Introduction to Endocrinology PDF

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Endocrinology Lecture 1- Principles of Endocrinology Endocrine vs Exocrine Glands: An endocrine gland secretes its products, o for example hormones, directly into the blood o adrenal gland secretes adrenaline made in the adrenal medulla directly into the blood An exocrine gland secretes its products o for example enzymes, into ducts that lead to the target tissue o salivary gland secretes saliva into the collecting duct which leads to the mouth. Pancreas: o performs both endocrine and exocrine function o releases insulin and glucagon directly into the blood (endocrine) o secretes pancreatic fluid into the pancreatic duct which leads to the duodenum (exocrine). Modes of Hormone Action Endocrine Neurocrineo similar to paracrine, but involving neurons Paracrineo cell produces a signal to induce changes in nearby cells, altering the behaviour of those cells Nervous System vs Endocrine System

Integration of Nervous and Endocrine Systems

Main Elements of the Endocrine System Endocrine Glands- Broadcaster Hormones- First Messengers Target tissues/cells- Hormone Receptors- Audience Hormone Receptors- Receiver Second Messengers- Transduce and amplify message Major Endocrine Glands

Main Factors Influencing Hormone Action

Negative Feedback Regulation in Endocrine Physiology:

Positive Feedback Regulation in Endocrine Physiology: (Ferguson Reflex )

Clinical Endocrinology

Summary: Hormones are signaling molecules carried in the bloodstream The endocrine and nervous systems work together to maintain homeostasis

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The endocrine system works more slowly than the nervous system but its effects can be much longer lasting The hypothalamus and pituitary glands play a key role in regulating the function of peripheral endocrine glands Hormone secretion is regulated by negative feedback inhibition, humoral factors and by neural inputs Hormone action is influenced by changes in the rate of hormone secretion, metabolism and target cell factors such as hormone receptor number and binding affinity Endocrine disorders can arise from defects in both endocrine and target cell as a result of hypo/hyper secretion and hypo/hypersensitivity respectively...