Circle all correct answers. May be more than one correct answer for each question.

1. Oxytocin

A. stimulates milk synthesis. Prolactin stimulates milk synthesis
B. is released from the anterior pituitary. released from posterior pituitary
C. stimulates milk let-down. 2
D. is synthesized by the uterus2
E. is synthesized by the posterior pituitary gland synthesized in hypothalamus

2. Progesterone 

A. is lowest during the proliferative phase 3 proliferative phase of uterus coincides with follicular phase of ovary
B. stimulates uterine contractions at menstruation ("menstrual cramps") progesterone inhibits contractility
C. is released from cells by exocytosis steroids can diffuse through membrane, don't require exocytosis
D. is never found in males Progesterone is made in males too as part of the pathway of aldosterone and cortisol and testosterone synthesis.
E. combines with receptors on the membrane of endometrial cells steroid hormones generally work by combining with intracellular receptors, but since we did have an example last semester, in which progesterone worked on a membrane-bound receptor, I decided to just not count this choice

3. The blood-testis barrier

A. prevents testosterone from diffusing into the seminiferous tubules. Steroids diffuse through membranes.
B. maintains a separation between the Leydig cells and the Sertoli cells.
C. prevents production of antibodies against spermatocytes. 3
D. is only found in males with 5-alpha reductase deficiency.
E. ensures that Sertoli cells and spermatogonia will not come in direct contact with one another.
F. results from tight junctions between adjacent Leydig cells. Between adjacent Sertoli cells

4. Rose of Sharon was a pregnant, young woman, when she underwent the harsh conditions with the Joads during the Depression in the American West, depicted in The Grapes of Wrath. At the end of the novel, she gives birth to a stillborn baby (that is, the baby is born dead). A few days later, her breasts are painfully swollen, as they are engorged with milk. The Joads happen upon an old man, who is dying, and gasps out a request for a drink. They have nothing to offer...but then Rose of Sharon goes to him, offering her breast, both to relieve her pain and to provide him with one last sip of fluid.

Great image for a Lit Hum paper, but the question here is about the biology of it: Why are her breasts filled with milk? In class, we discussed how an infant's sucking can stimulate milk production, but, in fact, there is some milk available in the breasts for the infant's first suckling, that is, something else is happening. We did not specifically discuss this, but you should be able to piece together what is happening. Your answer should include: a description of the relevant hormonal changes during pregnancy and at the end of pregnancy, how those hormones affect the breast tissue, and what changes occur at the end of pregnancy (ie, at birth) to allow milk production. You should mention what is happening in the hypothalamus, pituitary, placenta and breast, if appropriate.

Placenta 1--> Estrogen 1 ---> development of mammary gland ducts 1, increase in prolactin receptors 1, increase in prolactin gene expression 1, increase prolactin synthesis......> So would expect milk production. But:

Placenta --> Progesterone 1--> stimulates alveolar development in mammary glands 1, but also inhibits production of prolactin receptors 1, so mammary gland doesn't respond to estrogen-induced prolactin. And:

Hypothalamus---> dopamine (PIH) 2 -->prevents-->Anterior pituitary release of Prolactin

Late in pregnancy, PIH decreases 1, so the estrogen-induced prolactin can be released from the gland 1.

At parturition, the placenta is expelled, removing the source of progesterone so progesterone falls 2 , and  now estrogen-induced PRL receptors are active, and prolactin can stimulate milk production.

5. Circle correct answer. ONLY ONE correct answer for each question.

Consider each of these pairs of hormones. Which pair includes two hormones that are most different from each other?

A. LH and TSH
B. Prolactin and FSH 3 PRL is a single protein chain, like GH, FSH has alpha/beta subunits
C. hCG and ACTH Sorry for the confusion; I meant to write hCG and LH, which ARE similar, and I realized too late that I wrote ACTH, so we gave you credit if you wrote EITHER B or C.
D. Oxytocin and Vasopressin (ADH)
E. Estrogen and Testosterone

6. Which of the following is the major difference between the control of LH and ACTH secretion?

A. Hypothalamic control of LH is mainly via an inhibitory signal; control of ACTH is mainly via a stimulatory signal
B. ACTH is subject to negative feedback, LH is not.
C. LH is primarily controlled by a non-steroid molecule, inhibin; ACTH is primarily controlled by a steroid molecule, cortisol Inhibin inhibits FSH, not LH
D. LH release may be stimulated by a steroid hormone; ACTH release is inhibited by a steroid hormone. 3
E. LH is a glycoprotein, while ACTH is a steroid ACTH is also protein

7. Which one of these students would most benefit from using Science Citation Index: (All examples are made up, but assume that they're true!)

