Thursday, July 19, 2007

Compendium Review Seven -- Reproduction

Katie Meyers

Compendium Review Seven – Reproduction

Human Life Cycle

  • Overview of events in human life cycle
  • Aging

Reproductive Organs (Genitals)

  • 5 functions
  • Male reproductive system
    • Overview of male reproductive organs
    • Steps of male reproductive system
    • Ejaculation
    • Testes
  • Female reproductive system
    • Organs
    • External genitals
    • Meiosis
    • Female hormones
    • Uterine cycle – non-pregnant
    • Ovarian cycle – non-pregnant
    • Uterine and ovarian cycles – pregnant
    • Menopause

Birth Control Options, Infertility, and STDs

  • Birth Control – some examples
  • Infertility
  • STDs – sexually transmitted diseases
    • Viral
    • Bacterial
    • Prevention

Fetal Development at Birth

  • Fertilization
  • Implantation
  • Processes of Development
  • Extraembryonic membranes
  • Development stages
    • Pre-embryonic development
    • Embryonic development
    • Fetal development
  • Genital development
  • Pregnancy and birth
    • Parturition
    • Placenta
    • Mother/fetus blood never mixes
    • Umbilical cord
    • Maternal changes in female anatomy
    • How mother can prevent birth defects
    • Birth
      • 3 stages
    • Many different approaches

Human Life Cycle

  • Overview of events in human life cycle (in order)
    • Meiosis
      • “Reduction division”
      • Occurs only in sex organs
    • Fertilization
    • Fetal Development
    • Birth
    • Childhood/Adolescence
      • Puberty – when a child becomes, by a series of event, a sexually competent adult
        • Reproductive system does not fully function until puberty is complete
        • Occurs…
          • 11 – 13 in females
          • 14 – 16 in males
    • Adulthood


    • (found on slide 4 of Reproduction – BIO 156 PowerPoint presentation)
      • During this stage, adults’ sex organs perform meiosis in preparation of having children
    • Aging
    • Death
  • Changes to each of these stages is due to the aging process

Reproductive Organs (Genitals)

  • 5 functions
    • 1)
      • Males – produce sperm within testes
      • Females – produce eggs within ovaries
    • 2)
      • Males – nurture, transport, and eject sperm
      • Females – transport eggs to uterus
    • 3)
      • Males – penis delivers sperm to…
      • Females – …vagina – takes in sperm, ejects menstrual fluid, is birth canal
    • 4)
      • Females – uterus allows fertilized egg to develop and be nourished within a female
      • Females – breasts provide nourishment after birth
    • 5)
      • Both – testes/ovaries produce respective sex hormones
        • These hormones bring about masculinization/feminization
        • Females – allow pregnancy to continue
  • During sexual intercourse, both male and female will ideally experience orgasms
  • Male Reproductive System
    • (Overview of) Male Reproductive Organs


      • (found on slide 6 of Reproduction – BIO 156 PowerPoint presentation)
      • Testes – produce sperm and sex hormones; primary sex organ; plural (there are two)
        • Millions of sperm in just a few drops of testicular fluid
      • Scrotum – sacs that suspend testes (two of them)
      • Epididymides – ducts; store sperm; this is where sperm also matures
      • Vasa deferentia – conduct and store sperm
      • Seminal vesicles – contribute nutrients and fluid to semen
      • Prostate gland – contributes fluid to semen
      • Urethra – conducts sperm
      • Bulbourethral glands – contribute fluid containing mucous to semen
      • Penis – sexual intercourse organ
      • Prepuce – part of penis; removed during circumcision
    • Steps of the male reproductive system
      • Sperm is produced in left and right testes
      • The vas deferens (left, right) carry it up into the abdominal cavity
      • At base of penis, it (sperm) joins with urethra
      • Semen produced by prostate and seminal glands at the penis’s base
      • Ejaculation occurs
        • When sperm travel from testes, are joined by semen, and ejected through erect penis
    • At time of ejaculation, sperm leaves penis by means of semen
      • 3 types of vesicles/glands add secretions to seminal fluid (see above: seminal vesicles, prostate gland, bulbourethral glands)
      • Seminal fluid
        • Each component is different and has a particular function
          • Basic solution (more viable)
          • Sugar fructose (provide sperm with energy)
          • Prostaglandins (chemicals that contract uterus, moving sperm toward egg)
    • Testes
      • Begin developing inside abdominal cavity, descend into scrotal sacs during last two months of fetal development
      • Scrotum regulates their temperature by holding them closer/farther from body, depending on their current temperature and the environment
      • Each composed of…


