#12 The Reproductive System Flashcards
(22 cards)
Function of reproductive system
- Perpetuation of genetic material
- NOT essential for survival
Asexual Reproduction
Offspring and parents are genetically identical
Sexual Reproduction
Offspring are unique from parents
Two types
-Internal fertilization (within)
-External fertilization (outside- fish)
Sex differences
Males
- Sperm- “cheap” gametes
- Acyclic reproductive function
- No cycle, constantly producing
Females
- Ova- “expensive” gametes
- Cyclic reproductive function
- On a cycle
Path of sperm
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
Hormonal Control of Testes
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
Spermatogenesis
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
Path of Ova
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
Cyclical changes in:
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
Releasing hormone
Secreted by
-Hypothalamus
Major roles
-Regulates secretion of FSH and LH by pituitary
FSH
Secreted by
-Pituitary
Major roles
-Stimulates growth of ovarian follicle
LH
Secreted by
-Pituitary
Major roles
- Stimulates growth of ovarian follicle and production of secondary oocyte
- Promotes ovulation
Estrogen
Secreted by
-Ovarian follicle
Major roles
-Promotes growth of endometrium
Estrogen and progesterone
Secreted by
-Corpus luteum
Major roles
-Sharp drops promote menstruation
Pre-ovulation phase
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
Ovulation
Rising E levels (once over threshold) now has POSITIVE feedback on LH and FSH
LH surge triggers ovulation
Typically 1/2 way threw cycle
Post-ovulation phase
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)
Birth
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
Chem. contraception
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
Fertility
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
Contraceptive methods stats.
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)
STDs
Bacterial- antibiotics to treat
Viral
Protozoan (unicellular eukaryote)
Fungal
