Endocrinology Notes

Endocrinology Hormones - One of the body’s communication systems Jo and Ahina Learning Outcomes Define the terms endocrinology, endocrine, hormone, exocrine, paracrine and autocrine List the main endocrine organs List the main endocrine hormones and describe their physio...

Endocrinology Hormones - One of the body’s communication systems Jo and Ahina Learning Outcomes Define the terms endocrinology, endocrine, hormone, exocrine, paracrine and autocrine List the main endocrine organs List the main endocrine hormones and describe their physiological function, site of action and signalling mechanisms Describe the key characteristics (synthesis, transport and signalling mechanisms) of the main molecular types of hormones Describe the principles of positive and negative feedback Describe the basis of endocrine disease Compare primary and secondary endocrine dysfunction Key definitions Hormone Molecule released in one part of the body, affecting activity of cells in other parts of the body Endocrine gland produces and secretes hormones into the bloodstream (can affect distant targets) Endocrine organs: Tropic hormone Hormone that affects another Hypothalamus endocrine gland Pituitary gland Parathyroid glands Exocrine gland secretes its products into ducts Thyroid gland opening onto an epithelium Adrenal gland Ovaries/testes Pancreas Autocrine Relating to or denoting a substance secreted by a cell which affects surface receptors of the same cell Paracrine Relating to or denoting a substance secreted by a cell which affects only adjacent cells Endocrine Glands produce and secrete hormones into the bloodstream which are carried to target cells  2. Through detecting concentrations of something in the blood 3. Through nervous stimulation (electrical signal) 1. Through a hormone 3 ways to send a message  Steroid hormones are derived from Name the 4 molecular classifications of hormones: cholesterol Amine hormones Steroid hormones: Cortisol Catecholamines (dopamine, Testosterone, Oestrogen, Progesterone noradrenaline) Aldosterone Vitamin D Serotonin Peptide/protein hormones Thyroid hormones (technically a peptide, but behave differently) ADH Growth hormone Triiodothyronine (T3) Insulin Thyroxine (T4)  Another way to classify hormones! Is it …. Lipid Water soluble? soluble? Steroid hormones Amine hormones (e.g aldosterone, (e.g dopamine) cortisol, oestrogen) Peptide and protein Thyroid hormones hormones (e.g glucagon, insulin)  How are they transporte Lipid soluble d in the Water soluble circulate bound to blood? dissolve in transport proteins blood plasma thus synthesised by liver circulate in free (lipoproteins) form  How do they Lipid cause an Water soluble? soluble? Intracellular! effect on a Extracellular! cell? 1. Diffuses through phospholipid bilayer 1. Bind to receptor on cell surface (i.e the cell membrane) (usually G protein) 2. Binds to receptors in cytosol/nucleus 2. Activate G protein 3. Alters gene expression and protein 3. Activate proteins in cytoplasm to synthesis alter cell activity Feedback loops! Negative feedback loop: common and self-limiting Tropic hormone: CRH, ACTH Effector hormone: Cortisol Positive feedback loop: rare and self- reinforcing Tropic hormones : GnRH, LH, FSH Effector hormone: Estradiol Endocrine disease: something is Addison's out of balance Cushing’s disease syndrome Too little cortisol Too much cortisol Autoimmune response against E.g Too much adrenal cortex ACTH from tumour Reminder: Cortisol is a glucocorticoid hormone produced by the adrenal glands. Glucocorticoids are a class of steroid hormone Compare primary and secondary endocrine dysfunction Secondary Over/under- stimulation endocrine of the endocrine organ by dysfunction tropic hormones E.g Secondary Adrenal insufficiency Primary too much or too little of endocrine ‘effector hormone’ (e.g dysfunction cortisol) produced by the endocrine organ E.g Addison’s disease Thank you! Any questions?