A triplex for intestinal protection: Neurons, microbes, and goblet cells

The gastrointestinal tract, responsible for the digestion and absorption of nutrients, is safeguarded by the intestinal barrier, which consists of secretory, physical, and immune components. At the forefront is the secretory barrier, composed of essential elements such as mucus, gut microbiota, and defense proteins. They collaborate to break down food particles, facilitate nutrient absorption, and maintain optimal gut health. These secretory components ensure the smooth functioning of the...

Natural flora, body system defenses, and inflammation are natural barriers of the body against infectious agents regardless of previous exposure. Normal floras of the human body refer to the microbial population that colonizes the skin and mucous membranes.
In addition, many body organ systems have unique defenses against infection. The skin is an intact, multilayered surface preventing invasion by microorganisms unless impaired. Mucous membranes lining the mouth, nose, and eyelids are barriers...

The intestinal epithelial lining rapidly renews every 4 to 5 days. The renewal is facilitated by intestinal stem cells (ISCs) located at the base of the crypt– a gland located at the bottom of each villus. ISCs divide asymmetrically to form new stem cells and progenitor daughter cells. The daughter cells are called transit-amplifying (TA) cells which move upwards along the crypt and either differentiate into absorptive cells– the enterocytes or secretory cells– including the...

The gastric glands contain parietal cells that secrete hydrochloric acid (HCl) for digestion. The cells secrete HCl because it is highly corrosive and essential for breaking down food. To achieve this, they secrete hydrogen and chloride ions into the lumen of the gastric glands, which combine to form HCl.
Within parietal cells, carbonic acid is first formed through the reaction of water and carbon dioxide. The dissociation of carbonic acid releases bicarbonate and hydrogen ions. The bicarbonate...

The Enteric Nervous System (ENS) plays a pivotal role in regulating gastrointestinal or GI motor activity. This complex network of nerves, deeply embedded within the gut wall, responds to changes in the gut environment and receives input from both the autonomic nervous system and the central nervous system. By doing so, the ENS operates various programs tailored to the body's nutritional status and needs.
During periods of fasting, the ENS initiates the migrating myoelectric complex, a...

The neuronal supply to the gastrointestinal (GI) tract is essential for regulating various functions, including digestion, absorption, and movement of food. This intricate network of nerves is known as the enteric nervous system (ENS), often referred to as the "second brain" of the body.
The enteric nervous system consists of two major plexuses: the myenteric plexus (Auerbach's plexus) and the submucosal plexus (Meissner's plexus). These plexuses are located within the layers of...