hypothalamus-pituitary axis

what controls the secretion of the anterior pituitary hormones?

secretion of the hypothalamic hormones

where to the hypothalamic hormones travel?

through the hypothalamo-pituitary portal vessels to the anterior pituitary

what does corticotropin releasing hormone (CRH) do?

stimulates secretion of ACTH

what does gonadotropin releasing hormone (GnRH) do?

stimulates secretion of FSH/LH

what does growth hormone releasing hormone (GHRH) do?

stimulates the secretion of GH

what does somatostatin (GH inhibitory hormone) do?

inhibits secretion of GH

what does thyrotropin releasing hormone (TRH) do?

stimulates secretion of TSH

what does dopamine (prolactin inhibiting hormone) secrete?

• inhibits the secretion of prolactin

what type of neurons synthesize vasopressin and oxytocin?

hypothalamic

How do vasopressin and oxytocin get to the posterior pituitary?

via axonal transport to the neuronal terminals in the posterior pituitary

What is antidiuretic hormone (ADH)?

• it is also known as arginine vasopressin (AVP)

• the target cells are the renal tubule cells

• ADH stimulates the insertion of water channels (aquaporin) into renal tubule cells which stimulates more water reabsorption

• ADH also stimulates the contraction of vascular smooth muscle and thus the pressor or vasoconstriction function of ADH

what is oxytocin?

• major target cells are the female breast for milk ejection

• oxytocin also stimulates uterine contractions

what is the tropic effect of FSH/LH?

• stimulates gonads to produce hormones

• female gonad produces estradiol and progesterone

• male gonad produces testosterone

what is the tropic effect of growth hormone?

• stimulates the liver and body’s cells to secrete IGF-1

what is the tropic effect of thyroid stimulating hormone?

• stimulates the thyroid gland to secrete T3 and T4

what is the tropic effect of prolactin?

breast

what is the tropic effect of adrenocorticotropic (ACTH) hormone?

it stimulates the adrenal cortex to secrete glucocorticoids

what is the hierarchal control of long loop feedback regulation?

the hormone tells ant pit and hypothal to stop secreting

what is the simple short loop feedback regulation?

just tells the hypothalamus to stop

what is hyposecretion?

the endocrine gland secretes too little hormone

ex: low iodine intake can cause hypothyroidism

what is hypersecretion?

the endocrine gland secretes too much hormone

ex: increased GH secretions in gigantism and acromegaly

what is hyporesponsiveness?

a target cell has low response (decreased sensitivity) to a hormone

ex: insulin resistance in type 2 diabetes mellitus

what is hyperresponsiveness?

a target cell has too much response (increased sensitivity) to a hormone

ex: increased responsiveness to epi in patients with hyperthyroid ism, resulting in elevated resting HR