128 Endocrine Flashcards
Name the 4 types of hormones
- peptide
- aa derivatives
- steroid
- eicosanoids
Are peptide hormones water soluble or lipid soluble?
Water soluble
From which 2 sites is the peptide hormone somatostatin secreted from?
Hypothalamus and pancreas
Which 2 peptide hormones does the posterior pituitary secrete?
Vasopressin
Oxytocin
Which peptide hormone is secreted from the placenta?
hCG
Which 3 peptide hormones are released from the pancreas?
Glucagon
Insulin
Somatostatin
Where are steroid hormones synthesises?
Adrenal cortex
Where do the steroid hormones bind to receptors?
(cellular)
Nuclear membrane
Name the 3 zones of the adrenal cortex
- Zona glomerulosa
- Zona fasciculata
- Zona reticularis
Which steroid hormone is secreted from the Zona Glomerulosa of the adrenal cortex?
Aldosterone
What is the role of aldosterone?
Control of BP - acts on the distal convoluted tubules and collecting ducts in the kidney to increase resorption of H2O and increase BP
What is the mechanism by which aldosterone is released from the Zona glomerulosa of the adrenal cortex?
RAAS system –> renin secreted from the kidneys in response to electrolyte conc of the blood. This converts angiotensiogen into angiotensin I. Angiotensin I into angiotensin II by ACE secreted by the lungs. Angiotensin II makes adrenal cortex secrete aldosterone
Which glucocorticoid is secreted by the Zona fasciculata of the adrenal cortex?
Cortisol
Where is cortisol secreted from?
Zona fasciculata of the adrenal cortex
What is the role of cortisol? (3 listed)
- Control of carbohydrate metabolism
- increases aa conc in the blood by inhibiting protein synthesis in tissues
- promotes use of fat for energy
- stimulates gluconeogenesis in the liver
- Inflammatory response - suppresses by preventing Tcell proliferation
- Stress response - ie redistributing glu to the areas which need it most
Which steroid hormones are secreted from the zona reticularis in the adrenal cortex?
Sex hormones: androgens and oestrogens
Which amino acid are the catecholamines derived from?
Tyrosine
Which catecholamines are secreted by the adrenal medulla?
NA and adrenaline
Which amino acid derived hormones are secreted from the thyroid gland?
T3 - triiodothyronine
T4 - thyroxine
What are eicosanoids and what are they derived from?
Hormones/signalling molecules derived from PUFAs
Which eicosanoid is involved with inflammation and pain sensation?
prostaglandin
Which eicosanoid is involved with the increase of vascular permeability and vasodilation during inflammation?
thromboxanes
Which enzymes catalyse oxygenation of fatty acids to produce eicosanoids?
COX (cyclooxygenase) and LOX (lysil oxidase)
Which nucleus in the hypothalamus is responsible for circadian rhythm?
Suprachiasmatic nucleus
In the stress response, which hormone is released from the hypothalamus to act on the anterior pituitary?
CRH (corticotropin releasing hormone) –>ant pit secretes ACTH –> acts on the adrenal cortex –> secreted cortisol
Where is calcitonin secreted from?
Thyroid gland
What is the function of calcitonin? (3 ways in which it acts)
Acts to reduce serum [Ca2+] - opposite effect to PTH
- Inhibits Ca2+ absorption by the intestines
- Inhibits osteoclast activity in bones
- Inhibits renal tubular cell reabsorption of Ca2+ allowing it to be excreted in the urine
What is the function of PTH?
To increase serum [Ca2+] by:
- stimulating osteoclastic bone resorption
- It enhances active reabsorption of calcium and magnesium from distal tubules and the thick ascending limb
- It enhances the absorption of calcium in the intestine by increasing the production of activated vitamin D
Which cells produce PTH?
Chief cells of the parathyroid gland
Which cells of the pancreas secrete glucagon?
α cells of the pancreas
Which cells secrete insulin in the pancreas?
β cells
What is the effect of glucagon secretion by the pancreas?
Causes glucose production by the liver - glycogenolysis and gluconeogensis therefore prevents hypoglycaemia
What is the effect of insulin secretion by the βcells in the pacreas?
Reduction in glucose plasma levels - prevents gluconeogenesis by the liver and increases glucose transport into cells. Prevents hyperglycaemia