        • (found on slide 7 of Reproduction – BIO 156 PowerPoint presentation)
        • Lobules
          • Contain one to three seminiferous tubules
            • Packed with cells undergoing spermatogenesis (production of sperm) by meiosis
              • Seroti cells support, nourish, and regulate spermatogenesis
              • Sperm not ejaculated is reabsorbed by testicular tissue
              • It takes approximately 74 days for sperm to develop from spermatogenesis into sperm
                • Mature sperm (spermatozoa) – 3 parts
                  • Head – nucleus covered by acrosome (which stores enzymes to penetrate egg)
                  • Middle piece – has mitochondria that provide energy for tail movement
                  • Tail – flagellum
                  • Do not live more than 48 hours in female genital tract
        • Interstitial cells
          • Live between seminiferous tubules
          • Secrete sex hormone
            • Most important sex hormone is testosterone




    • (found on slide 9 of Reproduction – BIO 156 PowerPoint presentation)
      • Ovaries – produce eggs (oocytes) and sex hormones (estrogen and progesterone)
        • Site of initial meiosis, where unfertilized eggs are produced
      • Oviducts – conduct eggs; location of fertilization in uterine/fallopian tubes specifically; lined with cilia
      • Uterus (womb) – houses developing fetus
        • Placenta – sustains development of embryo/fetus
      • Cervix – contains opening to uterus
        • Hysterectomy – removal of cervix; a form of sterilization
      • Vagina – receives penis during sexual intercourse
        • Birth canal
        • Exit for menstrual flow
        • Acidic environment
    • External genitals
      • Collectively known as the vulva
        • 2 labia majora (folds of skin)
        • Mons pubis
        • Labia minora – similar to labia majora, just closer to vagina
          • Urethra and vagina openings inside labia minora
        • Glans clitoris
        • Hymen – partially closes vagina; ring of tissue (virginity)
    • Meiosis
      • Occurs in ovaries
      • Phase One
        • Occurs in fetal ovary
        • One egg per month (ovulation part of menstrual cycle) matures and bursts from ovarian wall and taken up into the fallopian tube
      • Phase Two
        • Occurs moment egg is fertilized, if that even happens
      • Possibly very large gap between phases
    • Female hormones
      • Ovaries’ production of hormones


        • (found on slide 10 of Reproduction – BIO 156 PowerPoint presentation)
        • Primary follicles – produce estrogen
        • Secondary follicles – produce estrogen and some progesterone
        • Corpus luteum – produces progesterone
      • Hypothalamus – same function in females as in males
        • Hormone secretion (GnRH, FSH, LH) not constantly present, but secreted at different rates during menstrual cycle
      • Estrogen – responsible for secondary female sex characteristics, e.g. body hair, fat distribution
      • Estrogen and progesterone both required for breast development
    • Uterine cycle – non-pregnant – average 28-day cycle
      • Menstruationdays 1-5
        • Endometrium breaks down
      • Proliferative phase – days 6-13
        • Endometrium rebuilds
      • Secretory phase – days 15-28
        • Endometrium thickens
        • Glands become secretory
    • Ovarian cycle – non-pregnant – average 28-day cycle (occurs simultaneously with uterine cycle)
      • Follicular phase – days 1-13
        • Follicle maturation occurs
        • Estrogen secretion prominent
      • Ovulation – day 14
        • LH spike occurs
      • Luteal phase – days 15-28
        • LH secretion occurs
        • Corpus luteum forms
        • Progesterone secretion prominent
    • Here is a picture of both the uterine and ovarian non-pregnant cycles


