10 Endocrine Glands Flashcards
Pituitary gland
Where is it?
Anterior secretion?
Posterior secretion?
Base of brain
Anterior: TSH, ACTH, FSH, LH, GH, MSH
Posterior:ADH, vasopressin, oxytocin
Thyroid gland
Where?
Secretions?
Anterior of trachea
T4 and T3
Parathyroid gland
Where?
Secretions?
lie on the dorsal of the thyroid gland
Parathormone (PH)
Adrenal gland
Where?
Secretion?
Top of the kidneys
Corticosteriods, androgens, estrogen, progestin
Pancreas
Where?
Secretions?
Its exocrine and endocrine
Left of and behind the stomach
Exocrine secretes digestive enzymes into the duodenum
Endocrine has cell clusters called islets of langerhans—> alpha cells secrete glucagon and beta cells secrete insulin
Glycoprotein peptide hormones Where they synthesised? Transported? Receptor location? Example?
Made in advance and stored in vesicles
Dissolved in plasma in blood for transport
Their receptor is on the plasma membrane which activates second messenger system
Examples: insulin, glucagon, prolactin, ACTH, PTH, gastrin
Steroid hormones Their synthesis? Transport? Receptor location? Examples?
Synthesised on demand from precursors
Bound to carrier protein in blood
Receptor located in cytoplasm or nucleus but sometimes membrane. Activation of genes.
Examples: oestrogen, androgen, aldosterone, progesterone and cortisol.
Catecholamines (aa derived hormone) Synthesis? Transport? Receptor location? Examples?
Made in advance and stored in secretory vesicles
Dissolved in plasma in blood
Receptor on cell membrane, activates secondary messenger.
Examples: adrenaline, noradrenaline.
Thyroid hormones (aa derived) Synthesis? Transport? Receptor location? Examples?
Made in advance, stored in secretory vesicles.
Bound to protein carrier in blood.
Receptor in nucleus, activates genes.
Examples: T4 and T3.
Hypothalamus
Whats it’s role?
What does it produce?/pituitary
Thermoregulation Plasma osmolality vie osmoreceptor HR/BP Feeding Circadian rhythm Stimuli from the autonomic NS Emotions, sexual behaviour, mood Lactation
Produces: vasopressin, oxytocin to the posterior pituitary through nerves where it is released.
Pituitary structure
Whats the portal circulatory route?
Two lobes:
Anterior (nerves stop before it)
Posterior (nerves run into it)
Passed through anterior through the portal system. Portal circulatory route differs as has an intermediate between capillaries. The intermediate is a portal vessels.
Development of the endocrine system
Happens from 5 weeks onwards in gestation.
Need to know
Direct stimulation of adrenal medulla from the nervous system.
All of these hormones are subject to constitutive and regulated merocrine secretion. So there is always a small concentration of these hormones in the blood
Thyroid gland
How stimulated?
If low T4/3?
If high T4/3?
Stimulated by thyroid stimulating hormone (TSH) and by thyroid stimulating antibodies (TSAbs) to produce T3 and T4
High T4/3: HYPERthyroidism
Low T4/3: HYPOthyroidism
Hashimoto’s
TSH level?
T4/3 level?
Antibodies?
Under active thyroid (hypo)
TSH: high
T4/3: low
Ab: Anti-TPO, anti-TG
Grave’s
TSH level?
T4/3?
Antibodies?
Hyperthyroidism, enlarged thyroid
TSH: low
T4/3: high
Ab: TSI and anti-TSH
Parafollicular cells
What are they? Where are they? What do they produce? Roles?
Neuroendocrine cells that migrate into the thyroid during thyroid development in the embryo.
Found between follicles.
Produce calcitonin.
Independant of thyroid hormone synthesis
Role to monitor plasma calcium concs and decreases levels. Also inhibits osteoclast activity in bones. Also inhibits renal calcium and phosphate reabsorption in tubular cells.
On H and E staining: nucleus not central.
Parathyroid gland
Sit on the back of the thyroid. 4 of them, in pairs.
Role: measures plasma calcium. When low, parathyroid makes more PTH which causes bones to release calcium into the blood and absorb more from the gastro intestinal tract. So does the opposite of parafollicular cells.
Adrenal glands
Sit on top of kidneys.
Cortex and medulla.
Medulla: makes adrenaline and noradrenaline
Cortex made of three layers and a capsule on outside.
Medulla not made of epithelial cells even though its a gland. Made of parenchymal and mesochymal cells known as chromaffin cells that are like neurons. They hae many myelinated, presynaptic sympathetic nerve fibres that pass directly to chromaffin cells. When nerve impulses reach these cells they release adrenaline and nor.
Adrenal cortex
Three layers
Outer: zona glomerulosa: produce mineralocorticoid, particularly aldosterone that regulates BP.
Middle: zona fasiculata: produce glucocorticoids, mobilise fats, proteins and carbs —> Important in fight or flight response.
Inner: zona reticularis: produce androgen precursors eg sex hormones.
Fight or flight
Adrenal cortical hormones: glucocorticoids (cortisol) and mineralcorticoids (aldosterones)
Pancreas
Structure?
Made up of a number of lobules of lobes. There are intacolated ducts that come together and come to the pancreatic duct. Whichjoins te bile duct to make the common bile duct.
Intercalated duct lined with cuboidal epithelial cells
Pancreas
Cell level structure
Made of islets of langerhans: alpha beta and delta cells mostly. There are also PP, D-1 and EC cells.
Pancreas exocrine function
Produces enzymes and bicarbonate eg trypsinogen and chymotrypsinogen and lipase and amylase
