#12 The Reproductive System

Question 1

Function of reproductive system

Answer 1

• Perpetuation of genetic material

- NOT essential for survival

Question 2

Asexual Reproduction

Answer 2

Offspring and parents are genetically identical

Question 3

Sexual Reproduction

Answer 3

Offspring are unique from parents
Two types
-Internal fertilization (within)
-External fertilization (outside- fish)

Question 4

Sex differences

Answer 4

Males

• Sperm- “cheap” gametes
• Acyclic reproductive function
  
  • No cycle, constantly producing

Females

• Ova- “expensive” gametes
• Cyclic reproductive function
  
  • On a cycle

Question 5

Path of sperm

Answer 5

Testes

• Produce sperm and sex steroids
• Housed in scrotum (skin and muscle, regulates temp.)

Epididymis
-Stores sperm while it matures

Vas Deferens
-Transports sperm to ejaculatory duct

Seminal Vesicles, Prostate Gland, Bulbourethral Gland
-Makes the other components that are added to make semen

Urethra

• Inside the penis
  
  • Made of erectile tissue that fills with blood

Question 6

Hormonal Control of Testes

Answer 6

Hypothalamus (in forebrain) secretes the Releasing Hormone

RH causes the release of
-FSH
•	Sperm production
-LH (anterior pituitary)
•	Testosterone (Males only)
          -Creates negative feedback
               ->Inhibits RH and LH
•	Sperm production

Question 7

Spermatogenesis

Answer 7

Seminiferous tubules

• Sperm cells start to develop here
  
  • Begin as round diploid cell along outer wall
  • Go through primary and secondary spermatocyte
  • Then develop as sperm cells
• When reach the center of seminiferous tubule, fully formed sperm cell

Epididymis

• Where the sperm:
  
  • Mature
  • Become motile
  • Are stored

Question 8

Path of Ova

Answer 8

Ovaries
-Produce ova and sex steroids
-Houses Follicles
•	Ova and surrounding layers
         -To nourish and protect ovum
         -Secrete sex steroids

Oviducts (Fallopian tubes)
• Site of fertilization

Uterus (Womb)
-Holds developing embryo/fetus
-Endometrium
•	Inner lining
•	Where implantation occurs

Cervix
-“Neck” of Uterus

Vagina

• Birth canal
• Copulation; receives sperm

Question 9

Cyclical changes in:

Answer 9

Ovary
-Growth of follicles
•	Primary oocyte
        -Present at birth
•	Growth of follicle
•	Maturate follicle
•	Rupture Follicle
        -Ovulates secondary oocyte
•	Corpus luteum
        -Releases progesterone
•	Degenerating corpus luteum
        -And process starts over, if no fertilization
-Ovulation
•	Release of egg cell (ovum) from one follicle

Hormone secretion

• Hypothalamus
• Anterior pituitary
• Ovaries

Uterus
-Proliferation (build up) of endometrium
-Menstruation
• Breakdown of endometrium

Question 10

Releasing hormone

Answer 10

Secreted by
-Hypothalamus

Major roles
-Regulates secretion of FSH and LH by pituitary

Question 11

FSH

Answer 11

Secreted by
-Pituitary

Major roles
-Stimulates growth of ovarian follicle

Question 12

LH

Answer 12

Secreted by
-Pituitary

Major roles

• Stimulates growth of ovarian follicle and production of secondary oocyte
• Promotes ovulation

Question 13

Estrogen

Answer 13

Secreted by
-Ovarian follicle

Major roles
-Promotes growth of endometrium

Question 14

Estrogen and progesterone

Answer 14

Secreted by
-Corpus luteum

Major roles
-Sharp drops promote menstruation

Question 15

Pre-ovulation phase

Answer 15

FSH stim. follicular development
Developing follicles secrete Estrogen
E exerts NEGATIVE feedback on LH and FSH (more imp. because don’t want another egg)
Menstruation

Question 16

Ovulation

Answer 16

Rising E levels (once over threshold) now has POSITIVE feedback on LH and FSH
LH surge triggers ovulation
Typically 1/2 way threw cycle

Question 17

Post-ovulation phase

Answer 17

Corpus Luteum forms and secretes Progesterone and E
-> inhibit LH and FSH
CL degenerates after 14 days
Endometrium max.
P (peaks then drops) and E drops
-> removal of neg. feedback allows LH and FSH to rise -> new follicle develops (new cycle begins)

Question 18

Birth

Answer 18

Estrogen

• from ovaries
• induces oxytocin receptors on uterus

Oxytocin

• protein
• from fetus and mother’s pituitary
• stimulates uterus to contract
• stimulates placenta to make Prostaglandins

Prostaglandins

• stimulates more contraction on uterus
• POSITIVE FEEDBACK to make more Prost. and to Oxytocin

Question 19

Chem. contraception

Answer 19

Pill

• synthetic E and P
• neg feedback suppress LH and FSH
• block follicle develop. and ovulation
• mucus hostile

Morning-after pill

• high does synthetic E and P
• blocks ovulation
• alters endo. to prevent implantation

Abortion pill

• blocks P receptors (which are to maintain baby)
• cause endo. to break down

Question 20

Fertility

Answer 20

Max. fertility
- ~5 days before and 1-2 days after ovulation

Calc. timing of ovulation

• ov. to menstruation usually 14 days (life span of CL)
• menstruation to ovulation more variable
• can be determined retroactively

Question 21

Contraceptive methods stats.

Answer 21

Preg. per 100 per year
Pill (correctly 0.1; typ. 5)
Vasectomy (correctly 0.1; typ. 0.15)
Tubal ligation (correctly 0.2; typ. 0.5)

Question 22

STDs

Answer 22

Bacterial- antibiotics to treat
Viral
Protozoan (unicellular eukaryote)
Fungal