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A canaliculus is an adaptation found on gastric parietal cells. It is a deep infolding, or little channel, which serves to increase the surface area, e.g. for secretion. The parietal cell membrane is dynamic; the numbers of canaliculi rise and fall according to secretory n
H + is pumped into the stomach by exchanging it with K +. This process also requires ATP as a source of energy; however, Cl − then follows the positive charge in the H + through an open apical channel protein. HCO 3 − secretion occurs to neutralize the acid secretions that make their way into the duodenum of the small intestine.
Gastric activity involved in digestion is divided into three phases of digestion known as the cephalic phase, the gastric phase, and the intestinal phase. These phases overlap and all three can occur simultaneously. [1] A fourth phase of acid secretion is known as the basal state which occurs in the times between meals (interdigestive phase).
The stomach is surrounded by parasympathetic (inhibitor) and sympathetic (stimulant) plexuses (networks of blood vessels and nerves in the anterior gastric, posterior, superior and inferior, celiac and myenteric), which regulate both the secretory activity of the stomach and the motor (motion) activity of its muscles. The stomach is distensible ...
There are two types of gastric gland, the exocrine oxyntic gland, and the endocrine pyloric gland. The major type of gastric gland is the oxyntic gland that is present in the fundus and the body of the stomach making up about 80 per cent of the stomach area. These glands are often referred to simply as the gastric glands.
Gastric acid or stomach acid is the acidic component – hydrochloric acid of gastric juice, produced by parietal cells in the gastric glands of the stomach lining. In humans, the pH is between one and three, much lower than most other animals, but is very similar to that of carrion eating carnivores , needing protection from ingesting pathogens .
Alkaline tide (mal del puerco) refers to a condition, normally encountered after eating a meal, where during the production of hydrochloric acid by the parietal cells in the stomach, the parietal cells secrete bicarbonate ions across their basolateral membranes and into the blood, causing a temporary increase in blood pH. [1]
On 2021, Stephen Quake guessed that the upper limit of the number of human cell types would be around 6000, based on a reasoning that "if biologists had discovered only 5% of cell types in the human body, then the upper limit of cell types to discover is somewhere around 6000 (i.e., 300/0.05)."