Which of these cells secrete hormones?

Answer Explanation

c. the intestines into the bloodstream

- Correct: During the process of absorption, nutrients from food pass from the intestines into the bloodstream. After food is broken down into its constituent nutrients through digestion in the stomach and small intestine, these nutrients are absorbed across the lining of the small intestine into the bloodstream. The small intestine is highly specialized for absorption, with villi and microvilli increasing the surface area available for nutrient absorption. Once absorbed into the bloodstream, nutrients are transported to various organs and tissues throughout the body to provide energy, support growth and repair, and maintain overall health.

a. the intestines into the bladder

- Incorrect: The bladder is part of the urinary system and is responsible for storing urine produced by the kidneys. Absorption of nutrients does not involve passage into the bladder.

b. the blood into the organs

- Incorrect: While nutrients absorbed into the bloodstream are indeed transported to various organs and tissues throughout the body, absorption itself occurs in the intestines, not directly from the blood into the organs.

d. the mouth into the stomach

- Incorrect: The mouth and stomach are primarily involved in the initial stages of digestion, including mechanical breakdown of food and the initiation of chemical digestion of carbohydrates and proteins. Absorption of nutrients occurs primarily in the small intestine, not from the mouth into the stomach.

Answer Explanation

d) all of the above

- Correct: All of the listed processes occur in the mouth:

a) Ingestion: The mouth is the entry point for food into the digestive system. Ingestion refers to the act of taking food or drink into the mouth.

b) Mechanical digestion: Mechanical digestion involves the physical breakdown of food into smaller pieces through actions such as chewing and mixing with saliva. In the mouth, the teeth tear and grind food into smaller particles, which increases the surface area for chemical digestion.

c) Chemical digestion: Chemical digestion involves the breakdown of food into smaller molecules by enzymes and other chemicals. In the mouth, salivary glands secrete saliva, which contains the enzyme amylase. Amylase begins the chemical breakdown of carbohydrates, converting starches into simpler sugars such as maltose.

Therefore, all of the processes listed—ingestion, mechanical digestion, and chemical digestion—occur in the mouth during the initial stages of digestion.

Answer Explanation

D. oral cavity

- Correct: Chemical digestion of carbohydrates begins in the oral cavity. Salivary glands in the mouth secrete saliva, which contains an enzyme called amylase. Amylase breaks down complex carbohydrates (such as starch) into simpler sugars (such as maltose) through hydrolysis. This process initiates the digestion of carbohydrates before the food bolus reaches the stomach or small intestine.

A. esophagus

- Incorrect: The esophagus is primarily involved in the propulsion of food from the mouth to the stomach through peristaltic contractions. It does not play a significant role in the chemical digestion of carbohydrates.

B. stomach

- Incorrect: While the stomach plays a role in the digestion of proteins through the action of gastric juices containing pepsin and hydrochloric acid, it does not contribute significantly to the digestion of carbohydrates. In fact, the acidic environment of the stomach may temporarily inhibit the activity of salivary amylase.

C. duodenum

- Incorrect: The duodenum is the first part of the small intestine where the majority of chemical digestion occurs. While the duodenum receives pancreatic enzymes and bile that aid in the digestion of carbohydrates, proteins, and fats, the initial chemical digestion of carbohydrates primarily occurs in the oral cavity with the action of salivary amylase.