Digestion: A Great Discovery
Unit #9 Assignment
Good morning everyone!! Are we ready for another exciting trip through the human body?! Today we will be following the food of 55 year old Harold who recently ate a hamburger and French fries and is now washing it down with a nice tall root beer. We will be following his meal through his GI tract and I will tell you all about all the structures that we will see on the way. Once we arrive at the distal ileum, we will make a small change to our route by getting into his blood stream. We will follow the superior mesenteric vein to the renal artery. Once there, we will travel through the ...view middle of the document...
The duodenum is 25 cm long and has many villi that absorb nutrients. If you look really close between the villi, you will see the glands that are responsible for secretion of alkaline mucus that protects the small intestine from the chymes acid. The villi contain blood capillaries and lymphatic vessel that is used to absorb lipids. In the middle part of the duodenum we come to two openings that are the minor and major duodenal papillae. This is where bile from the liver and pancreatic digestive fluid get put into the duodenum. (Patton & Thibodeau, 2008). Bile is a dark green to brown liquid that contains cholesterol, bile salt and bile pigments, while pancreatic juice contains mainly water and enzymes. Enzymes that can be found in the pancreatic juice are amylase, protease and Lipase as well as sodium bicarbonate. The chyme now enters the jejunum, or the second part of the small intestine, where absorption begins. The jejunum also contains numerous villi and also has many large circular folds that are called plicae circulares. These folds make nutrient absorption easier by increasing the surface area and the majority of nutrients are absorbed here. We will now enter the ileum with the chyme, which is the longest part of the small intestine. Like the other two parts of the small intestine, there are villi, as well as lymphoid tissue which contain large numbers of lymphocytes and generate immune response in case of pathogenic attacks. They chyme will not be broken down into small molecules and some of them get absorbed into the blood through membranes. We will be getting into the veins at this point because the ileum veins drain into the superior mesenteric vein which will get us into Harold’s circulatory system. You can tell that we are in the superior mesenteric vein because of the conjunction with the splenic vein which forms the hepatic portal vein. The hepatic portal vein drains the blood to capillary beds in the liver. We now enter the inferior vena cava and travel towards the right atrium of the heart where deoxygenated blood is moving to the right ventricle by way of the tricuspid valve and then into the pulmonary artery via the...