Definitions
Stomach
A muscular organ located on the left side of the upper abdomen, responsible for breaking down food using stomach acids and enzymes.
Peristalsis
A series of wave-like muscle contractions that move food through the digestive tract.
Small Intestine
The part of the gastrointestinal tract between the stomach and the large intestine, responsible for nutrient absorption.
Structure and Function of the Stomach
The stomach is divided into four main regions: the cardia, fundus, body, and pylorus. It serves several key functions in digestion, primarily the mechanical breakdown of food and the chemical digestion through gastric juices. These gastric juices contain hydrochloric acid and the enzyme pepsin, which begin the breakdown of proteins into peptides.
Movement in the Stomach
The movement in the stomach includes intrinsic contractions that help mix the food with digestive juices, forming a semi-liquid mixture called chyme. These contractions are promoted by the stomach's smooth muscle layers in a coordinated manner, often referred to as peristaltic waves.
Regulation of Stomach Movements
Gastric motility is influenced by neural and hormonal signals. The vagus nerve plays a crucial role in regulating contraction strength and frequency, while hormones such as gastrin stimulate gastric movements and secretion of gastric juices.
Anatomy and Function of the Small Intestine
The small intestine is composed of three main parts: the duodenum, jejunum, and ileum. It is the primary site for digestion and absorption of nutrients. Enzymes from the pancreas and bile from the liver further aid in breaking down food into its nutrient components.
Movements in the Small Intestine
The movement pattern in the small intestine primarily includes segmentation and peristalsis. Segmentation involves rhythmic contractions that mix intestinal contents, while peristalsis propels the food down the tract. These movements are crucial for the thorough mixing and absorption of nutrients.
To remember :
The stomach and small intestines play crucial roles in digestion through mechanical and chemical processes. The stomach initiates protein digestion and churns food into chyme, while the small intestine completes the digestive process and absorbs nutrients. Movements such as peristalsis are key to advancing the digestive contents, and are regulated by a complex interplay of neural and hormonal factors.
