REPRODUCTIVE SYSTEM
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reproductive_system.pptChapter 16
Reproductive System
Points to Ponder
- What is mitosis and meiosis?
- How many chromosomes do body and sex cells each have?
- Understand the anatomy of both the male and female.
- Know the functions of each structure in the male and female.
- What are the 3 parts of a sperm?
- How do hormones play a role in the male?
- Explain the ovarian and uterine cycles.
- Be able to discuss the levels of hormones during these cycles.
- Where do fertilization and implantation occur?
- Be able to discuss common birth control methods.
- What is infertility? What can cause this?
- What are the options if a person is infertile?
- Should we treat people who are infertile? Why or why not?
- Understand genital warts, genital herpes, HIV, hepatitis, chlamydia, gonorrhea, syphilis, bacterial vaginosis, trichomoniasis and candidiasis.
- Which of the above can be treated with antibiotics?
- Which birth control methods can help prevent STDs?
DNA in body and sex cells
Body cells:
Each body cell has 46 chromosomes (23 pairs) within the nucleus
Cells that have pairs of chromosomes are called diploid (2N)
Sex cells:
Gametes (egg and sperm) have only 23 chromosomes (1 of each pair) in their nuclei
Cells that have only 1 of each pair of chromosomes is called haploid (N)
During fertilization a sperm and egg combine to form a zygote and the chromosome number is restored to the diploid number of 46
16.1 Human life cycle
Mitosis and meiosis
Mitosis:
Is a type of duplication division in which a cell makes an exact copy of itself
This process is used for growth and repair of tissues
Used by body cells (cells other than sex cells)
Meiosis:
Is a type of reduction division in which a cell halves the number of chromosomes
This process is used to form eggs and sperm
Used by gametes
16.1 Human life cycle
Male anatomy
Scrotum (1)
Testes (2)
Epididymis (2)
Vas deferens (2)
Urethra (1)
3 glands
Penis (1)
16.2 Male reproductive system
Male anatomy: Scrotum and testes
Scrotum:
Sacs that hold the testes
Help regulate the temperature of the testes
Testes:
Paired organs that produce sperm and male sex hormones (made by interstitial cells)
Composed of seminiferous tubules where sperm are being produced
Epididymis:
Sperm mature and are stored here
16.2 Male reproductive system
Male anatomy: Scrotum and testes
16.2 Male reproductive system
Sperm production
Sperm are produced within the seminiferous tubules of the testes
Sertoli cells help nourish sperm and regulate the process of sperm production (spermatogenesis)
Sperm (spermatozoa) are stored and mature in the epididymis
16.2 Male reproductive system
Sperm anatomy
3 parts:
Head: covered by a cap called the acrosome which stores enzymes needed to penetrate the egg
Middle piece: contain mitochondria to make energy (ATP)
Tail: provides movement for the sperm
16.2 Male reproductive system
Male anatomy: Vas deferens and urethra
Vas deferens
Transports sperm to the urethra
Urethra
Transports sperm out of the body
16.2 Male reproductive system
Male anatomy: 3 glands that contribute to semen
Seminal vesicles – produce a sugary fluid that provide energy for the sperm
Prostate gland – produces an alkaline fluid to help buffer the acidic pH in the vagina
Bulbourethral glands – produce mucus that acts as a lubricant in the urethra
16.2 Male reproductive system
Male anatomy: Penis
Penis:
organ used for sexual intercourse and urination
Glans penis:
Intensely sensitive tip of the penis usually covered by foreskin
Circumcision is the removal of all or part of the foreskin
Erectile dysfunction (impotency) occurs when the erectile tissue does not expand enough to compress the veins
16.2 Male reproductive system
Hormonal regulation in males
Gonadotropin-releasing hormone (GnRH) – secreted by the thalamus to control release of other hormones
Follicle-stimulating hormone (FSH) – promotes the production of sperm
Luteinizing hormone (LH) – controls the production of testosterone
Testosterone – important for normal development and functioning of the male reproductive organs
16.2 Male reproductive system
Hormonal regulation in males
16.2 Male reproductive system
Female anatomy
Genital tract:
Ovaries
Oviducts
Uterus
Cervix
Vagina
- External genitals (vulva):
- Labia major
- Labia minor
- Mons pubis
- Clitoris
16.3 Female reproductive system
Female anatomy: Genital tract
Ovaries – produce eggs and sex hormones
Oviducts – moves eggs and normal site of fertilization
Uterus – normal site of implantation and fetal development
Cervix – opening to the uterus that can dilate during childbirth
Vagina – birth canal and the copulatory organ of the female
16.3 Female reproductive system
Female anatomy: Genital tract
16.3 Female reproductive system
Female anatomy: External anatomy
