Introduction to hormones and endocrine system Flashcards
Hormones control and regulate…
Reproduction Growth and development Body temperature Water levels Metabolism Body defences
Homeostasis
Maintenance of a relatively stable internal environment against constantly changing circumstances.
When hormones go wrong
Diabetes Cancer Acromegaly (Gigantism) Hyperthyroidism (Grave's disease) Cushings syndrome
Hormone
A chemical/protein synthesised by specific tissues and secreted into the bloodstream, whereby it is carried to non-adjacent sites in the body and exerts its actions.
How is the endocrine system organised?
Only target cells with receptors for a given hormone can alter their activities in response to the hormone.
The traditional endocrine system
Hypothalamus Pituitary gland Thyroid gland Parathyroid glands Adrenal glands Pancreas Ovaries Testes
Hypothalamus
Several hormones to regulate pituitary function
Pituitary gland
Several hormones to regulate endocrine tissue function
Thyroid gland
Thyroid hormone
Parathyroid glands
Parathyroid hormones
Adrenal glands
Cortisol, aldosterone, catecholamines
Pancreas
Insulin, glucagon
Ovaries
Oestrogen, progesterone
Testes
Testosterone
Endocrine
‘Internal secretion’
Steroid hormones
Synthesised from cholesterol Lipophilic and hydrophobic Intracellular receptors Nucleus mediated effects Slow action Lipid soluble hormone, therefore intracellular receptors
Example of Steroid hormones
Cortisol
Oestrogen
Testosterone
Progesterone
Non-steroid hormones
Polypeptides Modified amino acids Lipophilic and hydrophilic Cell surface receptors Membrane mediated effects Rapid action Water soluble hormone, therefore cell surface receptors
Example of Non-steroid hormones
Insulin
Tyrosine (EG Catecholamines and dopamine)
Tryptophan (EG 5-HT and melatonin)
Main hormone classes
Cholesterol (Steroid)
Tyrosine (Non-steroid)
Tryptophan (Non-steroid)
Protein/polypeptide (Non-steroid)
Cholesterol (Steroid)
Adrenal cortex (cortisol and aldosterone) Ovaries and placenta (Oestrogen and progesterone) Testes (Testosterone)
Tyrosine (Non-steroid)
Catecholamine (Adrenaline and Noradrenaline)
Thyroid hormones (Triiodothyronine and Thyroxine)
Dopamine
Tryptophan (Non-steroid)
Pineal gland (melatonin) GI tract, platelets and CNA (5-HT - Serotonin)
Protein/polypeptide (Non-steroid)
Hypothalamus (TRH, GnRH and GHRH)
Pituitary gland (TSH, FSH, LH, GH, ACTH, ADH and Oxytocin)
Pancrease/GI tract (Insulin and Glucagon)