    • (found on slide 11 of Reproduction – BIO 156 PowerPoint presentation)
    • Here is a picture of both the uterine and ovarian pregnant cycles – unlike non-pregnant cycle, progesterone does not drop (because it helps maintain uterus wall in preparation of pregnancy)


    • (found on slide 12 of Reproduction – BIO 156 PowerPoint presentation)
    • Menopause – when ovarian cycle stops
      • Begins between the ages of 45 and 55

Birth Control Options, Infertility, and STDs

  • Birth Control – some examples


    • (found on slide 13 of Reproduction – BIO 156 PowerPoint presentation)
    • Abstinence – most reliable
      • Prevents transmission of STDs
    • Family planning – on of the least effective options
      • 70% family planners succeed with the program
    • Specifically female
      • Contraceptives – medications, e.g. birth control pills
      • Contraceptive implants – capsule that utilizes synthetic progesterone, prevents ovulation
      • Contraceptive injections – either progesterone only or a progesterone/estrogen mix
        • From a few weeks to three months between shots
      • Contraceptive vaccines – immunize woman to hormones associated with egg production, e.g. HCG
      • “Morning-after pills” – emergency contraception
      • Intrauterine device (IVD) – small molded plastic piece inserted into uterus by physician
        • Mostly inhibits fertilization
        • Makes implanting impossible
      • Diaphragm – soft latex cup with flexible rim
        • Lodges behind pubic bone, fits over cervix
        • Individually fitted
        • Used with spermicidal jelly or cream
        • Put in no more than two hours before sexual activity
        • Remove at least six hours after sexual activity
      • Female condom – large polyurethane tube
        • Open end has ring that covers external genitals
        • Considered a barrier method
          • Renewed interest in STD protection possibility
      • Tubal ligation – cuts and seals oviducts
        • Brings about sterilization
        • Should be considered permanent
    • Specifically male
      • Male condom – latex sheath goes over erect penis
        • Better form of protection if used with spermicide
        • Same as female condom in that it is considered a barrier method
          • Renewed interest in STD protection possibility
      • Vasectomy – cuts and seals vas deferens


        • (found on slide 8 of Reproduction – BIO 156 PowerPoint presentation)
        • Form of sterilization
        • Should be considered permanent
  • Infertility
    • Definition – failure of a couple achieving pregnancy after one year of effort (unprotected, regular intercourse)
    • Estimated 15% of couples infertile
      • 40% -- males; low sperm count or much abnormal sperm
      • 40% -- females; body weight
      • 20% -- both
    • Assisted reproductive technologies
      • Artificial Insemination by Donor – sperm placed into vagina by physician
      • In Vitro Fertilization – conception in lab glassware
      • Gamete Intrafallopian Transfer – similar to IVF
        • Eggs removed and reintroduced in same procedure/time period
      • Surrogate mothers – paid women bring stranger’s baby to term
      • Intracytoplasmic sperm injection
        • Used in sever male fertility problems
        • One sperm directly injected into egg
  • STDs – sexually transmitted diseases
    • Viral – none curable yet
      • HIV infection – fatal
      • Genital warts
        • Caused by human papillomavirus (HPV)
      • Genital herpes
        • Caused by herpes simplex virus
          • Type One – cold sores, fever blisters
          • Type Two – genital herpes
      • Above two very common and uncomfortable
      • Hepatitis
        • Infects liver by failure, cancer, or death
        • Easily transmittable
        • No immediate consequences
        • ABCDEG
          • A – not sexually transmitted; fecal to mouth
          • BCDEG – transmitted by…
            • Sexual contact
            • Contaminated blood
          • B – most common sexually transmitted hepatitis; can lead to liver failure
          • CDEG – liver cancer possibilities; no vaccines yet available
    • Bacterial – curable with antibiotics
      • Chlamydia
      • Gonorrhea – 40% strains now resistant to antibiotic therapy
      • Syphillis – 3 stages
      • Bacterial vaginosis (BV)
        • Responsible for about 50% of vaginitis in American women
        • “Caused by a disruption of the normal flora in the vagina leading to an overgrowth of certain bacteria” (from slide 16 of Reproduction – BIO 156 PowerPoint presentation)
      • Candida albicans
        • Overgrowth of normal yeast in vagina
        • Characterized by – tissue that is red, inflamed, itchy; with, curdy discharge sometimes too
        • Women using birth control hormones/antibiotics more prone
      • Trichomonas vaginalis
        • Caused by a type of protozoan
        • Causes – frothy discharge, foul smell, itching
        • Common cause of vaginitis
    • Ways to prevent STD transmission
      • Abstinence
      • Long-term monogamous relationship(s)
      • Be aware of partner’s STD history and risky (STD-wise) behavior
      • Practice safe sex

