Term
| What hormones are secreted in the posterior pituitary? Where are the cell bodies located that secrete these hormones? |
|
Definition
ADH (vasopressin) and oxytocin
The cell bodies are located in the supraoptic and paraventricular nuclei of the hypothalamus |
|
|
Term
| What is the purpose of short portal veins? |
|
Definition
| They connect the posterior pituitary lobe to the anterior pituitary lobe, perhaps moving components from the posterior pituitary to regulate the anterior pituitary |
|
|
Term
|
Definition
GH is synthesized by the somatotrope cells of the anterior pituitary
GH gene transcription is increased by growth hormone releasing hormone from the hypothalamus |
|
|
Term
| What blocks GH secretion? |
|
Definition
|
|
Term
| Is GH secretion pulsatile or steady? Why is this important? |
|
Definition
Pulsatile
The periodic absence of GH is important for maintaining the synthetic functions of GH while minimizing its insulin-antagonistic actions |
|
|
Term
| What stimulates GH secretion? What inhibits GH secretion? |
|
Definition
Stimulators: hypoglycemia, slow wave sleep, amino acids, puberty, stress, exercise
Ibhibitors: glucose, REM sleep |
|
|
Term
| What are the characteristics of the GH receptor? |
|
Definition
It is synthesized by a single chain glycoprotein; the receptors dimerize by two receptors binding GH at different sites; excess GH prevents dimerization
Receptor synthesis is stimulated when the circulating GH is low; insulin and estrogen also promote GH receptor synthesis; GH receptor synthesis is inhibited by high circulating concentrations of GH and by fasting |
|
|
Term
| When are GH growth promoting effects observed? What are they due to? |
|
Definition
The effects are observed 12-18 hours after GH levels increase
This is due to the induction of IGF synthesis in the liver |
|
|
Term
| What are the clinical symptoms of giantism/acromegaly? |
|
Definition
Accelerated growth
Insulin resistance
Mild carbohydrate intolerance |
|
|
