BIOS 256 Week 2 Case Study Lower GI
Student Name
Chamberlain University
BIOS-256: Anatomy & Physiology IV with Lab
Prof. Name
Date
Week 2: Case Study 2
1. What happens when the small intestine receives chyme from the stomach?
Once the stomach has processed food into chyme, this semi-liquid substance enters the small intestine, beginning with the duodenum. Here, it is blended with bile from the liver and digestive enzymes from the pancreas. These secretions help break down proteins, carbohydrates, and lipids further. The muscular movements known as segmentation churn the chyme, ensuring that it mixes thoroughly with digestive juices and comes into contact with the intestinal lining, or mucosa, to maximize nutrient absorption.
Peristaltic contractions subsequently push the chyme through the small intestine, passing through the jejunum and eventually into the ileum. Tiny finger-like projections called villi and even smaller microvilli line the small intestine, dramatically increasing surface area and aiding in the absorption of digested nutrients into the bloodstream. As digestion nears completion in the ileum, most fats, proteins, and carbohydrates have been absorbed.
At this stage, hormones such as cholecystokinin and peptide YY are released, signaling satiety, or the sensation of fullness. Remaining undigested food components travel toward the large intestine through the ileocecal valve, entering the cecum, a pouch-like structure that temporarily holds the material. From there, slow peristalsis propels the waste through the colon.
Within the colon, bacteria ferment the remaining carbohydrates, generating beneficial substances like vitamin B and K, as well as short-chain fatty acids. As the contents pass into the sigmoid colon, water is absorbed, converting the material into a more solid form. This solidified waste, now known as stool, is stored in the sigmoid colon until mass movements shift it into the rectum. The rectum stretches as it fills, activating the defecation reflex. The anus, controlled voluntarily by external muscles, ultimately allows for the expulsion of feces (Saladin, 2020).
2. What are two important functions of the small intestine?
The small intestine plays a pivotal role in digestion and absorption. Its two primary functions are:
- Digestion and Nutrient Absorption: It breaks down food using enzymes and absorbs essential nutrients—including carbohydrates, proteins, fats, vitamins, and minerals—into the bloodstream.
- Waste Transportation: After digestion, it transfers any undigested waste toward the large intestine and begins absorbing remaining water and electrolytes (Children’s Hospital, 2022).
Week 2: Case Study 3
3. What are two important functions of the large intestine?
The large intestine performs essential roles in the body, particularly in the later stages of digestion. Its key functions include:
- Motility and Elimination: Movements such as haustral churning (which helps mix and compact the waste), regular peristalsis, and mass peristalsis (which pushes waste toward the rectum) help in the elimination of fecal matter.
- Absorption and Microbial Action: It absorbs vitamins, particularly vitamin K and certain B vitamins, that are produced by intestinal bacteria. These microbes also assist in breaking down remaining nutrients and maintaining gut health (Saladin, 2020).
| Function Type | Description |
|---|---|
| Motility | Haustral churning, peristalsis, and mass movements push contents forward |
| Absorption and Bacteria | Vitamins are synthesized by bacteria and absorbed; fermentation also occurs |
4. Where would the pain be located in this case?
If a patient is experiencing pain related to the large intestine, particularly involving the sigmoid colon or descending colon, the discomfort is typically localized to the left lower quadrant (LLQ) of the abdomen (Saladin, 2020).
5. What are two functions of the peritoneum?
The peritoneum, a thin membrane lining the abdominal cavity and covering the abdominal organs, has several critical functions:
- Protection and Support: It anchors abdominal organs in place and provides them with a cushion, preventing injury and allowing them to maintain anatomical position.
- Conduit for Vessels and Nerves: It serves as a passageway for blood vessels, lymphatics, and nerves that supply the abdominal organs. This ensures proper nutrient delivery and communication between the organs and the rest of the body (Saladin, 2020).
| Peritoneal Function | Description |
|---|---|
| Organ Protection | Cushions and secures abdominal organs |
| Conduit Function | Allows passage of blood vessels, lymphatics, and nerves |
References
Children’s Hospital of Pittsburgh. (2022). Differences in small & large intestines: Children’s Pittsburgh. Retrieved November 6, 2022, from https://www.chp.edu/our-services/transplant/intestine/education/about-small-largeintestines
BIOS 256 Week 2 Case Study Lower GI
Saladin, K. S. (2020). Anatomy & Physiology: The Unity of Form and Function (9th ed.). McGraw-Hill Higher Education (US).