MEDI211 Lecture Notes - Lecture 1: Protein Kinase, Enzyme Inhibitor, Guanine
Week 3 Lecture 1 – Endocrine 1
Lecture Objectives:
•To gain understanding of the hypothalamic - pituitary axes in the body
Early Endocrine experiments:
•Berthold in 1849 castrated rosters which showed behavioural and anatomical differences -
smaller cobs and wattles, reduced sexual interest and less aggression towards other rosters.
•Berthold then replaced these removed testes back into the body cavity of the rosters, which
restored the behaviour and secondary characteristics. The nerves were still severed during the
removal, so Berthold concluded that the testes influence the behavioural and characteristics
of the roster by secreting a fluid.
•These hormonal effects were also seen from Eunuchs in ancient Egypt and china.
Endocrine system:
•Functional system of communication between cells
•Major functions of the endocrine system include:-maintaining homeostasis eg. Metabolism
and water balance-Regulation of reproduction, growth and development
•Hormones are released from endocrine organs, and travel in blood to the target cells.
•Three groups of hormones: peptides, steroids and amines.
Peptide Hormones: chains of 3-200 amino acids —> short proteins.
•Solubility: water soluble —> travel freely in blood.
•Storage: Peptide hormones are stored in secretory vesicles (like insulin)
•Secretion: via exocytosis --> build up of Ca2+ near the vesicles causes them to move and
release an active hormone.
•Transport: most circulate free in the blood
•Receptors: membrane-spanning with extracellular ligand-binding site.
Biosynthesis of peptide hormones: peptide hormones are manufactured by:
•Pancreas: insulin, glucagon, somatostatin, pancreatic polypeptide
•GI tract: ghrelin, GLP-1
•Adipose tissue: leptin
•Pituitary gland: LH, FSH, ACTH, TSH, prolactin
•Parathyroid: parathyroid hormone
•Hypothalamus: NPY, POMC
•Kidneys: renin, a-hydrolylase (Vit D3 pathway)
Peptide hormones are synthesised in their specialised endocrine cells, then are stored as pre-
hormones, ready to be secreted.
Process of peptide hormone synthesis:
Transcription of mRNA —> ribosomes on RER —> processing by Golgi apparatus —>
vesicular storage —> released via exocytosis
Process of peptide hormone synthesis:
•mRNA transcribed from DNA strand
•Ribosomes read mRNA group to form amino acids then a protein
•A signal sequence of early proteins binds to the RER.
•Protein is synthesised in the RER.
•During the synthesis stage, the proteins bind to the RER
•Ribosome unit continues tor read mRNA until completion
•Ribosomes dissociate from mRNA and protein is now synthesised
•Synthesised protein is transported to Golgi apparatus where it is processed into vesicles,
secreted into cytosol, then exocytosed from cell when conditions are right.
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Document Summary
To gain understanding of the hypothalamic - pituitary axes in the body. Berthold in 1849 castrated rosters which showed behavioural and anatomical differences - smaller cobs and wattles, reduced sexual interest and less aggression towards other rosters. Berthold then replaced these removed testes back into the body cavity of the rosters, which restored the behaviour and secondary characteristics. The nerves were still severed during the removal, so berthold concluded that the testes influence the behavioural and characteristics of the roster by secreting a fluid. These hormonal effects were also seen from eunuchs in ancient egypt and china. Major functions of the endocrine system include:-maintaining homeostasis eg. metabolism and water balance-regulation of reproduction, growth and development. Hormones are released from endocrine organs, and travel in blood to the target cells. Three groups of hormones: peptides, steroids and amines. Peptide hormones: chains of 3-200 amino acids > short proteins. Solubility: water soluble > travel freely in blood.
