Key Concepts that will cover
Male reproductive system
Female reproductive system
Hormones involved with reproduction
Ovulation and uterine cycle
Gametogenesis
The Male Reproductive System Delivers Sperm
Testes produce sperm
–Scrotum: sac of skin and smooth muscle that holds the testes
–Maintains testes at a slightly lower temperature
–Seminiferous tubules within testes: produce sperm
Epididymis and : sperm become motile and are ductus deferens
stored here
Ductus deferens: transports sperm to where it becomes the
ejaculatory duct
Route of sperm through male reproductive structures
–Seminiferous tubules
–Epididymis
–Ductus deferens
–Ejaculatory duct
–Penis
Accessory Glands Help Sperm Survive
Semen: mixture of sperm and secretions of accessory glands
Seminal vesicles
–Secrete fructose (provides source of energy for sperm) and
produce/secrete most of the seminal fluid
Prostate gland
–Secretes watery alkaline fluid to raise vaginal pH
Bulbourethral gland
–Secretes lubricating mucus
–Cleanses urethra
Sperm Production Requires Several Cell Divisions
Several cell divisions (mitosis and meiosis) in seminiferous tubules
produce sperm
Cell divisions produce a large number of sperm with half the number of
chromosomes of somatic cells (haploid)
Sperm (and eggs) are referred to as gametes and are haploid
Sequence of cell types, leading to sperm
–Spermatogonia (2 ), primary spermatocyte (2 ), secondary n n
spermatocyte ( ), spermatids ( ), sperm ( )n n n
Sertoli cells provide support, nourishment
Testosterone Affects Male Reproductive Capacity
Testosterone
–Steroid hormone produced by in testes interstitial cells
(between seminiferous tubules)
–Function:
–Controls growth and function of male reproductive tissues
–Stimulates aggression and sexual behavior
–Controls development of secondary sexual characteristics
–Determines rate of sperm formation
Hormones that regulate testosterone and sperm production
–Gonadotropin-releasing hormone ( ) from hypothalamus GnRH
stimulates release of LH and FSH
–LH (from anterior pituitary) stimulates production of testosterone
–FSH (from anterior pituitary) may enhance sperm formation with
Sertoli cells
–Inhibin: produced by Sertoli cells, inhibits secretion of FSH
Negative feedback loop maintains constant blood concentration of
testosterone
The Female Reproductive System Produces Eggs and Supports
Pregnancy
Ovaries
–Release oocytes (immature eggs) and secrete the hormones
estrogen and progesterone
Oviduct (Fallopian tube)
–Leads from the ovary to the uterus
–Fertilization occurs in the upper third of the oviduct
–Three to four day trip through oviduct to uterus
Ovaries
–Release oocytes (immature eggs) and secrete the hormones
estrogen and progesterone
Oviduct (Fallopian tube)
–Leads from the ovary to the uterus
–Fertilization occurs in the upper third of the oviduct
–Three to four day trip through oviduct to uterus
Vagina
–Organ of sexual intercourse and birth canal
External genitalia
–Labia majora and minora
–Clitoris
Mammary Glands Nourish the Infant
Breasts contain mammary glands
Mammary glands are modified sweat glands, part of the integumentary
system
Specialized for lactation (production of milk)
Hormonal control of lactation:
–Prolactin (anterior pituitary hormone)—stimulates milk
production
–Oxytocin (posterior pituitary hormone)—stimulates contractions
that eject milk
Menstrual Cycle Consists of Ovarian and Uterine Cycles
Pattern of changes, which cycles every 28 days
Controlled by hormones of pituitary gland and ovaries
Begins at puberty and continues until menopause, except during
pregnancy
Consists of two linked cycles
–Ovarian cycle
–Series of changes in ovaries associated with oocyte
maturation
–Controlled by FSH and LH
–Uterine cycle
–Changes in the endometrial lining of the uterus
–Controlled by estrogen and progesterone
The Ovarian Cycle: Oocytes Mature and Are Released
Immature follicle of primary oocyte and granulosa cell develops; FSH
and LH increase
Granulosa cells divide and produce zona pellucida around oocyte
Antrum develops within follicle; some estrogen and progesterone are
secreted
Secondary oocyte and polar body are produced; follicle matures
(Graafian follicle)
Increasing estrogen causes surge of LH; ovulation occurs
Corpus luteum formed from follicle; large amounts of estrogen and
