Repro Endocrinology

Question 1

Simple neural reflex

Answer 1

Delivers neurotransmitters via neurons directly to target tissue

Question 2

Neuroendocrine reflex

Answer 2

Hormones enter blood and are delivered to a remote target tissue

Question 3

What is the hypothalamo-hypophyseal portal system and what is its function?

Answer 3

axons from the surge center and tonic center of the hypothalamus terminate in blood vessels going to the anterior pituitary. This allows minute quantities of released hormones to reach the anterior pituitary before they are diluted in circulation

Question 4

How are neurohormones released from the PVN (paraventricular nucleus) of the hypothalamus?

Answer 4

Axons from here extend into the posterior pituitary where they release hormones into the capillary plexus into systemic circulation

Question 5

What is the difference between the M and F hypothalamus?

Answer 5

M only have a tonic center. F have a tonic and surge center

Question 6

Explain the mechanism of defeminization

Answer 6

Testosterone crosses the blood brain barrier and is converted to estradiol. Estradiol suppresses the surge center
(Alpha-fetoprotein binds estradiol in F and prevents it from crossing the BBB)

Question 7

Physiologic definition of puberty

Answer 7

Ability of hypothalamus to produce enough GnRH to support gametogenesis

Question 8

Describe the 5 factors that contribute to maturation of the hypothalamus

Answer 8

1. Nutritional status (glucose, FAs, presence of leptin)
2. Threshold body size
3. Genetics
4. Environmental cues (pheromones)
5. Photoperiod (long/short days, month of birth)