There are several barriers for sperm.

Fluids in the female reproductive tract prepare the sperm for fertilization through a process called capacitation.

Contact between the sperm and oocyte

Sperm penetrates 2 protective layers

A typical In vitro fertilization (IVF) procedure begins with egg collection.

The period of time required for the full development of a fetus in utero.

Following fertilization, the zygote and its associated membranes, together referred to as the conceptus.

Approximately 3 days after fertilization, a 16-cell conceptus reaches the uterus.

Once inside the uterus, the conceptus floats freely for several more days. It continues to divide, creating a ball of approximately 100 cells, and consuming nutritive endometrial secretions called uterine milk while the uterine lining thickens.

At the end of the first week, the blastocyst comes in contact with the uterine wall and adheres to it, embedding itself in the uterine lining via the trophoblast cells beginning the process of implantation.

The blastocyst typically implants in the fundus of the uterus or on the posterior wall.

A significant percentage (50–75 percent) of blastocysts fail to implant; when this occurs, the blastocyst is shed with the endometrium during menses.

When implantation succeeds and the blastocyst adheres to the endometrium, the superficial cells of the trophoblast fuse with each other, forming the syncytiotrophoblast, a multinucleated body that digests endometrial cells to firmly secure the blastocyst to the uterine wall.

The trophoblast secrets what hormone?

If the embryo implants in the inferior portion of the uterus, the placenta can potentially grow over the opening of the cervix, a condition call placenta previa.

In the vast majority of ectopic pregnancies, the embryo does not complete its journey to the uterus and implants in the uterine tube, referred to as a tubal pregnancy.

During the second week of development, with the embryo implanted in the uterus, cells within the blastocyst start to organize into layers.

The embryo, which takes the shape of an oval-shaped disc, forms an indentation called the primitive streak along the dorsal surface of the epiblast.

In embryogenesis, cells migrate toward and through the primitive streak and then move laterally to create two new layers of cells.

Identify the 1st layer of cells in embryogenesis

Identify the 2nd layer of cells in embryogenesis

Identify the 3rd layer of cells in embryogenesis

Whereas the ectoderm and endoderm form tightly connected epithelial sheets, the mesodermal cells are less organized and exist as a loosely connected cell community.

This germ layer gives rise to cell lineages that differentiate to become the central and peripheral nervous systems, sensory organs, epidermis, hair, and nails.

Mesodermal cells ultimately become the skeleton, muscles, connective tissue, heart, blood vessels, and kidneys.

This germ layer goes on to form the epithelial lining of the gastrointestinal tract, liver, and pancreas, as well as the lungs.

During prenatal weeks 4–12, the developing placenta gradually takes over the role of feeding the embryo.

The mature placenta is composed of tissues derived from the embryo, as well as maternal tissues of the endometrium.

The placenta connects to the conceptus via the umbilical cord, which carries deoxygenated blood and wastes from the fetus through two umbilical arteries; nutrients and oxygen are carried from the mother to the fetus through the single umbilical vein.

The umbilical cord is surrounded by the amnion, and the spaces within the cord around the blood vessels are filled with Wharton’s jelly, a mucous connective tissue.

Identify the ways the placenta functions in nutrition and digestion.

How does the placenta function in respiration?

Identify the ways the placenta functions in edocrine

What is the correct order of organogenesis?

The embryo folds laterally and again at either end, forming a C-shape with distinct head and tail ends.

The folding of the embryo essentially creates a tube, called the primitive gut, that is lined by the endoderm.

In the first few weeks of life, organogenesis begins to take place.

The heart begins beating

The eye pits form, limb buds become apparent, and the rudiments of the pulmonary system are formed

Uncontrolled fetal limb movements begin to occur

The facial structure is more complex and includes nostrils, outer ears, and lenses

The head is nearly as large as the rest of the embryo's body, and all major brain structures are in place and the external genitalia are apparent, but at this point, male and female embryos are indistinguishable

Bone begins to replace cartilage in the embryonic skeleton through the process of ossification.

Sexual differentiation does not begin until the fetal period, during weeks 9–12.

