W3006     Fall 2003                   Physiology           Mini-exam #2                           CU ID___________________

Question 1-7:   10 points each  Answers in blue. Points and explanations in red.

1.   Consider a typical 28-day menstrual cycle.  If fertilization occurs, the blastocyst will implant on about day
a.  1     b.  14      c. 19     d. 28     e. 33   into an endometrium which is     a.  proliferating    b.  secretory 

2.   What usually prevents ectopic pregnancies from happening?    Circle one & explain your answer in one sentence.
a.  pH of secretions   b. movement of cilia   (5 points) c.  digestive enzymes   d. large number of sperm   e.  corpus luteum

 Movement of cilia propel ovulated oocyte towards ampulla, and after fertilization, propel fertilized ovum towards unterus, preventing it from implanting in the oviduct or in the abdominal cavity.  (5 points)

3.   In trying to determine why a couple is infertile, doctors run some tests on a man’s semen.  In one case, it is found that the semen has very low levels of fructose.  It is most probable that

a.  there’s a blockage in the seminal vesicle ducts  Fructose is normally secreted from the seminal vesicles
b.  the blood-testes barrier has been broken
c.  the prostate gland has become enlarged
d.  the sperm that are produced have many deformities, such as two tails or two heads

4.   Inhibins have been found to act both on the anterior pituitary gland and on Leydig cells.  Inhibins can therefore be said to have _________   effects.    Circle all correct answers.
a.  neurocrine   b. endocrine    c.  autocrine   d. paracrine   e.  neuroendocrine   f. exocrine  
Inhibins are secreted by Sertoli cells, so they're action on Leydig cells would be from nearby (paracrine) and action on pituitary would be via the blood (endocrine).

5.  Sertoli cells have been found to produce the enzyme that converts androgens to estrogens.  In this sense, Sertoli cells are most like      a.  Leydig cells   b.  theca cells   c. granulosa cells    Granulosa cells convert androgens (from the theca) to estrogens.

6.  Number the following in order of their occurrence, with 1= first to occur, 2= second to occur, etc.

__1_ beginning of first meiotic division of oocyte  prenatally
__5_ formation of corpus albicans
__3_ peak LH secretion  
__2_ peak estrogen secretion  
__4_ peak progesterone secretion

7.   Certain plants are used by South African traditional healers to treat menstrual pain.  Scientists examined these plants, and found that some of them produce substances that inhibit cyclooxygenase (COX), the enzyme responsible for producing prostaglandins from arachidonic acid.  If these plants inhibit the muscle contractions involved in menstrual cramps, then you would expect that a woman with menstrual cramps has high levels of prostaglandins in the part of the uterus known as  the ____myometrium__________.

8.  Explain the role of Androgen Binding Protein. (15)
Sertoli cells secrete ABP (5 points) which binds the testosterone secreted by the Ledig cells (5 points), ensuring that a high concentration of testosterone will remain locally, as needed for spermatogenesis  (5 points)

9.  List the similarities and differences between LH and hCG, in terms of their structure and function. (15)

 Similarities and differences in structure:  5 points
Both are glycoproteins, consisting of two peptide chains, with the alpha subunit identical in both.
LH and hCG have somewhat different beta subunits.  

Similarities and differences in function: 5 points
Both can maintain the corpus luteum, stimulating it to secrete progesterone.
LH functions in this way right after ovulation.   hCG functions after ovulation.

Source: 5 points
LH: secreted by the anterior pituitary gland.
hCG: secreted by the trophoblast, chorion, placenta.