True or False
The enterogastric, gastrocolic, and gastroileal reflexes all play roles in coordinating gastrointestinal activity after eating.

A. Lysozyme:This enzyme functions as an antimicrobial agent by cleaving the peptidoglycan walls of certain bacteria. It provides a non-specific immune defense within the oral cavity. It possesses no catalytic activity toward carbohydrates or starches.

B. Salivary amylase:Also known as ptyalin, this enzyme initiates the hydrolysis of complex polysaccharides into smaller oligosaccharides like maltose. It operates at an optimal neutral pH within the mouth. This is the first step of chemical carbohydrate digestion.

C. Pepsin:This protease is secreted by gastric chief cells as pepsinogen and is activated by hydrochloric acid in the stomach. It is specialized for the cleavage of peptide bonds in proteins. It does not participate in carbohydrate breakdown.

D. Salivary lipase:This enzyme is secreted by von Ebner’s glands on the tongue to begin the hydrolysis of triglycerides. It targets dietary lipids rather than carbohydrates. Its activity continues within the stomach due to its acid-stable nature.

A. Lymphatic vessels:These vessels primarily transport chylomicrons and large lipid-soluble molecules from the intestinal mucosa. While some signaling molecules may enter lymph, enteroendocrine hormones are not specifically targeted here. They utilize the vascular route for systemic distribution.

B. Bloodstream:Hormones eventually reach the systemic circulation to exert their physiological effects on distant target organs. However, the immediate site of secretion from the basal membrane of the cell is not the vessel lumen. The bloodstream is the secondary destination.

C. Interstitial fluid:Enteroendocrine cells are basal secretors that release regulatory peptides into the surrounding extracellular space. From this fluid, the hormones diffuse into local fenestrated capillaries to enter the circulation. This is the primary site of hormonal release.

D. Gastric pits:These are invaginations of the gastric mucosa where exocrine cells, such as parietal and chief cells, discharge their secretions. Enteroendocrine cells do not secrete into the lumen. Their products are released basally to act as hormones.