Discussion
Initial Post Instructions
The digestive system is composed of two parts: the alimentary canal and the accessory digestive structures. These two parts of the system work together to break down food into absorbable units and eliminate the non-digested material as feces. Let’s begin by identifying each of the organs in the alimentary canal and the accessory digestive structures.
Choose one organ/structure and post details about it to begin the discussion. Choose a different organ for each of your follow up posts to ensure everyone has an opportunity to contribute.
Writing Requirements
- Minimum of 2 posts (1 initial & 1 follow-up)
- Minimum of 2 sources cited (assigned readings/online lessons and an outside source)
- APA format for in-text citations and list of references
Answer
Post 1: The Stomach
The stomach is a vital organ in the digestive system located between the esophagus and the small intestine. It plays a crucial role in the mechanical and chemical digestion of food. The stomach is a muscular sac that expands to accommodate food and mixes it with digestive juices, turning it into a semi-liquid substance called chyme.
The stomach has three main regions: the fundus, body, and pylorus. The fundus is the uppermost part of the stomach, which is primarily involved in storing swallowed food. The body is the central portion responsible for mixing and churning the food with digestive enzymes and acids. The pylorus is the lower region that connects the stomach to the small intestine through the pyloric sphincter.
The stomach has specialized cells that secrete gastric juices. These secretions include hydrochloric acid, which helps break down food and kill bacteria, and enzymes such as pepsin, which initiates the digestion of proteins. The stomach also produces mucus to protect its lining from the corrosive effects of the acidic environment.
The digestion process in the stomach involves both mechanical and chemical actions. The muscular walls contract and relax in a rhythmic manner, creating a churning motion that helps mix the food with gastric juices. This mechanical action, known as peristalsis, further breaks down the food into smaller particles. The gastric juices, particularly the hydrochloric acid and pepsin, start the chemical breakdown of proteins into peptides.
References:
- Tortora, G. J., Derrickson, B. H. (2017). Principles of Anatomy and Physiology. Wiley.
- Saladin, K. S. (2018). Anatomy & Physiology: The Unity of Form and Function. McGraw-Hill Education.
