1.Explain the main principles the endocrine system operation. a) Endocrine glands – are specialized organs that make hormones; secrete them into blood. Purely endocrine glands do not have ducts. Examples: pituitary gland, thyroid gland and adrenal gland. b) Hormones- hormone is a biologically active substance release by a specialized cell and affecting the function of other cells. c) Receptors- Only cells with receptors will respond to a hormone. Receptors are always proteins, are very specific-respond to only one kind of hormone. A cell with receptors for a hormone is called a target cell for that hormone. 2. Explain the difference between an endocrine and an exocrine gland; give examples of exocrineglands. a) Endocrine glands are organs that make hormones, and secrete them into the blood they do not have ducts (pituitary, thyroid, and adrenal gland) b) Exocrine glands they secrete things on the surface of the body and always have ducts (salivary, sebaceous, lacrimal, and digestive glands) 2. Give an example of a gland that has both exocrine and endocrine functions. a) Pancreatic gland – endocrine part makes hormones insulin and glucagon and exocrine part makes digestive enzymes. 4. Give examples of some organs that are not specialized endocrine glands, but produce hormones. a) Heart – ANP b) kidney – EPO and renin c) adipose tissue – leptin d) Skin-cholecalciferol. 5. Explain the term “paracrine” – how is it different from “endocrine”? a) Paracrine- have only local effects - affect cells in the same tissue only. Example: prostaglandins. b) Endocrine–secreted in the blood, have systemic effects - affects cells at other locations in the body. Some endocrine hormones can also have paracrine effects.
6. Explain the terms “antagonistic effect”, “synergistic effect” and “permissive effect” as related to hormone action. a) Antagonistic effect- hormones that produce opposite effects. For example, insulin lowers blood glucose, glucagon raises blood glucose b) Synergistic effect- two different hormones that produce the same effect. For example, both thyroid hormone and growth hormone cause body growth. c) Permissive effect- when one hormone is required for another to have effect. 7. Give examples of negative and positive feedback involving hormones and explain what the purpose of either one is. a) Negative feedback mechanisms- control many long term states such as body temperatures and hydration. Most of the feedback mechanisms that regulate hormones in the human body are negative feedback systems.