Endocrine Intro PDF

Introduc)on to Endocrinology Endocrine System Regulates the body’s internal environment via endocrine glands Collec9on of cells/glands that produce and release hormones Hormones are released in the blood stream o Transported to distant parts of the body o Bind to target to elicit effect Endocrine sys...

Introduc)on to Endocrinology Endocrine System Regulates the body’s internal environment via endocrine glands Collec9on of cells/glands that produce and release hormones Hormones are released in the blood stream o Transported to distant parts of the body o Bind to target to elicit effect Endocrine system compliments the nervous system, however both are very different Nervous system has direct effects o Faster response 9me o Short ac9ng o NT released Endocrine system has indirect effects o Seconds, hours , days, weeks to respond o Slow ac9ng o Travels via bloodstream to find receptors o Long term effects: once endocrine system stops secre9ng, we can s9ll see effects for hours, days, weeks Exocrine glands secrete substances into ducts (not blood) and transport them away to salivary or sweat ducts Direct or Indirect Travel Method in Body Response Time Response Stop Time Nervous System Direct Axons/nerves Fast Fast Endocrine System Indirect Bloodstream Not as fast as NS, slower Prolonged stop due to residual hormone in bloodstream Endocrine System: Hormone Signaling Hormones o Chemicals messengers that have an effect on target cells distant from hormones secre9ng cells o Founda9on of endocrine system Signal transduc=on pathways mediate the sensing and processing of external s9muli o Detect, amplify, and integrate external signals to generate responses such as changes in enzyme ac9vity, gene expression, or ion-channel ac9vity o Steps in Signal Transduc9on: § A s9mulus arrives at endocrine gland § Induces a secretory cell (gland) to release a signaling molecule (hormone) § Hormone binds to receptor on target cell’s plasma membrane § Binding to receptor ini9ates a signaling cascade inside cell (signal transduc9on) § Signaling cascade induces a specific response in the cell based on the cell’s needs Endocrine System: Hormones Physiological level of hormones are very important o When low ➔ glands produce and release more hormones o When high ➔ glands will stop producing and releasing hormones o Even small amount of hormones produced, can lead to huge effects (must be in physiological levels) How are hormones measured? through laboratory tests such as blood, urine, saliva ex. Cor9sol test (saliva), HCG (urine) Hormones role in regula9ng: o Growth o Reproduc=on o Sex differen=a=on o Metabolism o Fluid and Electrolyte balance o Internal homeostasis Hormone Classifica9on Classified based on Composi=on and where they interact w target cell 2 main types: o Steroids (cholesterol) § Lipid soluble § Easily pass phospholipid plasma membrane of target cells o Non-steroids (proteins) § water soluble § NOT easily passed through phospholipid bilayer of target cells § Interact with receptor sites on the cell surface § Proteins, glycoproteins, pep9des, amino acid deriva9ves Protein are made of long chain AA ex. insulin and glucagon Glycoprotein are aWached w carbohydrate group that aWaches to AA ex. thyroid s3mula3ng hormone Pep9de are short chain AA ex. oxytocin Amino acid deriva9ve are Single AA Hormone Non-Steroid Steroid Cor9sol (hydrocor9sone) Aldosterone Estrogens Progesterone Testosterone Proteins Growth Hormone Prolac9n Parathyroid Hormone Calcitonin Adrenocor9cotropic Insulin Glucagon Glycoproteins FSH LH Thyroid S9mula9ng (TSH) Pep>des ADH Oxytocin Melanocyte-s9mula9ng (MSH) Somatosta9n Thyrotropin releasing (TRH) Gonadotropin releasing (GnRH) Atrial Natriure9c (ANH) Amino Acid Deriva>ves Amines Norepinephrine Epinephrine Melatonin Iodinated Amino Acids Thyroxine (T4) Triiodothyronine (T3) Endocrine Glands: Produce and excrete hormones and work together to achieve response Organ Brain Neck Lungs Pancreas Kidney Pelvic region Hormone Hypothalamus, pituitary and pineal gland Thyroid and parathyroid glands Thymus between lungs Behind the stomach; Exocrine and Endocrine Adrenal glands on top of kidneys Ovaries (Women), testes (men) Pineal Gland “Sleep gland” that produce melatonin (sleep-wake cycle) Hypothalamus “control center” Links CNS and endocrine system S9muli taken as impulses from brain and passes to pituitary gland 5 hormones: o Thyrotropin releasing hormone o Cor9cotropin releasing hormone o Growth hormone releasing hormone o Prolac9n releasing hormone o Gonadotropin releasing hormone o Releasing hormone = s3mulates another gland to release new hormone o -tropin = goes to another 3ssue to produce a new hormone Tissues in the body can release hormones and not be part of endocrine func9on Ex. Kidney producing erythropoie3n Pituitary Gland “Master Gland” Take signals from hypothalamus and send them to almost all the other endocrine glands Control other endocrine glands by ac9va9ng their release of hormones Divided into two sec9ons: Anterior and Posterior lobes Anterior (communica*on w hypo via hormone) o Thyroid s9mula9ng hormone (TSH) by Thyrotropin o Adrenocor9cotropic hormone (ACTH) by Cor*cotropin o Growth hormone (increase growth and protein synthesis) o Prolac9n (increase milk produc9on) o Gonadotropin ➔ Luteinizing Hormone (LH) and Follicle s9mula9ng hormones Posterior (communica*on w hypo via neurons) o An9diure9c hormone (ADH) o Oxytocin Posterior Pituitary Gland (Communicates w hypothalamus via neurons) Oxytocin o Uterus and smooth muscle in the breast contract to eject milk ADH: An9-diure9c hormone o Released during dehydra=on to maintain hydra9on o Stops urina9on Pancreas Endocrine o Produce hormones: Insulin and glucagon o Role of Insulin and Glucagon: § Control of blood sugar § Insulin released AFTER meal to REDUCES blood glucose § Glucagon released during FASTING to INCREASES blood glucose for energy Exocrine o Produce chemicals for ducts o Part of the diges=ve systems, o Release enzymes such as proteases Hypothalamus ↓ Anterior Pituitary ↓ Prolac9n ↓ Milk Produc=on Thyroid and Parathyroid Glands Thyroid: Endocrine =ssue that wraps around the front of the trachea o (80%) T3 Triiodothyronine (most ac=ve thyroid hormone) o (20%) T4 Thyroxine (Metabolism, development and catecholamines release; can be converted to T3 as needed o Calcitonin decreases calcium in blood, bones reabsorb Parathyroid glands: 4 small glands embedded in posterior of thyroid gland release parathyroid hormone (PTH) o Opposes the ac=vity of calcitonin o maintains calcium homeostasis o Increase calcium by releasing into blood from bone o Ca important for growth, muscle contrac9on Thymus Near Lungs Development and matura9on of T-cells Adrenal Gland On top of kidneys Hypothalamus released Cor=cotropin releasing hormone à s9mulates ACTH for adrenal gland to perform Adrenal cortex (shell) ➔ steroids produc9on o Cor>sol: Increase blood glucose, suppress the immune system o Aldosterone: Increase reabsorp9on of sodium in blood, § Increase blood pressure, blood volume and maintain hydra9on § Also increases water reten9on Adrenal medulla (core) o Ac9vated by Adrenocor9cotropic from Pituitary o NeurotransmiWers for sympathe9c § Noradrenaline (norepinephrine) § Adrenaline (epinephrine) Ovaries and Tes9cles GNRH → Gonadotropin for ovaries and testes FSH → S9mulates follicle and egg matura9on Ovaries: o LH s9mulates ovula=on and progesterone o FSH s9mulates follicle matura=on and estrogen o FSH is for uterus prepara9on Testes: o LH s9mulates leydig cells producing testosterone o FSH s9mulates sertoli cells producing androgens binding protein (ABP) o Both FSH and ABP important for sperm produc9on