Endocrine Physiology Summary Notes for Dentistry (Year 1)
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Course
Biomedicine in Relation to Dentistry (4NNYBD01)
Institution
Kings College London (KCL)
Concise and easy to access notes on the physiology of the endocrine system for first year dental students.
Covers hormone classification, pancreas structure, insulin & diabetes, the physiology of the pituitary gland, hypothalamus, adrenal gland, adrenal cortex, thyroid gland & parathyroid gland, ...
Peptide Hormones
• Polypeptides/glycoproteins
• The majority of hormones – includes all hormones of hypothalamus, pituitary,
parathyroids, pancreas & GI tract
• Synthesis: transcription + translation → preprohormone → cleave to prohormones
• Storage: in cells as granules in secretory vesicles (as prohormones)
• Transport: diffuse into leaky capillaries
• Half-life: short – polar / water-soluble → dissolve in plasma unbound
• Mechanism: bind to cell membrane receptors → secondary messenger activation
Steroid Hormones Eicosanoids
• Fat-soluble lipids derived from cholesterol • Local chemical messengers
• 3x 6-carbon rings & 1x 5-carbon ring • Exert a wide variety of effects in different
• Produced by adrenal glands, gonad & placenta organs & tissues
• Synthesis: in mitochondria & smooth ER • Autocrine or paracrine
• Storage: not stored – release depends on rate of • Derived from arachidonic acid (fatty acid)
synthesis
• Transport: diffuses across plasma membranes
• Half-life: long – circulates blood bound to Amine Hormones
proteins • Modified amino acids derived from
• Mechanism: binds to intracellular (nuclear) tyrosine
receptors → alters gene expression • Classified as thyroid or catecholamines
Thyroid Hormones Catecholamines
• Storage: in thyroid glands, bound to • Storage: intracellularly in secretory glands
thyroglobulin • Transport: water soluble – does not cross
• Transport: lipid-soluble – can cross plasma cell membrane
membranes • Half-life: short – circulates dissolved in
• Half-life: long – circulates blood bound to plasma unbound
proteins • Mechanism: binds to cell membrane
• Mechanism: binds to intracellular (nuclear) receptors → secondary messenger activation
receptors → alters gene expression
Hormone Storage Solubility Half-Life Receptor
Peptide Secretory vesicles Water-soluble Short Cell membrane
Released
Steroid Lipid-soluble Long Nuclear
immediately
Thyroid Thyroid gland Lipid-soluble Long Nuclear
Hormon
Amine
Catecholamine Secretory glands Water-soluble Short Cell membrane
, Pancreas
Islets of Langerhans
• Small, round clusters of cells embedded within exocrine
pancreas
• Cells smaller + more lightly stained than exocrine cells
• Main cell types:
o A → secrete glucagon (~20%)
o B → secrete insulin (~70%)
o D → secrete somatostatin (5-10%)
o F → secrete pancreatic polypeptide (1-2%) A Cells B Cells
(Glucagon) (Insulin)
Insulin Structure
• Peptide hormone
produced from
proinsulin
• A-chain with 21
amino acids
• B-chain with 30
amino acids
• Connected by 2
disulphide bonds
Glucagon Insulin
• Hyperglycaemic hormone, alongside • The only hypoglycaemic hormone (glucose →
adrenaline & cortisol (glycogen → glucose) glycogen)
• Secretion stimulated by low blood glucose, • Secretion stimulated by raised blood [glucose],
high blood [amino acid] & adrenaline raised blood [amino acid], secretin or glucagon
• Metabolic effects: • Metabolic effects:
o Mobilises fuel – maintains blood glucose o Promotes growth & food storage after
during fasting meal
o Activates glycogenolysis & o Stimulates glycogenesis (glycogen
gluconeogenesis in liver synthesis + storage)
o Activates uptake of amino acids by liver o Stimulates lipogenesis (fatty acid
for gluconeogenesis – transdeamination synthesis + storage from CHO) when
o Activates release of FA from adipose intake exceeds glycogen storing capacity
tissue and oxidation / ketone body o Stimulates amino acid uptake + protein
formation in liver synthesis
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