Biology is designed for multi-semester biology courses for science majors. It is grounded on an evolutionary basis and includes exciting features that highlight careers in the biological sciences and everyday applications of the concepts at hand. To meet the needs of today’s instructors and students, some content has been strategically condensed while maintaining the overall scope and coverage of traditional texts for this course. Instructors can customize the book, adapting it to the approach that works best in their classroom. Biology also includes an innovative art program that incorporates critical thinking and clicker questions to help students understand—and apply—key concepts.

By the end of this section, you will be able to:Explain the processes of digestion and absorptionCompare and contrast different types of digestive systemsExplain the specialized functions of the organs involved in processing food in the bodyDescribe the ways in which organs work together to digest food and absorb nutrients

To reinforce students' understanding of the human digestion process, the functions of several stomach and small intestine fluids are analyzed, and the concept of simulation is introduced through a short, introductory demonstration of how these fluids work. Students learn what simulation means and how it relates to the engineering process, particularly in biomedical engineering. The teacher demo requires vinegar, baking soda, water and aspirin.

The digestive system is amazing: it takes the foods we eat and breaks them into smaller components that our body can use for energy, cell repair and growth. This lesson introduces students to the main parts of the digestive system and how they interact. In addition, students learn about some of the challenges astronauts face when trying to eat in outer space.

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"Past research has already tied our gut microbiome to many diseases. However, most research to date has focused on the large intestine, as collecting stool samples is less invasive than sampling the small intestine. Recently, researchers used standard-of-care endoscopies as an opportunity to collect samples from the first section of the small intestine, the duodenum. Using quantitative sequencing, they evaluated the patients' microbial loads. They found preliminary evidence of microbes traveling from the mouth to the small intestine, as 89% of the microbial taxa found in duodenum samples were also present in saliva samples from the same patient. Within the duodenum, the researchers identified a collection of bacterial taxa that, when present, often dominated the microbial population. These ‘disruptor taxa’ appeared to replace the strict anaerobes common in the duodenum and were more prevalent in individuals with the serious GI disorder small intestinal bacterial overgrowth (SIBO)..."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.

The duodenum is the proximal part of the small intestine and extends from the pylorus of the stomach to the jejunum. It has descending and ascending portions and both portions have digestive and absorptive functions.

This activity was designed for blind learners, but all types of learners can use it to understand how villi function in the small intestine. The purpose of this activity is to examine a model of the inside of the small intestine to support understanding of the function of villi in digestion.

The ileum is the terminal portion of the small intestine and continues from the jejunum. It opens into the caecum at the ileocaecal orifice. The intestinal epithelium is mainly absorptive, with much less digestion occurring compared to the duodenum and the jejunum.

The jejunum continues from the duodenum and leads into the ileum. It is the longest part of the small intestine and is highly coiled. It has digestive and absorptive functions.

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"Alterations to the microbial communities that live in our gut are being linked to various diseases But researchers are only beginning to understand these links Although mouse models have proven incredibly useful, they suffer from a major drawback Laboratory mice have a persistent tendency to re-introduce microbes into their bodies when they ingest feces -- a behavior known as coprophagy A new study shows that this habit can dramatically re-shape the upper gut microbiome and its function Researchers fit mice with special “tail cups” to prevent coprophagy They then compared the microbiomes of these non-coprophagic mice with the microbiomes of standard (coprophagic) lab mice The differences were striking Compared with conventional, coprophagic mice, non-coprophagic mice showed patterns more similar to those found in the human small intestine including lower microbiota density fewer microbes intolerant to oxygen and a higher ratio of conjugated bile acids, which are important for digesting fats.."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.

The small intestine extends from the pylorus of the stomach to the caecum. The small intestine recieves chyme from the stomach. It is the main site of chemical degradation and absorption of chyme. Fats are exclusively broken down in this part of the alimentary tract. Carbohydrates and proteins that are not degraded in the small intestine are available for microbial fermentation in the large intestine. The small intestine produces enzymes for digestion of protein, carbohydrate and fat and absorbs the products of their digestion. Enzymes are produced by glands in the intestinal wall and the pancreas. The gall bladder produces bile which emulsifies fats for digestion. Absorption is facilitated by ridges in the small intestine and by the presence of villi and microvilli.