Functions of reproductive systems Ch 27 28 Produce

Functions of reproductive systems (Ch. 27 -28) • Produce gametes… • meiosis • ovarian cycle • …that can combine to form an offspring… • sex/fertilization • …that can develop inside the mother… • implantation into endometrium of uterus • organogenesis • placenta • …and ultimately be expelled from the womb… • myometrium of uterus • …and grow up! • lactation (milk production) Marieb & Hoehn (2019), Figure 28. 2 1

Ch. 27: Test Question Templates • Q 1. Given semen analysis (semenalysis) data, provide fertilityrelated advice to the person whose semen was analyzed. • Example: Bob and his partner feel that they are not ready to have a child. To assess the risk of an accidental pregnancy, Bob undergoes a semenalysis. His sperm count is 53, 000 sperm per milliliter of semen; motility is 40%. What should you tell Bob? • Q 2. Given a detailed diagram of ovarian and uterine histology and related hormone levels, answer questions about cause and effect and/or the correspondence between ovarian and uterine events. • Example: Consult Figure 27. 25 of Marieb & Hoehn (2019). Why does the endometrium thin out at the start of a new cycle? 2

Gamete production: meiosis for physiologists Gametes = sex cells. Let’s count chromosomes! Most human cells have 46 (2 n), but gametes only have 23 (n). Q 1. What’s the purpose of meiosis, in terms of the number of chromosomes per cell? Marieb & Hoehn (2019), Figure 27. 2 3

Why does the Y matter? In other words, how does the Y chromosome determine biological sex? Q 1. What is the key GENE on the Y chromosome? Q 2. What does this gene do? Q 3. What happens when this gene is mutated and nonfunctional? Marieb & Hoehn (2019), Figure 27. 27 4

Male fertility Structure and function of sperm parts Structure Function Head Midpiece Tail Marieb & Hoehn (2019), Figure 27. 12 5

Male fertility: consider both quantity & quality of sperm Q 1. Does this person have reduced fertility? Why or why not? Q 2. Why are so many sperm normally made? (Don’t you just need one good one? ) forums. steroid. com 6

Male fertility: erection Erection facilitates the delivery of sperm into a female. In humans, erections are achieved via a buildup of blood in the penis. Blood gets trapped there for 2 mechanisms… Q 1. Why would it be counterproductive for the corpus spongiosum to become as engorged as the corpora cavernosa? Q 2. How does Viagra work? youtube. com/watch? v=lw. GV 6 XRo 8 nc 7

Male fertility: vasectomies Purpose: prevent pregnancy! Q 1. How is this done? Q 2. Are vasectomies reversible? stlurology. com/conditions-treatments/vasectomy/

Female fertility: ovulation and menstrual cycle and their hormonal control Hypothalamus secretes _____ Anterior pituitary secretes ______ Gonads secrete ______ Worksheet from Murray Jensen et al. (2014): • Model 1: Ovarian Events • Model 2: + Sex Steroid Hormones [estrogen, progesterone] • Model 3: + Gonadotropins [FSH, LH] • Model 4: + Uterine Cycle Marieb & Hoehn (2019), Figure 27. 23 9

Worksheet: The Menstrual Cycle M. Jensen et al. 2014 (like Marieb & Hoehn Figure 27. 18) 10

Q 1. How many days are shown for this ovarian cycle? Can this cycle length vary? Q 2. What changes can be seen in the follicle between days 0 and 12? Q 3. The ovarian cycle has 2 phases (follicular and luteal) and one event (ovulation). Complete the table below with information from Model 1. Q 4. After ovulation, the follicular cells become a structure called the corpus luteum. What is ovulation? What happens to the oocyte? Q 5. The corpus luteum secretes estrogen and progesterone. Examine the size of the corpus luteum from days 15 to 28 in Model 1 and predict how changes in the size of the corpus luteum affect its endocrine function. M. Jensen et al. (2014) 11

M. Jensen et al. 2014 (like Marieb & Hoehn Figure 27. 18) NOTE: Ovulation is an event at day 14, NOT a phase from day 12 to day 16! 12

Q 6. Name the two sex steroid hormones shown in Model 2. Q 7. For each of these hormones, name the ovarian phase during which it reaches its peak. Q 8. Why do you think plasma levels of both sex steroid hormones decrease near the end of the cycle? Q 9. Do estrogen levels peak before, at, or after ovulation? M. Jensen et al. (2014) 13

Model 3: Ovarian Events + Plasma Levels of Gonadotropins and Sex Steroid Hormones NOTE: Ovulation is an event at day 14, NOT a phase from day 12 to day 16! M. Jensen et al. (2014) 14

Q 10. The anterior pituitary secretes 2 gonadotropins (hormones that target the gonads). Name them (both full names and abbreviations). Q 11. Using the diagram at right, show the location of the anterior pituitary and ovaries. How do gonadotropic hormones move from the anterior pituitary to the ovaries? Q 12. Plasma gonadotropin levels peak on day 13. What ovarian event immediately follows the LH surge? Q 13. What do you think is the main function of FSH? Of LH? (Consider both their full names and the relationships illustrated in Model 3. ) M. Jensen et al. (2014) 15

Model 4: Ovarian Events + Plasma Levels of Gonadotropins and Sex Steroid Hormones + Uterine Cycle Q 14. Which part of the uterus is shown in Model 4? Q 15. Which uterine event signals the start of the uterine cycle? M. Jensen et al. 2014 (like Marieb & Hoehn Figure 27. 18) 16

Q 16. Fill in the chart below with information pertaining to the 3 phases of the uterine cycle. Q 17. Each phase of the uterine cycle is associated with a phase of the ovarian cycle. Fill in the table below to show these associations. Q 18. Is the uterine cycle more directly influenced by gonadotropin or sex steroid levels? Explain your reasoning. M. Jensen et al. (2014) 17

Q 19. During the luteal phase, is there a relationship between the levels of progesterone and the thickness of the endometrium? Q 20. Based on your answer to the previous question, what is the main function of progesterone? Q 21. Why is it important for the endometrium to increase in thickness and vascularity during the menstrual cycle? M. Jensen et al. (2014) 18

Promoting pregnancy (or avoiding it) Q 1. Which hormone is the best indication that a woman is ovulating? (see previous slides) Perhaps counterintuitively, low levels of estrogen and/or progesterone can work as a birth control pill by keeping the body in the “negative feedback” range, preventing the LH surge! Sherwood et al. (2013), Figure 16 -18 a 19

FYI: other forms of birth control Marieb & Hoehn (2019), Ch. 28 20

Ch. 27: Additional Resources • Sex Verification Testing of Athletes • Biological Sex is not always black and white! • https: //media. hhmi. org/biointeractive/click/testingathletes/index. html • Dr. C’s reproduction songs: “LH Surge, ” “Tiny Sperm, ” “The Uterus”… • https: //faculty. washington. edu/crowther/Misc/Songs/ • Other suggestions? Let me know… 21

Answer key for Suggested Lecture Outline file • You should already have access to answers to some of the questions (Check Your Understanding, online Practice Quiz, online Practice Test) • Answers to pre-lecture questions and end-of-chapter Review Questions will be in the Presenter Notes that accompany this slide. 22