Chapter 16 Reproductive System Body somatic 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 Such cells that have only 1 of each pair of chromosomes are called haploid n During fertilization a sperm and an egg combine to form a zygote and the chromosome number is restored to the diploid number 2n of 46 Mitosis and meiosis Mitosis 1 diploid 2n parent cell produces 2 diploid 2n daughter cells A type of duplication division in which a cell makes an exact copy of itself A process used for growth and repair of tissues Used by body somatic cells cells other than sex cells 46 chromosomes duplicate before the process Then they are divided into 2 daughter cells with 46 each Meiosis males A type of reduction division in which a cell halves the number of chromosomes A process used to form gametes sex or germ cells eggs in females and sperms in Divides 23 in one and 23 in the other Every gamete join to make the baby and sum 46 Male Anatomy Human Life Cycle Male anatomy Scrotum and testes Body is 2oC lower than body temperature Scrotum Testes Sacs that hold the testes Help regulate the temperature of the 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 Sperms 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 Sperm production Sperm anatomy 3 parts The head is covered by a cap called the acrosome which stores enzymes needed to penetrate the egg The middle piece contains mitochondria to make ATP The tail provides movement for the sperm Spermatogenesis produces sperm cells Male anatomy Vas deferens and Urethra Vas deferens Urethra Transports sperms to the urethra Transports sperms out of the body Male anatomy 3 glands that contribute to semen Seminal vesicles produce a sugary fluid that provides energy for the sperm Prostate gland produces an alkaline fluid to help buffer the acidic pH of the vagina Bulbourethral glands produce mucus that acts as a lubricant Hormonal regulation in males Gonadotropin releasing hormone GnRH secreted by the hypothalamus to control release of pituitary 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 Female anatomy Genital tract The ovarian cycle The ovary An 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 menstrual cycles Ovulation is the monthly release of an oocyte from the ovary when a follicle ruptures Oogenesis Anatomy of ovary Ovarian cycle and Hormonal Control This is the development release of an immature oocyte It is controlled by GnRH from hypothalamus that causes release of FSH LH from ovary The Ovarian cycle 2 phases Follicular phase Luteal 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 LH promotes the development of the corpus luteum that functions to secrete progesterone When pregnancy does not occur menstruation begins The Uterine cycle A 28 day cyclic event in the uterus Days 1 5 low levels of estrogen and progesterone cause the inner uterine lining endometrium to disintegrate and menstruation occurs Days 6 13 proliferative phase increase in estrogen causes 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 Fertilization Union of a sperm and egg nucleus to form a zygote Normally occurs in an oviduct fallopian tube Pregnancy Begins with implantation Usually 6 days after fertilization Some common birth control methods Abstinence not engaging in sexual intercourse Hormonal control Birth control pills block FSH and LH release to stop follicular development and ovulation Contraceptive injections of hormones progesterone and or estrogen stop ovulation Contraceptive implants use synthetic progesterone to prevent ovulation Note Abstinence and use of condoms are the only methods that protect against STDs Barrier methods Sterilization An IUD is a small plastic piece inserted into the uterus to prevent implantation Condoms male and female block fertilization The diaphragm is a soft latex cup that covers the cervix so sperm cannot enter the uterus Vasectomy consists of cutting and sealing the vasa deferentia Tubal ligation consists of cutting and sealing the oviducts 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 mifepristone causes loss of an implanted embryo 95 effective 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 What are your options if you are infertile Adoption legal custody of a non biological child Assisted reproductive technologies ART Artificial insemination by a donor AID sperm are placed inside the vagina by a trained In vitro fertilization IVF conception occurs in laboratory glassware then embryos are physician transferred to a woman s uterus Gamete intrafallopian transfer GIFT similar to 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 Sexually transmitted diseases STDs Viral diseases cannot be treated with antibiotics but there are some antivirals HIV AIDS Auto Immuno Deficiency Syndrome Genital warts Genital herpes Hepatitis Bacterial
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