Development

What marks the beginning and end of the prenatal period?

Begins with fertilization and ends ~38 weeks later with birth.

What are the three periods of prenatal development?

Pre-embryonic, embryonic, and fetal periods.

What occurs during the pre-embryonic period?

The zygote becomes a multicellular blastocyst and implants in the uterus.

What happens during the embryonic period?

Rudimentary versions of major organ systems appear in the developing body.

What defines the fetal period?

Development from the end of the embryonic period to birth, with the organism called a fetus.

What is a zygote?

A single diploid cell formed by the fusion of male sperm and female secondary oocyte.

What is the acrosome reaction?

Release of digestive enzymes from the sperm's acrosome to allow penetration into the zona pellucida.

What major event occurs on day seven of development?

Implantation of the blastocyst into the uterine wall begins.

What is the role of hCG after implantation?

It signals the corpus luteum to maintain production of progesterone and estrogen.

What forms the bilaminar germinal disc?

Differentiation of embryoblast cells into hypoblast and epiblast layers.

What is the function of the yolk sac?

Site for blood cell and blood vessel formation.

What does the amnion do?

Encloses the embryo in a fluid-filled sac to protect it.

What is the placenta's role in development?

Connects the embryo/fetus to the mother, facilitating nutrient and waste exchange.

What is organogenesis?

The process of forming the body's organs during development.

When does gastrulation occur?

In the third week of embryonic development.

What are the three primary germ layers formed during gastrulation?

Ectoderm, mesoderm, and endoderm.

What is the significance of the primitive streak?

It signifies where cells of the epiblast migrate to form germ layers.

What is neurulation?

Development of the nervous system from the ectoderm.

What structures originate from the mesoderm?

Muscles, bones, and cartilage, among others.

What changes occur in the endoderm during development?

Forms the epithelial linings of various body systems.

How do teratogens affect development?

They may cause malformations or abnormal development during pregnancy.

What characterizes the fetal period?

Maturation and rapid growth of tissues and organs.

What significant changes occur from weeks nine to twelve in fetal development?

Primary ossification centers appear, and external reproductive organs begin differentiation.

What hormonal changes happen during the first trimester?

hCG levels rise, maintaining the uterine lining.

What is the main purpose of the first trimester?

To develop from zygote to embryo and then to early fetus.

Describe the effect of progesterone during pregnancy.

Promotes growth of the uterine lining and prevents contractions.

What happens to the mother's body during the second trimester?

Increased growth of the fetus and expansion of maternal tissues.

What cardiovascular changes occur during pregnancy?

Increased plasma volume and cardiac output.

What respiratory changes do expecting mothers experience?

Shortness of breath due to pressure on the diaphragm.

What is the role of relaxin during pregnancy?

Promotes blood vessel growth and prepares the uterus for labor.

What happens during the true labor phase?

Regular contractions signify the onset of childbirth.

What is the role of oxytocin during labor?

Stimulates uterine contractions and milk ejection during breastfeeding.

What are the stages of true labor?

Dilation stage, expulsion stage, and placental stage.

What occurs during the dilation stage of labor?

The cervix thins and dilates, with regular contractions.

What is lochia?

Vaginal discharge after childbirth consisting of blood, mucus, and uterine tissue.

What hormonal changes occur post-delivery?

Decreases in estrogen and progesterone, leading to regression of body changes.

What stimulates lactation?

Prolactin and oxytocin are crucial for milk production and release.

What are the two types of breast milk produced?

Colostrum and true milk.

What defines the term genetics?

The study of heredity and variation in organisms.

What is karyotype?

A graphical representation of an individual’s chromosomes.

What is the primary function of genes?

To provide instructions for protein production.

What is the chromosomal composition in human somatic cells?

23 pairs of chromosomes, including autosomes and sex chromosomes.

What organ undergoes significant changes after the expulsion of the placenta?

The uterus returns to its pre-pregnancy size through contractions.

What hormone is critical for the contraction of the uterus postpartum?

Oxytocin facilitates uterine contractions after delivery.

What protective function does amniotic fluid provide to the embryo?

It protects the embryo from mechanical shock and dehydration.

What is the role of the umbilical cord?

Facilitates nutrient and oxygen exchange between the mother and fetus.

What is the definition of capacitation in sperm?

Physiological conditioning that sperm undergo to fertilize an oocyte.

What process describes the division of the zygote into more cells without growth?

Cleavage.

What is the name for the fluid-filled cavity inside the blastocyst?

Blastocyst cavity.

What layers does the trophoblast form during implantation?

Cytotrophoblast and syncytiotrophoblast.

What triggers the release of human chorionic gonadotropin (hCG)?

Contact of the blastocyst with uterine nutrients.

What main feature characterizes the embryonic period?

Formation of all major organ systems.

What fetal development occurs during weeks twenty-one to thirty-eight?

Major weight gain and final maturation of organs.

What does the chorion form during pregnancy?

It becomes the outermost membrane forming the placenta.

What complication might arise from high levels of progesterone in pregnancy?

Heartburn and indigestion due to relaxed smooth muscle in the GI tract.

What is the impact of hyperemesis gravidarum?

Severe nausea and vomiting, leading to dehydration and weight loss.

What is the significance of the primitive node in embryonic development?

It guides the development of key body axes during gastrulation.

What effect does relaxin have during labor?

It causes relaxation of connective tissue, aiding the birth process.

What are Braxton-Hicks contractions?

Irregular, practice contractions that do not signify true labor.

How does the placenta function as an endocrine organ during pregnancy?

It produces hormones such as progesterone and estrogen to support pregnancy.

What is the function of the placenta after the first trimester?

It takes over hormone production from the corpus luteum.