GI System Part 2 Flashcards
Describe the role of short reflex pathways in the control of digestive function.
Detect changes in the stomach and small intestine, causing the ENS to respond and make a change.
Describe the role of long reflex pathways in the control of digestive function.
The stimulus is detected by the CNS, which triggers the ENS to respond and make a change.
Describe the role of gastrointestinal hormones in the control of digestive function.
Leptin is a hormone released from adipose cells when calories exceed demands, It suppresses hunger and increases metabolism.
Orexigenic factors oppose Leptin.
What are the three major types of receptors that monitor conditions in the lumen of the GI tract?
Chemoreceptors
Osmoreceptors
Mechanoreceptors
What is the distinction between long and short reflex pathways?
Long reflex pathways are detected through an external stimulus that is processed by the CNS. Short reflex pathways are stimulated internally through receptors.
What do the terms cephalic phase, gastric phase, and intestinal phase refer?
The neural and endocrine pathways of GI control
What is the function of saliva? How is it’s secretion regulated?
Saliva starts the breakdown of food. Saliva is regulated by the salivary center in the medulla oblongata, which controls autonomic output to the salivary glands.
What is the function of stomach acid? How is it’s secretion regulated?
Stomach acid kills bacteria and aids in digestion. It’s secretion is regulated by parasympathetic nervous system, chemoreceptors, and mechanoreceptors.
What is the function of pancreatic juice? How is it’s secretion regulated?
The function of pancreatic juices is to breakdown food in the small intestine. The secretion of pancreatic juice is influenced by the cephalic phase, gastric phase, and intestinal phase stimuli, although the last is predominant. The strongest influences on pancreatic secretion of the hormone CCK and secretin, which are released in response to the presence of food in the duodenum.
What is the function of bile? How is it’s secretion regulated?
Bile increases the digestion of fats. CCK and secretin are responsible for regulating the entry of bile into the duodenum. In response to increased acidity in the duodenum, secretin acts on the liver to stimulate bile secretion; the presence of protein digestion products and fat in the duodenum stimulates the secretion of CCK, which by promoting gallbladder contraction and relaxing of the sphincter of Oddi, allows bile to flow into the duodenum.
What is the role of carbonic anhydrase in stomach acid secretion? Which other ions are secreted along with H+ Ions?
Carbonic acid converts carbon dioxide and water into hydrogen ions and bicarbonate.
Which would be expected to stimulate gastric acid secretion?
A. Distension of the stomach
B. Distension of the doudenum
C. Increased protein digestion products in the stomach
D. Increased acidity in the duodenum
E. Increased osmolarity in the duodenum
A and C
Which would be expected to stimulate the secretion of enzymes or bicarbonate-rich fluid by the pancreas?
A. Increased acidity in the duodenum
B. a rise in plasma CCK levels
C. a rise in plasma secretin levels
D. Decreased protein digestion products in the duodenum
E. Increased fat in the duodenum
A and D
Define peristalsis and describe it’s roll in digestion.
a wave of momentary contraction that travels along the length of a hollow vessel or organ, such as the GI tract, that moves feces forward.
Define segmentation and describe it’s role in digestion.
alternating contractions between intestinal segments that mix chyme.
