Reproduction & Development RQ

2. Reproduction & Development RQ • How many sperm can a mature man make in a day? • Normally, how many mature eggs does a female’s ovaries release over her life? • Through what process are gametes produced? • How many days after fertilization does the baby blastocyst implant in the uterine wall? • What hormone does the embryo secrete telling the mom’s body that she’s pregnant?

3. Production of sperm Delivery of sperm to the female 1. What are the two functions of the male reproductive system?

4. 2. Where do sperm form and what are the associated structures that help transport them? • Sperm are made in the testes, which are housed by the scrotum (which needs to stay cool for sperm production) • Maturation of sperm after meiosis takes about 74 days (can make 300 million sperm every day) • Epididymis – tubes where the sperm mature • Vas deferens – sperm hang out here for 2 – 3 months until they go to the urethra • Seminal vesicles – secrete sugar-rich fluids for the sperm for energy • Prostate gland – secretes an alkaline fluid for the sperm to move & survive • Bulbourethral glands – secrete fluid that will neutralize the female’s acidic environment • ALL of this stuff together = semen

5. 3. What happens to males during puberty? Which hormones are specifically involved? • Puberty = development of secondary sex characteristics for sexual maturity • The hypothalamus tells the pituitary to secrete FSH and LH • FSH will stimulate the production of sperm cells • LH will cause testosterone production • Testosterone causes the growth & maintenance of the sex organs, increases body hair, muscle mass, and bone length, and deepens the voice 

7. 4. Briefly describe the basic parts of the female reproductive system. • Functions – to produce eggs, to receive sperm, and provide an environment for an embryo to grow and develop • Ovaries – allow for egg maturation • Oviducts – tube for egg transport from the ovary to the uterus • Uterus – muscular organ where the baby develops • Cervix – narrow opening out the uterus into the vagina (how the baby leaves) 

9. 5. What happens to females during puberty? • The hypothalamus tells the pituitary to secrete FSH and LH • FSH stimulates the development of follicles in the ovary • A follicle is a group of epithelial cells that surround a developing egg • FSH causes the ovaries to release estrogen • Estrogen causes the development of the secondary sex characteristics in females • Growth & maintenance of sex organs, growth of bones & broadening of hips, body hair, fat deposits, and of course the menstrual cycle 

11. 6. How are eggs produced and released? • When a female is born, she already has 2 million potential eggs (primary oocytes) that have stopped development at Prophase 1 of meiosis • Most of these will break down, and at puberty the ovaries only have @ 40,000 • Once a month several of these oocytes finish meiosis and one egg ruptures out of the ovary (ovulation) and passes into the oviduct • About 400 eggs will be ovulated over the course of a female’s life 

13. 7. Briefly overview the flow, follicular, and luteal phases of the menstrual cycle. • Menstrual cycle – the series of changes that occur to produce an egg and prepare the uterus for a baby • Repeats about once a month • The corpus luteum (the part of the follicle left from the egg being released) secretes progesterone and estrogen • Progesterone maintains the lining of the uterus in preparation for fertilized egg implantation 

15. Continued… (using a 28 day cycle) • Flow phase: Day 1-5 • The lining of the uterus (the endometrium) passes out of the uterus through the cervix • Contractions (cramps) help expel this stuff • Follicular phase: Day 6 -14 • A developing primary oocyte secretes estrogen which repairs the endometrium • Estrogen levels peak, and LH causes ovulation • Luteal phase: Day 15 – 28 • Named for the corpus luteum, which produces estrogen and progesterone which thickens the endometrial lining in prep for a zygote • If no fertilization, back to the flow phase • If implantation, endometrium begins nourishment 

18. 8. Describe the process of fertilization and implantation of an egg. • Released egg only stays alive for 24 hours sperm (can live for 48 hours) must be present in the oviduct in those first hours of ovulation for fertilization to occur • 300 to 500 million sperm are delivered, but most die because of the acidic female environment • Only a few hundred make it to the oviducts • Once a sperm gets to the egg, the egg membrane changes electric charge, preventing other sperm from fertilizing 

20. Continued… • Egg nucleus + sperm nucleus = fertilized egg (zygote) • This zygote continues to the uterus, undergoing mitosis as it goes • After 6 days the zygote gets to the uterus, and is now a hollow ball of cells called a blastocyst • When this attaches to the uterine lining, it has “implanted”

