Question

All of the following is true about the digestive system except
A. Digestive enzymes from the pancreas are released via a duct into the duodenum
B. Peristalsis is a wave of smooth-muscle contraction that proceeds along the digestive tract
C. In the small intestines, villi absorbs nutrients into both the lymphatic and circulatory systems
E. The low pH of the stomach is essential in order for carbohydrate digestive enzymes to function
F. The release of bile from the gallbladder is triggered by the hormone cholecystokinin

Answer 1

Digestion is a metabolic reaction wherein food breaks down into nutrients. Nutrients such as carbohydrates, proteins, fats, and vitamins are derived from food sources. Carbohydrates include starch, sugar, fiber, etc. Proteins are derived from foods such as eggs, meat, beans, etc.

Step by step answer: Digestion is the metabolic process wherein the food breakdowns into smaller and smaller portions until they can be absorbed and incorporated into the body. This is a major function carried out by the human digestive system. The digestive system of humans includes the gastrointestinal tract and other solid organs such as the pancreas, gallbladder, and liver that facilitate the digestion process. The gastrointestinal tract constitutes the mouth, oesophagus, stomach, small intestine, large intestine, and anus. In the first stage of the digestion process, gastric secretions are released in response to the smell and sight of food, this is called the cephalic phase. This stage involves the breakdown of food by chewing. Digestive enzymes present in the mouth then chemically breakdown the food furthermore. Once the food reaches the inside of the body, different digestive enzymes are released that facilitate the absorption and assimilation of nutrients. We will further discuss it in the context of the options provided.
One of the solid organs of the digestive system includes the pancreas. They are located behind the stomach in the abdomen. They function as a gland and have both digestive exocrine function and endocrine function. They are responsible for secreting digestive enzymes such as amylase, lipase, and trypsin. These digestive enzymes are released into the duodenum to facilitate the absorption of proteins, fats and carbohydrates. The gallbladder secretes bile into the duodenum to carry out digestion. In conclusion, option A is true about the digestive system.
Peristaltic waves propel a bolus along the digestive tract. A bolus is a ball of food that is transformed in the stomach into chyme. Food moves to different processing stations in the digestive tract with the involvement of a series of wave-like muscle contractions known as peristalsis. Peristalsis initiates in the oesophagus when a bolus of food is swallowed. Option B is also true about the digestive system, based on the particulars mentioned.
Nutrients are absorbed in the small intestine. The walls lining the small intestine have Villi that help in nutrient absorption into the lacteals of the lymphatic system and the capillaries of the circulatory system. Therefore, option C is also true about the digestive system.
Proteins are digested from ingested food in the stomach by the action of the pepsin enzyme. The pepsin is activated at lower pH (1.5 to 2). The stomach lining consists of parietal cells, which secrete hydrochloric acid that lowers the pH of the stomach. The salivary amylase enzyme present in saliva breaks down starch into maltose (sugar) and requires a pH of 6.5 to 7. Carbohydrates are digested in the small intestine by pancreatic amylase which requires a pH of 7.5 to function. In conclusion, higher levels of pH are required for the digestion process. Therefore, Option D is not true about the digestive system.
Cholecystokinin is a digestive hormone. It is released with secretion by the introduction of hydrochloric acid or fatty acids stomach or when food reaches the first portion of the small intestine (duodenum).

Therefore, option E is also true about the digestive system.

Note: Large intestine is known as the largest part of the gastrointestinal tract. Water absorption and waste storage prior to excretion are done here. Defecation is known as the removal of waste from the body.