Labia major – 2 large folds of fatty skin
Labia minor – 2 small folds just inside the labia major that contain the opening to the urethra and vagina
Mons pubis – fatty skin covered in coarse hair
Clitoris – erectile organ and site of intense sexual feeling
16.3 Female reproductive system
The ovarian cycle: The ovary
- Contains many follicles each containing an immature egg (oocyte)
- At puberty a female has ~300,000-400,000 follicles
- During the lifetime of a female only ~400 follicles mature
- One follicle matures each month from puberty until menopause (end of ovarian and uterine cycles discussed next)
Ovulation is the monthly release of an oocyte from the ovary when a follicle ruptures
16.4 Female hormone level
Anatomy of the ovary
16.4 Female hormone level
The ovarian cycle
- This is the formation and release of an immature egg
- Controlled by GnRH from the hypothalamus
- 2 phases:
Follicular phase:
FSH promotes the development of a follicle that secretes estrogen
An estrogen spike leads to a surge in LH and ovulation around day 14 in the 28-day cycle
Luteal phase:
LH promotes the develop of the corpus luteum that functions to secrete progesterone
When pregnancy does not occur menstruation begins
16.4 Female hormone level
Hormonal control of the ovaries
16.4 Female hormone level
The uterine cycle
- A 28-day cyclic event in the uterus:
Days 1-5: low level of estrogen and progesterone causing the inner uterine lining (endometrium) to disintegrate and menstruation occurs
Days 6-13 (proliferative phase): increase in estrogen causing the endometrium to thicken
Day 14: ovulation usually occurs
Days 15-28 (secretory phase): increase in progesterone causes endometrium to double or triple in thickness in preparation for the developing embryo. If the egg is not fertilized then the corpus luteum regresses and the endometrium breaks down
16.4 Female hormone level
Hormones in the ovarian and uterine phase
16.4 Female hormone level
Fertilization and Pregnancy
Fertilization – union of a sperm and egg nucleus normally in the oviduct to form a zygote
Pregnancy – begins with implantation usually ~6 days after fertilization
16.4 Female hormone level
Some common birth control methods
Abstinence – not engaging in sexual intercourse
Hormonal control:
Birth control pills: blocks FSH and LH release to stop follicular development and ovulation
Contraceptive injections: injection of hormones (progesterone and/or estrogen) to stop ovulation
Contraceptive implants: synthetic progesterone to prevent ovulation
Barrier methods:
IUD: small plastic piece inserted into the uterus to prevent implantation
Condom (male and female): blocks fertilization
Diaphragm: soft latex cup that covers the cervix so sperm cannot enter the uterus
Sterilization:
Vasectomy: cutting and sealing the vas deferens
Tubal ligation: cutting and sealing the oviducts
Note: Abstinence and the use of condoms are the only methods that protect against STDs
16.5 Control of reproduction
Some common birth control methods
16.5 Control of reproduction
Sterilization
16.5 Control of reproduction
What about pills that can be taken after intercourse?
Preven, a morning-after pill, upsets the normal uterine cycle so an embryo has a hard time implanting (85% effective)
RU-486 causes loss of an implanted embryo (95% effective)
16.5 Control of reproduction
What is infertility and what causes it?
- This is the inability to achieve pregnancy after one year of regular, unprotected intercourse
- Causes:
Overweight females
Low sperm count
Blocked oviducts
Endometriosis
16.5 Control of reproduction
What are your options if you are infertile?
- Adoption – legal custody of a non-biological child
- Assisted reproductive technologies:
Artificial insemination by a donor (AID): sperm are placed inside the vagina by a trained physician
In vitro fertilization (IVF): conception occurs in laboratory glassware then embryos are transferred to a woman’s uterus
Gamete intrafallopian transfer (GIFT): similar as IVF except the eggs and sperm are placed in the oviducts immediately after they have been brought together
Surrogate mothers: women are legally paid to have babies
Intracytoplasmic sperm injection (ICSI): a single sperm is injected into an egg typically when a man has infertility problems
16.5 Control of reproduction
Bioethical focus: Should infertility be treated?
- What are some drawbacks of the procedures:
- Surgery and collection of eggs have risks such as organ damage and bleeding
- Fertility drugs can have side effects including life-threatening problems
- IVF usually creates many embryos some are frozen or donated while others are destroyed
- There is a significant increase in multifetal births which can result in a difficult pregnancy as well as complications to the fetus
- What happens to frozen embryos?
- Who should be treated?
