Gastric Functions and Insulin Secretion Gas excretion is primarily stimulated by gastric inhibitory volume, which also promotes insulin secretion. Acetylcholine from the parasympathetic nervous system enhances salivary and gastric secretions while norepinephrine regulates sphincter contractions through sympathetic control.
Nervous System Control of Stomach Motility The stomach's myenteric plexus connects sympathetic and parasympathetic systems to regulate motility. Increased parasympathetic activity boosts secretion and peristalsis, whereas heightened sympathetic outflow reduces these functions.
Role of Gastrin in Digestive Regulation Gastrin release occurs in response to stretch receptors activated by food intake or partially digested proteins. The vagus nerve stimulates gastrin production via feedback mechanisms involving both short (local) responses and long (central) pathways.
Pepsin Production Linked to Stomach Acidity Acidity within the stomach activates chief cells to produce pepsinogen, which converts into active pepsin at optimal pH levels for protein digestion. This process is inhibited if pH exceeds certain thresholds, affecting digestive efficiency.
'Intrinsic Factor' Importance for Vitamin Absorption 'Intrinsic factor' produced by parietal cells aids vitamin B12 absorption; its absence can lead to macrocytic anemia post-gastrectomy due to impaired nutrient uptake from lack of intrinsic factor synthesis after surgery on G-cells producing gastrins