Chapter 8: Six Primary Organs Of The Digestive System

Explanation
The mouth is responsible for mechanically breaking down food using the teeth and moistening it with saliva. The teeth help to break the food into smaller pieces, making it easier to swallow and digest. The salivary glands produce saliva, which lubricates the food and helps in the formation of a bolus, a soft mass of chewed food that is ready to be swallowed. Therefore, the correct answer is mouth.

Explanation
The pharynx is the correct answer because it is the common passageway for both respiration and digestion. It is located at the back of the throat and plays a crucial role in swallowing. The muscular contractions in the pharynx help move the swallowed bolus into the esophagus, allowing it to continue its journey through the digestive system. The salivary glands, mouth, and liver are not directly involved in this process.

Explanation
The esophagus is responsible for moving the bolus by peristalsis down into the stomach. Peristalsis is a series of coordinated muscle contractions that help propel food and liquids through the digestive system. The esophagus is a muscular tube that connects the throat to the stomach, and it uses peristalsis to push the food down into the stomach for further digestion and absorption. The teeth are involved in the initial breakdown of food, while the stomach and pancreas have different roles in the digestive process.

Explanation
The stomach plays a crucial role in the digestion process by reducing food to a digestible state. It does this by breaking down food through muscular contractions and mixing it with digestive juices, such as stomach acid and enzymes. This process converts the food into a semiliquid state called chyme, which can then move into the small intestines for further digestion and absorption of nutrients. Therefore, the stomach is responsible for the initial breakdown of food before it is passed on to the intestines.

Explanation
The small intestines are responsible for the majority of digestion and absorption of nutrients. This organ has a large surface area due to its length and villi, which increases the efficiency of nutrient absorption. The small intestines receive partially digested food from the stomach and further break it down with the help of enzymes from the pancreas and bile from the liver. The nutrients are then absorbed into the bloodstream and transported to body cells through the circulatory system. The large intestines, salivary glands, and liver have other important functions in the digestive system, but they do not play a primary role in digestion and absorption.

Explanation
The large intestines are responsible for reabsorbing water from fecal material, storing waste, and eliminating it through the rectum and anus. This process helps to concentrate the waste material and form solid feces. The small intestines, on the other hand, primarily absorb nutrients from digested food. The stomach breaks down food with the help of acid and enzymes, while the liver plays a role in detoxification and the production of bile.