Identify and describe the six major processes involved in gastrointestinal activ
ID: 3475192 • Letter: I
Question
Identify and describe the six major processes involved in gastrointestinal activity.
What role do hormones play in hunger and satiety?
Outline the usual pathway for digestion and absorption of triglycerides (fats).
Explain the role of the hormones cholecystokinin and secretin in regulating the release of bile and pancreatic juices.
Why is it necessary for the stomach contents to be so acidic?
How does the stomach protect itself from digestion?
Identify three ways the small intestine is modified to increase the surface area for digestion and absorption.
Explanation / Answer
1.Hunger and satiety in the body are regulated by two hormones 'Leptin' and 'Ghrelin'. Leptin is a hormone which suppresses appetite whereas Ghrelin increases appetite.
When there is decrease in energy content of body, the Ghrelin hormone concentration increases in blood and the body feels hungry and vice-versa.
2.The digestion of fat starts in small intestines by the emulsification of fat molecules with the help of bile juice secreted by liver.
The emulsified fat is then broken down by pancreatic Lipases(enzyme secreted by pancreas) into fatty acids and Glycerol.
3. Cholecystokinin along with secretin hormone is secreted by epithelial cells of small intestine. They stimulate gallbladder to contract and release stored bile into intestine and also stimulates secretion of pancreatic juice by pancreas.
The stimulus for the release of these hormones is the presence of partially digested fats and proteins in the duodenum of small intestines.
4. The acidic environment of the stomach kills the bacteria present in the food. It also activates the enzyme 'Pepsin ' which converts proteins into amino acids.
5. The stomach protects itself by secreting sticky, neutralising mucus that binds to stomach wall.
6. Small intestines are very long, and contain small projections called villi and micro villi that increases their surface area for absorption.
It also has large number of blood capillaries that allow transportation of food molecules all over the body. They have also thin epithelial layer which enhances diffusion of small molecules.
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