Female Reproductive Physiology Flashcards

Flashcards about Female Reproductive Physiology

Fertilization

Sperm must be introduced to the female reproductive tract. Most ejaculated sperm do not make the 5-inch trip to join with the oocyte due to several factors such as leaking, acidic vaginal environment or immune cells.

Fertilization

Oocyte must be ejected (ovulated) from the ovary. The potential for fertilization is highest during the first few days after ovulation because the oocyte is only viable for 12-24 hours, but sperm can survive for up to five days in the female reproductive tract.

Contraceptive Methods: Condoms, Diaphragms, Cervical caps and sponges

Ways to prevent sperm from moving beyond the vagina.

Rhythm method

Timing when ovulation occurs; sex BEFORE ovulation has a higher probability of pregnancy, while sex AFTER ovulation has a slightly lower chance.

Fertilization

Sperm that reach the oocyte release acrosomal enzymes to digest the zona pellucida. After penetration, meiosis II continues creating a polar body and mature ovum; Then the zona pellucida hardens. Maternal and paternal chromosomes combine, forming the zygote or fertilized egg.

Sex Determination

Oocytes have an X chromosome, while sperm can have either an X or Y chromosome. Sperm with the X-chromosome tend to be more robust and can last longer than those with the Y-chromosome. Intercourse before ovulation increases the chance of a baby girl.

Morula

A solid mass of cells (~32) formed within 24 hours of fertilization, resulting from mitotic divisions of the zygote.

Blastocyst

A more complex hollow structure that the developing embryo becomes as it travels down the fallopian tube for 4-5 days.

Trophoblast

The outer cell layer of the blastocyst that invades the endometrium, creating parts of the placenta and chorion.

Inner cell mass

The cluster of cells at one end of the blastocyst that will form the embryo.

hCG (human chorionic gonadotropin)

Secreted by the trophoblast and chorion after implantation, preventing the corpus luteum from degenerating during the first trimester of pregnancy and maintaining high progesterone and estrogen levels. After the first trimester, the placenta secretes progesterone and estrogen.

Placenta Development

hCG promotes the formation of the placenta. Extra-embryonic mesoderm forms the chorion that delivers embryonic blood through chorionic villi, which form the umbilical artery and veins. The endometrium forms sinuses that fill with material blood, allowing the diffusion of substances without mixing fetal and material blood.

First Trimester

The embryo develops and obtains nutrients from the placenta. Maternal and embryonic circulatory systems exchange materials like oxygen, water, nutrients, and waste. At 8 weeks, all major adult structures are present in the fetus, and the heartbeat can be detected.

Umbilical Vein

One umbilical vein carries oxygen and nutrients toward the fetal heart.

Umbilical Arteries

Two umbilical arteries carry carbon dioxide and waste from the fetal heart to the placenta.

Fetal Circulation

The umbilical vein picks up O2 and nutrients and enters the inferior vena cava (IVC) near the liver. Oxygen saturation is about 80%. The ductus venosus directs blood from the umbilical vein superior to the liver into the IVC, bypassing the liver.

Foramen Ovale

Moves most of the oxygenated blood in the inferior vena cava directly to the left atrium.

Ductus Arteriosus

Moves blood from the pulmonary artery to the aortic arch. Blood in the descending aorta is only partially oxygenated and goes to the lower body, while blood sent to the head, neck, and upper limbs has a higher oxygen concentration.

Second and Third Trimesters

The uterus grows enough to become apparent. The fetus continues to grow. The fetus's activity increases and may be visible through the abdominal wall. Childbirth begins with labor and strong, rhythmic uterine contractions.

Anatomical Changes During Pregnancy

The uterus pushes into the abdominal and pelvic cavities, pressing against the diaphragm, urinary bladder, and pelvic blood vessels. Increased pressure in the abdominopelvic cavity pushing on organs and preventing drainage of legs. Relaxin causes pelvic ligaments and pubic symphysis to relax, widen, and become flexible. Lumbar curvature becomes accentuated (lordosis).

Labor

The process of the fetus being expelled from the uterus through the vagina. During the last few weeks of pregnancy, fetal cortisol increases causing the placenta to release more estrogen, and oxytocin receptors in the uterus increase.

Oxytocin and Prostaglandins in Labor

Mother and fetus secrete oxytocin, and the placenta releases prostaglandins, causing the cervix to soften and uterine contractions to increase, leading to the release of more oxytocin.

Dilation Stage of Labor

True labor begins when dilation occurs and uterine contractions occur regularly, usually producing pain. Contractions move from the upper part of the uterus toward the vagina, becoming more vigorous and rapid, and the cervix softens. The amniotic sac ruptures, and fluid is released. The cervix fully dilates at 10 cm.

Expulsion Stage of Labor

Begins from full dilation to complete delivery of the infant. Crowning occurs when the largest dimension of the baby’s head distends the vulva.

Placental Stage of Labor

Strong uterine contractions compress blood vessels limiting bleeding and shear off the uterine wall

Changes After Birth

The circulatory pattern needs to change so that deoxygenated blood in the pulmonary circuit is delivered to the lungs and oxygenated blood in the systemic circuit is delivered to the body systems. Then the umbilical cord is cut, and the baby takes its first breath.