Chapter 16 The Female Reproductive System

The Reproductive System Gonads – primary sex organs Testes in males Ovaries in females Gonads produce gametes (sex cells) and secrete hormones Male – sperm (gametes) and testosterone (hormones) Female - Ova (eggs) and progesterone and estrogen (hormones)

Female Reproductive System Function: Produce eggs and sex hormones Estrogen and progesterone Prepare to nurture a developing embryo for nine months

Female Reproductive System Ovaries Duct System Uterine tubes (fallopian tubes) Uterus Vagina External genitalia

Female Reproductive System Figure 16.8a

Ovaries Paired ovaries located in the peritoneal cavity Composed of ovarian follicles (sac-like structures) Structure of an ovarian follicle Oocyte - immature egg Follicle cells Figure 16.7

Ovarian Follicle Stages Primary follicle – contains an immature oocyte Graafian (vesicular) follicle – growing follicle with a maturing oocyte Ovulation – when the egg is mature the follicle ruptures Occurs about every 28 days The ruptured follicle is transformed into a corpus luteum

Support for Ovaries Suspensory ligaments – secure ovary to lateral walls of the pelvis Ovarian ligaments – attach medially to uterus Broad ligament – a fold of the peritoneum, supports the uterine tubes, uterus and vagina

Female Reproductive System Ovaries Duct System Uterine tubes (fallopian tubes) Uterus Vagina External genitalia

Uterine (Fallopian) Tubes Receive the ovulated oocyte Provide a site for fertilization Attaches to the uterus Does not physically attach to the ovary Some eggs are lost

Uterine Tube Function Fimbriae – finger-like projections at the distal end that receive the oocyte Cilia inside the uterine tube and peristalsis slowly move the oocyte towards the uterus (takes 3–4 days) Fertilization occurs inside the uterine tube

Uterine Tube Function Gonorrhea bacteria sometimes infects the periotoneal cavity - between the ovary and fallopian tube because it is not connected Causes severe inflammation called pelvic inflammatory disease (PID) Major cause of female infertility

Uterus (womb) Never been pregnant – size and shape of a pear Located between the urinary bladder and rectum Hollow, thick-walled organ Functions of the uterus Receives, retains and nourishes a fertilized egg

Regions of the Uterus Body – main portion Fundus – area where uterine tube enters Cervix – narrow outlet that protrudes into the vagina

Three Layers (walls) of the Uterus Endometrium Inner layer Allows for implantation of a fertilized egg Sloughs off if no pregnancy occurs (menses) Myometrium Middle layer of smooth muscle; contractions and orgasms Serous layer Outer visceral peritoneum

Vagina Extends from cervix to exterior of body Behind bladder and in front of rectum Serves as the birth canal Receives the penis during sexual intercourse Hymen – partially closes the vagina until it is ruptured

External Genitalia (Vulva) Mons pubis Fatty area overlying the pubic symphysis Covered with pubic hair after puberty Labia – skin folds Labia majora Labia minora Figure 16.9

External Genitalia Vestibule Clitoris Enclosed by labia majora Contains opening of the urethra and the greater vestibular glands (produce mucus) Clitoris Contains erectile tissue Corresponds to the male penis

Oogenesis The total supply of eggs are present at birth Ability to release eggs begins at puberty Reproductive ability ends at menopause Female gametes are produced by meiosis Oocytes are matured in developing ovarian follicles

Oogenesis Oogonium – female stem cells found in a developing fetus Oogonia undergo mitosis to produce primary oocytes Primary oocytes are surrounded by cells that form primary follicles in the ovary

Oogenesis Primary oocytes are inactive until puberty Follicle stimulating hormone (FSH) causes some primary follicles to mature Ovarian cycle - primary follicles grow and mature each month Meiosis starts inside maturing follicle Produces a secondary oocyte and the first polar body Meiosis is completed after ovulation only if sperm penetrates

Oogenesis Figure 16.10

Menstrual (Uterine) Cycle Cyclic changes of the endometrium Regulated by cyclic production of estrogens and progesterone Stages of the menstrual cycle Menses – functional layer of the endometrium is sloughed Proliferative stage – regeneration of functional layer Secretory stage – endometrium increases in size and readies for implantation

Hormone Production by the Ovaries Estrogens Produced by follicle cells Endometrium is repaired and grows thick Forms glands in the endometrium Lack of estrogen and progesterone causes endometrium to slough off (menses) http://resources.schoolscience.co.uk/ABPI/new/resources/hormones/en-flash/menstrualCycle.html

Hormone Production by the Ovaries Estrogens Cause secondary sex characteristics Enlargement of accessory organs Development of breasts Appearance of axillary and pubic hair Increase in fat beneath the skin Widening and lightening of the pelvis Onset of menses