Gonads can develop into male or female sexual organs, and are connected to a central cavity called the cloaca via Müllerian ducts and Wolffian ducts

During male fetal development, the gonads become the testes and associated epididymis, the Müllerian ducts degenerate, the Wolffian ducts become the vas deferens, and the cloaca becomes the urethra and rectum.

During female fetal development, the gonads develop into ovaries, the Wolffian ducts degenerate, the Müllerian ducts become the uterine tubes and uterus, and the cloaca divides and develops into a vagina, a urethra, and a rectum.

The fetal circulatory system is integrated with the placenta via the umbilical cord so that the fetus receives both oxygen and nutrients from the placenta.

Identify the structures of the fetal circulatory system

The brain continues to expand, the body elongates, and ossification continues

Marked by sensory organ development

As the fetus grows and limb movements become more powerful, the mother begins to feel quickening, or fetal movements.

Characterized by rapid weight gain, which is important for maintaining a stable body temperature after birth

The fetus continues to lay down subcutaneous fat from week 31 until birth.

How long does a full-term pregnancy last from conception to birth?

Because it is easier to remember the first day of the last menstrual period (LMP) than to estimate the date of conception, obstetricians set the due date as 284 days (40.5 weeks) from the LMP.

The 40 weeks of an average pregnancy are usually discussed in terms of three trimesters, each approximately 13 weeks.

During the second and third trimesters, the pre-pregnancy uterus grows dramatically to contain the fetus, causing a number of anatomical changes in the mother.

Virtually all of the effects of pregnancy can be attributed in some way to the influence of hormones—particularly estrogens, progesterone, and hCG.

During weeks 7–12 from the LMP, the pregnancy hormones are primarily generated by the corpus luteum.

As the placenta develops and the corpus luteum degenerates during weeks 12–17, the placenta gradually takes over as the endocrine organ of pregnancy.

A hormone secreted by the corpus luteum and the placenta that helps prepare the mother's body for childbirth.

The anterior pituitary enlarges and ramps up its hormone production during pregnancy, raising the levels of thyrotropin, prolactin, and adrenocorticotropic hormone (ACTH).

What are the most obvious anatomical signs of pregnancy?

What factors cause weight gain in pregnant mothers?

Additional breast tissue and dramatically increased blood volume also contribute to weight gain.

During the first trimester, the mother does not need to consume additional calories to maintain a healthy pregnancy.

About how much weight does a pregnant mother gain per month?

Morning sickness is nausea and vomiting during pregnancy.

The source of pregnancy nausea is thought to be the increased circulation of pregnancy-related hormones, specifically circulating estrogen, progesterone, and hCG.

A common gastrointestinal complaint during the later stages of pregnancy is gastric reflux, or heartburn, which results from the upward, constrictive pressure of the growing uterus on the stomach.

The downward pressure of the uterus also compresses the urinary bladder, leading to frequent urination.

Blood volume increases substantially during pregnancy, so that by childbirth, it exceeds its preconception volume by 30 percent, or approximately 1–2 liters.

As the fetus grows, the uterus compresses underlying pelvic blood vessels, hampering venous return from the legs and pelvic region, which can result in many pregnant women developing varicose veins or hemorrhoids.

During the second half of pregnancy, the respiratory minute volume (volume of gas inhaled or exhaled by the lungs per minute) increases by how much?

The growing uterus exerts upward pressure on the diaphragm.

During the last several weeks of pregnancy, the pelvis becomes more elastic.

The dermis of the skin stretches extensively to accommodate the growing uterus, breast tissue, and fat deposits on the thighs and hips.

Striae

An increase in the melanocyte-stimulating hormone, in conjunction with estrogens, darkens the areolae and creates a line of pigment from the umbilicus to the pubis called the linea nigra.

As the pregnancy enters its 7th month, progesterone levels plateau & then drop.

These levels rise in maternal circulation

The increasing ratio of estrogen to progesterone makes the myometrium more sensitive to stimuli that promote contractions.

