Question

2. Control of digestive activity includes secretions from glands and movement of materials through the alimentary canal.

• Describe the use of a nerve plexus and two neurotransmitters in reducing gut motility, say during stress.
• Describe the roles of CCK and secretin in the pancreas. What other roles can you think of for CCK?

Answer 1

Myenteric Plexus is the main plexus that Helps in controlling gastric motility.While mostly associated with excitatory muscle activity, there is also an inhibitory function of the myenteric plexus. Possibly through secretion of vasoactive intestinal polypeptide (or some other inhibitory peptide), the myenteric plexus can inhibit intestinal sphincter muscles such as the pyloric sphincter and the ileocecal valve, which normally impede the movement of gut contents.

2 Neurotransmitter that reduce Gut motility are VIP,Nitric Oxide.They Acts directly on smooth muscle to cause smooth muscle relaxation which cause reduced gastric motility.

Role of cholecystokinin and Secretin

cholecystokinin acts on pancreatic acinar cells----secrete large quantities of digestive enzymes.

secretin acts on the pancreas to stimulate duct cells to secrete water and bicarbonate.

Other role of CCK

*CCK mediates digestion in the small intestine by inhibiting gastric emptying.

*Stimulate the delivery of Bile from Pancreas

*Inhibition of Acid Secreation

*Inhibition of Food Intake.