Lecture 4 - the Hypothalamic - Pituitary Axis

What does the endocrine anterior pituitary secrete?

FSH, LH, TSH, ACTH, GH, PRL

What does the neural posterior pituitary secrete?

ADH, oxytocin

What is another name for pituitary?

Hypophysis

What is derived from the embryonic brain tissues?

the hypothalamus and posterior pituitary

What is derived from the roof of the mouth (endocrine tissues)?

anterior pituitary

Where are the pituitaries?

within the bony structure of sella turcica

Which pituitary has arterial blood supply?

posterior

The hypothalamic releasing hormone stimulates what?

secretion of A.P. hormone

This inhibits the secretion of the A.P. hormone

Hypothalamic inhibitory hormone

GnRH affects the release of which anterior pituitary hormone?

LH and FSH

TRH affects the release of which anterior pituitary hormone?

TSH

CRH affects the release of which anterior pituitary hormone?

ACTH

GHRH affects the release of which anterior pituitary hormone?

GH

SST affects the release of which anterior pituitary hormone?

GH

DA affects the release of which anterior pituitary hormone?

Prolactin (PRL)

The hypothalamic pituitary target axis is controlled by?

Negative Feedback

Prolonged elevation in an AP hormone leads to what?

hypertrophy

Prolonged deficiency in an AP hormone leads to what?

atrophy

What is the significance of the hypothalamic-pituitary portal vessel?

its the only blood supply to the anterior pituitary

T/F: hypothalamic factors in a healthy individual are typically high enough to measure in the systemic blood

FALSE; they are usually too low to measure

What are the hypothalamic releasing hormones?

GnRH, TRH, CRH,, GHRH

What are the hypothalamic inhibitory hormones?

DA, SST

What are Ectopic hormones?

hormones produced by tumors of tissues that are not normally engaged in the production of that hormone

What is panhypopituitarism?

loss of all anterior pituitary function

What is an example of panhypopituitarism?

Sheehan’s syndrome

What is Sheehan’s syndrome?

results from postpartum hemorrhage leading to blood clots blocking the hypothalamic pituitary portal vesselWhat

What does excess GH before puberty result in?

gigantism

What does excess GH after puberty result in?

acromegaly

What is the distinction between gigantism and acromegaly?

the height; gigantism is long bone growth while acromegaly is the abnormal growth of hands, feet, face, and other parts of the body

What is the metabolic effect of excess GH?

increased insulin insensitivity; will develop type 2 diabetes mellitus

Where is ADH and Oxytocin synthesized?

in the soma/cell body in the hypothalamus

Explain the secretion process of ADH and oxytocin in the posterior pituitary gland

stimuli received by cell body in the hypothalamus, action potentials are generated in the hypothalamus, action potentials are propagated to the posterior pituitary, secretion of ADH and oxytocin from the PP into general circulation

What happens if you have too little ADH or impared ADH receptors?

Diabetes insipidus

What does ADH stimulate?

water re-absorption by the kidney

What does oxytocin stimulate?

smooth muscle contraction and modulates the neuronal activities

What is an example of an integrated response?

Suckling