30th September 2016 Endocrinology Endocrine Concepts Hormones Hormones are chemical messengers released from one cell (or tissue), which processes a specific, receptor-mediated change in another cell (or tissue). Hormones are involved in: - Development - proliferation, growth, and differentiation - Metabolism - energy storage, metabolic rate, and temperature - Reproduction - sexual maturation and behaviour, pregnancy and lactation - Fluid homeostasis - water balance, salt levels, blood volume, and pressure Cells mostly communicate with junctions and synapses. However, cells that communicate with hormones, communicate with cells across the body using the blood stream. Is endocrinology important? It is very important because hormones regulate the majority of the bodily processes. They are that important that drugs (synthetic hormones) are prescribed to patients that have hormone related diseases: - Insulin for diabetes - Thyroxin for thyroid diseases - Contraceptive pill - HRT (Hormone Replacement Therapy) - Androgen blockers - Steroids Physically and clinically important! Glands A gland is an organ that synthesises and releases a substance into the bloodstream, body cavity, or skin. - Tissues that secrete hormones. Endocrine - into the bloodstream
Endocrinology 30th September 2016 Glands can be: - Endocrine - Exocrine - Mucous - Sebaceous - Serous Pituitary Thyroid Thymus a: Testes Brain Adrenal Pancreas Kidney Ovary Uterus Endocrine Glands Tissues with endocrine function include: - Kidney - erythropoietin (EP) - Heart - atrial natriuretic peptide (ANP) - Gut - gastrin, secretin - Adipocytes - leptin, adiponectin - Pancreas - Insulin (1% endocrine islets of Langerhans alpha/beta cells) Model Endocrine System Stimulus (+ve, or -ve) Gland (Usually -ve) Hormone A (Concentration change) Hormone B (+ve, or -ve) Target tissue Hormone A & B may be the same !! Action Negative/positive feedback loop - Hormone A brings about the action, and hormone B feeds back to gland to inhibit or encourage action of gland.
Endocrinology 30th September 2016 Cell to Cell Communication via Hormones Target Autocrine Hormone Cell A Cell A Target Paracrine Hormone Cell A Cell B Endocrine Hormone Response Response Target Hormone Cell A Bloodstream Axon Neurocrine >Hormone Cell A neurone Bloodstream Cell B Target Hormone Cell B Response Response Autocrine - self-activation; feeds of its own hormone Paracrine - activates surrounding cells; close by cells Endocrine and Neurocrine - activates those cells that are across the body via the bloodsteam Hormone Synthesis Protein & peptide hormones Steroid hormones Nucleus A. gene transcription B. mRNA to RER C. translation on RER Rough ER D. post-translational processing E. packaging into secretory vesicles Golgi F. exocytosis 1. Hydrolysis of esters and release of cholesterol 2. Cholesterol to pregnenolone Mitochondrion Aston University 3. Processing Smooth ER 4. diffusion