A. Before falling down an elevator shaft, Dr. Drake Ramoray had published a study showing that pizza-eating correlates with intelligence, and Joey wants to know whether anyone has followed up on this to determine whether there is a cause-and-effect relationship. 3 SCI allows you to search for published articles that cite a previous published article.
B. After her mother returns as a cat, Phoebe wants to find out whether there are any scientific studies on transmigration of souls.
D. Rachel hypothesizes that oxytocin, "the love hormone", is released by women upon purchasing new shoes at Bloomingdale's, and she is trying to decide whether to use RIA or bioassay to test her hypothesis.
D. Ross is moving to England, and hopes to get a job at the Natural History Museum. He wants to find out what research on human evolution has been published by the scientists there, so that he can read their work before going for an interview.

8. A recent scientific paper described the following study: Tiny termal probes were inserted into the diapers of babies from birth to 4 years, and the temperature of the scrotum was measured. Half of the babies always wore cotton diapers, half wore the usual plastic-covered disposable diapers. The average temperature was higher when disposable diapers were worn.

A. Why would the scientists think it's important to know whether diapers affect scrotal temperature? That is, what is the hypothesis that they are testing?

High temperatures can inhibit spermatogenesis. (In lecture, I mentioned that testes descend into the scrotum, usually just before birth, since the temperature in the abdominal cavity is too high for spermatogenesis.) Some recent studies have suggested that the average sperm count of men has decreased over the past 25-50 years (although there is not universal agreement about the methods used to reach this conclusion). The scientists here hypothesized that this decrease sperm count might be the result of an increased scrotal temperature due to wearing plastic-coated diapers during infancy. 2

B. This experiment can most accurately be described as a. correlational b. interventional c. observational-prospective  2  d. observational-retrospective

If the scientists looked at two groups of infants, those whose Moms believed in cloth diapers, those who were into disposables, and followed them for 4 years, then this would fall into the category we described as observational-prospective. If you understood the question to imply that the scientists put the babies in a particular type of diaper, then "interventional" would've been appropriate, and you got credit for this, provided your alternative experiment below was NOT an interventional one.

C. You have been hired as spokesperson for the Absorbent Hygiene Products Manufacturers Association, and you want to convince the public that disposable diapers are perfectly safe.

a) Design an experiment to test the scientists' hypothesis, using one of the other experimental designs listed in part B (that is, not the design that the scientists used).

b) Explain the disadvantages of doing the study using the scientists' design, and what would be the advantages of using your design.

3 points for designing an alternative expt using a design different from theanswer you gave in part B; 3 points for critiquing the faults of the scientists' design and the advantage of yours.

Circle all correct answers for each question:

9. (Answer both parts) You perform a radioimmunoassay of the type described in class. To determine the amount of hormone in your unknown sample, you'll need to measure the amount of radioactivity in the A. precipitate   2 B. supernatant.

and you would expect that higher radioactivity indicates that there is A. more B. less  2 hormone in your sample.

10. A false positive may occur in the rabbit-based pregnancy test if

A. it is done in the summer, so the rabbit releases sperm
B. the rabbit is under stress, so it releases hCG
C. the rabbit happens to release an ovulatory LH surge 3
D. the rabbit produces antibodies against the human hormone
E. the woman has androgen-insensitivity syndrome

11. Interleukins have been shown to A. raise 3  B. lower the set point for regulation of body temperature. Via prostaglandins

12. In recent years, doctors have tried to treat Congenital Adrenal Hyperplasia in the fetus. When a mother has given birth to one CAH baby, and she gets pregnant a second time, the doctors can use prenatal testing to determine whether the second fetus has inherited the mutant gene. If so, they can treat the fetus by administering hormone prenatally. Which one of these hormones would you expect them to give to the fetus to ensure normal genital development?

