Flashcards in Neuro-endocrine interactions Deck (34)
what is the significance of neurones-endocrine interactions?
Many physiological functions are dually regulated by the nervous and endocrine systems. (e.g. blood pressure)
where do the nervous and endocrine systems interact at?
at the hypothalamus and the pituitary gland
Describe the pituitary gland (aka hypophysis).
a small endocrine gland located in a bony cavity at the base of the brain just below the hypothalamus
what are the two lobes of the pituitary gland ?
-posterior pituitary /neurohypophysis
-anterior pituitary/ adenohypophysis
what makes up the two lobes?
-posterior - composed of nervous tissue
-anterior- consist of glandular epithelial tissue
When is there an intermediate lobe in humans?
During fatal development -site of release of MSH
How does the hypothalamus control the release of hormones from the posterior pituitary?
connects to the hypothalamus by a neural pathway
How does the hypothalamus control the release of hormones from the anterior pituitary?
connects to the hypothalamus by a unique vascular link
where does the hypothalamus lie?
lies at the base of the brain, just dorsal to the pituitary gland
how does the pituitary connect to the base of the brain?
the infundibular stalk
what are the 6 hormones released from the anterior pituitary and what are their functions?
-Growth Hormone (GH) - stimulates IGF-1 production
-Adrenocorticotrophic hormone- stimulates adrenal cortex to make corticosteroids
-Thyroid stimulating hormone
(TSH) - stimulates thyroid follicular cells to make thyroid hormone
-Prolactin (PRL) - initiates and maintains milk productions
-Luteinizing hormone (LH) - stimulates gonads (leydig cells/testosterone)
-Follicle stimulating hormone (FSH)-stimulates gonads
what are the 2 hormones released from posterior pituitary and what are their functions?
-arginine vasopressin (ADH) - promotes water retention
-Oxytocin - stimulates uterus to contract and promotes milk ejection
what two peptide hormones are classed as neuro hormones and why?
-Vasopressin and oxytocin - because they are synthesised and secreted by nerve cells
where are vasopressin and oxytocin stored?
Stored in vesicles in nerve terminals
How is the peptide hormones released?
action potential promotes exocytosis of hormone into the blood-directly released into systemic circulation
what lobe stores the hormones and release the hormones?
posterior pituitary does not produce hormones
what makes action potentials fire down nerves?
- increased ECF osmolality
-hypothalamic neurones fire
-increased H20 permeability of kidney tubules
-increased H20 reabsorption in kidney
-decreased urine output
how are anterior pituitary hormones specialised?
one cell type produces mainly one hormone
what are the anterior pituitary cell types and what do they produce?
-Somatotrophs produce growth hormone
-Thyrotrophs produce thyroid stimulating hormone (TSH)
-Corticotrophs produce adrenocorticotrophic hormone (ACTH)
-Gonadotrophs produce FSH and LH
-Lactotrophs produce prolactin
what is the specialised blood supply that links hypothalamus directly to anterior pituitary?
hypothalamic- hypophyseal portal system
what hormones can stimulate and inhibit secretion?
what is the releasing factor and inhibiting factor?
-Growth Hormone Releasing Hormone (GHRH)
what is the releasing factor of the thyroid stimulating hormone?
Thyrotrophin releasing hormone (TRH)
what is the releasing factor and inhibiting factor of the prolactin (PRL)?
-Prolactin Releasing Factor (PRF)
-Prolactin inhibiting factor (PIF – dopamine)
what is the releasing factor of the adrenocorticotrophic hormone hormone (ACTH)?
Corticotrophin Releasing Hormone (CRH)
what is the releasing factor of the LH/FSH?
Gonadotrophin Releasing Hormone (GnRH)
what can overcome negative feedback of hormone secretion?
CNS via the hypothalamus
what are the two types of negative feedback loops can be observed?
what is the short feedback loop of hormone secretion?
inhibit hormone 2 by product of hormone 3