Fetal Development and Birth

  • Fertilization – union of sperm and egg resulting in zygote


  • (found at http://www.bio.davidson.edu/Courses/Molbio/MolStudents/spring2005/Dresser/sperm%20and%20egg%20fusion.jpg)
    • Flagellum on sperm finds (swims towards) egg
    • Sperm head only (nucleus) fuses with egg’s nucleus
    • Zygote receives cytoplasm and organelles from mother only
    • Approximately one week from fertilization to implantation
      • During that week, only mitosis occurs
  • Implantation
    • Normally in uterine wall
    • Ectopic pregnancy – when a fertilized egg implants before getting to uterine wall, e.g. oviduct
      • Can be dangerous, lead to hemorrhaging
    • First step to take if pregnancy is suspected – find where zygote implanted
  • Processes of Development
    • Cleavage – occurs during mitotic cell division of the zygote
    • Growth – cell division accompanied by daughter cells becoming larger
    • Morphogenesis – shaping of the embryo
      • First evident when some cells move/migrate compared to the other cells – such movements make embryo assume various shapes
    • Differentiation – when cells take on specific structure and/or function
  • Extraembryonic membranes


  • (found at http://img.tfd.com/dorland/thumbs/amnion.jpg)
    • Outside embryo
    • 4 types
      • Chorion – develops into fetal half of placenta
      • Allantois – extends away from embryo
        • Deal with kidneys/urinary tract and has umbilical blood vessels
      • Yolk sac – first to appear of the four
        • Contains many blood vessels – first site of blood cell formation
      • Amnion – enlarges relative to embryo/fetus
        • Contains cushioning fluid to protect embryo/fetus
  • Overview of early embryonic development (about first month)
    • “Basic body plan laid down”
    • “No organs formed”
    • “Placenta develops”
    • “Very little growth, fetus still tiny”
    • Above quotes from slide 20 of Reproduction – BIO 156 PowerPoint presentation
  • Development Stages
    • Pre-embryonic development
      • Contains the events of the first week
        • Zygote division while traveling down oviduct to uterus


    • (found on slide 19 of Reproduction – BIO 156 PowerPoint presentation)
    • Embryonic development


      • (from slide 20 of Reproduction – BIO 156 PowerPoint presentation)
      • Goes from second week to end of second month
      • Week two – embryo begins implanting in uterus
        • Gastrulation occurs
          • Turns inner cell mass into embryonic disk
          • An example of morphogenesis
          • At completion, there is…
            • 3 primary germ layers


