Endocrinology 1 - Introduction Hormones Chemical messengers released from one cell that produce a specific receptor mediated change in another cell Hormones are involved in: - Development - Metabolism - Reproduction - Fluid homeostasis Glands An organ that synthesises and releases substances into the bloodstream, body cavity or skin Glands can be; Endocrine eg. pancreas Exocrine Mucous Serous Sebaceous Endocrine Tissues with endocrine function include; Kidney - erythropoietin (EP) Heart - atrial natriuretic peptide (ANP) Gut - gastrin, secretin Adipocytes (fat sources) - leptin, adiponectin Pancreas - insulin Endocrine Systems; Listen to this part again Communication Autocrine reaction eg. Pancreatic beta cells Release hormones that they take in themselves Paracrine reactions Cells releases hormones that binds to receptors on neighbouring cells Endocrine reactions Goes into the bloodstream and the binds to distant cell Neurocrine Hormones produced in a nerve and travels down the axon into the blood Hormone Synthesis Protein & Peptide Hormones a. Gene Transcription b. mRNA to RER c. translation on RER d. post-translational processing e. packaging into secretory vesicles
f. exocytosis Steroid Hormones a. hydrolysis of esters and release of cholesterol b. cholesterol to pregnenolone c. processing d. diffusion Peptide Hormones Synthesised from amino acids and are typically; - processed in several stages - n-terminal signal sequence cleavages in ER - post-translational processes eg. glycosylation in ER - cleavage of pro-hormone by endopeptidases in cell pre-pro-PTH (115 residues) - inactive hormone pro-PTH (90 PTH (8ff residues) - active hormone Steroid Hormones Grouped by the receptor they bind to; Glucocorticoids eg. cortisol Mineralocorticoids eg. aldosterone Androgens eg. testosterone Oestrogens eg. oestradiol Progestogens eg. Progesterone Synthesis of steroid hormone; Feedback Mechanisms Neuroendocrine Axis: Brain Hormone/Neurotransmitter Pitumiry Hormone Hormone Other gland n & tetes, thymgh? ersity Signal to pituitary gland\hormone send to target tissue Target tissue release effector hormone which will send a signal back to the brain Releasing Hormones: - First hormone scale dthe releasing hormone which will bind to a receptor - When binds it will release a econf hormones, a tropic hormone
- Which will affect target gland which will release the hormone that causes a change e.g. Testosterone A tropic hormone - hormones that have endocrine alands as their - This hormone also feedbacks to the hypothalamus This is a; generic endocrine feedback loop Outside factor Hypothalamus Long loop Releasing/Iskibiting homoje Effect Pituitary Topic harmane Short loop Target Tissue Eg. HPA-Axis Stress +ve Hypothalamus +ve CRH A single molecule of cortisol exerts negative feedback Anterior pituitary +ve ACTH -ve Adrenal cortex Cortisol Stress stimulates the hypothalamus Crh binds to anterior pituarity Acth tracel through blood to adrenal cortex Cortisol will be released Cortisol will feddbak to hypithalaum and decresed crh production Cortisol . I bone function · 1 bone resorption . I connective tissue · Inhibit inflammatory and immune response · Maintain muscle function, o I muscle mass · Modulate emotional tone, wakefulness · îglomerular filtration · and water clearance · Facilitate maturation of the foetus · Maintain cardiac output, o endothelial permeability o arteriolar tone