Study the diagram given below and then answer the questions that follow :
(a) Name the cells of the pancreas that produce (1) glucagon (2) insulin.
(b) State the main function of (1) glucagon and (2) insulin.
(c) Why is the pancreas referred to as an exo-endocrine gland ?
(d) Why is insulin not given orally but is injected into the body ?
(e) What is the technical term for the cells of the pancreas that produce endocrine hormones ?
(f) Where in the body is the pancreas located ?
a. Glucagon: Alpha cells of the islets of Langerhans
Insulin: Beta cells of the islets of Langerhans
b. Insulin: It maintains the levels of glucose (sugar) in the blood.
Glucagon: It raises the blood glucose levels by stimulating the breakdown of glycogen to glucose in the liver.
c. An endocrine gland is one which does not pour its secretions into a duct, while an exocrine gland is a gland which pours its secretions into a duct. Because the pancreas produces hormones such as insulin, glucagon and somatostatin directly into the blood and not into a duct, it functions as an endocrine gland. Because it secretes the pancreatic juices for digestion via a duct, it functions as an exocrine gland. Hence, the pancreas is an exo-endocrine gland.
d. Insulin is not administered orally because the digestive juices degrade insulin, and thus the insulin is ineffective in the body.
e. Islets of Langerhans
f. The pancreas is located in the abdomen behind the stomach.