Which nutrients can be absorbed without first being digested in the human gastrointestinal tract?

Answer Explanation

B) digestive system

- Correct: Gastric bypass surgery involves the reduction of the stomach's size, typically to hold only about 1 ounce of food instead of its normal capacity of 3 pints or more. This surgery drastically impacts the digestive system because it alters the anatomy and physiology of the gastrointestinal tract. By reducing the stomach's size, gastric bypass surgery restricts the amount of food that can be consumed at one time, leading to reduced calorie intake and aiding in weight loss. Additionally, the rearrangement of the digestive tract may affect the absorption of nutrients, potentially leading to changes in nutrient absorption and metabolism.

A) excretory system

- Incorrect: While changes in diet and weight loss resulting from gastric bypass surgery may indirectly affect the excretory system, the primary impact of this surgery is on the digestive system itself, not the excretory system.

C) circulatory system

- Incorrect: Although obesity and associated health conditions may impact the circulatory system, such as increasing the risk of cardiovascular disease, the direct impact of gastric bypass surgery is on the digestive system, not the circulatory system.

D) respiratory system

- Incorrect: Gastric bypass surgery does not directly impact the respiratory system. While weight loss resulting from the surgery may improve respiratory function in individuals with obesity-related respiratory conditions such as sleep apnea, the surgery primarily affects the digestive system by altering the anatomy and function of the gastrointestinal tract.

Answer Explanation

C) polysaccharide that is synthesized and stored within the human liver

- Correct: Glycogen is a polysaccharide, which means it is a complex carbohydrate composed of many glucose molecules linked together. It is synthesized and stored primarily in the liver and muscles of humans and other vertebrates. Glycogen serves as a form of energy storage, allowing organisms to store glucose for later use when energy demands are high or when glucose availability is low.

A) complex carbohydrate that is often stored in red blood cells

- Incorrect: While glycogen is a complex carbohydrate, it is not stored in red blood cells. Red blood cells do not contain nuclei or organelles, including glycogen storage structures.

B) complete protein necessary for the synthesis of cell membranes

- Incorrect: Glycogen is not a protein. It is a carbohydrate used for energy storage. Proteins are composed of amino acids and are involved in various cellular functions, including the synthesis of cell membranes, but glycogen does not play a direct role in this process.

D) by-product of sucrose digestion within the pancreas

- Incorrect: Glycogen is not a by-product of sucrose digestion within the pancreas. Sucrose is a disaccharide composed of glucose and fructose, and it is broken down into its component sugars by enzymes in the small intestine, not the pancreas. Glycogen is synthesized and stored in the liver and muscles as a form of energy storage.

Answer Explanation

The digestive system provides materials in the form of nutrients from food, such as carbohydrates, fats, and proteins. These nutrients are broken down during digestion and absorbed into the bloodstream.

The respiratory system provides oxygen, which is necessary for cellular respiration, the process by which ATP (adenosine triphosphate) is produced in cells. Oxygen is inhaled into the lungs and diffuses into the bloodstream to be transported to cells throughout the body.