In the 8th month of pregnancy, fetal cortisol rises, which boosts estrogen secretion by the placenta and further overpowers the uterine-calming effects of progesterone.

The common sign that labor will be short is called what?

During labor, this area of the brain boosts its secretion of oxytocin (a hormone that stimulates the contractions of labor).

As labor nears, oxytocin begins to stimulate stronger, more painful uterine contractions.

Finally, stretching of the myometrium and cervix by a full-term fetus in the vertex (head-down) position is regarded as a stimulant to uterine contractions.

For vaginal birth to occur, the cervix must dilate fully to how many centimeters?

True labor progresses in a positive feedback loop in which uterine contractions stretch the cervix, causing it to dilate and efface, or become thinner.

Begins when the fetal head enters the birth canal and ends with birth of the newborn

The most common vertex presentation associated with the greatest ease of vaginal birth

The fetus faces the maternal spinal cord and the smallest part of the head (the posterior aspect called the occiput) exits the birth canal first.

The delivery of the placenta and associated membranes commonly referred to as the afterbirth

Marks the beginning of the postpartum period— the period of approximately 6 weeks immediately following childbirth during which the mother’s body gradually returns to a non-pregnant state

During gestation, the partially collapsed lungs are filled with amniotic fluid and exhibit very little metabolic activity

Several factors stimulate newborns to take their first breath at birth

First, labor contractions temporarily constrict umbilical blood vessels, reducing oxygenated blood flow to the fetus and elevating carbon dioxide levels in the blood

High carbon dioxide levels cause acidosis and stimulate the respiratory center in the brain, triggering the newborn to take a breath

The first breath of a baby is typically taken within how many seconds of birth?

The process of clamping and cutting the umbilical cord collapses the umbilical blood vessels

The ductus venosus degenerates to become the ligamentum venosum beneath the liver

Flow of blood temporarily reverses direction through the foramen ovale, moving from the left to the right atrium, and blocking the shunt with two flaps of tissue

The ductus arteriosus constricts as a result of increased oxygen concentration, and becomes the ligamentum arteriosum

The first consumption of breast milk or formula floods the neonatal gastrointestinal tract with beneficial bacteria that begin to establish the bacterial flora

The fetal kidneys filter blood and produce urine, but the neonatal kidneys are still immature and inefficient at concentrating urine

Newborns produce very dilute urine, making it particularly important for infants to obtain sufficient fluids from breast milk or formula

The Apgar score was introduced in 1952 by the anesthesiologist Dr. Virginia Apgar as a method to assess the effects on the newborn of anesthesia given to the laboring mother

What is the five criteria of the APGAR?

APGAR scores are taken at 1 minute after birth and again at 5 minutes after birth

High APGAR scores (out of a possible 10) indicate the baby has made the transition from the womb well, whereas lower scores indicate that the baby may be in distress

The process by which milk is synthesized and secreted from the mammary glands of the postpartum female breast in response to an infant sucking at the nipple

The mammary gland is composed of milk-transporting lactiferous ducts

Balloon-like structures lined with milk-secreting cuboidal cells, or lactocytes, that are surrounded by a net of contractile myoepithelial cells.

Clusters of alveoli that drain to a common duct

The lactating female has 12–20 lobules organized radially around the nipple

Milk drains from lactiferous ducts into lactiferous sinuses that meet at 4 to 18 perforations in the nipple, called nipple pores

The pituitary hormone that is instrumental in the establishment and maintenance of breast milk supply

Near the fifth week of pregnancy, the level of circulating prolactin begins to increase, eventually rising to approximately 10–20 times the pre-pregnancy concentration

After childbirth, the baseline prolactin level drops sharply, but it is restored for a 1-hour spike during each feeding to stimulate the production of milk for the next feeding

When the infant suckles, sensory nerve fibers in the areola trigger a neuroendocrine reflex that results in milk secretion from lactocytes into the alveoli

Releases oxytocin which stimulates myoepithelial cells to squeeze milk from the alveoli

It takes less than 1 minute from the time when an infant begins suckling (the latent period) until milk is secreted (the let-down)