Endocrine System: Pancreas

Describe the histology of the pancreas.

*Acinar cells - Exocrine cells, 99% of which are arranged in clusters called acini. *Scattered among the acini are 1-2 million tiny clusters of endocrine tissue called pancreatic islets/islets of Langerhans.

Which pancreatic islet cell secretes glucagon and what is its main action?

*Secreted by Alpha Cells. *Increases blood sugar levels.

Which pancreatic islet cell secretes insulin, and what is its main action?

*Secreted by Beta Cells. *Decreases blood glucose levels.

Which pancreatic islet cell secretes somatostatin, and what are its 3 main actions?

*Secreted by Delta Cells. Actions: 1. As a paracrine to inhibit both insulin and glucagon release from beta and alpha cells. 2. Slow absorption of nutrients from the GI tract. 3. Inhibits GH.

Signs and symptoms of lipidemia and ketoacidosis.

1. Acetone breath. 2. Hypernea. 3. Nausea/Vomiting/abdominal pain. 4. Cardiac irregularities. 5. CNS depression/coma.

Besides high blood sugar, what are 3 other stimuli for insulin secretion?

1. Acetylcholine liberated from axon terminals of parasympathetic vagus nerve fibers. 2. Amino acids arginine and leucine that are present after protein rich meals. 3. Glucose-dependent insulinotropic peptide [GIP], secreted by enteroendocrine cells in response to the presence of glucose in GI tract.

What are the 4 hormone secreting cell types found in the Islets of Langerhans? What does each secrete?

1. Alpha Cells --> Glucagon. 2. Beta Cells --> Insulin. 3. Delta Cells --> Somatostatin. 4. F Cells --> Pancreatic polypeptide.

What are the 3 anatomical parts of the pancreas?

1. Head - this is where the duodenum curves around. 2. Body. 3. Tail - points to spleen.

Which pancreatic islet cell secretes pancreatic polypeptide, and what are its 3 main actions?

1. Inhibits somatostatin secretion. 2. Inhibits gallbladder contraction. 3. Inhibitis secretion of digestive enzymes by the pancreas.

Signs and symptoms of hyperglycemia.

1. Polyruia. 2.Dehyrdation. 3. Soft eyeballs. 4. Polydipsia. 5. Fatigue. 6. Weight loss. 7. Polyphagia.

Besides low blood glucose levels, glucagon can also be stimulated by what 2 things?

1. Sympathteic nervous system [eg. exercise.]. 2. Rise in blood amino acids if blood glucose level is low.

2 hormones that indirectly stimulate secretion of insulin by causing elevated blood glucose.

1. hGH. 2. ACTH.

Glucagon acts to increase blood glucose levels in what 2 ways?

Acts on hepatocytes to: 1. Convert glycogen into glucose. 2. Form glucose from lactic acid and certain amino acids.

Insulin acts to decrease blood glucose levels in which 6 ways?

Acts on various cells in the body to: 1. Accelerate facilitated diffusion of glucose into cells. 2. Speed conversion of glucose into glycogen. 3. Increase uptake of amino acids and increase protein synthesis. 4. Speed synthesis of fatty acids. 5. Slow conversion of glycogen into glucose. 6. Slow glucose formation from lactic acid and amino acids.

Which endocrine cells are the 2nd most abundant?

Alpha cells, constituting 17 % of pancreaic islet cells.

Which of the endocrine cells is most abundant?

Beta Cells, constituting 70% of pancreatic islet cells.

What is glycogenesis?

Conversion of glucose into glycogen

What is glycogenolysis?

Conversion of glycogen into glucose.

True or False: Glucagon inhibits insulin release.

False. Gucagon actually stimulates insulin release!

What is gluconeogenesis?

Formation of glucose from lactic acid or amino acids.

Somatostatin is the same as which hormone secreted by the hypothalamus?

Growth hormone inhibiting hormone.

Where is the pancreas located?

In the curve of the duodenum.

Where is glucoagon stored?

In the liver and skeletal muscle.

Are insulin and glucagon regulated by the hypothalamus and the pituitary?

No, they are primarily regulated by negative feedback due to blood glucose levels.

What is the function of the exocrine cells in the pancreas?

Secrete digestive enzymes involved in the breakdown of carbohydrates, proteins, and fats.

What is lipogenesis?

Synthesis of fatty acids.

The exocrine portion of the pancreas develops as an outpouching of what?

The GI tract.

True of False Insulin inhibits Glucagon.

True.

True or false: The Pancreas is both an exocrine and endocrine gland.

True.

When is insulin released?

When blood glucose levels are high.

When is glucagon released?

When blood glucose levels are low.