Difference Between Small and Large Intestine

Main Difference – Small vs Large Intestine

Small and large intestine are the two portions of the intestine. Intestine is one of the components of the alimentary canal which is found between the stomach and the anus. Duodenum, jejunum, and ileum are the three components of the small intestine while cecum, colon, rectum, and anal canal are the four components of the large intestine. Small intestine contains circular layers of longitudinal muscles. However, in the large intestine, these longitudinal muscles are arranged in three bands called Teniae coli. The main difference between small and large intestine is that small intestine absorbs digested nutrients whereas large intestine absorbs water from the indigestible residue.

Key Areas Covered

1. What is Small Intestine
      – Definition, Components, Function
2. What is Large Intestine
      – Definition, Components, Function
3. What are the Similarities Between Small and Large Intestine
      – Outline of Common Features
4. What is the Difference Between Small and Large Intestine
      – Comparison of Key Differences

Key Terms: Alimentary Canal, Cecum, Colon, Duodenum, Ileum, Jejunum. Large Intestine, Nutrients, Small Intestine, Water

What is Small Intestine

Small intestine is the part of the intestine which runs between the stomach and the large intestine. It is 4.5-7.0 m long and processes 2 gallons of liquids per day. Segmentation is the type of mechanical digestion that occurs in the small intestine. Duodenum, jejunum, and ileum are the three components of the small intestine. Duodenum receives food from the stomach through the pylorus. As this food is semi-digested, the duodenum continuous the digestive process by receiving enzymes as well as bile from the liver, pancreas, and gallbladder. The middle section of the small intestine is the jejunum. It rapidly carries food by wave-like contractions of the circular, longitudinal muscles. Ileum receives food from the jejunum. The longest part of the small intestine is the ileum. Most nutrients of the digested food are absorbed by the ileum. The anatomy of the small intestine is shown in figure 1.

Figure 1: Small Intestine

Small intestine is the major component of the alimentary canal that absorbs nutrients from food. It has a surface area of about 250 square meters for absorptive purposes. Three features are involved in increasing the surface area of the intestine: mucosal folds, villi, and microvilli. The histological structure of the wall of the small intestine is shown in figure 2.

Figure 2: Small Intestine Histology

The mucosal folds are the circular folds in the inner surface of the small intestine. They regulate the flow of digested food through the small intestine as well. Villi are the tiny projections of the folds which are covered with nutrient-absorbing cells. Microvilli are tiny, hair-like structures which increase the surface area of each of those cells.

What is Large Intestine

Large intestine is the terminal part of the intestine, which is wider and shorter than the small intestine. It is about 1.5 m long. The large intestine is much shorter and broader than the small intestine. The path inside the large intestine is straight to a certain degree. The food that arrives at the large intestine is already digested, and their nutrients have been absorbed by the small intestine. Hence, the main purpose of the large intestine is to absorb water from the indigestible food. The anatomy of the large intestine is shown in figure 3.

Figure 3: Large Intestine

Cecum, colon, rectum, and anal canal are the four components of the large intestine. Cecum is about two inches long and passes food from the ileum to the colon. The major section of the large intestine is the colon. Ascending colon, transverse colon, descending colon, and sigmoid colon are the four components of the colon. Rectum is the final section of the digestive tract in which the indigestible materials are collected. The elimination of the indigestible materials occurs through the anal canal.

Similarities Between Small and Large Intestine

• Both small and large intestine are two components of the alimentary canal.
• Both small and large intestine absorb substances from the food.

Difference Between Small and Large Intestine

Definition

Small Intestine: Small intestine is a part of the intestine, which runs between the stomach and the large intestine.

Large Intestine: Large intestine is the terminal part of the intestine, which is wider and shorter than the small intestine.

Length

Small Intestine: Small intestine is long (4.5 – 7.0 m).

Large Intestine: Large intestine is shorter than the small intestine (1.5 m).

Width

Small Intestine: Small intestine is narrow (3.5-4.5 cm).

Large Intestine: Large intestine is broader than the large intestine (4.0 -6.0 cm).

Components

Small Intestine: Duodenum, jejunum, and ileum are the three components of the small intestine.

Large Intestine: Cecum, colon, rectum, and anal canal are the four components of the large intestine.

Circular Folds

Small Intestine: Small intestine consists of circular folds in the internal surface.

Large Intestine: Large intestine lacks circular folds on the internal surface.

Villi

Small Intestine: Small intestine consists of villi in the internal surface.

Large Intestine: Large intestine lacks villi.

Peyer’s Patch

Small Intestine: Some parts of the small intestine contain Peyer’s patches.

Large Intestine: Large intestine does not have Peyer’s patches.

Longitudinal Muscles

Small Intestine: Small intestine contains circular layers of longitudinal muscles.

Large Intestine: Longitudinal muscles of the large intestine are arranged in three bands called Teniae coli.

Haustra

Small Intestine: Small intestine does not contain haustra.

Large Intestine: Large intestine contains haustra.

Epipolic Appendages

Small Intestine: Small intestine lacks epipolic appendages.

Large Intestine: Large intestine contains epipoplic appandages.

Wall

Small Intestine: The wall of the small intestine is smooth.

Large Intestine: The wall of the large intestine is sacculated.

Digestion

Small Intestine: Small intestine is involved in digestion.

Large Intestine: Digestion is not a function of the large intestine.

Hormones

Small Intestine: Small intestine secretes hormones.

Large Intestine: Large intestine does not secrete hormones.

Mobility

Small Intestine: Small intestine shows small movements.

Large Intestine: Large intestine is a comparatively fixed structure.

Absorption

Small Intestine: Small intestine absorbs most of the nutrients in the digested food.

Large Intestine: Large intestine absorbs water from the indigestible portion of the food.

Conclusion

Small and large intestine are the two parts of the intestine of the alimentary tract of the animals. Small intestine is involved in the digestion of food as well as the absorption of nutrients. Large intestine absorbs water. The main difference between small and large intestine is the function of each structure in the animal body.

Image Courtesy:

1. “Blausen 0817 SmallIntestine Anatomy” – “Medical gallery of Blausen Medical 2014”. WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436. – Own work (CC BY 3.0) via Commons Wikimedia
2. “2418 Histology Small IntestinesN” By OpenStax College – Anatomy & Physiology, Connexions Web site. Jun 19, 2013 (CC BY 3.0) via Commons Wikimedia
3. “2420 Large Intestine” By OpenStax College – Anatomy & Physiology, Connexions Web site. Jun 19, 2013 (CC BY 3.0) via Commons Wikimedia