progesterone are secreted
If fertilization and pregnancy occurs
Chorion (embryonic tissue) secretes human chorionic
gonadotropin (hCG)
hCG is detected by pregnancy tests
hCG causes corpus luteum to continue to produce estrogen and
progesterone for another 9–10 weeks
After 9–10 weeks, the placenta takes over progesterone and
estrogen production
High levels of estrogen and progesterone prevent ovulation
during pregnancy
The Uterine Cycle Prepares the Uterus for Pregnancy
Series of changes that occur in endometrium as it prepares for the
possible arrival of a fertilized egg
Menstrual phase
–Days 1–5
–Estrogen and progesterone decrease
–Endometrial lining degenerates
–Menstruation occurs
Proliferative phase
–Days 6–14
–Estrogen and progesterone increase
–Endometrial lining proliferates
Ovulation
–Day 14
Secretory phase
–Days 15–28
–Corpus luteum produces progesterone and estrogen
–Endometrium continues to proliferate
–Uterine glands mature
–Uterus is prepared to accept and nourish a
fertilized egg
–
Cyclic Changes in Hormone Levels Produce the Menstrual Cycle
Cycles of hormones of pituitary and reproductive structures
–Positive feedback
–In proliferative phase, increasing estrogen causes surge in
LH, which in turn causes ovulation
–Negative feedback
–In secretory phase, steady levels of estrogen and
progesterone inhibit LH and FSH release
Human Sexual Response, Intercourse, and Fertilization
Human sexual response
–Excitement: increased sexual awareness and arousal
–Plateau: intense and continuing arousal
–Orgasm: peak of sexual sensations
–Resolution: abatement of arousal
–Male sexual response: orgasm, marked by ejaculation, refractory
period
–Female sexual response: orgasm, marked by rhythmic muscular
contractions
Fertilization: One Sperm Penetrates the Egg
Fertilization
–Ejaculate: may contain several hundred million sperm
–Sperm may reach egg within hours to a day or more
–One sperm penetrates egg within the oviduct
–Sperm may be viable for up to 5 days within the female
reproductive tract
Birth Control Methods: Controlling Fertility
Abstinence: not having intercourse
Surgical sterilization
–Vasectomy in males: cut and tie off both ductus deferens
–Tubal ligation in females: cut and tie off both oviducts
Hysteroscopy in females: cauterize the oviducts to seal them
Birth Control Methods: Pills, Injections, Patches, and
Rings
Birth control pills (oral contraceptives)
–Combination of synthetic progesterone and estrogen
–Inhibit release of FSH and LH
Hormone injections
–Depo-Provera (lasts 3 months)
Hormone patch
–Ortho Evra
Vaginal ring
–NuvaRing
Implant
–Implanon Nexplanon and ; progesterone-containing rod under
skin
Birth Control Methods: Hormonal Methods: Pills,
Injections, Patches, and Rings
Block ovulation—quite effective
–Advantages:
–May reduce cramps and menstrual flow
–Some protection against ovarian and uterine cancers
–Disadvantages:
–Side effects include acne, headaches, fluid retention, high
blood pressure, blood clots
–Do not protect against sexually transmitted diseases (STDs)
Other Birth Control Methods
IUDs: Intrauterine devices
–Small plastic or metal piece inserted into uterus
–Create mild chronic inflammation that prevents fertilization or
implantation
–Mirena: includes progesterone-like drug
Diaphragms and cervical caps
–Prevent sperm from entering the cervix
–Effectiveness improved when used with spermicides
Chemical spermicides
–Kill sperm cells
Condoms
–Trap ejaculated sperm
Natural alternatives
–Rhythm method, withdrawal
After intercourse pills
–Ella
Single pill, within five days after intercourse
Prevents ovulation or implantation
–Plan B (morning after pill)
–Mifeprex (RU-486)
Prevents implantation of pre-embryo
Causes regression of endometrial lining
May be prescribed to induce an early abortion, up to seven
weeks after becoming pregnant
Elective Abortion Methods:
–Mifiprex can be used up to seven weeks after pregnancy onset
–Vacuum suctioning of uterus
–Surgical scraping of uterine lining
–Infusion of strong saline solution
The Future in Birth Control
Currently in research and development:
–Male birth control: reduces sperm production
–Vaccines for women
–Vaccine against hCG (human chorionic gonadotropin)
–Vaccine against sperm
Infertility: Inability to Conceive
