the majority of the digestive process that didn’t happen in the stomachs and absorbs many nutrients through its particular structure made of villi (similar to ‘small fingers’), which have the role to ‘collect’ the nutrients and move them into the blood and lymphatic systems.The small intestine is formed by duodenum, jejunum and ileum, and in the next three episodes we will analyse all of them!

Let’s see now some of the most important structures and functions of the duodenum.

Structure

The duodenum is the proximal section of the small intestine, and it is located between the pylorus (which connect the small intestine with the ) and the jejunum, where the digesta leaving the stomach are mixed with secretions that come from the pancreatic and the bile ducts.
In general, the intestinal wall is made of numerous “finger-like” projections called villi that have the role to increase the intestinal surface area in order to improve the nutrients absorption.
Moreover, muscular tissue is present; in fact, it is important to have muscular contractions which aid the mixing of the digesta and the movement of them into the next section of the intestine, the jejunum — we will talk about this section in the next episode.

Function

In the duodenum, the digesta coming from the stomachs arrived with a pH of roughly 2.5, which is too low for the intestinal structure. For this reason, secretion from the gallbladder and the pancreas mix with the partially digested matter to increase the pH to 7–8, which is the optimum for the correct functioning of the enzymes of the small intestine. These secretions have the main role to aid the digestion, in fact, throughout the small intestine we can observe an active nutrient absorption, which include also the rumen bypass proteins.

Take home messages

• The duodenum is the proximal section of the small intestine, and it is located between the pylorus (which connect the small intestine with the abomasum) and the jejunum
• The intestinal wall is made of numerous “finger-like” projections called villi that have the role to increase the intestinal surface area in order to improve the nutrients absorption
• Muscular contractions aid the mixing of the digesta and the movement of them into the next section of the intestine
• Secretion from the gallbladder and the pancreas mix with the partially digested matter to increase the pH to 7–8, which is the optimum for the correct functioning of the enzymes of the small intestine

Originally published at https://rubenriosa.com on June 12, 2020.