Lecture 34

Question 1

what is the internal and external male reproductive anatomy

Answer 1

internal
- epididymis, vas deferens, urethra
- accessory glands: prostate, seminal gland
- sperm maturation and hormone synthesis
- fluid generation, sperm transport
external
- scrotum, testes, penis
- sperm generation
- common exit for sperm and urine
- male sexual function, erogenous zone

Question 2

how does the male reproductive system work

Answer 2

• 3 accessory glands contribute to secretions to semen
• > seminal vesicle, prostate gland, bulbourethral gland (fluid secretion)
• testis is the site of sperm and hormone production
• scrotum = skin on the head, hold the testes outside the abdominal cavity to keep them below body core temp
• sperm matures better at low body temp = more air flow = better
• vas deferens transport sperm from testes to urethra
• prostate gland surrounds the urethra

Question 3

explain the penis anatomy in more detail

Answer 3

• penis has 2 types of erectile tissue
• erection occurs when spaced in erectile tissue fill with blood
• the end of the penis is glans
• posterior indentation, frenulum, is most sensitive
• erogenous zone, exit for both the reproductive and urinary systems

Question 4

explain what happens inside and between the tubules during spermatogenesis

Answer 4

• efficient at 2C below body temp
  inside
• sperm produced in seminiferous tubules
• spermatogonia= developing sperm cells from edge to center
• sertoli cells, form blood testes barrier, regulate sperm development, provide nourishment
  between
• interstitial cells/leydig cells secrete testosterone important for male characteristics and sperm production

Question 5

explain spermatogenesis

Answer 5

• birth -> testes contain immature germ cells, quiescent until puberty
• puberty -> meiosis begins (DNA replication, meiosis l, meiosis ll)
  -> primary spermatocyte (4n) divides into 2 secondary spermatocytes (2n)
  -> secondary spermatocyte (2n) divides into two spermatids (n)
• each round of meiosis produces 4 spermatids that mature into sperm
• gametogenesis continues throughout life
• aging changes: andropause - testicular mass decreases, erectile disfunction, reduced sperm count (even though sperm production continues)

Question 6

what do sertoli cells do

Answer 6

• secrete proteins to support sperm production
• tight junction between sertoli cells

Question 7

what are the internal and external parts of the female reproductive anatomy

Answer 7

internal
- ovaries, ovarian tubes, uterus
- cervix, vagina
- ova maturation and transport
external
- vulva
- mons pubis, clitoris, labia, urethral and vaginal orifice
- separate exit for urinary and reproductive tracts
- female sexual function

Question 8

explain the vagina anatomy in more detail

Answer 8

• vulva
  erogenous zone consists of
• mons pubis: pubic region covered by hair
• labia (minor/major) -> inner and outer folds of skin that cover the vaginal opening
• clitoris -> pleasure center (sole function)

Question 9

explain oogenesis

Answer 9

• birth -> 500000 primary oocytes present
• puberty - primary oocyte (4n) gives rise to one ovum (n)
• 1x12x40= 420 mature ova will be released at ovulation
• oocytes are produced during monthly cycles (28 days)
• ovarian cycle = maturation and release of ovum
• uterine cycle = building up and shedding uterine lining
• reproductive senescence (menopause) occurs at age 50

Question 10

explain how tropic hormonal control works for female reproductive system

Answer 10

• brain controls reproduction
• hypothalamus-anterior-pituitary peripheral gland
• GnRH from hypothalamus controls release of FSH and LH
• FSH and LH act on the gonads
• LH promotes release of sex hormones
• FSH promotes gamete production (or maturation)
  -hormonal control and ovarian/uterine cycles are highly complex

Question 11

explain how the uterine and ovarian cycle are connected

Answer 11

• in menses phase of the uterine cycle = tertiary and dominant follicle (follicular phase
• during proliferative phase (UC) = estrogen rising = ovulation = LH rising
• during secretory phase = progesterone rising = corpus luteum formation and mature corpus luteum
• mature follicle releases ovum during ovulation
• after release follicle becomes corpus luteum
  -> secretes progesterone to maintain uterine lining until CL dies

Question 12

explain fertilization

Answer 12

• fusion of sperm (n) and ovum (n) leads to formation of a diploid (2n) -> zygote
• usually occurs in the uterine tube
• dividing blastocyst implants in uterine lining
  1. ovulation
  2. day 1 = fertilization
  3. days 2-4 = cell division takes place
  4. day 4-5 blastocyst reaches uterus
  5. day 5-9 blastocyst implants
• sperm and egg plasma membrane fuse, triggering the cortical reaction

Question 13

what is the efficacy of various contraceptive methods

Answer 13

• no contraception = 85% chance of getting pregnant
• IUD + contraceptive = <1%
• pill = 9%
• spermicides = 28%
• diaphragm, cervical cap, sponge = 12-24%

Question 14

explain parturition

Answer 14

• fetus is normally head down pressing on the cervix
• cervical stretch causes release of oxytocin
• cervix dilates and uterine contractions begin
• further stretch and dilation of the cervix leads to more oxytocin production
• delivery occurs when cervix is fully dilated and uterine contraction pushes the fetus through the vaginal canal
• an alternate delivery method it a caesarean section
• labor controlled by positive feedback until ended with delivery