Regulation of GI System Flashcards
What are the two main components of neural regulation in digestion?
- Enteric nervous system (ENS)
- Autonomic nervous system (ANS)
How does the parasympathetic nervous system affect digestion?
It stimulates digestion, increasing motility and secretions.
How does the sympathetic nervous system affect digestion?
It inhibits digestion, reducing motility and blood flow.
What are the three phases of regulation?
Cephalic, gastric and intestinal
What triggers the cephalic phase of digestion?
The sight, smell, taste, or thought of food.
What happens during the cephalic phase?
The CNS stimulates saliva, gastric acid, and digestive enzyme secretion
What stimulates the gastric phase?
Stomach distension and the presence of peptides in the stomach.
What is the intestinal phase triggered by?
The presence of chyme in the duodenum.
Which hormone increases appetite and where is it secreted?
Ghrelin, secreted by the stomach when it is empty.
Which hormone signals satiety and where is it secreted?
Leptin, secreted by adipose tissue.
What role does insulin play in appetite regulation?
Promotes satiety by acting on the hypothalamus.
What hormones are released during digestion to suppress appetite?
Peptide YY (PYY) and Cholecystokinin (CCK)
What is peristalsis?
Wave-like contractions that propel food through the digestive tract.
What is segmentation?
Alternating contractions that mix chyme in the small intestine.
What are short reflexes in the ENS and give an example.
Reflexes confined entirely to the ENS, independent of the CNS. For example, the local stretch of the intestinal wall triggers nearby peristalsis and secretion.
