1. Objectives
• Explain what is meant by the term
endocrine gland.
• Describe the cellular structure of an islet of
Langerhans from the pancreas.
• Outline the role of the pancreas as an
endocrine gland.
4. Pancreas
• Exocrine Gland: a gland that secretes
externally through a duct
• Endocrine Gland: a gland that secretes
hormones into the bloodstream.
5. Pancreas
• The pancreas has an exocrine portion
that secretes digestive enzymes that
are carried through a duct to the
duodenum. The endocrine portion
consists of the pancreatic islets,
which secrete glucagons and insulin.
6. Objectives
• Explain how the blood glucose
concentration is regulated by negative
feedback control mechanisms, with
reference to insulin and glucagon.
• Discuss the importance of homeostasis in
mammals, and explain the principles of
homeostasis in terms of receptors,
effectors and negative feedback.
7.
8.
9.
10.
11.
12. Hormones
• Most hormones circulate in blood, coming
into contact with essentially all cells.
However, a given hormone usually affects
only a limited number of cells, which are
called target cells. A target cell responds
to a hormone because it bears receptors
for the hormone.
• The effector is usually an organ.
13. Objectives
• Explain the advantages of treating
diabetics with human insulin produced by
genetic engineering.