Infertility: inability to achieve pregnancy after a year of trying
Many causes of infertility
–Number and quality of sperm
–Less than 60 million/ejaculation is considered infertile
–Pelvic inflammatory disease (PID)
–Scarred, blocked oviducts
Many causes of infertility (continued)
–Abnormal production of FSH and/or LH
–Irregular menstrual cycles
–Endometriosis
–Strongly acidic vaginal secretions
–Decreased reproductive capacity with age
–Miscarriage (spontaneous abortion)
Enhancing Fertility
Artificial insemination
Artificial reproductive technologies (ARTs)
–Both sperm and eggs are handled outside of the body
–Method of choice for women with blocked or damaged oviducts
–Immature eggs must first be harvested from a woman
–Once eggs are harvested, there are a variety of different
techniques
In vitro fertilization (IVF)
–Fertilization in test tube outside of the body
–After several cell divisions, embryo is inserted into the uterus via
the vagina
GIFT (gamete intrafallopian transfer)
–Unfertilized eggs and sperm placed directly in oviduct
ZIFT (zygote intrafallopian transfer)
–Fertilized egg is placed in oviduct
Fertility-enhancing drugs
–Boost production of developing eggs
–May result in multiple births
Surrogate motherhood
Sexually Transmitted Diseases (STDs)
Transmitted by sexual contact, including
–Genital, oral-genital, anal-genital
Can be very damaging or deadly
May affect organs outside of the reproductive system
Some are not treatable
Infectious agents include viruses, bacteria, protozoa, fungi, and
arthropods
Bacterial STDs: Syphilis
Caused by bacteria Treponema pallidum
Three phases
–Primary: lesion in genital area
–Secondary: rash
–Bacteria invades blood, lymph nodes, nervous system,
bones
–Tertiary: widespread damage to nervous system and
cardiovascular system
Congenital syphilis: transmitted by infected mother to fetus
Treatment: penicillin
Bacterial STDs: Gonorrhea
Caused by bacteria Neisseria gonorrhoeae
Male symptoms: penile discharge, painful urination
Female symptoms: vaginal discharge, burning sensation when
urinating
–Females are often asymptomatic
Can be passed to newborn during birth, causing a serious eye infection
If untreated, can lead to inflammation, scarring, and infertility
Usually can be treated with antibiotics
Bacterial STDs: Chlamydia
Caused by bacteria Chlamydia trachomatis
Often goes undiagnosed due to mildness of symptoms
–Men: penile discharge, burning upon urination
–Women: vaginal discharge, burning and itching sensation
If untreated, may lead to pelvic inflammatory disease in women
Can infect newborn during birth
Treatment: antibiotics
Viral STDs: HIV and Hepatitis B
HIV: one of the most dangerous STDs
–Slowly destroys the immune system, causing AIDS (acquired
immunodeficiency syndrome)
–Treatment may achieve remission, but no cure
Hepatitis B virus
–More contagious than HIV, but not as deadly
–Affects liver
–Vaccine available for prevention
Viral STDs: Genital Herpes and Human Papillomavirus (HPV)
Genital herpes: virusHerpes simplex
–Painful blisters may recur periodically
–Drugs will suppress outbreaks and contagious phase, but no cure
–May infect infants during birth
Human papillomavirus (HPV)
–Many strains can cause warts in genital area
–Two types cause cervical cancer
–Vaccines to prevent cervical cancer: Gardasil, Cervarix
–CDC recommends that all children (girls and boys) be
vaccinated at age 11 or 12 (before first sexual contact)
Other STDs: Yeast Infections
Candida albicans (yeast): normally present but may overgrow
–Pain, inflammation, discharge
–Can be passed sexually
–May follow antibiotic treatment for bacterial infections
–Treatment: topical or oral antifungal medication
Other STDs: Trichomoniasis
Trichomoniasis: caused by protozoan Trichomonas vaginalis
–Women:
–Vaginitis—inflammation of vagina
–Frothy foul-smelling discharge
–Men:
–Inflammation of penis, discharge
–Treatment: Flagyl (metranidazole)
Other STDs: Pubic Lice
Tiny arthropod, related to spiders
Commonly called “crabs”
Prefer to live on pubic hair
Cause intense itching and skin irritation
Treatment: anti-lice medication
Clothes and bedding should be thoroughly washed in hot water
Protecting Yourself Against STDs
Choose partner wisely
Communicate
Use suitable barriers
Get tested and treated
Get vaccinated (Hepatitis B and HPV)
