DASC20010 Lecture Notes - Lecture 22: Peptide Hormone, Binding Protein, Adrenal Medulla
5 Aug 2018
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Document Summary
Other intracellular communication: paracrine, permeates around local area- local inflammation, autocrine, stimulates the cells themselves and may stimulate like cells, positive feedback mechanism, neurohormones, link between nervous and hormone system. Hormone categories are based on chemical classification: peptides & proteins, consist of specific amino acids arranged in chains of varying lengths, majority of animal hormones. Peptide hormone synthesis & secretion: large precursor proteins- preprohormones- synthesised by ribosomes on the rer. Lipid-soluble: diffuse out of cell as they are secreted: cholesterol- common precursor for all steroid hormones, requires series of enzymatic reactions- modify the type and position of side groups attached to the cholesterol framework. For each conversion- requires enzymes found in mitochondria or er: cannot be stored after their formation. Hormone transport: peptide, water soluble, circulate in free form, some exceptions e. g insulin-like growth factor 1, peptides secreted- and are active in circulation. Abnormal endocrine activity: too low: hyposecretion- hypothyroidism, decrease tissue responsiveness.