22. 9. List and describe the purpose of the various embryonic membranes. • Amnion: filled with amniotic fluid • Shock absorber and temperature regulation • Allantois: outgrowth of the digestive tract • Blood vessels from this form the umbilical cord which attaches the embryo to the uterine wall • Chorion: outer membrane (surrounds amnion) • 12 days after fertilization, chorionic villi begin to grow into the uterine wall • These two together form the placenta 

24. 10. What structures allow the exchange of materials between embryo and mom? • The placenta deliver nutrients and carries wastes away from the embryo • Maternal blood vessels lie very close to the embryo’s chorionic villi, allowing the diffusion of these nutrients from mom and wastes from baby across the placenta, which is connected by the umbilical cord • The waste products are excreted by the mom 

26. 11. How is a pregnancy maintained? • the developing zygote implants • it starts to secrete hCG (human chorionic gonadotropin)… • which keeps the corpus luteum alive & secreting progesterone… • which in turn maintains the endometrial lining… • Until the 3rd or 4th month when the placenta takes over 

28. 12. What are the three different processes of fetal development? • Growth – the actual increase in the number of cells • Development – as these cells move and arrange themselves into specific organs • Cellular differentiation – these cells begin to perform specific tasks and functions 

30. 13. What happens during the first trimester? • A woman may not know she is pregnant • The embryo is very sensitive to outside influences • Drugs, environmental influences, malnourishment • All the organ systems are formed by the 8th week and is now a “fetus” • At the end of this trimester, the baby is 28 grams (1 ounce) and 7.5cm (3 inches) from head to butt • Gender can be determined 

32. 14. What happens during the second trimester? • 4th month is mostly limited to fetal body growth • 5th month mom can feel the fetus • 6th month – eyes are open & lashes form • Baby could possibly survive outside of the womb with lots of medical intervention • At the end of this trimester the baby is 650 grams (22 ounces) and 34cm (13 inches) long 

34. 15. What happens during the third trimester? • Mass of fetus more than triples • Kid is kicking, stretching, and moving freely • 8th month fat is deposited beneath the skin in preparation for newborn insulation • Baby’s systems are developed and can now survive outside of the uterus • By the end of this trimester, the baby is on average 3300 grams (7 pounds) and 51cm (20 inches) long 

36. 16. How can genetic disorders be predicted? • Genetic counseling • Will use medical histories of the parents and families (pedigrees) • Biochemical analyses of bloodwork • Karyotypes • DNA analysis 

38. 17. What is the first stage of birth? Describe how this happens.(Oww…) • Dilation of the cervix • Mild contractions are stimulated by the baby pushing on the cervix • This causes the release of the hormone oxytocin • The contractions open (dilate) the cervix to allow the baby to leave the uterus • Dilation needs to get to 10cm (4 inches) • Contractions get closer together and intensify • Usually the amniotic sac will rupture (water breaking) 

40. 18. What happens during the “expulsion” stage? • The cervix is fully dilated • The uterine contractions get so strong that the baby is forced out of the uterus, through the cervix, and into the birth canal • The mom’s abdominal muscles contract with the uterus, pushing even stronger • This stage USUALLY lasts 20 minutes to an hour 

42. 19. What is the placental stage of birth? • Happens 10 – 15 minutes after the baby is born • The placenta separates from the uterine wall and all membranes are released from the mom’s body (afterbirth) • Uterine muscles keep contracting, constricting the uterine blood vessels to mom doesn’t excessively bleed 

43. You might not want to see this…

44. 20. Which hormone regulates growth? How does it do this? • Human growth hormone (hGH) is secreted by the pituitary • Acts on all cells, but mostly on the skeleton and skeletal muscles • Works by increasing the rate of protein synthesis and fat metabolism • Thyroxin, estrogen, and testosterone help too 

46. 21. What changes occur during infancy? • First two years of life • Lots of growth • 2x birth weight by 5 months old • 3x birth weight by 12 months old • 4x birth weight by 24 months old • Increase in physical coordination • Learns to roll, sit, crawl, and walk • Increase in mental development • Begins to speak 

48. 22. What happens as someone grows from child to adult? • Childhood- period from infancy to puberty • Relatively steady growth • Develops ability to reason and solve problems • Adolescence- from puberty till max growth • Growth spurts are typical • 5-8cm in one year for some teenage boys • Maximum height is achieved • Determined by heredity, nutrition and environment • Organs have reached maximum mass 

49. 23. What kinds of stuff happens to your body as you get older? • Metabolism and digestion are slower • Skin loses some elasticity • Less pigment is produced (gray hair) • Bones become thinner and more brittle • Vertebral disks get compressed (shorter) • Vision and hearing diminish • Some people stay just as smart and active as always! 