Hypothalamus and Pituitary Gland Content support revision basis Flashcards
what is the relationship between hypothalamus and pituitary
Interaction of the endocrine and nervous systems in the regulation of homeostasis
What do neurons in the supra and paraventricular nuclei of hypothalamus project into and do
Neurons with cell bodies in the supra and paraventricular nuclei of hypothalamus project into posterior pituitary gland, directly releasing hormones into venous drainage
What do neurons with cell bodies in medial hypothalamic nuclei project into and do
Neurons with cell bodies in medial hypothalamic nuclei project into median eminence, releasing tropic hormones into pituitary portal veins
What do tropic hormones influence
Tropic hormones influence cells in anterior pituitary gland to produce hormones circulating in the body
Give 2 examples of gonadotropins
FSH and LH
Where do gonadotropes play integral roles
hypothalamus-pituitary-testis axisand thehypothalamus-pituitary-ovary axis
What hypothalamic releasing hormone is FSH and LH secretion regulated by
gonadotropin-releasing hormone (GnRH)
Where is GnRH released from
released from neurons of the arcuate and preoptic nuclei of the hypothalamus.
What are 2 types of GnRH secretion and what 3 factors can influence GnRH secretion
2 types of secretion: pulsatile or episodic
3 factors that can influence GnRH secretion: stress, exercise and diet.
What is the frequency of GnRH secretion that increases LH secretion
At a frequency of 1 pulse per hour, GnRH preferentially increases LH secretion
What is the frequency of GnRH secretion that increases FSH secretion
at a frequency of 1 pulse per 3 hours, GnRH preferentially increases FSH secretion.
What does LH stimulate in males and from where does this come from
LH stimulates testosterone production from the Leydig cells of the testes
What is the main male androgen
Testosterone is the main male androgen
What does testosterone feed back to the hypothalamus to do? What does it do when it reaches the level of the pituitary gland
Testosterone feeds back on the hypothalamus to inhibit GnRH secretion and at the level of the pituitary to inhibit LH secretion
What is the most important role of HPG axis in female reproduction
to control the uterine (menstrual) and ovarian cycles
What are the spheres of follicles in the thyroid composed of
Spheres of follicles composed of follicular cells and parafollicular cells
What do follicular cells produce and where is this thing stored?
Follicular cells produce thyroid hormone, stored in colloid lumen
What do parafollicular cells (C cells) produce
Parafollicular cells (C cells) make calcitonin
What do principal (chief) cells do?
they are Predominant and secrete PTH
How many iodines does T3 and T4 have respectively
T4 = 4 iodides
T3 = 3 iodides
What does T4 act as
acts as a plasma reserve
What does T3 act as
acts as the active form of T4
Which 3 locations is T4 converted to active T3?
T4 is converted to active T3 in peripheral tissues, brain and pituitary gland
What is the production of T4 and T3 catalyzed by
Catalysed by Thyroid Peroxidase (TPO)
What are the 2 stages of T4/T3 production
Stage 1. Iodination
Stage 2. Coupling
What 3 molecules make T4
2 x DIT with Tgb
What 3 molecules make T3
1x DIT, 1x MIT and Tgb