16.5 Control of reproduction
Sexually transmitted diseases (STDs):
Viral diseases: cannot be treated with antibiotics but there are a few antivirals
HIV
Genital warts
Genital Herpes
Hepatitis
Bacterial diseases: can be treated with antibiotics
- Chlamydia
- Gonorrhea
- Syphillis
16.6 Sexually transmitted infections
STD’s: HIV/AIDS
- HIV causes AIDS, the last stage of an HIV infection, in which the helper T cell count is low and the immune system is compromised leading to a suite of opportunistic infections
- No cure but there is a treatment called highly active antiretroviral therapy (HAART) that can limit HIV reproduction
16.6 Sexually transmitted infections
STD’s: Genital warts
- Caused by human papillomaviruses (HPVs)
- Transmitted through skin to skin contact
- Can be transmitted without symptoms
- Most people do not have symptoms but for the few that do most of them see warts, and flat lesions, most often on the penis or opening to the vagina
- Associated with cervical cancer (up to 90% of cases)
- Most often found through regular pap smear screenings in women
- Can be transmitted to a baby during birth
- New vaccine was developed this year to help prevent cervical cancer
16.6 Sexually transmitted infections
STD’s: Herpes
- Caused by herpes simplex virus (HSV)
- Two types
- Type 1 is usually found above the waist
- Type 2 is usually found below the waist (genital herpes)
- Transmitted through skin to skin contact and secretions
- Can be transmitted when there are no symptoms
- Usually have painful ulcers periodically in the same place(s) each time
- Outbreaks occur when the virus is reactivated by stress, sunlight, fever, lack of sleep etc…
- No cure but there are drugs that can keep outbreaks to a minimum or stop them entirely
- Can cause problems in a fetus during birth
16.6 Sexually transmitted infections
STD’s: What do herpes ulcers look like?
16.6 Sexually transmitted infections
STD’s: Hepatitis
- An infection of the liver by one of 6 viruses (Hep A,B,C,D,E,G)
- Hep B: most commonly sexually transmitted hepatitis
- Transmitted through sexual contact and by contaminated blood
- Hepatitis B can lead to liver failure
- Vaccine available for both Hep A and B
16.6 Sexually transmitted infections
STD’s: Chlamydia
- Very common bacterial infection in men and women
- Some men and most women do not have symptoms
(~ 18-21 days after exposure) but if they do:
- Male symptoms: burning during urination and a mucoid discharge
- Female symptoms: vaginal discharge and symptoms of a UTI
- If the infection reaches the uterus, oviducts and the ovaries it can lead to pelvic inflammatory disease (PID) and sterility
- Can be transmitted to a baby during birth (causes inflammation of the eyes and/or pneumonia)
16.6 Sexually transmitted infections
STD’s: Gonorrhea
- Also a common bacterial infection in men and women
- Male symptoms (~3-5 days after contact): pain during urination and a thick, greenish yellow penile discharge
- Female symptoms: uncommon to have vaginal discharge
- Can also lead to PID and sterility in men and women
- Resistance to antibiotics is common in this bacterium
- Can be contracted by a baby during birth leading to an eye infection and even blindness
16.6 Sexually transmitted infections
STD’s: Syphilis
- A bacterial infection with 3 stages:
- Stage 1 (1-8 weeks after infection): hard chancre at the site of infection
- Stage 2 (3-4 months after infection): non-itchy rash even found on the soles of feet and the palms of the hands; may also see hair loss and gray patches on mucous membranes
- Stage 3 (5-20 years after infection and continues until death): affects the cardiovascular and/or nervous systems: gummas (large ulcers) can develop on the skin and internal organs
- These stages are separated by latent periods that make the stages hard to link together and the disease hard to diagnose
- Syphilis can cross the placenta and affect the fetus
16.6 Sexually transmitted infections
Recognizing the 3 stages of syphilis
16.6 Sexually transmitted infections
Other common infections of the reproductive tract
Bacterial vaginosis (BV):
Accounts for ~ 50% of vaginitis in American women
Caused by a disruption of the normal flora in the vagina leading to an overgrowth of certain bacteria
Trichomoniasis
Caused by a protozoan
Can cause a frothy discharge, with a foul smell and itching
Common cause of vaginitis
Candidiasis
An overgrowth of normal yeast (fungus called Candida) in the vagina
- Characterized by tissue that is red, inflammed and itchy; sometimes a white, curdy discharge as well
- Birth control hormones and use of antibiotics make women more prone to this overgrowth
16.6 Sexually transmitted infections
Health focus: Preventing transmission of STDs?
- Abstinence
- Develop long-term monogamous relationships
- Be aware if your partner is an intravenous drug user because prevalence of STDs are higher in that group
- Avoid anal-rectal intercourse
- Uncircumcised males are more likely to be infected so use caution
- Practice safer sex
- Always use a latex condom during intercourse
- Avoid oral sex
- Limit or do not use alcohol and drugs that can impair your judgment or change your behavior
16.6 Sexually transmitted infections
