Pendahuluan

1. Pendahuluan • Ruanglingkup Endokrinologi • Penggolongan hormon • Mekanisme umum biosintesis hormon • Mekanisme umum kerja hormon

2. Ruanglingkup Endocrinology = a course about biological communication systems and information transfer between cells and tissues . • Membahas tentang konsep-konsep endokrinologi, biosintesis, mekanisme kerja dan metabolisme hormon; mekanisme umpan balik, koordinasi dan integrasi sistem endokrin pada hewan dalam proses perkembangan, pertumbuhan, reproduksi dan osmoregulasi; interaksi antara faktor-faktor lingkungan dengan sistem endokrin.

3. The Endocrine System • This system is subject to complex regulatory mechanisms that govern hormone synthesis, release, transport, metabolism and delivery to the interior of the target cells, and expression and activity of the hormone receptor itself and its downstream signaling machinery. The endocrine system also has complex relationships with the other major system of communication between cells, the nervous system, as well as with the immune system. It exerts widespread effects on development, growth, and metabolism.

4. Human Endocrine Organs In the brain: • Anterior pituitary glandproduces corticotropin (ACTH), thyroid-stimulating hormone (TSH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), growth hormone (GH), and prolactin (PRL); • Posterior pituitary gland produces antidiuretic hormone (ADH) and oxytocin; • Hypothalamus produces releasing and inhibitory factors that regulate secretion of the anterior pituitary hormones; • Pineal gland produces melatonin. In the periphery • Thyroid gland (thyroid hormones), • Parathyroid gland (parathyroid hormone [PTH]), • Adrenal gland (corticosteroids, epinephrine), • Ovaries and testis (sex steroids), and • Pancreas(insulin, glucagon and somatostatin). Organs that are not traditionally considered to be part of the endocrine system also produce hormones. • Kidneyproduces renin that converts angiotensinogen to angiotensin I and erythropoietin that stimulates blood cell production. • Adipose tissue produces several hormones, including leptin, an important mediator of body weight, and resistin, which regulates sensitivity to insulin and may be involved in the pathology of type 2 diabetes. • Heartproduces natriuretic peptides. Some molecules traditionally thought to be metabolic intermediates, such as fatty acids and bile acids, are now known to function as hormones.

6. Pusat Endokrin pada Serangga (After Gullan and Cranstorn 2000)

7. Elements of an Endocrine System • Sender = Sending Cell • Signal = Hormone • Nondestructive Medium = Serum & Hormone Binders • Selective Receiver = Receptor Protein • Transducer = Transducer Proteins & 2ndary Messengers • Amplifier = Transducer/Effector Enzymes • Effector = Effector Proteins • Response (2ndary signal) = Cellular Response (2ndary hormones)

8. Hormone • A molecule that functions as a message within an organism; its only function is to convey information. • Because of this function, physical descriptions of a chemical suspected of being a hormone are inadequate to indicate the molecule's role in a biological system. A molecule is a hormone only when described in the context of its role in a biological communication system. Definition of a hormone requires testing of that molecule in a biological response system, running a bioassay.

9. Chemical Composition of Hormones

10. Target Organs • Target organs mount a response to a given hormone. They must express an appropriate cognate hormone receptor protein and molecules that mediate the receptors' downstream effects. Hormone Receptors • Hormone receptors are proteins with bifunctional properties of recognition of the hormone (ie, ability to distinguish the hormone from other molecules to which they are exposed) and transduction of the information from binding to downstream receptor effects. The hormone acts as an allosteric effector that alters receptor conformation, and this conformational alteration transmits (transduces) binding information into postreceptor events that influence cellular function. Some hormones (eg, insulin, GH, PRL, leptin, catecholamines) bind cell surface receptors, whereas others (eg, steroids, thyroid hormones) bind intracellular receptors that act in the nucleus. Some hormones (eg, estrogens and progestins) bind multiple receptors, which are present on both the cell surface and inside the cell.

11. Komunikasi Antar Sel Kerja sebuah sinyal dimulai ketika sinyal tersebut berikatan dengan sebuah reseptor spesifik. Protein reseptor itu bisa tertanam di dalam membran plasma sel target itu atau bisa juga berada di dalam sel target itu.

12. Forms of Intercellular Communication • Endocrine: secretion of a hormone by one cell with transmission via the blood, lymph, or intercellular fluid to a second, target, cell. • Paracrine: secretion of a hormone by one cell with transmission via intercellular fluid to a second, nearby cell. • Autocrine: secretion of a hormone by one cell with reception and response by the same cell. • Pheromonal: secretion by one organism and sensation and response by a second.

14. http://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapter10/animation__mechanism_of_steroid_hormone_action__quiz_1_.htmlhttp://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapter10/animation__mechanism_of_steroid_hormone_action__quiz_1_.html