BPK 105 Study Guide - Final Guide: Muscularis Mucosae, Loose Connective Tissue, Nerve Plexus
27 Apr 2018
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Module 11 - Review Questions - Part 1
1. Briefly describe the functions of the digestive system. [4 marks]
The functions of the digestive system include the following:
1. Ingestion of food.
Food and water enter the body through the mouth.
2. Digestion of food.
During the process of digestion, food is broken down from complex
particles to smaller molecules that can be absorbed.
3. Absorption of nutrients.
The epithelial cells that line the lumen of the small intestine absorb the
small molecules of nutrients (amino acids, monosaccharides, fatty acids, vitamins, minerals, and
water) that result from the digestive process.
4. Elimination of wastes.
Undigested material, such as fiber from food, plus waste products
excreted into the digestive tract are eliminated in the feces.
2. Describe the structure and general functional roles of the four tunics (layers)
of the digestive tract (Figure 16.2). Briefly highlight the differences between the
different organs related to their specialized functions. [6 marks]
Nearly all segments of the digestive tract consist of four layers, called tunics. These are the
mucosa, the submucosa, the muscularis, and a serosa or an adventitia (figure 16.2):
1. The innermost tunic, the mucosa, consists of mucous epithelium, a loose connective tissue
called the lamina propria, and a thin smooth muscle layer, the muscularis mucosae. The
epithelium in the mouth, esophagus, and anus resists abrasion, and the epithelium in the
stomach and intestine absorbs and secretes.
2. The submucosa lies just outside the mucosa. It is a thick layer of loose connective tissue
containing nerves, blood vessels, and small glands. An extensive network of nerve cell
processes forms a plexus (network). Autonomic nerves innervate this plexus.
3. The next tunic is the muscularis. In most parts of the digestive tract it consists of an inner
layer of circular smooth muscle and an outer layer of longitudinal smooth muscle. Another nerve
plexus, also innervated by autonomic nerves, lies between the two muscle layers. Together, the
nerve plexuses of the submucosa and muscularis compose the enteric nervous system. This
nervous system, which is a division of the autonomic nervous system, is extremely important in
controlling movement and secretion within the tract (see chapter 8).
4. The fourth, or outermost, layer of the digestive tract is either a serosa or an adventitia. The
serosa consists of the peritoneum, which is a smooth epithelial layer, and its underlying
connective tissue. Regions of the digestive tract not covered by peritoneum are covered by a
connective tissue layer called the adventitia, which is continuous with the surrounding
connective tissue.
Document Summary
Module 11 - review questions - part 1: briefly describe the functions of the digestive system. The functions of the digestive system include the following: ingestion of food. Food and water enter the body through the mouth: digestion of food. Undigested material, such as fiber from food, plus waste products excreted into the digestive tract are eliminated in the feces: describe the structure and general functional roles of the four tunics (layers) of the digestive tract (figure 16. 2). Briefly highlight the differences between the different organs related to their specialized functions. Nearly all segments of the digestive tract consist of four layers, called tunics. The epithelium in the mouth, esophagus, and anus resists abrasion, and the epithelium in the stomach and intestine absorbs and secretes: the submucosa lies just outside the mucosa. It is a thick layer of loose connective tissue containing nerves, blood vessels, and small glands. An extensive network of nerve cell processes forms a plexus (network).
