••• Chapter 52^ Hypothalamic-Pituitary-Ovarian-Uterine Axis^521
❍ Why does the female pituitary gland increase in size by about 10% during pregnancy?
Because of the hypertrophy of prolactin (PRL) secreting cells.
❍ What percentage of cells in the pituitary gland are gonadotropes?
Approximately 10%
❍ What six hormones are secreted by the anterior pituitary?
Growth hormone (GH).
Adrenocorticotropic hormone (ACTH).
Thyroid-stimulating hormone (TSH).
Prolactin (PRL).
Luteinizing hormone (LH).
Follicle-stimulating hormone (FSH).
❍ Which hormones share a similar alpha unit?
LH, FSH, TSH, (and hCG).
❍ What hormones are secreted by the posterior pituitary?
Oxytocin and ADH (vasopressin).
❍ What is the action of oxytocin?
It stimulates uterine contraction during labor and elicits milk ejection by myoepithelial cells of the mammary
ducts.
❍ What fold increase in oxytocin receptors occurs throughout pregnancy and labor?
Number of oxytocin receptors increases 80-fold throughout the pregnancy and doubles during the labor.
❍ What is the time of the peak in oxytocin levels?
During the LH surge.
❍ What is the action of ADH?
It causes increased rates of Na+ and Cl- reabsorption and enhances permeability within the collecting ducts of the
renal medulla.
❍ What is the function of LH in the adult female?
Stimulate maturation of the Graafian follicle and its production of estradiol.
❍ What is the half-life of FSH?
3 to 4 hours.
❍ What is the function of FSH in the adult female?
Causes follicular rupture, ovulation, and establishment of the corpus luteum.