Hormone Production by the Ovaries Progesterone Produced by the corpus luteum Helps maintain pregnancy Causes endometrial glands to begin secretion of nutrients Maintains the myometrium in an inactive state if implantation of an embryo has occurred

Mammary Glands Present in both sexes, but only function in females Modified sweat glands Function is to produce milk (lactation) Stimulated by sex hormones (mostly estrogens) to increase in size

Stages of Pregnancy and Development Fertilization Embryonic development Fetal development Childbirth

Fertilization The oocyte is viable for 12 to 24 hours after ovulation Sperm are viable for 12 to 48 hours after ejaculation Sperm cells must make their way to the uterine tube for fertilization to be possible

Mechanisms of Fertilization Membrane receptors on an oocyte pulls in the head of the first sperm cell to make contact The membrane of the oocyte does not permit a second sperm head to enter The oocyte then undergoes its second meiotic division Fertilization occurs when the genetic material of a sperm combines with that of an oocyte to form a zygote

The Zygote First cell of a new individual The result of the fusion of DNA from sperm and egg The zygote begins rapid mitotic cell divisions The zygote stage is in the uterine tube, moving toward the uterus

The Embryo Developmental stage from the start of cleavage until the ninth week The embryo floats free in the uterus temporarily Uterine secretions are used for nourishment

The Blastocyst Ball-like circle of cells Secretes human chorionic gonadotropin (hCG) to produce the corpus luteum to continue producing hormones The late blastocyst implants in the wall of the uterus (by day 14)

Derivatives of Germ Layers Primary germ layers are eventually formed Ectoderm (outside layer) Nervous system Epidermis of the skin Mesoderm (middle layer) Everything else Endoderm (inside layer) Mucosae Glands

Development After Implantation The embryo is surrounded by the amnion (a fluid filled sac) An umbilical cord forms to attach the embryo to the placenta

Development from Ovulation to Implantation

Functions of the Placenta Forms a barrier between mother and embryo (blood is not exchanged) Delivers nutrients and oxygen Removes waste from embryonic blood

The Fetus (Beginning of the Ninth Week) All organ systems are formed by the end of the eighth week Activities of the fetus are growth and organ specialization A stage of tremendous growth and change in appearance By 270 days (nine months) the fetus is full-term and ready to be born

In Vitro Fertilization http://video.nationalgeographic.com/video/player/science/health-human-body-sci/human-body/ivf-sci.html

Sexually Transmitted Diseases Disease spread from one person to another during sexual contact. Infect millions in US each year There are more than 25 different diseases Viral Human papilloma virus (HPV) Herpes (genital) Hepatitis A, B, and C (generally B) Human immunodeficiency virus (HIV) Bacterial Syphilis Gonorrhea Chlamydia

Sexually Transmitted Diseases Viral Herpes (genital) ~45 million people are infected with it Two types of herpes (HSV -1 causes oral herpes and HSV -2 causes genital herpes) Symptoms include pain and itching in infected areas Lesions in the genital areas and buttocks No cure for the virus

Sexually Transmitted Diseases Viral Humanpapilloma virus (HPV) About 80% of humans are infected 100 different types of HPV and ~ 30 are STD Usually no symptoms but some can lead to genital warts No cure for the virus Some types can lead to cervical cancer Females – have a vaccine to prevent HPV

Sexually Transmitted Diseases Viral Hepatitis A, B, and C (generally B) Hepatitis B attacks your liver and usually leads to death ~1.25 million Americans infected with Vaccine available to prevent infection Usually no symptoms but some experience jaundice, and flu symptoms No cure for the virus

Sexually Transmitted Diseases Viral Human immunodeficiency virus (HIV) Virus attacks your immune system (t-helper cells that fight off infections Eventually the body cannot fight off infections When this happens the person acquires AIDS First few weeks feel like you have the flu but then no symptoms No cure for the virus but medications to help

Sexually Transmitted Diseases Bacterial Syphilis Majority of sufferers are males Syphilis can be treated if caught early If untreated it can lead to heart problems, blindness and death Primary syphilis results in painless sores, secondary syphilis results in a rash with a fever and fatigue, third stage can last for years and end in blindness, numbness, and death

Sexually Transmitted Diseases Bacterial Gonorrhea (the clap) Most people infected are under the age of 30 Can be cured by antibiotics Difficult to diagnose because it usually presents with urinary symptoms

Sexually Transmitted Diseases Bacterial Chlamydia (‘silent disease’) Most common STD ~ 3 million cases per year Usually no symptoms but some people experience discharge and painful urination Antibiotics can cure the infection