HPA Hormones & Targets and Posterior Pituitary Hormones

00:00 When dealing with hypothalamic pituitary axis hormones and targets, we really need to talk about four main items.

00:12 And that is, What is the anterior pituitary target? What stimulates it? That's the hypothalamic hormone.

00:22 And then, What pituitary hormone is released? And then, Where is it going? And what is it going to do? Let's start off with CRH.

00:32 This will stimulate corticotropes to release ACTH.

00:40 ACTH then binds to the adrenal cortex and causes release of hormones.

00:49 The TRH stimulates thyrotropes.

00:56 And that releases TSH which than goes to the thyroid gland to cause the release of T3 and T4.

01:06 Growth hormones releasing hormone or GHRH, goes to somatotropes and somatotropes release growth hormone.

01:18 This has a lot of widespread effects causing growth and anabolic type of response.

01:25 Somatostatin also goes to somatostropes but it is a negative inhibitor of growth hormone and it effects on growth hormone are widespread.

01:38 Because if you prevent the release of growth hormone, growth hormone will not have it's growth like effects.

01:46 Somastostatin is interesting because it inhibits more than just somatostropes.

01:53 It also inhibits thyrotropes.

01:56 This will change the TSH levels and therefore, inhibit thyroid hormone release.

02:04 The next hypothalamic hormone we need to deal with is GRH.

02:09 GRH will stimulate gonadotropes and that will release lutenizing hormone or LH.

02:17 LH effects the gonads and will start androgren production.

02:22 GRH also does one other thing, it also releases follicles stimulating hormones or FSH.

02:31 That too helps maturation processes occur in the gonads.

02:39 Things like follicle formation and spermatogenesis.

02:42 Finally we have dopamine.

02:45 Dopamine acts on lactotropes and causes the inhibition of the release of prolactin.

02:55 So you normally would get prolactin release unless dopamine is present.

03:00 When dopamine is present it inhibits prolactin.

03:03 Prolactin is very important with the mammary glands.

03:07 This will allow for milk production.

03:09 The posterior pituitary hormones again come directly from the hypothalamus.

03:16 These posterior pituitary hormones are oxytocin.

03:20 And oxytocin primarily, effects the uterus as well as breast tissue or mammary glands.

03:29 Antidiurectic hormone is the other posterior pituitary hormone.

03:34 And that effects places like the collecting duct on the renal tubule to help you reabsorb water.