Problem 19 - Anatomy and Physiology of Animals

Question

Which of these cells secrete hormones? a. parietal cells b. mucous neck cells c. enteroendocrine cells d. chief cells

Step-by-Step Solution

Answer

Enteroendocrine cells secrete hormones.

Step 1: Identify Cell Types and Their Functions

To determine which cells secrete hormones, we first need to understand the function of each cell type. - Parietal cells are located in the lining of the stomach and are responsible for secreting hydrochloric acid and intrinsic factor. - Mucous neck cells produce mucus to protect the stomach lining from acid. - Enteroendocrine cells are specialized cells in the gastrointestinal tract that produce and secrete hormones. - Chief cells produce pepsinogen, an inactive enzyme precursor that is converted to pepsin by stomach acid.

Step 2: Determine Which Cells Secrete Hormones

From the functions listed for these cells, enteroendocrine cells are the ones known to secrete hormones. They release hormones such as gastrin, cholecystokinin, and secretin, which play roles in digestive processes.

Step 3: Select the Correct Answer

Based on the information provided, the only cells among the options given that secrete hormones are the enteroendocrine cells. Thus, option (c) is the correct answer.

Key Concepts

Parietal cells

Parietal cells are located in the lining of the stomach. They play a crucial role in the digestion process by releasing two vital substances:

• Hydrochloric acid (HCl): This acid helps in breaking down food in the stomach. It makes the stomach's environment acidic, which is necessary for the digestion of proteins.
• Intrinsic factor: This is essential for the absorption of vitamin B12 in the small intestine. Without vitamin B12, our bodies would struggle to produce red blood cells properly.

In essence, parietal cells do not secrete hormones. Instead, they focus on creating a suitable environment for other digestive processes to occur effectively.

Gastrointestinal hormones

The gastrointestinal tract relies on hormones to manage digestion and coordinate various functions. Among the cells in the gut, enteroendocrine cells stand out by producing and releasing crucial hormones such as:

• Gastrin: This hormone stimulates the parietal cells to produce hydrochloric acid. It also promotes stomach motility, which aids in mixing food.
• Cholecystokinin (CCK): Released to signal the gallbladder to release bile and the pancreas to secrete enzymes. It ensures fats are properly digested.
• Secretin: Helps regulate the pH of the digestive tract by signaling the pancreas to release bicarbonate. This neutralizes the stomach acid entering the small intestine.

These hormones guide different organs to work together smoothly, ensuring that food is broken down and nutrients are absorbed efficiently.

Digestive system

The digestive system is an intricate network of organs that work together to break down food, absorb nutrients, and eliminate waste. It begins with the mouth and extends through the esophagus, stomach, and intestines, ending at the rectum and anus.
Each part of the digestive system has its own specialized function, such as

• Teeth and saliva in the mouth start the mechanical and chemical breakdown of food.
• The stomach uses enzymes and acids to turn food into a semi-liquid form called chyme.
• The small intestine is where most nutrient absorption occurs.
• The large intestine reabsorbs water and forms waste products.

Within the digestive system, specific cells such as parietal cells and enteroendocrine cells carry out specialized tasks. While parietal cells focus on maintaining an acidic environment for digestion, enteroendocrine cells release hormones that regulate digestive activity, ensuring the body efficiently processes and absorbs nutrients.