A. cortisol B. ACTH C. estrogen D. aldosterone E. androgen (any one of them)

Explain how this treatment prevents development of some symptoms of CAH. Your answer should include an explanation of the defect that normally occurs in CAH, and how this prevents normal sexual differentiation.

ACTH stimulates conversion of cholesterol to progesterone, which can then be used to roduce cortisol and aldosterone. In CAH, the defect is lack of the enzyme to produce cortisol and aldosterone. 3

Normally, cortisol exerts negative feedback effects on the hypothalamus (to inhibit CRH) and on the anterior pituitary (to inhibit ACTH). But if cortisol is absent (due to the CAH defective gene), then there is less negative feedback, and ACTH increases. 3 This leads to an increase in progesterone production (in the steroidogenic pathway) which cannot be converted to cortisol or aldosterone, and is shunted instead to the production of androgens.  3

Androgens act on the undifferentiated genitals, to cause them to differentiate in the male direction, 3 so the CAH female can develop male-like genitals. If given exogenously, cortisol can exert the needed neg fdbk, so ACTH and androgens decline, and the masculinization of the genitals is prevented.  3

An excess of ACTH and androgens is the problem, so you wouldn't want to give more of these. Estrogen wouldn't be helpful: differentiation in the female direction requires a lack of androgens, not the presence of estrogens. Aldosterone treatment would replace only one of the missing hormones, but this is less needed prenatally, when salt and water balance is aided by exchange with the mother. Aldosterone doesn't feedback on ACTH, so it wouldn't help with preventing male-like genitals.

13. Which of these is a neuroendocrine secretion:

A. Dopamine 1  secreted from hypothalamus into portal vessel, where it's also known as PIH
B. Oxytocin 1
C. GnRH 1
D. Inhibin
E. ACTH

14. TDF acts as a transcription factor to inhibit transcription of the gene for _____________, so that the testes do not produce estrogen.

A. 5-alpha reductase
B. prostaglandins
C. eicosanoids
D. aromatase 3
E. cholesterol

15. Which of these pairs are homologous structures (that is, derived from the same tissue)

A. ovary and testes 2
B. vas deferens and oviduct
C. penis and vagina This may have been confusing, since a small part of the labia is homologous with a small part of the penis, so we just didn't count this choice one way or another.
D. clitoris and vagina
E. clitoris and penis 2

16. (Note: This question is based on the article you read, not on material covered in lecture.)

Back in the 1970's, scientists assumed that the timing of parturition was based on some "clock" within the mother, which told her "when it was time" to give birth, totally without regard to anything happening in the fetus. But an observation by sheep farmers revealed that the fetus also plays a role. Farmers noticed that some sheep seemed to have abnormally long pregnancies, then died without giving birth. When they examined the fetuses, they were surprised to find that they had huge adrenal glands. Subsequent studies showed that the sheep had been grazing on a type of clover, which contains phytoestrogens, that is, plant compounds that have some similarity to estrogens.

A. These phytoestrogens must have been a. stimulating b. inhibiting the estrogen receptor.

B. Why did this delay parturition? Why were the fetal adrenals huge? Your answer should include a diagram showing the hormones that are involved in the timing of birth in the sheep, and also indicate (in essay form) where phytoestrogens interact with this pathway, and why the adrenals are so large.

In fetus: 2

Hypothalamus 1--> CRH 1-->Anterior pituitary- 1->ACTH 1-->adrenal cortex 1-->cortisol 1

In placenta: 1

Fetal cortisol--> converts progesterone 1 to estrogen 1

Estrogen--> increases connexins (gap junctions) between adjacent uterine cells, increases oxytocin receptors, increases prostaglandins, which in turn increase collagenase and allow cervical dilation. Estrogen also shifts the E/P ratio in favor of estrogen, increasing the contractility of the uterus. 3

At the end of gestation: the ability of cortisol to exert neg fdbk decreases, and ACTH therefore increases. The cortisol should be inducing E, which would lead to earlier parturition, but the phytoestrogens are blocking the E receptor, so parturition doesn't occur. BUT ACTH is increasing, and this meanwhile does stimulate further growth of the fetal adrenal cortex. 2