              • (found on slide 21 of Reproduction – BIO 156 PowerPoint presentation)
              • Ectoderm
              • Mesoderm
              • Endoderm
            • Embryonic disk has become embryo
      • Week three – two important organ systems appear
        • Nervous system
        • Heart (both third and fourth weeks)
      • Week four – body stalk (future umbilical cord) connect embryo to chorion; limb buds (flippers) appear
      • Week five – head enlarges; sense organs gain prominence; visual development (possible to see) of eyes, ears, and nose
      • Week six to week eight – embryo changes into recognizable human being; head achieves normal relationship with body; neck region develops; nervous system responsive (to reflex actions); all organ systems established
    • Fetal development – fetus is recognizably human
      • Month three – fingernails appear; gender distinguishable by ultrasound
      • Month four – skeleton visible; hair begins appearing; cartilage begins being replaced by bone
      • Month five – heartbeat heard; vernix caseosa (cheesy protective coating) begins being deposited; mother begins feeling movment – pregnancy obvious
      • Month six – body covered with lanugo (fine hair); wrinked and reddish skin
      • Month seven – testes descend into scrotum; eyes are open; possible for baby to survive if born now
      • Month eight – body hair begins disappearing; depositing of subcutaneous fat begins
      • Month nine – fetus ready for birth and about 20 ½ inches long and 7 ½ pounds
    • Male and female development of genitals


    • (found at http://www.mie.utoronto.ca/labs/lcdlab/biopic/fig/41.13.jpg)
      • Development of gonads and ducts, development of external genitals
      • Sex of fetus determined at fertilization
        • Males – XY
          • Male XX syndrome
        • Females – XX
          • Female XY syndrome
        • Both syndromes result in ambiguous sex determination
        • Gonads do not start developing until the seventh week
        • At six weeks, males and females have same types of ducts
        • At fourteen weeks, primitives testes/ovaries are located deep inside abdominal cavity
  • Pregnancy and birth
    • Parturition – process of birthing offspring
    • Placenta – source of progesterone and estrogen during pregnancy
      • 2 sides
        • Fetal side – contributed by chorion
        • Maternal side – consisting of uterine tissue
      • Placental hormones cause…
        • Fluctuations in energy levels
        • Uterus relaxation
        • Pulmonary values to increase
        • Stress incontinence
        • Decreased venous return
        • Edema
        • Varicose veins
        • Stretch marks (Striae gravidarum)
        • Peptide hormone (from placenta) brings about pregnancy-induced diabetes
    • Mother/fetus blood never mixes


    • (found at http://images.main.uab.edu/healthsys/ei_0181.gif)
    • Umbilical cord – fetus’s lifeline
      • Contains umbilical arteries and vein
    • Maternal changes in female anatomy
      • Shift in organs
        • Bladder and rectum pushed superiorly and squeezed, resulting in changes in urination and defecation patterns
        • Stomach is compressed, making the mother eat more often, but less at every meal
        • Appetite change due to immune response changing to avoid possible poisons for the fetus’s sake
      • “Postural changes to compensate for anterior weight” (found on slide 22 of Reproduction – BIO 156 PowerPoint presentation)
      • Breasts enlarge because of milk production
        • First milk production begins around the sixth month of pregnancy
    • How mother can prevent birth defects
      • Get a physical exam
      • Have good health habits
      • Avoid…
        • Drinking alcohol
        • Smoking cigarettes
        • Taking illegal drugs
        • Taking medications not approved by your physician
        • Exposure to environmental toxins and radiations
      • Help prevent conditions associated with birth
    • Birth
      • 3 stages

      • (found at http://www.scienceclarified.com/images/uesc_02_img0089.jpg)
        • Stage One
          • Effacement – taking up the cervix – done by uterine contractions
          • Amniotic membrane ruptures, if it has not already
          • First stage of parturition ends once cervix is completely dilated
        • Stage Two
          • Beings when uterine contractions occur every one to two minutes and last about one minute each
          • Mother has desire to push, or bear down
          • As soon as head is delivered physician may hold head and guide it downward
          • After birth, umbilical cord is cut and tied once baby is breathing normally and functioning independently
        • Stage Three
          • Afterbirth (placenta) is delivered about 15 minutes after delivery
    • Many different approaches to the birthing and the child-raising processes

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