Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Nuclear magnetic resonance spectroscopy of proteins wikipedia , lookup
Protein purification wikipedia , lookup
Intrinsically disordered proteins wikipedia , lookup
Protein–protein interaction wikipedia , lookup
Protein mass spectrometry wikipedia , lookup
Protein structure prediction wikipedia , lookup
Western blot wikipedia , lookup
Growth hormone wikipedia , lookup
Lecture 13 – Endocrine System 1 Slower process, more widespread, longer lasting Organs & tissues of the endocrine system Compare & contrast the nervous & endocrine systems Nervous system Neurotransmitters Delivery via synapse Endocrine system Hormones Delivery via bloodstream Similarities Specific receptors Noradrenaline, Adrenaline Maintains homeostasis Regulated by negative feedback Compare the major chemical classes of hormones Amino acid derivatives Hormones are divided into 3 groups based on their chemical structure The chemical composition determines how it can travel in the blood & how it interacts with a specific cell Water soluble – travel in the blood in their own state as blood is water based Amin acid hormones Also referred to as amine hormones. Amine hormones are synthesized from the amino acids tryptophan or tyrosine Peptide/Protein Steroid hormones hormones Consist of short The primary hormones derived from lipids chains of amino acids are steroid hormones & are derived from the whereas protein lipid cholesterol. hormones are longer No soluble in water (hydrophobic) must polypeptides travel to their target cell bound to a transport protein Peptide hormones Travel in the blood in their natural state Peptide/protein hormones Peptide hormones consist of short chains of amino acids whereas protein hormones are longer polypeptides Glycoproteins – Consist of more than 200 amino acids in length & accommodate CHO side chains. They include hormones such as thyroid stimulating hormone (TSH), luteinizing hormone (LH), & follicle stimulating hormone (FSH) produced in the anterior lobe of the pituitary gland Short polypeptides/small proteins – this is a large & diverse group of hormones which range in size from short chain polypeptides such as oxytocin & vasopressin, to small proteins which includes such hormones as growth hormone & prolactin. This group of hormones includes all hormones secreted by the hypothalamus, posterior pituitary, heart, thymus, digestive tract & the pancreas in addition to several others Lipid Derivatives Steroid hormones (e.g. cortisol, oestrogen, thromboxane A2, Prostaglandin E) The primary hormones derived from lipids are steroid hormones & are derived from the lipid cholesterol. Steroid hormones are not soluble in water hydrophobic) therefore must travel to their target cell bound to a transport protein Steroid Hormones – because blood is water-based, lipid derived hormones must travel to their target cell bound to a transport protein. This more complex structure extends the halflife of steroid hormones much longer than that of hormones derived from amino acids. A hormone’s half-life is the time required for half the concentration of the hormone to be degraded. E.g. the lipid-derived hormone cortisol has a half-life of approx. 60-90 mins. In contrast, the amino acid-derived hormone adrenaline/epinephrine has a half-life of approx. 1 minute Eicosanoids – These are important paracrine factors which are involved in the coordination of cellular activities & enzymatic processes. Eicosanoids include leukotriene’s & prostaglandins, the later of which can be converted into thromboxane’s & prostacyclin’s in some tissues Cell membrane hormone action e.g. Catecholamine’s, peptide hormones Hormone (first messenger) Receptor on cell membrane Second Messenger Metabolic reactions to alter cell activity G proteins & hormone activity (water-soluble) Figure 1 (17.5) Binding of water soluble hormones Figure 17.5 Binding of water-soluble hormones – Water soluble hormones cannot diffuse through the cell membrane. These hormones must bind to a surface cell-membrane receptor. The receptor then initiates a cell-signaling pathway within the cell involved G proteins, adenylyl cyclase, the secondary messenger cyclic AMP (cAMP), and protein kinases. In the final step, these proteins kinases phosphorylate proteins in the cytoplasm. This activates proteins in the cell that carry out the changes specified by the hormone The hormone remains outside the cell but triggers a cascade of events Intracellular hormone action lipid derived hormones. E.g. steroid hormones ( can diffuse straight through the cell) Lipid hormone Diffuses through cell membrane Forms hormone-receptor complex Activates/inactivates specific genes Changes target cell structure