Question

1. What step is unique in endocrine system communication compared to the synapse?

2. What is the major benefit to an animal of a nervous system instead of merely an endocrine system?

3. How is the pancreas both an endocrine and an exocrine gland?

Indicate the signals that trigger the release of thyroid hormone and epinephrine.
4. Release of T4:
5. Release of Adrenalin:

Answer 1

1) Endocrine system isbthe system of ductless gland that secretes hormones directly into the circulatory system to be carried long distance to other target organs regulating key body and organ functions.Endocrine signalling is slow to initiate but is prolonged in response.

2)The major benefit to animal of a nervous system the signals are more rapid when compared to endocrine system where signals are slow to initiate.

3) Pancreas is a mixed gland has both exocrine and Endocrine glands.The exocrine part constitutes about 85% it has acinar and duct tissue which secrete enzymes to breakdown proteins ,lipids , carbohydrates in food.

The endocrine part constitutes about 15%, it includes islets of Langerhans which secretes the hormones insulin and glucagon to control blood sugar levels throughout the body.

4)When there is decrease in Thyroxine in blood the thyroid releasing hormone(TRH) from hypothalamus stimulates thyroid stimulating hormone(TSH) from anterior pituitary.TSH stimulates the thyroid follicle cells to release Thyroxine(T4).

5)The sympathetic nervous system acting via splanchnic nerves to the Adrenal medulla, stimulate the release of calcium triggers the exocytosis of chromaffin granules and thus release the adrenaline into blood stream.