Endocrinology - Endocrine Glands Flashcards
Primary endocrine glands
Parathyroid glands
Pineal gland
Hypothalamus
Pituitary gland
Thyroid gland
Adrenal gland
Pancreas
Ovaries
Testes
Placenta (pregnant females)
Embryological development
Up growth from roof of mouth
Down growth of the brain
Hypothalamus
Cell bodies and the neurons responsible for the secretion of hypothalamic-releasing factors (hormones)
Releasing factors pass along the portal vessels to reach capillary bed of the anterior pituitary, to control secretion of anterior pituitary hormones
Endocrine axis
Interactions between the hypothalamus, pituitary and peripheral endocrine glands, with feedback regulation of hormone secretion, to maintain physiological homeostasis
“master switchboard”
Hypothalamus
Releasing hormone
+/-
Anterior pituitary
Tropic hormone
+
Peripheral endocrine gland
Peripheral hormone
Target cell response
Gonadotropin-releasing hormone
Stimulates the release of luteinizing hormone (LH) and folicle-stimulating hormone (FSH)
Growth Hormone-Releasing Hormone
Stimulates the release of somatotropin/growth hormone
Somatostatin inhibits the release of GH
Thyrotropin-releasing hormone
Stimulates the release of thyrotropin (TSH)
Somatostatin also inhibits the release of TSH as well as GH
Prolactin
Under a predominant inhibitory influence from the hypothalamus by dopamine
Thyrotropin-releasing hormone also stimulates the release of prolactin
Corticotropin-releasing hormone (CRH)
Stimulates the release of corticotropin
Neuroendocrine cells
Synthesise vasopressin and oxytocin (in cell bodies located in the hypothalamus)
What happens in the posterior pituitary
Neuroendocrine cells synthesise vasopressin and oxytocin
Hormones are transported along neurons stored in the axon termini
Two hormones:
Arginine vasopressin (AVP)
Oxytocin
Two hormones Actions with Blood Vessels and Kidney
Blood vessels - Vasoconstriction via V1 receptors at higher AVP
Kidney - Distal convoluted tubules and collecting ducts to increase permeability and hence re absorption of water via V2 receptors
Melatonin
Control of the body’s circadian rhythm in synchrony with the light-dark cycle
Melatonin uses
Treat insomnia and jet lag
